Hugh Owen Thomas , a pioneer of modern orthopedic surgery


X-ray of a  hip replacement


This image, taken in September 2006, shows extensive repair work to the right  acetabulum  six years after it was carried out (2000). The onset of arthritis, a bone/joint disease, has made further joint damage visible.


Radiography  to identify eventual  bone fractures  after a knee injury


Orthopedic implants to repair fractures to the radius and ulna. Note the visible break in the ulna. (right forearm)


Anterior and lateral view x-rays of fractured left leg with  internal fixation  after surgery


Ligament Advanced Reinforcement System (LARS) artificial ligament. The two end sections are the intraosseous portions and center portion is the intra-articular region.


PET artificial ligament coated with hyaluronic acid coating. Collagen tissue infiltration is evident.


Rate of knee injury among patients with failed ligament augmentation and reconstruction system


An x-ray of intramedullary nailing in a tibial fracture


A person getting a CT scan.


The  SL angle  is an indicator of dorsal intercalated segment instability deformity (DISI). The SL angle goes between: [ 1 ]   - A line through the long axis of the  scaphoid bone .  - A line perpendicular to the distal articular surface of the  lunate bone .  It should normally be 30°-60°. [ 1 ]


Biospace Med logo


oneFIT Medical logo


ALARA logo


The Tree of  Andry


A spinal muscle exercise performed by lying in the prone position and performing alternating shoulder flexions and hip extensions


A Chêneau brace achieving correction from 56° to 27° Cobb angle


A pair of AFO (Ankle Foot Orthosis) braces being used to aid bilateral  foot drop


Codification of Orthoses


Patient after  spinal cord injury  with incomplete paraplegia (lesion height L3) with a knee-ankle-foot orthosis with an integrated stance phase control knee joint


Description of the functions of the large muscle groups used to define the functional elements of a paralysis orthosis intended to compensate for restricted muscle functions


The Amsterdam Gait Classification facilitates the assessment of the gait pattern in CP patients and patients with traumatic brain injury and helps to determine the gait type.


The N.A.P. Gait classification facilitates the assessment of the gait pattern in stroke patients and helps to determine the gait type.


Determination of the strength levels of the large muscle groups, taking into account the muscular fatigue typical of MS patients using the example of the muscle group of the dorsal extensors


Ankle-foot orthosis for the care of patients after  stroke ,  cerebral palsy ,  multiple sclerosis  and other paralyzes of the dorsiflexors and plantar flexors. Designation of the orthosis according to the body parts included in the orthosis fitting: ankle and foot, English abbreviation: AFO for ankle-foot orthoses.


Ankle-foot orthosis (AFO) manufactured using old technology from polypropylene in a variant that is also called "Hinged AFO". It can be used to support an isolated  foot drop , but it will block plantar flexion. This AFO cannot transmit the high forces required to counterbalance weak plantar flexors while standing and walking.


Knee-ankle-foot orthosis for the treatment of patients e.g. with paraplegia after  spinal cord injury ,  poliomyelitis  or  multiple sclerosis . Designation of the orthosis according to the body parts included in the orthosis fitting: knee, ankle and foot, English abbreviation: KAFO for knee-ankle-foot orthoses.


A custom ankle-foot orthotic (AFO) specifically designed and fabricated based on a runner's individual foot and ankle anatomy and biomechanics


Knee orthosis with toothed gear segment joints for the care of patients e.g. after a cruciate ligament tear. Designation of the orthosis according to the body parts included in the orthosis fitting: the knee, English abbreviation: KO for knee orthoses.


Knee bandage/Knee brace


Measurement of pelvic tilt during physical examination to determine whether spinal orthoses are indicated to treat  scoliosis


Halo brace used to immobilize the cervical spine


Jewett hyperextension body brace fitted to adolescent female patient in full support body suit. Designated TLSO as the orthosis fits the thoracic, lumbar and sacroiliac regions, making for a thoraco-lumbo-sacral orthosis.


AFO  for a child. It can be used to support an isolated  foot drop  by blocking the plantar flexion with all negative consequences. (Designation of the  orthosis  according to the body parts included in the orthosis fitting: ankle and foot, English abbreviation: AFO for  ankle-foot orthoses ) The photo does not show the most modern manufacturing technology. Such orthoses were also called Hinged-AFO or orthopedic splint.


An example of Stimson maneuver. The person is lying on their stomach with a 4 kg weight tied to their wrist.


Cunningham technique


Zones of a hip prosthesis, by the DeLee and Charnley system, [ 1 ]  and the Gruen system. [ 2 ]


A 3D CT reconstruction showing a Le Fort I fracture (arrow indicates fracture line)


The facial skeleton


AO classification


Salter–Harris Fracture Types


Ligaments of the  ankle .


A bone cutter


Hacksaw -type surgeon's saw used by  Dr. David Jones  at the  Battle of Bunker Hill


A  costotome  in the open position


The Codman triangle


Dynamic hip screw


Fracture supported by dynamic hip screw


Gilula carpal arcs.


Scaphoid pseudarthrosis, before and after treatment with Herbert screw.


Illustration of two types of hip spica casts


An  x-ray  image of a spiral fracture to the left  humerus  (upper arm bone) of a 27-year-old male. The injury was sustained during a fall.


Staples for epiphysiodesis in the bone, Blount's disease treatment - rtg. snapshots and biomechanical experiments [ 8 ]


An x-ray showing calcific deposits in the area of the tendons of the rotator cuff muscles


Spinal surgeons operating on a patient's back


CT scan showing markedly thickened  ligamentum flavum  (yellow ligament) causing  spinal stenosis  in the lumbar spine.


