Vibration of the tendon without vision has a major impact on  postural  orientation. [ 15 ]  Vibration of the tendon causes movement backwards and the illusion of a forward body tilt in standing subjects. [ 16 ]  This is because vibrations stimulate  muscle spindles  in the calf muscles. The muscle spindles alert the brain that the body is moving forward, so the  central nervous system  compensates by moving the body backwards.


Inflammation  of the Achilles tendon is called  Achilles tendinitis . Achilles  tendinosis  is the soreness or stiffness of the tendon, particularly worse when exercising, and generally due to overuse. [ 17 ]  The most common symptoms are sharp achy pain and swelling around the affected tendon. [ 18 ] [ 19 ] [ 20 ]  The pain is typically worse at the start of exercise and decreases thereafter. [ 21 ]  Stiffness of the ankle may also be present. [ 17 ]  Onset is generally gradual. [ 18 ]


It commonly occurs as a result of overuse such as  running . [ 17 ] [ 21 ]  Other risk factors include trauma, a lifestyle that includes little exercise,  high-heel shoes ,  rheumatoid arthritis , and medications of the  fluoroquinolone  or  steroid  class. [ 18 ]  Diagnosis is generally based on symptoms and  examination . [ 21 ]


While  stretching  and exercises to strengthen the back are often recommended for prevention, evidence to support these measures is poor. [ 22 ] [ 23 ] [ 24 ]  Treatment typically involves rest, ice,  non-steroidal antiinflammatory agents  (NSAIDs), and  physical therapy . [ 17 ] [ 18 ]  A  heel lift  or  orthotics  may also be helpful. [ 17 ] [ 21 ]  In those in whose symptoms last more than six months despite other treatments, surgery may be considered. [ 17 ]  Achilles tendinitis is relatively common. [ 17 ]


Achilles tendon degeneration (tendinosis) is typically investigated with either  MRI  or  ultrasound .  In both cases, the tendon is thickened, may demonstrate surrounding inflammation by virtue of the presence of paratenonitis, retrocalcaneal or retro-achilles  bursitis . Within the tendon, increased blood flow, tendon fibril disorganisation, and partial thickness tears may be identified. Achilles tendinosis frequently involves the mid portion of the tendon but may involve the insertion, which is then known as enthesopathy. Though  enthesopathy  may be seen in the context of advancing age, it is also associated with  arthritis  such as  gout  and the  seronegative spondyloarthritides .  Achilles tendinosis is a known risk factor for calf muscle tears. [ 25 ]


Achilles tendon rupture  is when the Achilles tendon breaks. [ 26 ]  Symptoms include the sudden onset of sharp pain in the  heel . [ 18 ]  A snapping sound may be heard as the tendon breaks and walking becomes difficult. [ 27 ]


Rupture typically occurs as a result of a sudden bending up of the foot when the calf muscle is engaged, direct  trauma , or long-standing tendonitis. [ 27 ] [ 26 ]  Other risk factors include the use of  fluoroquinolones , a significant change in exercise,  rheumatoid arthritis ,  gout , or  corticosteroid  use. [ 28 ] [ 26 ]  Diagnosis is typically based on symptoms and  examination  and supported by  medical imaging . [ 26 ]  Achilles tendon rupture occurs in about 1 per 10,000 people per year. [ 26 ]  Males are more commonly affected than females. [ 28 ]  People in their 30s to 50s are most commonly affected. [ 26 ]


Prevention may include stretching before activity. [ 27 ]  Treatment may be by surgery or  casting  with the toes somewhat  pointed down . [ 29 ] [ 26 ]  Relatively rapid return to weight bearing (within 4 weeks) appears acceptable. [ 29 ] [ 30 ]  The risk of re-rupture is about 25% with casting. [ 26 ]  If appropriate treatment does not occur within 4 weeks of the injury outcomes suffer. [ 31 ]


Tendon xanthomas  are cholesterol deposits that commonly develop in the Achilles tendon of people with lipid metabolism disorders such as  familial hypercholesterolemia . [ 32 ]


The Achilles tendon is often tested as part of a  neurological examination . In this examination, the tendon is hit with a  tendon hammer . This tests the S1 and S2  spinal nerves : a normal response is  plantar flexion  (downward movement) of the foot. [ 33 ]


Level or portion of tendon affected: [ 34 ]


The Achilles tendon is short or absent in  great apes , but long in arboreal  gibbons  and humans. [ 38 ]  It provides elastic energy storage in hopping, [ 39 ]  walking, and running. [ 38 ]  Computer models suggest this energy storage Achilles tendon increases top running speed by >80% and reduces running costs by more than three-quarters. [ 38 ]  It has been suggested that the "absence of a well-developed Achilles tendon in the nonhuman African apes would preclude them from effective running, both at high speeds and over extended distances." [ 38 ]


The  central tendon  of the  diaphragm  is a thin but strong  aponeurosis  situated slightly anterior to  the vault formed by the muscle , resulting in longer posterior muscle fibers.


It is inferior to the  fibrous pericardium , which fuses with the central tendon of the diaphragm via the pericardiacophrenic  ligament .


The  caval opening  (at the level of the  T8 vertebra ) passes through the central tendon. This transmits the  inferior vena cava [ 1 ]  and  right phrenic nerve .


The central tendon is shaped somewhat like a  trefoil   leaf , consisting of three divisions or  leaflets  separated from one another by slight indentations. The right leaflet is the largest, the middle (directed toward the  xiphoid process ) the next in size, and the left the smallest.


The central tendon is composed of several planes of  fibers , which intersect one another at various angles and unite into straight or curved bundles—an arrangement which gives it additional  strength .


During  inspiration , the diaphragm contracts, causing the central tendon to be drawn inferiorly which partially flattens the domes bilaterally. The result is an increase in the  thoracic  volume and a reduction in intra-thoracic  pressure . This reduction allows air to enter the lungs, enhancing venous return. During inspiration, the central tendon retains its shape due to its tendinous nature, and prevents constriction of the inferior vena cava.


Rarely, a central tendon defect may be involved in a central  congenital diaphragmatic hernia . [ 2 ]  This may be repaired with thoracoscopic surgery. [ 2 ]


This article incorporates text in the  public domain  from  page 406  of the 20th edition of   Gray's Anatomy   (1918)


The  common extensor tendon  is a  tendon  that attaches to the  lateral epicondyle  of the  humerus .


The common extensor tendon serves as the upper attachment (in part) for the superficial muscles that are located on the posterior aspect of the  forearm :


The tendon of extensor carpi radialis brevis is usually the most major tendon to which the other tendons merge. [ 2 ]


The common extensor tendon is the major attachment point for extensor muscles of the forearm. This enables finger extension and aids in forearm supination.


Lateral elbow pain can be caused by various  pathologies  of the common extensor tendon. [ 3 ]   Overuse injuries  can lead to  inflammation . [ 4 ] [ 5 ]   Tennis elbow  is a common issue with the common extensor tendon. [ 6 ] [ 4 ] [ 7 ]


The  common flexor tendon  is a  tendon  that attaches to the  medial epicondyle  of the  humerus  (lower part of the bone of the upper arm that is near the elbow joint).


It serves as the upper attachment point for the superficial muscles of the front of the  forearm :


Linburg–Comstock variation  is an occasional  tendinous  connection between the  flexor pollicis longus  and the  flexor digitorum profundus  of the  index , the  middle finger  or both. It is found in around 21% of the population. [ 1 ]  It is an  anatomical variation  in humans, which may be viewed as a  pathology  if it causes symptoms. It was recognised as early as the 1800s, but was first described by Linburg and Comstock in 1979. [ 2 ]


Although Linburg–Comstock variation remains  asymptomatic , a number of case reports suggested that symptoms could develop after a forceful  extension  of the  index finger  with the thumb in a  flexed  position. [ 3 ] [ 4 ]  Symptoms also develop from heavy and repetitive use of the wrist and  forearm  and can also develop in those who require fine and independent functionality of the fingers, such as musicians. [ 3 ] [ 4 ]


This abnormality is clinically evident when the patient is unable to flex the thumb without flexing the distal  interphalangeal joint  of the index or middle finger or vice versa.


Flexor tenosynovitis is a common finding in the patients with Linburg–Comstock syndrome. Another  hypothesis  is that anatomical variations, which in this case is an additional tendon slip, may act as  space-occupying lesions  and potentially contribute to  carpal tunnel syndrome . [ 5 ]


Linburg–Comstock variation and syndrome may result from  phylogenetic  differences between human and  non-human primates . Phylogenetically, the flexor pollicis longus and the flexor digitorum profundus both originate from a common  mesodermal  mass. [ 6 ]  In non-human primates, there is only one flexor muscle for all the fingers, whereas in humans, the flexor pollicis longus becomes distinct. [ 7 ]  Linburg–Comstock syndrome may be viewed as an  evolutionary  persistent structure. It is still inconclusive whether or not the connection is congenital or acquired at a later time point in life. [ 8 ]


Multiple types of the connection between the flexor pollicis longus and the flexor digitorum profundus were described: [ 9 ]


The examiner passively restricts the flexion of the fingers while the examinee attempts to actively flex the thumb. [ 10 ]  A positive test is marked by restricted active thumb flexion with pain or cramping discomfort in the palmar and radial sides of the distal (lower) forearm or wrist. [ 10 ]  The  magnetic resonance imaging  (MRI) can confirm and localise Linburg and Comstock syndrome. [ 10 ]  As reported by Karalezli, magnetic resonance imaging was performed on all patients diagnosed with positive test, and there were tendinous connection in all cases. [ 11 ]


Surgery may be performed by excising or splitting the tendinous connection to form two separate tendons, depending on the nature of the connection. [ 12 ]   Muscle  belly associated with the symptoms may also be removed. [ 6 ]


This variant occurred bilaterally (in both hands) in 14% and unilaterally in 31% (either in left or right hand) out of 194 patients as reported by the original study. [ 2 ]  Four cases were responsible for  chronic tenosynovitis . [ 2 ]  A recent meta analysis reported that the connection is present in 21% of the population. [ 1 ]


In  human anatomy , the  quadriceps tendon  works with the  quadriceps muscle  to extend the leg. All four parts of the quadriceps muscle attach to the  shin  via the  patella  (knee cap), where the quadriceps tendon becomes the  patellar ligament . It attaches the quadriceps to the top of the patella, which in turn is connected to the shin from its bottom by the patellar ligament. A tendon connects muscle to bone, while a ligament connects bone to bone. [ 1 ]


Injuries are common to this tendon, with tears, either partial or complete, being the most common.  If the quadriceps tendon is completely torn, surgery will be required to regain function of the knee. [ 2 ]   Without the quadriceps tendon, the knee cannot extend.  Often, when the tendon is completely torn, part of the kneecap bone will break off with the tendon as well. [ 2 ]   It can rupture resulting in  quadriceps tendon rupture . [ 3 ]


It has been studied in the analysis of  patellofemoral pain syndrome . [ 4 ]


A  retinaculum  ( pl. :  retinacula ) is a band of thickened  deep fascia  around  tendons  that holds them in place. [ 1 ]  It is not part of any  muscle .  Its function is mostly to stabilize a tendon. The term retinaculum is  Neo-Latin , [ 2 ]  derived from the  Latin  verb  retinere  (to retain). Specific retinacula include:


Paratenonitis  occurs where a tendon rubs over a bony surface. It is presented with acute  edema  and  hyperaemia  of the paratenon with infiltration of inflammatory cells. After few hours or few days,  tendon sheath  is filled by fibrinous exudate and leads to  crepitus . In chronic paratenonitis fibroblasts appear along with perivascular lymphocytic infiltrate. Peritendinous tissues become macroscopically thickened and new connective tissue adhesions occur. In paratenonitis, inflammatory cells are found in the cellular elements of the paratenon and in the vascular ingrowth. [ 1 ]


A  fascia  ( / ˈ f æ ʃ ( i ) ə / ;  pl. :  fasciae   / ˈ f æ ʃ i i /  or  fascias ; [ 1 ]  adjective  fascial ; from  Latin    band ) is a generic term for  macroscopic   membranous  bodily structures. [ 2 ] : 42   Fasciae are classified as  superficial ,  visceral  or  deep , and further designated according to their anatomical location. [ 3 ]


The knowledge of fascial structures is essential in  surgery , as they create borders for infectious processes (for example  Psoas abscess ) and haematoma. An increase in pressure may result in a  compartment syndrome , where a prompt  fasciotomy  may be necessary. For this reason, profound descriptions of fascial structures are available in anatomical literature from the 19th century.