CT scan image of large herniated disc in the lumbar spine.


CT scan of laminectomy showing scar formation (highlighted in red)causing new stenosis.


Myelogram  showing typical findings of arachnoiditis in the lumbar spine.


CT scan showing post operative scarring and arachnoiditis.


CT scan showing two views of L4-5 disc herniation


Foot with a typical arch


Flat feet of a child are usually expected to develop into high or proper arches, as shown by feet of the mother.


A woman in her thirties dorsiflexes, showing an absence of arches, over-pronated navicular and hallux valgus in the toes typically associated with flat feet.


Flatfoot in a 55-year-old female with ankle and knee arthritis.


Acquired Flat foot deformity with clinical soft tissue swelling.


A girl with genu recurvatum of her right leg due to  polio


MRI of shoulder after dislocation with Hill–Sachs lesion and labral  Bankart's lesion


Hill–Sachs lesion post-shoulder dislocation


X-ray at left shows anterior dislocation in a young man after trying to get up from his bed. X-ray at right shows same shoulder after reduction and internal rotation, revealing both a  Bankart lesion  and a Hill-Sachs lesion.


Feet of a person with Larsen syndrome: Note the small size and joint abnormalities.


Olecranon fracture


Fracture (left) and repair (right) with three pins, wires, and incision closure with staples


A Sgarlato's angle of more than 15° indicates pigeon toe. [ 9 ]


Flat feet  with planovalgus deformity


Normal person [left] vs Kyphosis patient [right]


Scoliosis [left] vs Normal [right]


Sciatica often results in pain radiating down the leg.


Left: Illustration of herniated spinal disc, superior view. Right: MRI showing herniated L5-S1 disc (red arrow tip), sagittal view.


Illustration of fibrovascular bands restricting mobility of the sciatic nerve in multiple directions, like a splattering of glue


Straight leg  test sometimes used to help diagnose a lumbar herniated disc


X-ray  of shoulder osteoarthritis.


Patient with  Pes Planus


X-ray image showing the location of the measurements.


X-ray image showing the location of the calcaneal inclination ( calcaneal pitch ).


Correct alignment of the subtalar joint


Sagittal magnetic resonance images of ankle region synovitis


A potential complication of a vertebral compression fracture is  avascular necrosis  of the vertebral body, which is called  Kümmel's disease , and may appear with the  intravertebral vacuum cleft sign  (at white arrow in image). [ 4 ]


Gigli wire saw


Hand operated, a gigli saw is useful in performing cranial surgeries.


The mechanical functions of the Ilizarov apparatus derive from the tension mechanics of the shaft bow of a horse harness. (the decorated arch behind the head of the horse)


Ilizarov apparatus: The Soviet athlete Valeriy Brumel holds a model of the external fixation apparatus that repaired the broken tibia bone and the broken ankle bones of his right leg. (1968)


Location and position of the tibia bones (red) in the legs.


Location and position of the fibula bones (red) in the legs


Osteotomes used in dental implantation


Bernhard Heine's osteotome


Component parts of the osteotome, and the instrument in use


A Taylor Spatial Frame on the left leg consisting of metal rings, pins and struts


Elektrische Gipssäge, by Ortopedia, Kiel, Germany


Biceps massage for Cunningham Technique


Friedrich Hessing  (date unknown)


Monument to Hessing;  by  Eugen Boermel


AHIP Protector


Short arm  thumb spica cast on a  teenager


Fibreglass long leg cast immobilizing the leg for a tibial fracture


Long leg cast for tibial fracture


Newly applied short leg cast


Plaster of Paris short leg walking cast with toeplate


Cotton and plaster casting material (plaster cast), 4ply


Fibreglass and polyurethane casting material, 4ply


FlexiOH orthopedic cast for foot and ankle fracture


An orange short arm cast with a fiberglass top layer being cut and removed with a specialized cast saw


Hippocrates: a conventionalized image in a Roman "portrait" bust (19th-century engraving)


Orthopedic implant example seen with X-ray


Orthopedic surgeon making adjustments to a metal plate in a patient's ankle


Capener finger splint


Illustration of an Ankle Stirrup Splint


Finger splint


AAOS Building – Rosemont, IL


Jeannie L Peeper  IFOPA Founder and President


Frederick S Kaplan Co-Director Center for Research in FOP.


Eileen Shore Co-Director Center for Research in FOP


National Institute of Traumatology & Orthopaedic Rehabilitation (NITOR)


National Institute of Traumatology and Orthopaedic Rehabilitation (NITOR)


"The Baptist" was the site of one of the first  artificial hip  replacements in the  United States .


New England Baptist Hospital


New England Baptist campus on Parker Hill


Three distinct types of muscle (L to R): Smooth (non-striated) muscle in internal organs, cardiac or heart muscle, and skeletal muscle.


Main areas of muscle weakness in different types of dystrophy


Acceleromyography - Quantitative neuromuscular monitoring using the TOF-Watch.


Acceleromyography using the TOF- Watch


The antagonistic pair of biceps and triceps working to flex the elbow.


The biceps flexes the lower arm. The brachioradialis, in the forearm, and brachialis, located deep to the biceps in the upper arm, are both synergists that aid in this motion.


The seven general types of skeletal muscle


Rectus femoris  (in red). Origin includes the  anterior inferior iliac spine  and part of the  acetabulum . Insertion is into the  patellar tendon . Action is extension of the knee and flexion of the hip.