Fasciae were traditionally thought of as passive structures that transmit mechanical tension generated by muscular activities or external forces throughout the body. An important function of muscle fasciae is to reduce friction of muscular force. In doing so, fasciae provide a supportive and movable wrapping for nerves and blood vessels as they pass through and between muscles. [ 4 ]


In the tradition of medical dissections it has been common practice to carefully clean muscles and other organs from their surrounding fasciae in order to study their detailed topography and function. However, this practice tends to ignore that many muscle fibers insert into their fascial envelopes and that the function of many organs is significantly altered  when their related fasciae are removed. [ 5 ]  This insight contributed to several modern biomechanical concepts of the human body, in which fascial tissues take over important stabilizing and connecting functions, by distributing tensional forces across several joints in a network-like manner similar to the architectural concept of tensegrity. [ 6 ]
Starting in 2018 this concept of the fascial tissue serving as a body-wide tensional support system has been successfully expressed as an educational model with the  Fascial Net Plastination Project .


Fascial tissues – particularly those with tendinous or aponeurotic properties – are also able to store and release elastic potential energy.


A  fascial compartment  is a section within the body that contains  muscles  and  nerves  and is surrounded by fascia. In the  human body , the  limbs  can each be divided into two segments: The  upper limb  can be divided into the  arm  and the  forearm  and the sectional compartments of both of these – the  fascial compartments of the arm  and the  fascial compartments of the forearm  contain an anterior and a posterior compartment. The lower limbs can be divided into two segments – the  leg  and the  thigh  – and these contain the  fascial compartments of the leg  and the  fascial compartments of the thigh .


Fascia itself becomes clinically important when it loses stiffness, becomes too stiff, or has decreased shearing ability. [ 7 ]  When inflammatory  fasciitis  or trauma causes  fibrosis  and adhesions, fascial tissue fails to differentiate the adjacent structures effectively. This can happen after surgery, where the fascia has been incised and healing includes a  scar  that traverses the surrounding structures.


The  Fascial Net Plastination Project  (FNPP) is an anatomical research initiative spearheaded by fascia researcher  Robert Schleip . The project aims to enhance the study of fascia through the technique of  plastination . Led by an international team of fascia experts and anatomists, the FNPP resulted in the creation of a full-body fascia plastinate known as  FR:EIA  (Fascia Revealed: Educating Interconnected Anatomy). [ 8 ]  This plastinate provides a detailed view of the human fascial network, allowing for a better understanding of its structure and function as an interconnected tissue throughout the body.


FR:EIA was unveiled at the 2021  Fascia Research Congress  and is currently exhibited at the  Body Worlds  exhibition in Berlin. This project represents a significant contribution to the visualization of fascia and has the potential to influence future research in fields such as medicine, physical therapy, and movement science. [ 8 ] [ 9 ]


There exists some controversy about what structures are considered "fascia" and how they should be classified. [ 10 ] [ 11 ]


The current version of the International Federation of Associations of Anatomists divides into: [ 10 ]


Two former, rather commonly used systems are:


Superficial fascia is the lowermost layer of the  skin  in nearly all of the regions of the  body , that blends with the  reticular dermis  layer. [ 13 ]  It is present on the  face , over the upper portion of the  sternocleidomastoid , at the  nape  of the  neck  and overlying the  breastbone . [ 14 ]  It consists mainly of loose  areolar  and fatty  adipose   connective tissue  and is the layer that primarily determines the shape of a body. [ medical citation needed ]  In addition to its  subcutaneous  presence, superficial fascia surrounds  organs ,  glands  and  neurovascular bundles , and fills otherwise empty space at many other locations. It serves as a storage medium of  fat  and  water ; as a passageway for  lymph ,  nerve  and  blood vessels ; and as a protective padding to cushion and insulate. [ 15 ]


Superficial fascia is present, but does not contain fat, in the  eyelid ,  ear ,  scrotum ,  penis  and  clitoris . [ 16 ]


Due to its  viscoelastic  properties, superficial fascia can stretch to accommodate the deposition of adipose that accompanies both ordinary and  prenatal  weight gain. After  pregnancy  and weight loss, the superficial fascia slowly reverts to its original level of tension.


Visceral fascia (also called  subserous fascia ) suspends the organs within their cavities and wraps them in layers of connective tissue  membranes .  Each of the organs is covered in a double layer of fascia; these layers are separated by a thin  serous membrane .


Visceral fascia is less extensible than superficial fascia.  Due to its suspensory role for the organs, it needs to maintain its tone rather consistently. If it is too lax, it contributes to organ  prolapse , yet if it is  hypertonic , it restricts proper organ  motility . [ 18 ]


Deep fascia is a layer of  dense fibrous connective tissue  which surrounds individual  muscles  and divides groups of muscles into  fascial compartments .
This fascia has a high density of  elastin  fibre that determines its  extensibility  or resilience. [ 19 ]  Deep fascia was originally considered to be essentially avascular but later investigations have confirmed a rich presence of thin blood vessels. [ 20 ]  Deep fascia is also richly supplied with  sensory receptors . [ 21 ]  Examples of deep fascia are  fascia lata ,  fascia cruris ,  brachial fascia ,  plantar fascia ,  thoracolumbar fascia  and  Buck's fascia .


Abdominal fascia  refers to the various types of  fascia  found in the  abdominal  region. Fascia is a sheet of  connective tissue  that is found beneath the skin that attaches, stabilizes, encloses, and separates muscles and other internal organs. Everyone has fascia, as it is part of how the human body is composed. Fascia is organized by layer, and can also be classified by location or function in the body. While abdominal fascia is quite a simple part of how the human body is made up, there are other implications and involvements that abdominal fascia is a part of.


In a 2016 study, abdominal superficial fascia was collected from both male and female  cadavers . [ 1 ]  The elastic, collagen, and hydroxyproline components were sampled and then studied. It was found that the elastic, collagen, and hydroxyproline components were higher in upper abdomen regions compared to lower abdomen regions. [ 1 ]  This could be a reason as to why bulging of the abdomen and skin sagging occurs more in the lower regions of people, compared to the upper regions. This study that was conducted could lead to further discussions and studies in finding ways to manage obesity.


In a study from January 2011, Mechanical properties of abdominal human fascia were studied according to the direction of loading and localization. [ 2 ]  Human umbilical (UF) and  transversalis fascia (FT) have been studied to understand the differences in mechanical properties of the human body. [ 2 ]  The differences between the mechanical properties of both UF and FT were not significant according to localization; therefore, the mechanical properties of human abdominal fascia are not controlled by the localization. [ 2 ]


Another study from 2018, showed differences in mechanical and structural properties of human fascia and their gender differences. [ 3 ]  While the study was done on fascia from the thighs, the results which were comparing the differences between males and females, can also be applied to understanding the abdominal area of males and females. [ 3 ]  Ultimately, it was found that the fascia lata at the lateral site was thicker and longitudinally directed fibers had higher rates of distribution compared to other sites.  [ 3 ]


It can be involved in certain forms of  breast reconstruction . [ 4 ]


The  pectoral fascia  is very thin over the upper part of the  pectoralis major , but thicker in the interval between it and the  latissimus dorsi , where it closes in the axillary space and forms the  axillary fascia . Axillary fascia, together with the skin, forms the base of the axilla.


This article incorporates text in the  public domain  from  page 436  of the 20th edition of   Gray's Anatomy   (1918)


The  axillary sheath  is a fibrous sheath that encloses the  axillary artery  and the three cords of the  brachial plexus  to form the  neurovascular bundle . [ 1 ] [ 2 ] [ 3 ]  It is surrounded by the  axillary fat . [ 1 ] [ 2 ]  It is an extension of the prevertebral fascia of the  deep cervical fascia [ citation needed ]  and is continuous with the  carotid sheath  at the  venous angle . [ 4 ]


A  brachial plexus nerve block  can be achieved by injecting anaesthetic into this area. [ 5 ] [ 6 ]


This article incorporates text in the  public domain  from  page 586  of the 20th edition of   Gray's Anatomy   (1918)


Buck's fascia  ( deep fascia of the penis , [ 1 ] [ 2 ]   Gallaudet's fascia [ 3 ]  or  fascia of the penis ) is a layer of  deep fascia  covering the three erectile bodies of the  penis . [ 4 ]


Buck's fascia is continuous with the  external spermatic fascia  in the  scrotum  and the  suspensory ligament of the penis .


On its ventral aspect, it splits to envelop corpus spongiosum in a separate compartment from the tunica albuginea and corporal bodies. [ 5 ]


Sources differ on its proximal extent. Some state that it is a  continuation  of the  deep perineal fascia , [ 6 ]  whereas others state that it fuses with the  tunica albuginea . [ 5 ]


The  deep dorsal vein of the penis , the cavernosal veins of the penis, and the para-arterial veins of the penis are inside Buck's fascia, but the  superficial dorsal veins of the penis  are in the superficial ( dartos ) fascia immediately under the skin.


The name Buck's fascia is named after  Gurdon Buck , an American  plastic surgeon .


The  cervical fascia  is fascia found in the region of the neck.


It usually refers to the  deep cervical fascia . However, there is also a  superficial cervical fascia . [ 1 ]


The  clavipectoral fascia  (costocoracoid membrane; coracoclavicular fascia) is a strong  fascia  situated under cover of the  clavicular  portion of the  pectoralis major .


It occupies the interval between the  pectoralis minor  and  subclavius , and protects the  axillary vein  and  artery , and  axillary nerve . [ 1 ]


Traced upward, it splits to enclose the subclavius, and its two layers are attached to the  clavicle , one in front of and the other behind the muscle; the deep layer fuses with the deep cervical fascia and with the sheath of the axillary vessels.