Different  skeletal   muscle types :  A: fusiform. B: unipennate. C: bipennate.  ( PCS: physiological cross-section )


Example of an atrophied muscle


Figure 1  Anatomical gear ratio. The line aw represents a muscle fiber of length m with its origin at w and insertion into an aponeurosis (TT') at a. The fiber shortens to length m' and moves its insertion the distance d to point b. Note that the shortening muscle fiber does not pull the aponeurosis along the line of action of the fiber but rather rotates around its origin. This is because the 3-dimensional structure of the muscle resists inward movement of the aponeurosis so that the distance between the fiber origin and the aponeurosis remains constant. For a very small shortening of the muscle, the distance ac represents the shortening of the muscle and is equal to ab*cosΦ where Φ is the instantaneous pennation angle. For a pennate muscle, cosΦ is always less than 1, meaning that the distance ac is always shorter than the distance ab, thus the muscle fiber shortening is 'amplified' by a factor of 1/cosΦ.


Molecular components of myofibrils. Muscle can only contract when actin binding sites are revealed for myosin heads to attach. Created by Servier Medical Art and used under a Creative Commons Attribution 3.0 Unported License.


Left: stress produced by asynchronous muscle under a stretch-hold-release-hold experiment. Right: stress-strain plot showing positive work production. The work generated is equal to the area enclosed by the work loop. Adapted from  Josephson, Malamud & Stokes 2000 .


Asynchronous muscles power flight in most insect species. a: Wings b: Wing joint c: Dorsoventral muscles power the upstroke d: Dorsolongitudinal muscles (DLM) power the downstroke. The DLMs are oriented out of the page.


Swammerdam's illustration of a nerve-muscle preparation.  He placed a frog thigh muscle in a glass syringe with a nerve protruding from a hole in the side of the container.  Irritating the nerve caused the muscle to contract, but the level of the water, and thus the volume of the muscle, did not increase.


3D rendering showing thick myocardium within the heart wall.


Differently oriented cardiac muscle fibers.


Cardiac muscle


Cardiac sarcomere structure


Illustration of a cardiac muscle cell.


Intercalated discs  are part of the cardiac muscle cell  sarcolemma  and they contain  gap junctions  and  desmosomes .


Dog cardiac muscle (400X)


The swirling musculature of the heart ensures effective pumping of blood.


The Norwegian mountain runner  Jon Tvedt  engaging in a strenuous run: it is suggested that the central governor ensures that such  endurance exertion  does not threaten the body's  homeostasis  and physical integrity


Medicine ball plank


From Army FM 3-22.9 page 4-16


The main anatomical planes of the human body, including median (red), parasagittal (yellow), frontal or coronal plane (blue) and transverse or axial plane (green).


Cardiac muscle histology 400x


Muscle Anatomy


Kangaroos  conserve energy between hops using elastic mechanisms


Frogs release stored elastic energy to jump


Galvanism: electrodes touch a frog, and the legs twitch into the upward position [ 1 ]


Johann Georg Sulzer


Luigi Galvani


Alessandro Volta demonstrates his battery to Napoleon.


Giovanni Aldini


Cartoon of a galvanized corpse


Mary Shelley


Carpal tunnel and thenar and hypothenar eminences


Using safety needles that prevent more than one use and accidental injections ensures sterility and prevents  needlestick injuries .


An intramuscular injection is performed perpendicular to the skin, close to a 90 degree angle.


Comparison of angle of intramuscular injection with other injection types


The pupil widens when the iris dilator muscle is stimulated and contracts. An extreme, though natural, case is shown


1:posterior segment 2:ora serrata 3:ciliary muscle 4:ciliary zonules 5:Schlemm's canal 6:pupil 7:anterior chamber 8:cornea 9:iris 10:lens cortex 11:lens nucleus 12:ciliary process 13:conjunctiva 14:inferior oblique muscule 15:inferior rectus muscule 16:medial rectus muscle 17:retinal arteries and veins 18:optic disc 19:dura mater 20:central retinal artery 21:central retinal vein 22:optic nerve 23:vorticose vein 24:bulbar sheath 25:macula 26:fovea  27:sclera 28:choroid 29:superior rectus muscle 30:retina


The pupil constricts when the iris sphincter muscle is stimulated and  contracts


The muscle is made up of several  myofibrils  packed into functional units surrounded by different layers of connective tissues ( epimysium ,  perimysium , and  endomysium ). The main contractile unit is mainly composed of protein filaments (myofilaments), namely myosin (thick filaments) and actin (thin filaments).


Structure of a skeletal muscle.


Shear displacements between two adjacent muscle fibers showing the endomysium in its (a) unconstrained state and (b) after shearing.


Attachment of the perimysium to the endomysium at the perimysial junctional plates (PJPs).


Striated skeletal muscle cells in microscopic view


A chicken embryo, showing the  paraxial mesoderm  on both sides of the neural fold.  The anterior (forward) portion has begun to form  somites  (labeled "primitive segments").


Some types of muscle architecture


Fiber angle of a pennate muscle


Coactivation of  biceps  and  triceps . The biceps’ EMG is on top, while the triceps’ EMG is on the bottom.


Depiction of  smooth muscle  contraction


Types of muscle contractions


In vertebrate animals, there are three types of muscle tissues: 1) skeletal, 2) smooth, and 3) cardiac


Organization of skeletal muscle


Structure of neuromuscular junction.


Picture showing the different interactions within the ECC pathway


Sliding filament theory: A sarcomere in relaxed (above) and contracted (below) positions


Cross-bridge cycle


Muscle length versus isometric force


Force–velocity relationship: right of the vertical axis concentric contractions (the muscle is shortening), left of the axis eccentric contractions (the muscle is lengthened under load); power developed by the muscle in red. Since power is equal to force times velocity, the muscle generates no power at either isometric force (due to zero velocity) or maximal velocity (due to zero force). The optimal shortening velocity for power generation is approximately one-third of maximum shortening velocity.


Swellings called varicosities belonging to an autonomic neuron innervate the smooth muscle cells.


Cardiac muscle


Key proteins involved in cardiac calcium cycling and excitation-contraction coupling


A simplified image showing earthworm movement via peristalsis


Asynchronous muscles power flight in most insect species. a: Wings b: Wing joint c: Dorsoventral muscles power the upstroke d: Dorsolongitudinal muscles (DLM) power the downstroke. The DLMs are oriented out of the page.


Electrodes touch a frog, and the legs twitch into the upward position [ 48 ]


A finger contracture caused by  Dupuytren's contracture .


Toe walking in an autistic individual


Athletes use a combination of strength training, diet, and nutritional supplementation to induce muscle hypertrophy.


Strength training is used to regulate muscle hypertrophy.


Testosterone helps to increase muscle hypertrophy.


Protein biosynthesis starting with transcription and post-transcriptional modifications in the nucleus. Then the mature mRNA is exported to the cytoplasm where it is translated. The polypeptide chain then folds and is post-translationally modified.


Muscle  fibres may be "microtorn" during microtrauma


Hypertrophy of cell


Posterior view of several hip muscles


Anterior view of several hip muscles


Posterior view of gluteus maximus and gluteus medius


Myoblasts (cells with a single nucleus, represented in violet) fusing together to form  muscle fibers  (multinucleated muscle cells) during myogenesis


Patient with  Waardenburg syndrome  III (Waardenburg Klein Syndrome) with wide-set eyes.


MyoD 1 (MYF3) .


Muscular Dystrophy  Histopathology .


Depiction of man exhibiting the  Gowers's sign : common symptom of centronuclear myopathy that results from the weakness of lower limb muscles.


Basic helix–loop–helix .


Filet  of  salmon  showing the zig-zag of myomeres


Fillet of  iridescent shark  showing the zig-zag of myomeres


Global view of a neuromuscular junction:  Axon Motor end-plate Muscle fiber Myofibril


Detailed view of a neuromuscular junction:  Presynaptic  terminal Sarcolemma Synaptic vesicle Nicotinic acetylcholine receptor Mitochondrion


Mind Map  showing a summary of  Neuromuscular nondepolarizing agent


Mind Map  showing a summary of  Neuromuscular depolarizing agent


Fig.1 A simple illustration of how two  acetylcholine  molecules bind to its receptive sites on the nicotinic receptor


Fig.2 A simple illustration of how  decamethonium  binds to the nicotinic receptor. The onium heads bind to two separate subunits of the ion-channel


Fig.3 A simple illustration of how  vecuronium  binds to the nicotinic receptor. Its D-ring binds to the receptor at two points and the lipophillic side of the molecule repels cations from flowing through the ion-channel


A pair of AFO (Ankle Foot Orthosis) braces being used to aid bilateral  foot drop


Codification of Orthoses


Patient after  spinal cord injury  with incomplete paraplegia (lesion height L3) with a knee-ankle-foot orthosis with an integrated stance phase control knee joint


Description of the functions of the large muscle groups used to define the functional elements of a paralysis orthosis intended to compensate for restricted muscle functions


The Amsterdam Gait Classification facilitates the assessment of the gait pattern in CP patients and patients with traumatic brain injury and helps to determine the gait type.


The N.A.P. Gait classification facilitates the assessment of the gait pattern in stroke patients and helps to determine the gait type.


Determination of the strength levels of the large muscle groups, taking into account the muscular fatigue typical of MS patients using the example of the muscle group of the dorsal extensors


Ankle-foot orthosis for the care of patients after  stroke ,  cerebral palsy ,  multiple sclerosis  and other paralyzes of the dorsiflexors and plantar flexors. Designation of the orthosis according to the body parts included in the orthosis fitting: ankle and foot, English abbreviation: AFO for ankle-foot orthoses.


Ankle-foot orthosis (AFO) manufactured using old technology from polypropylene in a variant that is also called "Hinged AFO". It can be used to support an isolated  foot drop , but it will block plantar flexion. This AFO cannot transmit the high forces required to counterbalance weak plantar flexors while standing and walking.


Knee-ankle-foot orthosis for the treatment of patients e.g. with paraplegia after  spinal cord injury ,  poliomyelitis  or  multiple sclerosis . Designation of the orthosis according to the body parts included in the orthosis fitting: knee, ankle and foot, English abbreviation: KAFO for knee-ankle-foot orthoses.


A custom ankle-foot orthotic (AFO) specifically designed and fabricated based on a runner's individual foot and ankle anatomy and biomechanics


Knee orthosis with toothed gear segment joints for the care of patients e.g. after a cruciate ligament tear. Designation of the orthosis according to the body parts included in the orthosis fitting: the knee, English abbreviation: KO for knee orthoses.


Knee bandage/Knee brace


Measurement of pelvic tilt during physical examination to determine whether spinal orthoses are indicated to treat  scoliosis


Halo brace used to immobilize the cervical spine


Jewett hyperextension body brace fitted to adolescent female patient in full support body suit. Designated TLSO as the orthosis fits the thoracic, lumbar and sacroiliac regions, making for a thoraco-lumbo-sacral orthosis.


Figure 1  Pennate muscle fiber arrangements: A,  unipennate ; B,  bipennate ; C, multipennate. Blue: anatomical cross-section. Green: physiological cross-section.