Medially, it blends with the fascia covering the first two  intercostal spaces , and is attached also to the first rib medial to the origin of the subclavius.


Laterally, it is very thick and dense, and is attached to the  coracoid process .


The portion extending from the first rib to the coracoid process is often whiter and denser than the rest, and is sometimes called the costocoracoid membrane.


Below this. it is thin, and at the upper border of the  pectoralis minor , it splits into two layers to invest the muscle; from the lower border of the pectoralis minor, it is continued downward to join the axillary fascia, and lateralward to join the fascia over the short head of the  biceps brachii .


The clavipectoral fascia is pierced by the  cephalic vein ,  thoracoacromial artery  and vein, lymphatics and  lateral pectoral nerve .


This article incorporates text in the  public domain  from  page 437  of the 20th edition of   Gray's Anatomy   (1918)


The  cribriform fascia  (also known as the  fascia cribrosa , or  Hesselbach's fascia ) is the portion of the superficial layer of the  deep fascia of leg  which extends between the  sartorius muscle ,  adductor longus muscle , and  inguinal ligament  to form the anterior portion of the  femoral canal . [ 1 ]


The cribriform fascia forms numerous openings to allow the passage of vessels and nerves, the most prominent of these being the  saphenous opening (saphenous hiatus)  (which gives passage to the  great saphenous vein ). [ 1 ]


An inferior aponeurotic thickening of the cribriform fascia - the  falciform margin of sphenous opening  - forms the inferior margin of the sapnenous opening, embracing the arch of the great saphenous vein. [ 2 ]


The cribriform fascia has been proposed for use in preventing  new vascularization  when surgery is performed at the join between the  great saphenous vein  and the  femoral vein . [ 3 ]


When the eponym is used, it is named for  Franz Kaspar Hesselbach . [ 4 ] [ 5 ]


This article incorporates text in the  public domain  from  page 468  of the 20th edition of   Gray's Anatomy   (1918)


The  dartos fascia ,  dartos tunic  or simply  dartos  is a layer of  connective tissue  found in the  penile shaft ,  foreskin  and  scrotum . [ 1 ]  The penile portion is referred to as the  superficial fascia of penis  or the  subcutaneous tissue of penis , [ 2 ]  while the scrotal part is the dartos proper. In addition to being continuous with itself between the scrotum and the penis, it is also continuous with  Colles' fascia  of the perineum and  Scarpa's fascia  of the abdomen. [ 1 ]


The dartos lies just below the skin, which places it just superficial to the external spermatic fascia in the scrotum and to  Buck's fascia  in the penile shaft. In the scrotum, it consists mostly of  smooth muscle . [ 3 ]  The tone of this smooth muscle is responsible for the wrinkled (rugose) appearance of the scrotum. [ 1 ]  In females, the same muscle fibers are less well developed and termed  dartos muliebris , lying beneath the skin of the  labia majora . The dartos fascia receives innervation from  postganglionic sympathetic nerve fibers  arriving via the  ilioinguinal nerve  and the  posterior scrotal nerve .


In the penis, the loose attachment of the dartos fascia to Buck's fascia is responsible for the high degree of mobility of the penile skin over the underlying tissue. [ 1 ]  It is also responsible for carrying the blood supply of the penile skin, a longitudinally-coursing anastomotic network of vessels that arise from the external pudendal vessels. [ 1 ]


In the scrotum, the dartos fascia acts to regulate the  temperature  of the  testicles , which promotes  spermatogenesis . It does this by expanding or contracting to wrinkle the scrotal skin.


The dartos muscle works in conjunction with the  cremaster muscle  to elevate the  testis  but should not be confused with the  cremasteric reflex .


The dartos fascia keeps the foreskin close to the glans penis throughout life. In infancy, the dartos fascia operates as a one-way check valve at the tip of the foreskin, allowing urine to pass out, but prohibiting the entry of foreign matter and pathogens.


There is an increase in elastic fibers with increasing maturity that allows the foreskin to become retractable by adulthood and glide freely back and forth.


Etymology:


Some dartos-related terms:


Deep fascia  (or  investing fascia ) is a  fascia , a layer of  dense connective tissue  that can surround individual  muscles  and groups of muscles to separate into  fascial compartments .


This fibrous connective tissue interpenetrates and surrounds the muscles, bones, nerves, and blood vessels of the body. It provides connection and communication in the form of  aponeuroses ,  ligaments ,  tendons ,  retinacula ,  joint capsules , and  septa . The deep fasciae envelop all bone ( periosteum  and  endosteum );  cartilage  ( perichondrium ), and blood vessels ( tunica externa ) and become specialized in muscles ( epimysium ,  perimysium , and  endomysium ) and nerves ( epineurium ,  perineurium , and  endoneurium ). The high density of  collagen  fibers gives the deep fascia its strength and integrity.  The amount of  elastin  fiber determines how much  extensibility  and resilience it will have. [ 1 ]


Examples include:


Deep fascia is less extensible than  superficial fascia .  It is essentially  avascular , [ 2 ]  but is richly  innervated  with  sensory receptors  that report the presence of pain ( nociceptors ); change in movement ( proprioceptors ); change in pressure and vibration ( mechanoreceptors ); change in the chemical milieu ( chemoreceptors ); and fluctuation in temperature ( thermoreceptors ). [ 3 ] [ 4 ]  Deep fascia is able to respond to sensory input by contracting; by relaxing; or by adding, reducing, or changing its composition through the process of fascial remodeling. [ 5 ]


Fascia may be able to contract due to the activity of  myofibroblasts  which may play a role in wound healing. [ 6 ]


The deep fascia can also relax. By monitoring changes in muscular tension, joint position, rate of movement, pressure, and vibration, mechanoreceptors in the deep fascia are capable of initiating relaxation.  Deep fascia can relax rapidly in response to sudden muscular overload or rapid movements.  Golgi tendon organs  operate as a feedback mechanism by causing myofascial relaxation before muscle force becomes so great that tendons might be torn.   Pacinian corpuscles  sense changes in pressure and vibration to monitor the rate of  acceleration  of movement. They will initiate a sudden relaxatory response if movement happens too fast. [ 7 ]   Deep fascia can also relax slowly as some mechanoreceptors respond to changes over longer timescales.  Unlike the Golgi tendon organs, Golgi receptors report joint position independent of muscle contraction. This helps the body to know where the bones are at any given moment.   Ruffini endings  respond to regular stretching and to slow sustained pressure.  In addition to initiating fascial relaxation, they contribute to full-body relaxation by inhibiting sympathetic activity which slows down heart rate and respiration. [ 3 ] [ 8 ]


When contraction persists, fascia will respond with the addition of new material. Fibroblasts secrete collagen and other proteins into the  extracellular matrix  where they bind to existing proteins, making the composition thicker and less extensible. Although this potentiates the  tensile strength  of the fascia, it can unfortunately restrict the very structures it aims to protect.  The pathologies resulting from fascial restrictions range from a mild decrease in joint  range of motion  to severe fascial binding of muscles, nerves and blood vessels, as in  compartment syndrome  of the leg.  However, if fascial contraction can be interrupted long enough, a reverse form of fascial remodeling occurs. The fascia will normalize its composition and tone and the extra material that was generated by prolonged contraction will be ingested by macrophages within the extracellular matrix. [ 9 ]


Like mechanoreceptors, chemoreceptors in deep fascia also have the ability to promote fascial relaxation.  We tend to think of relaxation as a good thing, however fascia needs to maintain some degree of tension.  This is especially true of ligaments.  To maintain joint integrity, they need to provide adequate tension between bony surfaces.  If a ligament is too lax, injury becomes more likely.  Certain chemicals, including  hormones , can influence the composition of the ligaments.  An example of this is seen in the  menstrual cycle , where hormones are secreted to create changes in the  uterine  and  pelvic floor  fascia.  The hormones are not site-specific, however, and chemoreceptors in other ligaments of the body can be receptive to them as well.  The ligaments of the knee may be one of the areas where this happens, as a significant association between the  ovulatory  phase of the menstrual cycle and an increased likelihood for an  anterior cruciate ligament  injury has been demonstrated. [ 10 ] [ 11 ]


The continuity of the deep fasciae within the human body inspired the artistic expression seen in the  Fascial Net Plastination Project , which is prominently displayed at the  Body Worlds  exhibition in Berlin. [ 12 ]


The  deep fascia of leg  or  crural fascia  forms a complete investment to the  muscles , and is fused with the  periosteum  over the subcutaneous surfaces of the  bones .


The  deep fascia  of the leg is continuous above with the  fascia lata  (deep fascia of the thigh), and is attached around the knee to the  patella , the  patellar ligament , the tuberosity and condyles of the  tibia , and the head of the fibula.


Behind, it forms the popliteal fascia, covering in the  popliteal fossa ; here it is strengthened by transverse fibers, and perforated by the  small saphenous vein .


It receives an expansion from the tendon of the  biceps femoris  laterally, and from the tendons of the  sartorius ,  gracilis ,  semitendinosus , and  semimembranosus  medially; in front, it blends with the periosteum covering the subcutaneous surface of the tibia, and with that covering the head and malleolus of the fibula; below, it is continuous with the transverse crural and laciniate ligaments.


It is thick and dense in the upper and anterior part of the leg, and gives attachment, by its deep surface, to the  tibialis anterior  and  extensor digitorum longus ; but thinner behind, where it covers the  gastrocnemius  and  soleus .


It gives off from its deep surface, on the lateral side of the leg, two strong intermuscular septa, the anterior and posterior peroneal septa, which enclose the  fibularis (peroneus) longus  and  brevis  muscles and separate them from the muscles of the anterior and posterior crural regions, and several more slender processes which enclose the individual muscles in each region.


A broad transverse intermuscular septum, called the deep transverse fascia of the leg, intervenes between the superficial and deep posterior crural muscles.


This article incorporates text in the  public domain  from  page 480  of the 20th edition of   Gray's Anatomy   (1918)


The  deep transverse fascia  or  transverse intermuscular septum of leg [ 1 ]  is a transversely placed, intermuscular septum, from the  deep fascia ,  between the superficial and deep muscles of the back of the leg.


At the sides it is connected to the margins of the  tibia  and  fibula .


Above, where it covers the  popliteus , it is thick and dense, and receives an expansion from the tendon of the  semimembranosus . It is thinner in the middle of the leg; but below, where it covers the tendons passing behind the  malleoli , it is thickened and continuous with the  laciniate ligament .


This article incorporates text in the  public domain  from  page 483  of the 20th edition of   Gray's Anatomy   (1918)


The  endothoracic fascia  is the layer of loose  connective tissue  deep to the  intercostal spaces  and  ribs , separating these structures from the underlying  pleura . This fascial layer is the outermost membrane of the  thoracic cavity .  The endothoracic fascia contains variable amounts of  fat .
It becomes more fibrous over the  apices  of the  lungs  as the  suprapleural membrane . It separates the  internal thoracic artery  from the parietal pleura.


The  external spermatic fascia  ( intercrural  or  intercolumnar fascia ) is a thin membrane, prolonged downward around the surface of the  spermatic cord  and  testis . It is separated from the  dartos tunic  by  loose areolar tissue . It is occasionally referred to as 'Le Fascia de Webster' after an anatomist who once described it.


The external spermatic fascia is derived from the  aponeurosis  of the  abdominal external oblique muscle . [ 1 ] [ 2 ]  It is acquired by the  spermatic cord  at the  superficial inguinal ring . [ 1 ]


This article incorporates text in the  public domain  from  page 1238  of the 20th edition of   Gray's Anatomy   (1918)


The  fascia lata  is the  deep fascia  of the  thigh . It encloses the thigh muscles and forms the outer limit of the  fascial compartments of thigh , which are internally separated by the  medial intermuscular septum  and the  lateral intermuscular septum . The fascia lata is thickened at its  lateral  side where it forms the  iliotibial tract , a structure that runs to the  tibia  and serves as a site of muscle attachment. [ 1 ]


The fascia lata is an investment for the whole of the thigh, but varies in thickness in different parts. It is thicker in the upper and lateral part of the thigh, where it receives a fibrous expansion from the  gluteus maximus , and where the  tensor fasciae latae  is inserted between its layers; it is very thin behind and at the upper and medial part, where it covers the  adductor muscles , and again becomes stronger around the knee, receiving fibrous expansions from the tendon of the  biceps femoris  laterally, from the  sartorius  medially, and from the  quadriceps femoris  in front.


The fascia lata surrounds the tensor fasciae latae muscle. It is a fibrous sheath that encircles the thigh subcutaneously. This encircling of the muscle allows the muscles to be bound together tightly. [ citation needed ]


The fascia lata is attached, above and behind (i.e. proximal and posterior), to the back of the  sacrum  and  coccyx ; laterally, to the  iliac crest ; in front, to the  inguinal ligament , and to the  superior ramus  of the  pubis ; and medially, to the  inferior ramus  of the pubis, to the inferior ramus and tuberosity of the  ischium , and to the lower border of the  sacrotuberous ligament .


From its attachment to the iliac crest it passes down over the  gluteus medius  to the upper border of the  gluteus maximus , where it splits into two layers, one passing superficial to and the other beneath this muscle; at the lower border of the muscle the two layers reunite.


Laterally, the fascia lata receives the greater part of the tendon of insertion of the gluteus maximus, and becomes proportionately thickened.


The portion of the fascia lata attached to the front part of the iliac crest, and corresponding to the origin of the tensor fasciae latae, extends down the lateral side of the thigh as two layers, one superficial to and the other beneath this muscle; at the lower end of the muscle these two layers unite and form a strong band, having first received the insertion of the muscle.


This band is continued downward under the name of the  iliotibial band  and is attached to the lateral condyle of the  tibia .


The part of the iliotibial band which lies beneath the  tensor fasciae latae  is prolonged upward to join the lateral part of the capsule of the  hip joint .


Below, the fascia lata is attached to all the prominent points around the  knee joint , viz., the  condyles  of the femur and tibia, and the  head of the fibula .


On either side of the  kneecap  it is strengthened by transverse fibers from the lower parts of the vasti muscles (three of the four  quadriceps ) which are attached to and support this bone.


Of these the lateral are the stronger, and are continuous with the iliotibial band.


The deep surface of the fascia lata gives off two strong intermuscular septa, which are attached to the whole length of the  linea aspera  and its prolongations above and below; the  lateral intermuscular septum , the stronger of the two, extends from the insertion of the  gluteus maximus  to the  lateral condyle , separates the  vastus lateralis  in front from the short head of the  biceps femoris  behind, and gives partial origin to these muscles; the  medial intermuscular septum  is the thinner one and separates the  vastus medialis  from the  adductor muscles .


Besides these there are numerous smaller septa, separating the individual muscles, and enclosing each in a distinct sheath.


The  deep fascia of the lower leg  is a continuation of the fascia lata. [ 2 ]


Since the 1920s fasciae latae from deceased donors have been used in reconstructive surgery. In 1999 preserved mashed fasciae latae became FDA-approved as  a tissue product designed to replace areas of lost fascia or collagen. [ 3 ]
The fascia lata normally performs the function of encircling and tightening the muscles in the thigh. Because of this function, it has been used as grafts for patients with facial paralysis. The fascia lata offers supports to the muscles that make up the face and this support increases the recovery of the facial muscles. The surgeons use the fascia lata as a sort of facial sling to support up the paralyzed face and loops the fascia lata around the center of the lower lip, the corner of the mouth and the center of the upper lip.
 [ 4 ]
A small portion of fascia lata harvested through a sub centimeter skin incision on the lower lateral side of the thigh is used for reconstructing the ear drum in tympanoplasty surgery.
A larger portion is used in nasal endoscopic skull base surgery.


It is named from its great extent. "Latus" give the superlative "Latissimus" meaning broadest or widest. [ 5 ]


The  fascia of Camper  is a thick superficial  layer of the anterior abdominal wall . [ 1 ] [ 2 ]


It is  areolar  in texture, and contains in its meshes a varying quantity of  adipose tissue . It is found  superficial  to the  fascia of Scarpa .


Superficial fascia is composed of two layers: the fatty outer layer, known as Camper's fascia, and the more membranous inner layer, called Scarpa's fascia. These parts of the superficial fascia are most prominent in the lower aspect of the abdominal wall below the level of the umbilicus. Camper's fascia is continuous inferiorly with the superficial fascia of the thigh. Medial and inferior to the pubic tubercle, in the male, Scarpa's fascia changes as it continues over the scrotum and forms  dartos tunic . This layer is highly infiltrated by elastic and smooth muscle fibers and contains a minimal amount of fat. Scarpa's fascia ends inferior to the inguinal ligament fusing with the fascia lata of the thigh. In the midline, just superior to the penis, Scarpa's fascia contributes to formation of the  fundiform ligament  of the penis. As Scarpa's fascia continues posteriorly onto the perineum, it is called  Colles' fascia . [ 3 ]


The structure was named after Dutch physician and anatomist Petrus Camper. [ 4 ]


This article incorporates text in the  public domain  from  page 408  of the 20th edition of   Gray's Anatomy   (1918)


The  fascia of perineum  ( deep perineal fascia ,  superficial investing fascia of perineum  or  Gallaudet fascia ) is the  fascia  which covers the muscles of the  superficial perineal pouch .  The muscles surrounded by the deep perineal fascia are the  bulbospongiosus ,  ischiocavernosus , and  superficial transverse perineal .
The fascia is attached laterally to the  ischiopubic rami  and fused anteriorly with the  suspensory ligament of the penis  or  clitoris .  It is continuous anteriorly with the  deep investing fascia  of the abdominal wall muscles, and in males, it is continuous with  Buck's fascia .


The  fascia of Scarpa  is the deep  membranous layer   (stratum membranosum)  of the  superficial fascia  of the abdomen. It is a  layer of the anterior abdominal wall . It is found  deep  to the  fascia of Camper  and  superficial  to the  external oblique muscle .


It is thinner and more membranous in character than the superficial  fascia of Camper , and contains a considerable quantity of orange elastic fibers.


It is loosely connected by areolar tissue to the aponeurosis of the  external oblique muscle , but in the midline it is more intimately adherent to the  linea alba  and the  pubic symphysis , and in the male, it is prolonged on to the dorsum of the  penis , forming the  fundiform ligament ; above, it is continuous with the  superficial fascia  over the rest of the  trunk ; inferiorly, it is continuous with the  fascia of Colles  of the  perineum ; however, it does not extend into the thigh as it just attaches to its fascia, which is known as  fascia lata ; medially and below, it is continued over the penis and  spermatic cord  to the  scrotum , where it helps to form the  dartos .


From the scrotum, it may be traced backward into continuity with the deep layer of the superficial  fascia of the perineum  (superficial perineal fascia or fascia of Colles).


In the female, it is continued into the  labia majora  and from there to the fascia of Colles. The Scarpa's fascia also thickens into a collagenous structure called the fundiform ligament of the  clitoris . [ 1 ]


It is named for Italian anatomist  Antonio Scarpa . [ 2 ]  His description of the membranous superficial fascia is vague in his 1809 hernia monograph. [ 3 ]  Life-size illustrations included by Scarpa do not identify the layer even though some show all the other anatomical layers of the abdominal wall in the inguinal region. A probable description of the fascia is in the text which discusses femoral (called crural) hernia in the male. Scarpa describes that "below the skin" we find "a layer of condensed substance forming the second covering of the hernia" which adheres to "the aponeurosis of the fascia lata". A little later he describes this layer as being membranous and he believes it has a role in containing this particular herniation. In 1810,  Abraham Colles  described detailed methods of dissection to expose membranous superficial fascia in the lower abdomen and the inguino-perineal region including the penis and scrotum.  Colles clearly associated the subcutaneous limitation of urine extravasation from a ruptured urethra with the attachments of the membranous superficial fascia to deeper structures. [ 4 ]


Scarpa's belief that the fascia stops hernias from forming is not thought to be true today. Some anatomists suggest the membranous superficial fascia is the scaffold which attaches the skin to the deeper structures so that the skin does not sag with gravity but still stretches as the body flexes or changes shape with exercise. [ 4 ]  The attachment of the fascia to deeper layers confines fluid which may have come from inside the body in certain diseases giving rise to  clinical signs  such as urethral disruption noticed by  Colles  and bruising in  Cullen's sign  or  Grey Turner's sign . [ 4 ]


Fascia training  describes sports activities and movement exercises that attempt to improve the functional properties of the muscular  connective tissues  in the human body, such as  tendons ,  ligaments ,  joint capsules  and muscular envelopes. Also called  fascia , these tissues take part in a body-wide tensional force transmission network and are responsive to training stimulation. [ 1 ]  As of 2018 the body-wide continuity of this tensional system has been expressed in an educational manner within the  Fascial Net Plastination Project . The FNPP brought together experts in  anatomy ,  dissection , and  plastination , and it was the first project of its kind to plastinate a complete human fascia specimen. [ 2 ]


Whenever  muscles  and joints are moved this also exerts mechanical strain on related  fascia . The general assumption in sports science had therefore been that muscle strength exercises as well as cardiovascular training would be sufficient for an optimal training of the associate  fibrous connective tissues . However, recent [ when? ]   ultrasound -based research revealed that the mechanical threshold for a training effect on tendinous  tissues  tends to be significantly higher than for muscle fibers. This insight happened roughly during the same time in which the field of fascia research attracted major attention by showing that fascial tissues are much more than passive transmitters of muscular tension (years 2007 – 2010). Both influences together triggered an increasing attention in sports science towards the question whether and how fascial tissues can be specifically stimulated with active exercises. Researchers who contributed to the initial scientific investigation of this direction include  Robert Schleip ,  Jan Wilke ,  Michael Kjaer  and  Adamantios Arampatzis . [ 3 ] [ 4 ] [ 5 ]


Fascia training follows the following principles: [ 4 ]


While good to moderate scientific evidence exists for several of the included training principles – e.g. the inclusion of  elastic recoil  as well as a training of proprioceptive refinement – there is currently insufficient evidence for the claimed beneficial effects of a fascia oriented exercises program as such, consisting of a combination of the above described four training elements. [ 6 ]


Self- myofascial release  using a foam roller or roller massager pre- and post-exercise has been observed to decrease soreness due to  DOMS . Self-myofascial release appears to have no negative effect on performance.  [ 7 ]


A  fascial compartment [ 1 ]  is a section within the body that contains  muscles  and  nerves  and is surrounded by  deep fascia . In the  human body , the  limbs  can each be divided into two segments – the  upper limb  can be divided into the  arm  and the  forearm  and the sectional compartments of both of these – the  fascial compartments of the arm  and the  fascial compartments of the forearm  contain an anterior and a posterior compartment. Likewise, the lower limbs can be divided into two segments – the  leg  and the  thigh  – and these contain the  fascial compartments of the leg  and the  fascial compartments of the thigh . [ 2 ]


If these segments are cut transversely, it is apparent that they are divided into multiple sections. These are called fascial compartments, and are formed by tough connective tissue  septa .