Pennation angle


Figure 2  Architectural gear ratio


Figure 1  Pennate muscle fiber arrangements. The green lines represent PCSA; the blue lines represent ACSA


Various different protein supplements


Muscle contraction based on  sliding filament theory


Molecular model of the Sarcomere in the A-band. Organization of the central region of the A-band (C-zone). The thin filaments (actin in green, tropomyosin in pink) and the thick filaments (myosins in the OFF state are depicted in shades of blue, titin in red) are densely packed within the sarcomere. The myosin-binding protein C (yellow) connects thick and thin filaments. Artistic representation based on publicly available models  [ 4 ] .


Cardiac sarcomere structure


Muscle types by fiber arrangement


Types of  pennate muscle . A –  unipennate ;  B –  bipennate ;  C –  multipennate


ATPase staining of a muscle cross section. Type II fibers are dark, due to the alkaline pH of the preparation. In this example, the size of the type II fibers is considerably less than the type I fibers due to denervation atrophy.


Structure of muscle fibre showing a sarcomere under  electron microscope  with schematic explanation.


Diagram of sarcoplasmic reticulum with terminal cisternae and  T-tubules .


Human embryo  showing  somites  labelled as  primitive segments .


Classes of levers present in the human skeletal muscular system


When a sarcomere contracts, the Z lines move closer together, and the I band becomes smaller. The A band stays the same width. At full contraction, the thin and thick filaments overlap.


Contraction in more detail


(a) Some ATP is stored in a resting muscle. As contraction starts, it is used up in seconds. More ATP is generated from creatine phosphate for about 15 seconds. (b) Each glucose molecule produces two ATP and two molecules of pyruvic acid, which can be used in aerobic respiration or converted to  lactic acid . If oxygen is not available, pyruvic acid is converted to lactic acid, which may contribute to  muscle fatigue . This occurs during strenuous exercise when high amounts of energy are needed but oxygen cannot be sufficiently delivered to muscle. (c) Aerobic respiration is the breakdown of glucose in the presence of oxygen (O2) to produce carbon dioxide, water, and ATP. Approximately 95 percent of the ATP required for resting or moderately active muscles is provided by aerobic respiration, which takes place in mitochondria.


Exercise-induced signaling pathways in skeletal muscle that determine specialized characteristics of slow- and fast-twitch muscle fibers


Jogging  is one form of aerobic exercise.


In  muscular dystrophy , the affected tissues become disorganized and the concentration of  dystrophin  (green) is greatly reduced.


Prisoner of war exhibiting muscle loss as a result of  malnutrition .


Skeletal muscle cell types include: very large multinuclear  muscle fiber cells ; small  endothelial cells  that line the inside of capillary blood vessels; small fibro-adipogenic progenitor cells (FAPs) which are muscle-fiber-adjacent multipotent mesenchymal stem cells that under different conditions can differentiate into adipocytes, fibroblasts or osteocytes.  Also shown are pericytes situated on the outer surface of blood capillaries where they interact with the underlying endothelial cells.  In addition,  satellite cells  are shown that can fuse with muscle fibers and contribute new myonuclei to muscle fibers, grow into  new myocytes , or support focal membrane damage repair. [ 98 ]


Regulation of transcription in mammals.   An active enhancer regulatory region is enabled to interact with the promoter region of its target gene by formation of a chromosome loop. This can allow initiation of messenger RNA (mRNA) synthesis by RNA polymerase II (RNAP II) bound to the promoter at the transcription start site of the gene. The loop is stabilized by one architectural protein anchored to the enhancer and one anchored to the promoter, and these proteins are joined together to form a dimer (red zigzags). Specific regulatory transcription factors bind to DNA sequence motifs on the enhancer. General transcription factors bind to the promoter. When a transcription factor is activated by a signal (here indicated as phosphorylation shown by a small red star on a transcription factor on the enhancer), the enhancer is activated and can now activate its target promoter. The active enhancer is transcribed on each strand of DNA in opposite directions by bound RNAP IIs. Mediator (a complex consisting of about 26 proteins in an interacting structure) communicates regulatory signals from the enhancer DNA-bound transcription factors to the promoter.


A  nucleosome  with  histone  tails set for transcriptional activation ....DNA in the nucleus generally consists of segments of 146  base pairs  of DNA wrapped around  nucleosomes  connected to adjacent nucleosomes by  linker DNA .  Nucleosomes consist of four pairs of histone proteins in a tightly assembled core region plus up to 30% of each histone remaining in a loosely organized  polypeptide  tail (only one tail of each pair is shown). The pairs of histones, H2A, H2B, H3 and H4, each have  lysines  (K) in their tails, some of which are subject to post-translational modifications consisting, usually, of acetylations [Ac] and methylations {me}. The lysines (K) are designated with a number showing their position as, for instance, (K4), indicating lysine as the 4th amino acid from the amino (N) end of the tail in the histone protein. The particular acetylations [Ac] and methylations {Me} shown are those that occur on nucleosomes close to, or at, some DNA regions undergoing transcriptional activation of the DNA wrapped around the nucleosome.


The skeletal muscle pump


Sliding filament theory: A  sarcomere  in relaxed (above) and contracted (below) positions


This model shows the four main and significant steps of the sliding filament theory as well as with a detailed visual.


Structure of muscle fibre (sarcomere) under electron microscope with schematic explanation


Diagrammatic explanation of sliding filament hypothesis


A depiction of a slow wave, contraction and electrical threshold in relation to smooth muscle tone and  resting membrane potential .