These compartments usually have a  nerve  and  blood  supply separate from their neighbours. The muscles in each compartment will often all be supplied by the same nerve.


Sometimes the segment is also covered by bone profoundly (as e.g. the  brachial fascia ). It is distinguished from  pharmacokinetic compartment , which is a defined volume of  body fluids .


Compartment syndrome is an acute medical problem following injury or surgery in which increased pressure (usually caused by inflammation) occurs within a compartment.


The  iliac fascia  (or  Abernethy's fascia [ citation needed ] ) is the  fascia  overlying the  iliacus muscle . [ 1 ]


Superiorly and laterally, the iliac fascia is attached to the inner aspect of the  iliac crest ; inferiorly and laterally, it extends into the thigh to unite with the  femoral sheath ; medially, it attaches to the periosteum of the ilium and  iliopubic eminence  near the  linea terminalis , and blends with the  psoas fascia  and - over the  quadratus lumborum muscle  - with the anterior layer of  thoracolumbar fascia . [ 1 ]


The iliac fascia overlies the femoral nerve, and  lateral femoral cutaneous nerve . [ 1 ]


It has the following connections:


At the  iliopectineal eminence  it receives the tendon of insertion of the  psoas minor , when that muscle exists.


Lateral to the  femoral vessels  it is intimately connected to the posterior margin of the  inguinal ligament , and is continuous with the  transversalis fascia .


Immediately lateral to the femoral vessels the iliac fascia is prolonged backward and medialward from the inguinal ligament as a band, the  iliopectineal fascia , which is attached to the iliopectineal eminence.


This fascia divides the space between the inguinal ligament and the hip bone into two lacunæ or compartments:


Medial to the vessels the iliac fascia is attached to the  pectineal line  behind the  conjoint tendon , where it is again continuous with the transversalis fascia.


This article incorporates text in the  public domain  from  page 466  of the 20th edition of   Gray's Anatomy   (1918)


The  iliopectineal arch  is a thickened band of fused  iliac fascia  and  psoas fascia [ 1 ]  passing from the posterior aspect of the  inguinal ligament  anteriorly across the front of the  femoral nerve  to attach to the  iliopubic eminence  of the hip bone posteriorly. The iliopectineal arch thus forms a septum which subdivides the space deep to the inguinal ligament into a lateral  muscular lacuna  and a medial  vascular lacuna . When a  psoas minor muscle  is present, its tendon of insertion blends with the iliopectineal arch


It is sometimes transected in treatment of  femoral nerve  entrapment. [ 2 ]


The  infraspinatous fascia  is a dense fibrous membrane, covering the  infraspinatous muscle  and fixed to the circumference of the  infraspinatous fossa ; it affords attachment, by its deep surface, to some fibers of that muscle. It is intimately attached to the  deltoid fascia  along the over-lapping border of the  deltoideus .


This article incorporates text in the  public domain  from  page 441  of the 20th edition of   Gray's Anatomy   (1918)


The  lumbar fascia  is the lumbar portion of the  thoracolumbar fascia . It consists of three fascial layers - posterior, middle, and anterior - that enclose two (anterior and posterior) muscular compartments. The anterior and middle layers occur only in the lumbar region, whereas the posterior layer (as part of the thoracolumbar fascia) extends superiorly to the inferior part of the neck, and the inferiorly to the dorsal surface of the sacrum. The  quadratus lumborum  is contained in the anterior muscular compartment (between anterior and middle layers), and the  erector spinae  in the posterior compartment (between middle and posterior layers). [ 1 ] : 274    Psoas major  lies anterior to the anterior layer. Various superficial muscles of the posterior thorax and abdomen arise from the posterior layer - namely the  latissimus dorsi , and  serratus posterior inferior . [ citation needed ]


The posterior layer and middle layer unite at the lateral margin of erector spinae, forming a though raphe; all three layers then unite at the lateral margin of quadratus lumborum, thus forming the aponeurotic origin of the transversus abdominis muscle. [ 2 ] : 814–815


The posterior layer is thick, being reinforced by the aponeurosis (origin) of the  latissimus dorsi muscle . [ 1 ] : 274   It consists of a superficial lamina derived primarily from the latissimus dorsi and serratus posterior inferior, and a deeper lamina which forms a retinacular sheet encapsulating the paraspinal muscles. [ 3 ]  The posterior layer is attached to the spinous processes of lumbar and sacral vertebrae, and to the  supraspinous ligament . [ 2 ] : 814–815


At sacral levels, the posterior layer attaches to the posterior superior iliac spines, and posterior iliac crest, fuses with the underlying erector spinae muscle aponeurosis, [ 2 ] : 814–815   and extends along the transverse tubercles of the sacrum. [ 1 ] : 274


In the thoracic region, the posterior layer (i.e. thoracic part of thoracolumbar fascia) attaches to the supraspinous ligament and spinous processes of all thoracic vertebrae, and to the costal angles of all ribs. It extends as far superiorly as the inferior part of the neck. [ 1 ] : 274


The middle layer is attached superiorly to the inferior margin of the 12th rib, and the  lumbocostal ligament , medially to the tips of transverse processes of lumbar vertebrae, and inferiorly to [ 2 ] : 814–815   the posterior part of the intermediate area of [ 4 ]  the iliac crest. [ 2 ] : 814–815


The anterior layer is the thinnest of the three layers. [ citation needed ]  The anterior layer forms the  lateral arcuate ligament  superiorly, is attached medially to anterior surfaces of transverse processes of lumbar vertebra, and is attached inferiorly to the  iliolumbar ligament  and adjoining  iliac crest . [ 2 ] : 814–815


The  ascending colon [ 1 ] : 257   and  descending colon [ 1 ] : 258   lie upon the lumbar fascia.


The lumbar fascia gives origin to the  latissimus dorsi muscle  (which arises from posterior layer of lumbar fascia), [ 1 ] : 40    abdominal internal oblique muscle  (which arises along the entire length of the lumbar fascia),  transversus abdominis muscle , [ 1 ] : 222   and  gluteus maximus muscle . [ 1 ] : 125


The psoas fascia (a part of the  iliac fascia ) laterally blends with the lumbar fascia. [ 1 ] : 272   The  lateral arcuate ligament  arises as a thickening of the lumbar fascia. [ 1 ] : 185   The superior band of the  iliolumbar ligament  is continuous with the anterior layer of lumbar fascia. [ 1 ] : 325   The inferior portion of the  supraspinous ligament  becomes indistinct amid the lumbar fascia. [ 1 ] : 424


Each  subcostal artery  passes across the anterior surface of the lumbar fascia before reaching the anterior abdominal wall. [ 1 ] : 276   Each  subcostal nerve  passes across the anterior aspect of the anterior layer of lumbar fascia. [ 1 ] : 278   The  ilioinguinal nerve  pierces the anterior layer of lumbar fascia posterior to the kidney to come to pass inferoanteriorly anterior to the anterior layer of lumbar fascia. [ 1 ] : 279


The lumbar fascia binds the deep muscles of the back to the spine and to the transverse processes of the vertebrae. Additionally the lumbar fascia is an attachment for the  gluteus maximus muscle  and the  latissimus dorsi muscle . [ citation needed ]


The  nuchal fascia  is a  fascia  covering the autochthonous musculature of the neck as a part of the  cervical fascia . It proceeds the  thoracolumbar fascia  to the top (cranial). The fascia itself is made of two parts: A superficial layer ( lat. :  Fascia nuchae superficialis)  and a deeper layer that is located among the  Trapezius muscle  and that sheaths the deeper cervical musculature from dorsal side. Expanding laterally, the fascia also covers the dorsal musculature. [ 1 ]   In the middle of the deeper layer a bulge is resided – the  nuchal ligament .


The  obturator fascia , or  fascia of the  internal obturator muscle ,  covers the pelvic surface of that muscle and is attached around the margin of its origin.


Above, it is loosely connected to the back part of the  arcuate line , and here it is continuous with the  iliac fascia .


In front of this, as it follows the line of origin of the  internal obturator , it gradually separates from the iliac fascia and the continuity between the two is retained only through the  periosteum .


It arches beneath the obturator vessels and nerve, completing the  obturator canal , and at the front of the pelvis is attached to the back of the  superior ramus  of the  pubis .


Below, the obturator fascia is attached to the  falciform process  of the  sacrotuberous ligament  and to the  pubic arch , where it becomes continuous with the superior fascia of the  urogenital diaphragm .


Behind, it is prolonged into the  gluteal  region.


The internal pudendal vessels and  pudendal nerve  cross the pelvic surface of the  internal obturator and are enclosed in a special canal— Alcock's canal —formed by the obturator fascia.


The  iliococcygeus  portion of the  levator ani  attaches to the lateral walls of the pelvis via the obturator fascia through the tendinous arch of the obturator fascia.


This article incorporates text in the  public domain  from  page 420  of the 20th edition of   Gray's Anatomy   (1918)


In  anatomy , the  orbital septum  ( palpebral fascia ) is a  membranous  sheet that acts as the anterior (frontal) boundary of the  orbit . It extends from the orbital rims to the  eyelids . It forms the fibrous portion of the eyelids. [ 1 ]


In the upper eyelid, the orbital septum blends with the tendon of the  levator palpebrae superioris , and in the lower eyelid with the  tarsal plate . [ 2 ]


When the eyes are closed, the whole orbital opening is covered by the septum and tarsi.  Medially it is thin, and, becoming separated from the  medial palpebral ligament , attaches to the lacrimal bone at its  posterior crest .  The medial ligament and its much weaker lateral counterpart, attached to the septum and orbit, keep the lids stable as the eye moves. [ 3 ]


The septum is perforated by the vessels and nerves which pass from the orbital cavity to the  face  and  scalp .


Orbital septum supports the orbital contents located posterior to it, especially orbital fat. The septum can be weakened by trauma or due to hereditary diseases. Anatomical structures important in the  blepharoplasty  operation (operation to strengthen the orbital septum) are located posterior to the orbital septum. [ 4 ]


The orbital septum is an important structure that separates anterior and posterior extent of the orbit. Orbital septum acts as a physical barrier that prevents the infection of the anterior part of the eye spreading posteriorly. For example,  preseptal cellulitis  mainly infects the eyelids, anterior to the orbital septum. Meanwhile,  orbital cellulitis  is located posterior the orbital septum, due to infections spreading from the  ethmoidal sinuses . The porous  lamina papyracea  separating the orbit from the ethmoidal sinus causes infection to spread between the orbit and ethmoidal sinuses. Infection of the ethmoidal sinuses can spread to the brain, causing  meningitis  and  cerebral abscess . Orbital cellulitis can also spread to the anterior orbit, by lifting the loosely attached  periosteum , causing subperiosteal abscess. [ 5 ]


Orbital septum appears as hypointense on both MRI T1 and T2 weighted images, in contrast with surrounding hyperintense fat. [ 6 ]


This article incorporates text in the  public domain  from  page 1026  of the 20th edition of   Gray's Anatomy   (1918)


The  pectoral fascia  is a thin lamina, covering the surface of the  pectoralis major , and sending numerous prolongations between its  fasciculi : it is attached, in the middle line, to the front of the  sternum ; above, to the  clavicle ; laterally and below it is continuous with the fascia of the  shoulder ,  axilla , and  thorax .


It is very thin over the upper part of the pectoralis major, but thicker in the interval between it and the  latissimus dorsi , where it closes in the  axillary space  and forms the  axillary fascia ; it divides at the lateral margin of the latissimus dorsi into two layers, one of which passes in front of, and the other behind it; these proceed as far as the spinous processes of the thoracic vertebrae, to which they are attached.


As the fascia leaves the lower edge of the pectoralis major to cross the floor of the axilla it sends a layer upward under cover of the muscle; this lamina splits to envelop the  pectoralis minor , at the upper edge of which it is continuous with the coracoclavicular fascia. The hollow of the armpit, seen when the arm is abducted, is produced mainly by the traction of this fascia on the axillary floor, and hence the lamina is sometimes named the  suspensory ligament of the axilla .


At the lower part of the thoracic region the deep fascia is well-developed, and is continuous with the fibrous sheaths of the  rectus abdominis .


This article incorporates text in the  public domain  from  page 435  of the 20th edition of   Gray's Anatomy   (1918)


The  pelvic fasciae  are the  fascia  of the  pelvis  and can be divided into:


Pelvic fascia extends to cover the organs within the pelvis.


It is attached to the fascia that runs along the pelvic floor along the  tendinous arch . The fascia which covers pelvic organs  can be divided according to the organs that are covered:


The part of the pelvic fascia on the pelvic floor covers both surfaces of the  levatores ani  muscle.


The layer covering the upper surface of the  pelvic diaphragm  follows, above, the line of origin of the Levator ani and is therefore somewhat variable. In front it is attached to the back of the  pubic symphysis  about 2 cm above its lower border.


It can then be traced laterally across the back of the  superior ramus of the pubis  for a distance of about 1.25 cm, when it reaches the  obturator fascia .


It is attached to this fascia along a line which pursues a somewhat irregular course to the  spine of the ischium .


The irregularity of this line is because the origin of the Levator ani, which in lower forms is from the  pelvic brim , is in man lower down, on the obturator fascia.


The diaphragmatic part of the pelvic fascia covers both surfaces of the  levatores ani . The inferior layer is known as the  anal fascia . It is attached above to the  obturator fascia  along the line of origin of the Levator ani, while below it is continuous with the superior fascia of the  urogenital diaphragm , and with the fascia on the  sphincter ani internus .


The  fascia of the piriformis  is very thin and is attached to the front of the  sacrum  and the sides of the  greater sciatic foramen ; it is prolonged on the muscle into the gluteal region.


At its sacral attachment around the margins of the  anterior sacral foramina  it comes into contact with and ensheathes the nerves emerging from these foramina.


Hence, the  sacral nerves  are frequently described as lying behind the fascia.


The  internal iliac artery ,  internal iliac vein , and their branches, on the other hand, lie in the subperitoneal tissue in front of the fascia, and the branches to the gluteal region emerge in special sheaths of this tissue, above and below the  piriformis muscle .


The  plantar fascia  or  plantar aponeurosis [ 1 ]  is the thick  connective tissue   aponeurosis  which supports the  arch  on the bottom ( plantar  side) of the  foot . Recent studies suggest that the plantar fascia is actually an  aponeurosis  rather than true fascia. [ citation needed ]  It runs from the  tuberosity  of the  calcaneus  (heel bone) forward to the heads of the  metatarsal bones  (the bone between each  toe  and the bones of the mid-foot).


The plantar fascia is the thick central portion of the fascia investing the plantar muscles. It extends between the medial process of the tuber calcanei [ 1 ]  and the proximal  phalanges  of [ citation needed ]  the toes. It provides some attachment to the flexor muscles of the toes. [ 1 ]


Distally, the plantar fascia becomes continuous with the fibrous sheaths enveloping the flexor tendons passing to the toes. At the anterior extremity of the sole - inferior to the heads of the metatarsal bones - the plantar aponeurosis forms the  superficial transverse metatarsal ligament . [ 2 ]


The plantar fascia is made up of predominantly longitudinally oriented  collagen  fibers. There are three distinct structural components: the  medial component , the  central component  ( plantar aponeurosis ), and the  lateral component  (see diagram at right). The central component is the largest and most prominent.


In younger people the plantar fascia is also intimately related to the  Achilles tendon , with a continuous fascial connection between the two from the distal aspect of the Achilles to the origin of the plantar fascia at the calcaneal tubercle. However, the continuity of this connection decreases with age to a point that in the elderly there are few, if any, connecting fibers. There are also distinct attachments of the plantar fascia and the Achilles tendon to the calcaneus so the two do not directly contact each other. Nevertheless, there is an indirect relationship whereby if the toes are  dorsiflexed , the plantar fascia tightens via the  windlass  mechanism. If a tensile force is then generated in the Achilles tendon it will increase tensile strain in the plantar fascia. Clinically, this relationship has been used as a basis for treatment for plantar fasciitis, with stretches and night stretch splinting being applied to the  gastrocnemius / soleus muscle  unit.


The plantar fascia contributes to support of  arch of the foot by acting as a tie-rod, where it undergoes tension when the foot bears weight. One  biomechanical  model estimated it carries as much as 14% of the total load of the foot. In an experiment using  cadavers , it was found that failure of the plantar fascia averaged at loads of 1189 ± 244  newtons [ 3 ]  (121 ± 24  kgf  or 267 ± 55  lbf ). Failure most often occurred at the proximal attachment to the calcaneus, which is consistent with the usual location of  symptoms  (i.e. in plantar fasciitis). Complete  rupture  or surgical release of the plantar fascia leads to a decrease in arch stiffness and a significant collapse of the  longitudinal arch of the foot . By modeling it was predicted such conditions would result in a 17% increase in vertical displacement and a 15% increase in horizontal elongation of the foot when it was loaded at 683 newtons (154 lbf). [ 4 ]  Surgical release also significantly increases both stress in the plantar  ligaments  and plantar pressures under the metatarsal heads. Although most of the figures mentioned above are from either  cadaver  studies or investigations using models, they highlight the relatively large load the plantar fascia is subjected to while contributing to the structural integrity of the foot.


The plantar fascia also has an important role in dynamic function during  gait . It was found the plantar fascia continuously elongated during the contact phase of gait. It went through rapid elongation before and immediately after mid-stance, reaching a maximum of 9% to 12% elongation between mid-stance and toe-off. [ 5 ]  During this phase the plantar fascia behaves like a spring, which may assist in conserving energy. In addition, the plantar fascia has a critical role in normal mechanical function of the foot, contributing to the "windlass mechanism". When the toes are dorsiflexed in the propulsive phase of gait, the plantar fascia becomes tense, resulting in elevation of the longitudinal arch and shortening of the foot (see 3A). One can liken this mechanism to a cable being wound around the drum of a windlass (see 3B); the plantar fascia being the cable, the metatarsal head the drum, and the handle, the  proximal phalanx .


The  presacral fascia  lines the anterior aspect of the  sacrum , enclosing the sacral vessels and  nerves .  It continues anteriorly as the pelvic  parietal fascia , covering the entire  pelvic cavity . [ 1 ]


The presacral fascia is limited postero-inferiorly, as it fuses with the mesorectal fascia,  lying above the  levator ani  muscle, at the level of the anorectal junction. [ 2 ]  These two fascias have been erroneously confused, [ 3 ]  though they are in fact, separate anatomical entities. The colloquial term, among colo-rectal surgeons, for this inter-fascial plane, is known as the  holy plane  of dissection first coined by Bill Heald. [ 4 ]  During rectal  surgery  and  mesorectum excision , dissection along the avascular alveolar plane between these two fascias, facilitates a straightforward dissection and preserves the sacral vessels and  hypogastric nerves .


Waldeyer's fascia  (a.k.a. rectosacral fascia) originates from the presacral parietal fascia at the S2 to S4 level fusing with the rectal visceral fascia at the posterior aspect of the rectum. Waldeyer's fascia divides the retrorectal space into a superior and inferior compartments. [ 5 ] [ 6 ]


Identification and preservation of the presacral fascia is of fundamental importance in preventing complications and reducing local recurrences of  rectal cancer . [ 7 ]   Hence attention to this anatomy is essential in contemporary rectal surgery.


The mesorectal fascia, also known as the fascia propria or the pelvic visceral fascia, has been originally described as the fascia recti in Waldeyer's publication, Das Becken.  Fascia recti is also a term commonly used among French surgeons to describe the mesorectal fascia. [ 8 ]   Confusingly, fascia recti is described in some anatomy books, referring to the fascia of the  rectus abdominis muscle .


The  rectoprostatic fascia  ( Denonvilliers' fascia ) is a membranous partition at the lowest part of the  rectovesical pouch . It separates the  prostate  and  urinary bladder  from the  rectum . [ 1 ]  It consists of a single fibromuscular structure with several layers that are fused together and covering the  seminal vesicles . It is also called  Denonvilliers' fascia  after French anatomist and surgeon  Charles-Pierre Denonvilliers . [ 2 ]


The structure corresponds to the  rectovaginal fascia  in the female. The rectoprostatic fascia also inhibits the posterior spread of prostatic adenocarcinoma; therefore invasion of the rectum is less common than is invasion of other contiguous structures.


The  rectovaginal fascia  (often called  rectovaginal septum  or sometimes  fascia of Otto ) is a thin structure separating the  vagina  and the  rectum .    This corresponds to the  rectoprostatic fascia  in the male. [ 1 ]


Perforations in it can lead to  rectocele . [ 2 ] [ 3 ]


The  renal fascia  is a dense,  elastic   connective tissue  envelope enclosing the  kidney  and  adrenal gland , together with the layer of  perirenal fat  surrounding these two. [ 1 ]


The renal fascia separates the  adipose capsule of kidney  from the overlying  pararenal fat . The deeper layers deep to the renal fascia are, in order, the adipose capsule (or perirenal fat), the  renal capsule  and finally the  parenchyma  of the  renal cortex . [ 2 ]  At the  renal hilum , the renal capsule extends into the  renal sinus . [ 1 ]


The renal fascia was originally described as consisting of two distinct structures: the anterior renal fascia (Gerota's fascia), and posterior renal fascia (Zuckerkandl's fascia); these two fasciae were said to fuse laterally to form the lateroconal fascia. Understanding of the structure of the renal fascia has subsequently evolved. [ 1 ]


This article incorporates text in the  public domain  from  page 1220  of the 20th edition of   Gray's Anatomy   (1918)


The  subcutaneous tissue of penis  (or  superficial penile fascia ) is continuous above with the  fascia of Scarpa , and below with the  dartos tunic  of the  scrotum  and the  fascia of Colles .