The dense bodies and intermediate filaments are networked through the sarcoplasm, which cause the muscle fiber to contract.


Diagram of  ileocaecal valve and sphincter


Hercules and the  Hydra  (ca. 1475) by  Antonio del Pollaiuolo . The hero is known for his strength.


Tensiomyography measurement unit


Tensiomyography measurement


Contraction time of muscle belly response to twitch stimulation for ED (fast muscle) and GCM (slow muscle) measured by tensiomyography. Contraction time is greater in slow muscles than in fast muscles [ 1 ]


Neuromuscular junction (closer view)  presynaptic terminal sarcolemma synaptic vesicles acetylcholine receptors mitochondrion


Tetanic Fade in Response to Evoked Electrical Stimulus in muscle Under a Non-Depolarizing Neuromuscular Blocking Agent or Under Phase 2 Block.


Response of Muscle Tissue to Evoked Tetanic Stimulation Under  Phase 1 Block Demonstrate Diminished Response.


Cardiac sarcomere  structure, featuring titin


Reconstruction of the thin (green) and thick filament from mammalian cardiac tissue. Myosin is in blue, MyBP-C is in yellow, and titin is in two shades of red (dark red for titin-alpha and light red for titin-beta).


Titin Ig domains. a) Schematic of part of a sarcomere b) Structure of Ig domains c) Topology of Ig domains. [ 24 ]


Sliding filament model of muscle contraction. (Titin labeled at upper right.)


Cardiac sarcomere structure featuring tropomyosin


Troponin activation. Troponin C (red) binds Ca2+, which stabilizes the activated state, where troponin I (yellow) is no longer bound to actin. Troponin T (blue) anchors the complex on tropomyosin.


A cutout of the thoracic wall showing the three layers of intercostal muscle - from the left wall.


Magnified view of a tendon


Ossified tendon from an Edmontosaurus bone bed in Wyoming (Lance Formation)


The achilles tendon,  tendo calcaneus  attaches distally to the calcaneual tuberosity, and arises superiorly from the triceps surae complex of the gastrocnemius and soleus muscles.


Achilles tendon at foetus


Microsopic image of a fascial structure ( Ligamentum nuchae ).


The endothoracic fascia is deep to the intercostal space


Anatomical diagrams illustrating the components of the plantar fascia.


Dissection of the plantar aponeurosis: LP, lateral part; CP, central part; MP, medial part; L, length; W, width.


Five central part plantar aponeurosis bundles.


The effect of dorsiflexing the toes on arch height (A). The windlass mechanism (B).


A hematoxylin and eosin stained image (high power) of the short spindle cells of a fetal rhabdomyoma.


Part of the myosin II structure.   Atoms in the heavy chain are colored pink (on the left-hand side); atoms in the light chains are colored faded-orange and faded-yellow (also on the left-hand side).


Myosin unrooted  phylogenetic tree


Sliding filament model  of muscle contraction.


Cardiac sarcomere structure featuring myosin


Self-inhibition of Myosin II. [ 21 ] [ 22 ] [ 23 ]  The movie begins with Myosin II in the 10S conformation with a folded tail domain, the blocked head and free head. [ 24 ] [ 25 ]  The movie schematically depicts tail unfolding and the resulting active 6S confirmation followed by tail folding back to the 10S conformation. [ 26 ] [ 27 ]  The illustration is conceptual: transitory states and diffusive motions associated with folding/unfolding are not shown. [ 28 ]


Crystal structure of myosin V motor with essential light chain – nucleotide-free


A ribbon diagram of the Myosin V molecular motor [ 38 ]  pseudo-colored to illustrate major subdomains. In the interest of visual clarity, important loops (which are often labeled separately in the literature) are not singled out. This perspective highlights the nucleotide-binding site and the separation of the U50 and L50 subdomains which form the actin-binding site cleft.


State of myosin VI from PDB 2V26 before the power stroke  [ 43 ]


Ion channel linked receptor Ions Ligand  (such as  acetylcholine )  When ligands bind to the receptor, the  ion channel  portion of the receptor opens, allowing ions to pass across the  cell membrane .


Botulinum toxin  injected in human face


Structure of diaphragm shown using a 3D medical animation still shot


Definition of  diaphragm  in Blount's 1707  Glossographia Anglicana Nova


Human diaphragm, transverse view from below, showing openings


X-ray  of chest, showing top of diaphragm.


Diaphragm and pleural cavities in amphibian (left), bird (center), mammal (right).  a,  mandible ; b,  genio-hyoid ; c,  hyoid ; d,  sterno-hyoid ; e,  sternum ; f,  pericardium ; g,  septum transversum ; h,  rectus abdominis ; i,  abdominal cavity ; j,  pubis ; k,  esophagus ; l,  trachea ; m, cervical limiting membrane of abdominal cavity; n, dorsal wall of body; o,  lung ; o',  air-sac . [ 24 ]


Human heart during an  autopsy


Computer-generated animation of a beating human heart


The human heart is in the middle of the  thorax , with its apex pointing to the left. [ 15 ]


Heart being dissected showing right and left ventricles, from above


Frontal section showing  papillary muscles  attached to the  tricuspid valve  on the right and to the  mitral valve  on the left via  chordae tendineae . [ 8 ]


Layers of the heart wall, including visceral and parietal pericardium


The swirling pattern of myocardium helps the heart pump effectively


Arterial supply to the heart (red), with other areas labelled (blue).