It is sometimes just called the "dartos layer". [ 1 ]


It attaches at the intersection of the body and glans. [ 2 ]


The term "superficial penile fascia" is more common, but "subcutaneous tissue of penis" is the term used by  Terminologia Anatomica .


This article incorporates text in the  public domain  from  page 1249  of the 20th edition of   Gray's Anatomy   (1918)


The  subcutaneous tissue of perineum  (or  superficial perineal fascia ) is a layer of  subcutaneous tissue  surrounding the region of the  perineal body .


The superficial fascia of this region consists of two layers, superficial and deep.


The  superior fascia of the urogenital diaphragm  is continuous with the  obturator fascia  and stretches across the  pubic arch .


If the obturator fascia be traced medially after leaving the  obturator internus muscle , it will be found attached by some of its deeper or anterior fibers to the inner margin of the  pubic arch , while its superficial or posterior fibers pass over this attachment to become continuous with the superior fascia of the  urogenital diaphragm .


Behind, this layer of the fascia is continuous with the inferior fascia and with the  fascia of Colles ; in front it is continuous with the fascial sheath of the  prostate , and is fused with the inferior fascia to form the  transverse ligament of the pelvis .


Some sources dispute that this structure exists. [ 1 ]  However, whether this layer is real or imagined, it still serves to describe a division of the contents of the perineum in many modern anatomy resources.


The  supraspinous fascia  completes the  osseofibrous  case in which the  supraspinatus muscle  is contained; it affords attachment, by its deep surface, to some of the fibers of the muscle.


It is thick medially, but thinner laterally under the  coracoacromial ligament .


This article incorporates text in the  public domain  from  page 440  of the 20th edition of   Gray's Anatomy   (1918)


The  temporoparietal fascia  (or  superficial temporal fascia ) [ 1 ] : 357  [ 2 ]  is a  superficial fascia  of the side of the head over the area of the  temporal fossa [ 2 ]  situated superficial to the  (deep) temporal fascia , [ 1 ] : 357  [ 2 ]  and deep to the skin and subcutaneous tissue of the region. [ 2 ]


The temporoparietal fascia consists of a thin layer of connective tissue. [ 3 ]  It measures some 2-3mm in thickness. [ 2 ]


The fascia unites anteriorly with the  orbicularis oris muscle , and the  frontalis muscle ; it unites posteriorly with the  occipitalis muscle . Inferior to the  zygomatic arch , the fascia is continuous with the  superficial muscular aponeurotic system ; both structures are continuous with the  platysma muscle  of the neck, creating a single continuous fascial layer between the scalp superiorly and the clavicle inferiorly. [ 2 ]


The fascia is situated superficial to the  (deep) temporal fascia , [ 1 ] : 357  [ 2 ]  with an intervening layer of (sources differ)  avascular   loose connective tissue  (the  innominate fascia ) situated in the interval between the two fasciae; this structural arrangement of loose superficial layers and deep rigit layers confers a combination of mobility coupled with structural integrity to the region. [ 2 ]


The  superficial temporal artery  and  vein , and the  auriculotemporal nerve  course within or just deep to the temporoparietal fascia, [ 1 ] : 357   and the frontal branch of the  frontal nerve (CN VII)  courses within the fascia. [ 2 ]


The temporoparietal fascia can serve as a donor tissue for  reconstructive surgery . It affords reliable flaps with good blood supply when the tissues of the region are intact (however, prior lesions to the region may compromise the blood supply of the tissues; creating flaps from such compromised tissue is contraindicated due to a risk of subsequent ischaemic necrosis of the flap). [ 2 ]


At the level of a line extending from the lower part of the  pubic symphysis  to the  spine of the ischium  is a thickened whitish band in this upper layer of the diaphragmatic part of the  pelvic fascia . It is termed the  tendinous arch  or  white line of the pelvic fascia , and marks the line of attachment of the special fascia (pars endopelvina fasciae pelvis) which is associated with the pelvic  viscera .
It joins the fascia of the pubocervical fascia that covers the anterior wall of the vagina. If this fascia falls, the ipsilateral side of the vagina falls, carrying with it the bladder and the urethra, and thus contributing to urinary incontinence. [ 1 ]


This article incorporates text in the  public domain  from  page 422  of the 20th edition of   Gray's Anatomy   (1918)


Tenon's capsule  ( / t ə ˈ n oʊ n / ), also known as the  Tenon capsule ,  fascial sheath of the eyeball  ( Latin :  vagina bulbi ) or the  fascia bulbi , is a thin membrane which envelops the eyeball from the  optic nerve  to the  corneal limbus , separating it from the orbital fat and forming a socket in which it moves.


The inner surface of Tenon's capsule is smooth and is separated from the outer surface of the  sclera  by the  periscleral lymph space . This lymph space is continuous with the  subdural  and  subarachnoid  cavities and is traversed by delicate bands of connective tissue which extend between the capsule and the sclera.


The capsule is perforated behind by the ciliary vessels and nerves and fuses with the sheath of the optic nerve and with the sclera around the entrance of the  optic nerve . In front it adheres to the  conjunctiva , and both structures are attached to the ciliary region of the eyeball.


The structure was named after  Jacques-René Tenon  (1724–1816), [ 1 ]  a French surgeon and pathologist.


Tenon's capsule is perforated by the tendons of the  ocular muscles  and is reflected backward on each as a tubular sheath. The sheath of the  obliquus superior  is carried as far as the fibrous pulley of that muscle, and that on the  obliquus inferior  reaches as far as the floor of the  orbit , to which it gives off a slip. The sheaths on the recti muscles are gradually lost in the  perimysium , but they give off important expansions. The expansion from the  rectus superior  blends with the tendon of the  levator palpebrae , and that of the  rectus inferior  is attached to the  inferior tarsus ; it is the space which lies between the sclera and the capsule. The expansions from the sheaths of the  recti lateralis  and  medialis  are strong, especially that from the latter muscle, and are attached to the  zygomatic bone  and  lacrimal bone  respectively; as they probably check the actions of these two recti, they have been named the medial and lateral  check ligaments .


Charles Barrett Lockwood  described a thickening of the lower part of Tenon's capsule, which he named the  suspensory ligament of the eye . It is slung like a hammock below the eyeball, being expanded in the center, and narrow at its extremities which are attached to the  zygomatic  and  lacrimal bones  respectively.


Tenon's capsule may be affected by a disease called idiopathic orbital inflammation, a condition of unknown etiology that is characterized by inflammation of one or more layers of the eye. The disease is also known as orbital inflammatory pseudotumor, and sometimes may only affect the  lacrimal gland  or the  extraocular muscles . [ 2 ]


Local anaesthetic may be instilled into the space between Tenon's capsule and the sclera to provide anaesthesia for eye surgery, principally cataract surgery. After applying local anaesthetic drops to anaesthetise the  conjunctiva , a small fold of conjunctiva is lifted off the eyeball and an incision made. A blunt, curved cannula is passed through the incision into the  periscleral lymph space  and a volume of  local anaesthetic  solution is instilled. The advantages are a reduced risk of bleeding and of penetration of the globe, compared to  peribulbar  and  retrobulbar  approaches. Akinesia (paralysis of the external eye muscles) may be less complete, however.


Toldt's fascia , is a discrete layer of  connective tissue  containing  lymphatic  channels. [ 1 ]  It is found between the two  mesothelial  layers that separate the  mesocolon  from the underlying  retroperitoneum . It was first described by the Austrian anatomist  Carl Toldt  (1840–1920) as a fascial plane formed by the fusion of the  visceral peritoneum  with the  parietal peritoneum . This was later called Toldt's fascia. [ 2 ]


The  transversalis fascia  (or  transverse fascia ) is the  fascial  lining of the anterolateral  abdominal wall [ 1 ] [ 2 ]  situated between the inner surface of the  transverse abdominal muscle , and the  preperitoneal fascia . [ 3 ] [ 2 ]  It is directly continuous with the  iliac fascia , [ 2 ]  the  internal spermatic fascia , [ citation needed ]  and  pelvic fascia . [ 2 ]


In the  inguinal region , the transversalis fascia is thick and dense; here, it is joined by fibers of the aponeurosis of the  transverse abdominal muscle . It becomes thin towards to the  diaphragm , blending with the fascia covering the inferior surface of the diaphragm. [ 2 ]


Posteriorly, it is lost in  the fat which covers the posterior surfaces of the kidneys [ clarification needed ] [ 2 ]


Below, it has the following attachments: posteriorly, to the whole length of the  iliac crest , between the attachments of the transverse abdominal and  Iliacus ; between the  anterior superior iliac spine  and the  femoral vessels  it is connected to the posterior margin of the  inguinal ligament , and is there continuous with the  iliac fascia . [ 2 ]


Medial to the femoral vessels it is thin and attached to the  pubis  and  pectineal line , behind the  inguinal falx , with which it is united; it descends in front of the femoral vessels to form the anterior wall of the  femoral sheath . [ 2 ]


Beneath the inguinal ligament it is strengthened by a band of fibrous tissue, which is only loosely connected to the ligament, and is specialized as the  iliopubic tract . [ 2 ]


The  spermatic cord  in the male and the  round ligament of the uterus  in the female pass through the transversalis fascia at the  deep inguinal ring , the entrance to the  inguinal canal . This opening is not visible externally. In the male, the transverse fascia extends downwards as the  internal spermatic fascia . [ 4 ]


The  umbilical fascia  (or  umbilicovesical fascia [ 1 ] ) is a thin fascial layer that extends between the  medial umbilical ligaments [ 2 ]  from the  umbilicus , [ 1 ]  and extends inferiorly, becoming continuous with the visceral fascia enclosing the  urinary bladder . [ 1 ] [ 2 ]


Rhabdomyoma  is a benign mesenchymal tumor of skeletal muscle, separated into two major categories based on site: Cardiac and extracardiac. They are further separated by histology: fetal (myxoid and cellular), juvenile (intermediate), and adult types. Genital types are recognized, but are often part of either the fetal or juvenile types. The fetal type is thought to recapitulate  immature skeletal muscle  at about week six to ten of gestational development.


Most fetal rhabdomyomas are tumors that develop in the head and neck or in the genital region. [ 1 ]  There are a number of cases which have been seen in association with  Gorlin syndrome . [ 2 ] [ 3 ]  However, cardiac myxomas are known to be associated with  tuberous sclerosis .


The tumor may be seen within the subcutaneous tissues (below the skin), [ 4 ]  mucosal surfaces or in soft tissue. Within the head and neck, the posterior ear region, skin of the face, and the tongue are the most commonly affected sites (about a 2:1 ratio of soft tissue to mucosa). [ 5 ] [ 6 ]  The tumors are well defined, non-specific usually solitary masses, but when seen in the head and neck (or genital region), they may be polypoid. Tumors range in dimension from a few millimeters up to 12.5 cm, with a mean of about 3.0 cm. Although there are isolated case reports, multifocality is very rare.


Fetal rhabdomyoma are separated into two histologic types: Myxoid and cellular. [ 7 ] [ 8 ]  However, irrespective of histologic type, these tumors almost never show necrosis or increased mitoses. However, a  cambium  layer, abnormal mitoses and nuclear pleomorphism is not seen.


Cellular fetal rhabdomyomas are composed of bland, primitive spindled cells. The spindle cells are haphazardly arranged primitive, elongated skeletal muscle cells. The cells are set within a well-developed fibromyxoid stroma. A different pattern (intermediate type) is predominantly composed of cells with better differentiation towards skeletal muscle. There are often large ganglion cell-like rhabdomyoblasts showing prominent nucleoli within nuclei that show vesicular chromatin distribution. Another population includes strap-like rhabdomyoblasts with darkly staining pink cytoplasm. Nearly all tumors show short to more sweeping fascicles of spindled rhabdomyoblasts. The tumor cells may infiltrate into adjacent skeletal muscle or fat. It is not uncommon to see peri-neural association, although not perineural infiltration. [ 9 ]


These tumors may be detected prenatally by ultrasound and MRI. [ 10 ]  Additionally, preoperative fine needle aspiration can be used to diagnose the tumor. [ 11 ]


A phosphotungstic acid hematoxylin stain may be used to highlight cross striations in the cytoplasm of the tumor cells. PAS with diastase will highlight the presence of glycogen in the tumor cells' cytoplasm. Immunohistochemistry will yield a positive reaction with a variety of myoid markers, including desmin, myoglobin, myogenin, MYOD1 and muscle specific actin. They may also be positive with vimentin, smooth muscle actin, and Leu-7.  However, the tumor cells are almost always negative with glial fibrillary acidic protein, S100 protein, cytokeratin, epithelial membrane antigen, CD68, FLI1, CD99 and CD56. Although not used as frequently now, electron microscopy will show thick and thin myofilaments, Z-bands: these are features of sarcometric differentiation. [ 12 ]


The differential diagnosis histologically includes  rhabdomyosarcoma ,  granular cell tumor ,  alveolar soft part sarcoma ,  hibernoma ,  oncocytoma , and  crystal storing histiocytosis , among others. [ 13 ]


Surgical excision is the treatment of choice. [ 14 ]  Recurrences are reported, but this is usually due to incomplete removal initially. [ 15 ] [ 16 ]  There is no role for chemotherapy or radiation therapy.


They present over a wide age range (birth to about 65 years), but within the head and neck region, about 50% of cases develop in patients younger than 15 years of age. Within the head and neck, males are affected about 2–3 times more often than females. [ 17 ]


Intramyocellular lipids  (or IMCL) are  fats  stored in droplets in  muscle cells . They provide an important energy source for working muscle. During exercise, a large amount of circulating  free fatty acids  are directed into muscle cells for energy; during rest, incoming fatty acids are instead stored in the muscle cell as  triglycerides  for later burning. [ 1 ]  However, an increase in muscle insulin resistance, caused by  obesity ,  diabetes mellitus type 2 , and  metabolic syndrome , will result in an excess accumulation of intramyocellular lipids. [ 2 ] [ 3 ]


Insulin glargine


Myosins  ( / ˈ m aɪ ə s ɪ n ,   - oʊ -/ [ 1 ] [ 2 ] ) are a  family  of  motor proteins  (though most often protein complexes) best known for their roles in  muscle contraction  and in a wide range of other  motility  processes in  eukaryotes . They are  ATP -dependent and responsible for  actin -based motility.


The first myosin (M2) to be discovered was in 1864 by  Wilhelm Kühne . Kühne had extracted a viscous protein from  skeletal muscle  that he held responsible for keeping the tension state in muscle. He called this protein  myosin . [ 3 ] [ 4 ]  The term has been extended to include a group of similar  ATPases  found in the  cells  of both  striated muscle tissue  and  smooth muscle tissue .


Following the discovery in 1973 of enzymes with myosin-like function in  Acanthamoeba castellanii , a global range of divergent myosin  genes  have been discovered throughout the realm of eukaryotes. [ 5 ]


Although myosin was originally thought to be restricted to  muscle cells  (hence  myo- (s) +  -in ), there is no single "myosin"; rather it is a very large superfamily of genes whose protein products share the basic properties of actin binding, ATP  hydrolysis  (ATPase enzyme activity), and force transduction. Virtually all eukaryotic cells contain myosin  isoforms .  Some isoforms have specialized functions in certain cell types (such as muscle), while other isoforms are ubiquitous.  The structure and function of myosin is globally conserved across species, to the extent that rabbit muscle myosin II will bind to actin from an  amoeba . [ 6 ] [ 7 ]


Most myosin molecules are composed of a  head , neck, and tail domain.


Multiple  myosin II  molecules generate force in  skeletal muscle  through a power stroke mechanism fuelled by the energy released from ATP hydrolysis. [ 8 ]  The power stroke occurs at the release of phosphate from the myosin molecule after the ATP hydrolysis while myosin is tightly bound to actin. The effect of this release is a conformational change in the molecule that pulls against the actin. The release of the ADP molecule leads to the so-called rigor state of myosin. [ 9 ]  The binding of a new ATP molecule will release myosin from actin. ATP hydrolysis within the myosin will cause it to bind to actin again to repeat the cycle. The combined effect of the myriad power strokes causes the muscle to contract.


The wide variety of myosin genes found throughout the eukaryotic phyla were named according to different schemes as they were discovered.  The nomenclature can therefore be somewhat confusing when attempting to compare the functions of myosin proteins within and between organisms.


Skeletal muscle myosin, the most conspicuous of the myosin superfamily due to its abundance in  muscle fibers , was the first to be discovered. This protein makes up part of the  sarcomere  and forms macromolecular filaments composed of multiple myosin subunits. Similar filament-forming myosin proteins were found in  cardiac muscle , smooth muscle, and nonmuscle cells. However, beginning in the 1970s, researchers began to discover new myosin genes in simple eukaryotes [ 5 ]  encoding proteins that acted as monomers and were therefore entitled Class I myosins. These new myosins were collectively termed "unconventional myosins" [ 10 ]  and have been found in many tissues other than muscle. These new superfamily members have been grouped according to phylogenetic relationships derived from a comparison of the amino acid sequences of their head domains, with each class being assigned a  Roman numeral [ 11 ] [ 12 ] [ 13 ] [ 14 ]  (see phylogenetic tree). The unconventional myosins also have divergent tail domains, suggesting unique functions. [ 15 ]  The now diverse array of myosins likely evolved from an ancestral  precursor  (see picture).


Analysis of the amino acid sequences of different myosins shows great variability among the tail domains, but strong conservation of head domain sequences. Presumably this is so the myosins may interact, via their tails, with a large number of different cargoes, while the goal in each case – to move along actin filaments – remains the same and therefore requires the same machinery in the motor. For example, the  human genome  contains over 40 different myosin  genes .


These differences in shape also determine the speed at which myosins can move along actin filaments. The hydrolysis of ATP and the subsequent release of the  phosphate  group causes the "power stroke", in which the "lever arm" or "neck" region of the heavy chain is dragged forward. Since the power stroke always moves the lever arm by the same angle, the length of the lever arm determines the displacement of the cargo relative to the actin filament.   A longer lever arm will cause the cargo to traverse a greater distance even though the lever arm undergoes the same angular displacement – just as a person with longer legs can move farther with each individual step.  The velocity of a myosin motor depends upon the rate at which it passes through a complete kinetic cycle of ATP binding to the release of ADP.


Myosin I, a ubiquitous cellular protein, functions  as monomer and functions in  vesicle  transport. [ 16 ]  It has a step size of 10 nm and has been implicated as being responsible for the adaptation response of the stereocilia in the inner ear. [ 17 ]


Myosin II  (also known as conventional myosin) is the myosin type responsible for producing  muscle contraction  in  muscle cells  in most animal cell types. It is also found in non-muscle cells in contractile bundles called  stress fibers . [ 18 ]


In muscle cells, the long  coiled-coil  tails of the individual myosin molecules can auto-inhibit active function in the 10S conformation or upon phosphorylation, change to the 6S conformation and join, forming the thick filaments of the  sarcomere . [ 29 ] [ 30 ]  The force-producing head domains stick out from the side of the thick filament, ready to walk along the adjacent actin-based thin filaments in response to the proper chemical signals and may be in either auto-inhibited or active conformation. The balance/transition between active and inactive states is subject to extensive chemical regulation.


Myosin III is a poorly understood member of the myosin family. It has been studied  in vivo  in the eyes of  Drosophila , where it is thought to play a role in  phototransduction . [ 31 ]  A human  homologue  gene for myosin III,  MYO3A , has been uncovered through the  Human Genome Project  and is expressed in the  retina  and  cochlea . [ 32 ]


Myosin IV has a single  IQ motif  and a tail that lacks any coiled-coil forming sequence. It has homology similar to the tail domains of Myosin VII and XV. [ 33 ]


Myosin V is an unconventional myosin motor, which is processive as a  dimer  and has a step size of 36 nm. [ 34 ]  It translocates (walks) along actin filaments traveling towards the barbed end (+ end) of the filaments. Myosin V is involved in the transport of cargo (e.g. RNA, vesicles, organelles, mitochondria) from the center of the cell to the periphery, but has been furthermore shown to act like a dynamic tether, retaining vesicles and organelles in the actin-rich periphery of cells. [ 35 ] [ 36 ]  A recent single molecule in vitro reconstitution study on assembling actin filaments suggests that Myosin V travels farther on newly assembling (ADP-Pi rich) F-actin, while processive runlengths are shorter on older (ADP-rich) F-actin. [ 37 ]


The Myosin V motor head can be subdivided into the following functional regions: [ 38 ]


Myosin VI is an unconventional myosin motor, which is primarily processive as a dimer, but also acts as a nonprocessive monomer. It walks along actin filaments, travelling towards the pointed end (- end) of the filaments. [ 44 ]  Myosin VI is thought to transport  endocytic  vesicles into the cell. [ 45 ]


Myosin VII is an unconventional myosin with two  FERM domains  in the tail region. It has an extended lever arm consisting of five calmodulin binding IQ motifs followed by a single alpha helix (SAH) [ 46 ]  Myosin VII is required for  phagocytosis  in  Dictyostelium discoideum ,  spermatogenesis  in  C. elegans  and  stereocilia  formation in mice and zebrafish. [ 47 ]


Myosin VIII is a plant-specific myosin linked to cell division; [ 48 ]  specifically, it is involved in regulating the flow of cytoplasm between cells [ 49 ]  and in the localization of vesicles to the  phragmoplast . [ 50 ]