Autonomic innervation of the heart


Development of the human heart during the first eight weeks (top) and the formation of the heart chambers (bottom). In this figure, the blue and red colors represent blood inflow and outflow (not venous and arterial blood). Initially, all venous blood flows from the tail/atria to the ventricles/head, a very different pattern from that of an adult. [ 8 ]


Blood flow through the valves


The cardiac cycle as correlated to the ECG


The x-axis reflects time with a recording of the heart sounds. The y-axis represents pressure. [ 8 ]


Transmission of a  cardiac action potential  through the heart's conduction system


Conduction system of the heart


The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarisation and repolarisation. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarisation and contraction of the cell; there is no resting potential. [ 8 ]


3D echocardiogram  showing the mitral valve (right), tricuspid and mitral valves (top left) and aortic valve (top right).  The closure of the heart valves causes the  heart sounds .


Cardiac cycle shown against ECG


Heart and its blood vessels, by  Leonardo da Vinci , 15th century


Animated heart


Elize Ryd  making a heart sign at a concert in 2018


A cross section of a three-chambered adult amphibian heart. Note the single ventricle. The purple regions represent areas where mixing of oxygenated and de-oxygenated blood occurs.  Pulmonary vein Left atrium Right atrium Ventricle Conus arteriosus Sinus venosus


Blood flow through the fish heart: sinus venosus, atrium, ventricle, and outflow tract


The tube-like heart (green) of the mosquito  Anopheles gambiae  extends horizontally across the body, interlinked with the diamond-shaped  wing muscles  (also green) and surrounded by  pericardial cells  (red). Blue depicts  cell nuclei .


Basic  arthropod  body structure – heart shown in red


Schematic of  cephalopod  heart


ECGs during sinus rhythm and  AVRT  from a 9-year-old girl with  Ebstein's anomaly  and a Mahaim accessory pathway.


The Caerphilly Heart Disease Study is an epidemiological prospective cohort.


Professor Peter Elwood and his team set up the Caerphilly Heart Disease Study in 1979.


The Caerphilly Study research team, photographed outside the South Wales MRC Unit in Cardiff during the 1980s.


The Caerphilly Study's mobile research unit, parked in the grounds of Caerphilly District Miners' Hospital


Figure 1: Calcium binding to troponin, exposes sites on the actin filaments, to which myosin binds. Using ATP, myosin moves the actin along. The myosin releases the actin, resets itself and binds to another actin binding site.


Blood flow through the valves


3D echocardiogram  viewed from the top, with the upper part of the ventricles removed and the mitral valve clearly visible (cusps are not clear and pulmonary valve not visible). On the left are two, two-dimensional views showing tricuspid and mitral valves (above) and aortic valve (below).


Blood flow diagram of the human heart. Blue components indicate de-oxygenated blood pathways and red components indicate oxygenated pathways.


Details of intercalated discs


Transmission of a  cardiac action potential  through the heart's conduction system


Diagrammatic conduction system of the heart


The prepotential is due to a slow influx of sodium ions until the threshold is reached followed by a rapid depolarization and repolarization. The prepotential accounts for the membrane reaching threshold and initiates the spontaneous depolarization and contraction of the cell; there is no resting potential. [ 1 ]


(a) There is long plateau phase due to the influx of calcium ions. The extended refractory period allows the cell to fully contract before another electrical event can occur. (b) The action potential for heart muscle is compared to that of skeletal muscle. [ 1 ]


Cardiac cycle shown against ECG


The cardiac cycle as correlated to the ECG


The x-axis reflects time with a recording of the heart sounds. The y-axis represents pressure. [ 1 ]


Autonomic Innervation of the heart cardioaccelerator and cardioinhibitory areas.


The wave of depolarization in a normal sinus rhythm shows a stable resting HR. Following parasympathetic stimulation, HR slows. Following sympathetic stimulation, HR increases. [ 1 ]


Cardiac output as shown on an ECG


Major Factors Influencing Cardiac Output - Cardiac output is influenced by heart rate and stroke volume, both of which are also variable. [ 1 ]


Weighing of the heart


Image of veins by William Harvey


Inscription on the pillar containing  Frédéric Chopin 's heart in Warsaw's  Holy Cross Church


Ludwika Jędrzejewicz  smuggled her brother's heart into Poland in 1850.


President  Bolesław Bierut  hands the urn containing Chopin's heart to Warsaw mayor  Stanisław Tołwiński  [ pl ]  in 1945.


The pillar in Holy Cross Church containing Chopin's heart


Frédéric Chopin's heart


Top view of a fresh decellularized, non-seeded, aortic homograft with three pliable cusps.


Framingham Heart Study physicians.


Minuteman  statue at the intersection of Main St. and Union Ave.


The Giant Heart exhibit


Sacred Heart of Jesus,  Church of Saint-Gervais-et-Saint-Protais ,  Paris , France


Holy card  depicting the Sacred Heart of Jesus,  c.  1880 . Auguste Martin collection, University of Dayton Libraries


Sacred Heart of Jesus ,  Portuguese painting  from the 19th century


Mystic Ecstasy  of  St. Gertrude the Great  – worshipper of the Sacred Heart of Jesus Christ (picture by  Pietro Liberi , at the  Abbey of Santa Giustina , Padua, Italy)


Picture of the Sacred Heart being adored by  Margaret Mary Alacoque  and  Mary of the Divine Heart


Jesus embracing all


The Sacred Heart of Jesus with the Jesuit priest  Bernardo de Hoyos


Sacred Heart at the centre of a  rose window , Parish of the Immaculate Conception,  São Paulo ,  Brazil


Stained-glass window with the Sacred Heart of Jesus in a parish church in Southern Germany


Statue of the Sacred Heart of Jesus in the  Sanctuary of the Apparitions  of  Pontevedra


Model of the  Scapular of the Sacred Heart  revealed by the Virgin Mary to  Estelle Faguette  in  Pellevoisin


John Eudes  defended the mystical unity of the Sacred Heart of Jesus and Immaculate Heart of Mary.


The Sacred Heart crowned with thorns, appearing on the  Miraculous Medal


The episode marked the return of  George Takei  as Ricardio.


Solemnity of the arrival of Dom Pedro I's heart in Brazil, in 2022


Dom Pedro I on his deathbed, by José Joaquim Rodrigues Primavera, 1834.


Bas-relief  from 1866 on the statue of Dom Pedro in  Praça da Liberdade , in  Porto , depicting the relic's arrival in the city.


A visual rendition of the Islamic model of the soul showing the position of "'qalb" relative to other concepts based on a consensus of 18 surveyed academic and religious experts. [ 1 ]


Determining viability from peak Ecc values.


The episode guest stars  George Takei .


Ancel Keys


S-ICD lead and generator position


Heart rate (HR) (first row), tidal volume (Vt) (second row), Vt and superimposed HR (third row). The HR modulation is clearly visible: HR increases with inspiration and decreases with expiration.


Heart rate (HR) (first row), ECG signal (ECG) (second row), and respiration (third row) for a newborn subject in a 15-seconds recording. HR expresses oscillations synchronous with respect to respiration.


RSA magnitude estimation based on a multivariate approach based on joint analysis of ECG and respiration. [ 15 ]  The green line shows the heart rate variations averaged over several breathing cycles. This clearly shows the trends that are typical of RSA.


Colchicine is commonly prescribed for gout treatment.


Muscular Weakness brought on by ANIM can induce sleep apnea


EMG is often used as a diagnostic tool for ANIM


Physical Therapy can be used to alleviate atrophy and soreness from ANIM


In this simplified brain circuit, damage to  orexin -secreting neurons in the hypothalamus can lead to inhibition of  motor neurons , thus lowering  muscle tone .


An example of  ragged red fibers


Hand contractures as seen in  Freeman–Sheldon syndrome


From this plot one can conclude that the virus is not causing the spasms, but well the stress induced by the situation.


Medicines that can be prescribed against the cricopharyngeal spasms.


Diastasis recti. 72-year-old man, epigastric protrusion when raising the head.


Abdominal ultrasound  of diastasis recti, being the distance between the green crosses.


Motor endplate of a person with rhabdomyolysis


Actin, and myosin


Renal tubules of exertional rhabdomyolysis


Compartment syndrome in muscle


DNA sequencing electropherograms of a typical FOP patient being compared to other 2 patients. The unsure base "N" indicates site heterozygous for mutation and wild-type gene.


Micrograph  of glycogen storage disease with  histologic  features consistent with  Cori disease .  Liver biopsy .  H&E stain .


Relative incidences of the main types of glycogen storage disease


Autosomal recessive inheritance


A commercially available formulation of HMB. Each  size 000 gelatin capsule  contains 1 gram of  HMB-Ca  and an unspecified amount of  microcrystalline cellulose  and  magnesium stearate .


This graph shows the plasma concentration of HMB (in units of  micromoles  per liter of  blood plasma ) over time following ingestion of a 1 gram dose of the calcium or free acid form of HMB. [ 1 ]


First synthetic routes to  β-hydroxy   β-methylbutyric  acid


Later synthetic routes to  β-hydroxy   β-methylbutyric  acid


Characteristic features, analogy, and pathophysiology of common types of hypertonia. GTO – Golgi Tendon Organ


Affected quadriceps (rectus femoris) in IBM


Affected arms and fingers in IBM


Inclusion body myositis histology


Inclusion body myositis MRI


Dantrolene sodium, the only available medical treatment for malignant hyperthermia


This is a mixed modality medical simulation of the treatment of malignant hyperthermia by anesthesia residents. The residents are managing care, mixing dantrolene and utilizing a cognitive aid at the bedside.


Muscle atrophy from "nondevelopment"


Muscle atrophy from intristic disease in an 18-year-old woman, weight 27 pounds (12.2 kg)


Muscle atrophy from intristic disease in a 17-year-old girl with chronic  rheumatism


This shows an example of the repetitive movement that may cause  tennis elbow .


Strabismus, an ocular condition that prevents both eyes simultaneously focusing on the same point


An x-ray of a spine affected by scoliosis belonging to a 15 year old


3D animation depicting strain


Na + /K + -ATPase maintains the normal gradients of sodium and potassium between cells and extracellular fluid, expending the cellular fuel  ATP  in doing so.


The non-selective beta blocker propranolol can rapidly improve the symptoms of hyperthyroidism, including attacks of TPP.


Karl Friedrich Otto Westphal


The presence of the sternalis in sagittal plane on CT (left) and on volume rendered CT 3D reconstruction (right).


Trace of saccades of the human eye on a face while scanning


Saccadic main sequence, showing single saccades from a participant performing a visually-guided saccade task. It is called "main sequence" because it looks like the  main sequence  in astrophysics.


Brodmann area 8


Figure 1. Motor Cortex of the Monkey Brain : Pictured above are the approximate locations of the SEF and FEF in the monkey brain which we know today.


Figure 2. Ferrier's Monkey Brain Map (1874).   The highlighted area labeled 'EF' is the area he observed to cause eye and head movements when electrically stimulated. [ 9 ]


Figure 3. Brodmann Brain Map : The SEF is located in the rostral supplementary motor area which corresponds to Area 6 in the above map. For reference, the FEF is located in Area 8.


Identify the following parts