Ear clearing ,  clearing the ears  or  equalization   is any of various maneuvers to equalize the pressure in the  middle ear  with the  outside pressure , by letting air enter along the  Eustachian tubes , as this does not always happen automatically when the pressure in the middle ear is lower than the outside pressure. This need can arise in  scuba diving ,  freediving / spearfishing ,  skydiving , fast descent in an  aircraft , fast descent in a  mine cage , and being put into pressure in a  caisson  or similar internally pressurised enclosure, or sometimes even simply travelling at fast speeds in an  automobile . [ 1 ] [ 2 ] [ 3 ] [ 4 ]


Normally the ears will clear automatically during a reduction in ambient pressure, but if they do not, a reverse squeeze may occur, which can also require clearing to avoid causing injury to the eardrum or inner ear.


People who do intense weight lifting, such as squats, may experience sudden conductive hearing loss due to air pressure building up inside the ear. [ citation needed ] [ clarification needed ]  An ear clearing maneuver will often relieve pressure in the middle ear, or pain if any.


The ears can be cleared by various methods, [ 2 ]  some of which pose a distinct risk of  barotrauma  including perforation of the eardrum:


No single method but the last is considered safest or most successful in equalization of the middle ear pressure. Using alternative techniques may improve the success individually when a technique fails. [ 9 ]


The pressure difference between the middle ear and the outside, if not released, can result in a burst  eardrum . [ 10 ]  This damages hearing, [ 11 ]  and if this occurs underwater, cold water in the middle ear chills the  inner ear , causing  vertigo . [ 12 ]  The pressure difference can also cause damage to other body air spaces, such as the  paranasal sinuses . [ 13 ]  This can also be caused by damaged  sinus  ducts.


To allow successful equalization when diving, it is important that the  diving suit  hood not make an airtight seal over the outside ear hole, and that earplugs not be worn. [ 2 ]  Diving is proscribed when a eustachian tube is congested or blocked, such as can occur with the  common cold , as this may cause what is known as a  reverse block ,  whereby descent is uninhibited as the Valsalva maneuver may still clear the eustachian tubes temporarily by force, but during ascent a blockage may stop the air in the middle ear (which is now at depth pressure) from escaping as the diver ascends. The eardrum then bursts outwards, causing the same hazards as with an ordinary burst eardrum, such as cold water in the middle ear deranging the working of the sense organs of balance in the inner ear. [ 14 ]


Nasal congestion may affect the sinus openings and the eustachian tubes and may lead to difficulty or inability to clear the ears.
To prevent congestion, allergies can be treated by the use of  antihistamines ,  decongestants  and  nasal sprays , and  allergy desensitization . Recently developed antihistamines do not cross the  blood–brain barrier  and do not produce drowsiness. [ 15 ]


Decongestants can have side effects such as speeding up heart rate which may have adverse effects in cases where there is underlying cardiovascular disease. Over-the-counter nasal sprays can produce a rebound effect causing greater congestion when the effect wears off, which can lead to reversed ear blockage on ascent. Some steroid nasal sprays do not have this side effect and can be very effective, but may also only be available by prescription.


Combinations of the same drugs are useful in non-allergic rhinitis. These medications can be very useful in controlling the nasal congestion problem. [ 15 ]


Divers get training in clearing the ears before being allowed to dive. [ 2 ]  Because of the potential for side effects of the valsalva maneuver, scuba divers and free-divers may train to exercise the muscles that open the Eustachian tubes in a gentler manner. The French underwater association ( Fédération Française d'Études et de Sports Sous-Marins ) has produced a series of exercises using the tongue and  soft palate  to assist a diver in clearing their ears by these techniques. These recommendations were based on work done at the Médecine du sport, Bd st Marcel, Paris. [ 16 ] [ 17 ]


With practice it is possible for some people to close the nostrils hands-free by contracting the  compressor naris  muscles. Some people are able to voluntarily hold their Eustachian tubes open continuously for a period of several seconds to minutes. The 'clicking your ears' can actually be heard if one puts one's ear to another person's ear for them to hear the clicking sound. Those that are borderline on learning this voluntary control first discover this via yawning or swallowing or other means; which after practice can be done deliberately without force even when there are no pressure issues involved. When the Eustachian tubes are deliberately held open, one's voice sounds louder in one's head than when they are closed.


Ear hair  is the  terminal hair  arising from  folliculary  cartilage inside the  external auditory meatus  in humans. [ 1 ]   In its broader sense,  ear hair  may also include the fine  vellus hair  covering much of the ear, particularly at the prominent parts of the anterior ear, or even the abnormal hair growth as seen in  hypertrichosis  and  hirsutism . Medical research on the function of ear hair is currently very scarce.


Hair growth within the ear canal is often observed to increase in older men, [ 2 ] : 206   together with increased growth of  nasal hair . [ 3 ]   Visible hair that protrudes from the ear canal is sometimes trimmed for cosmetic reasons. [ 4 ] : 97    Excessive hair growth within or on the ear is known medically as  auricular hypertrichosis . [ 5 ] : 125    Some men, particularly in the male population of India, have coarse hair growth along the lower portion of the helix, a condition referred to as "having  hairy  pinnae " ( hypertrichosis lanuginosa acquisita ). [ 6 ]


Hair is a  protein filament  that grows from  follicles  in the  dermis , or skin. With the exception of areas of  glabrous skin , the human body is covered in follicles which produce thick  terminal  and fine  vellus hair . It is an important  biomaterial  primarily composed of protein, notably  keratin .


Radhakant Bajpai, an Indian grocer, was recognized by  Guinness  in 2003 as having the longest ear hair in the world, measuring 13.2 cm. In a 2009 interview, when his hair had reached 25 cm, he said that he considered the long ear hair to be a symbol of luck and prosperity. [ citation needed ]


Ear pain , also known as  earache  or  otalgia , is  pain  in the  ear . [ 1 ] [ 2 ]  Primary ear pain is pain that originates from the ear. Secondary ear pain is a type of  referred pain , meaning that the source of the pain differs from the location where the pain is felt.


Most causes of ear pain are non-life-threatening. [ 3 ] [ 4 ]  Primary ear pain is more common than secondary ear pain, [ 5 ]  and it is often due to infection or injury. [ 3 ]  The conditions that cause secondary (referred) ear pain are broad and range from temporomandibular joint syndrome to inflammation of the throat. [ 3 ]


In general, the reason for ear pain can be discovered by taking a thorough history of all symptoms and performing a physical examination, without need for imaging tools like a CT scan. [ 3 ]  However, further testing may be needed if red flags are present like hearing loss, dizziness, ringing in the ear or unexpected weight loss. [ 6 ]


Management of ear pain depends on the cause. If there is a bacterial infection,  antibiotics  are sometimes recommended and over the counter pain medications can help control discomfort. [ 7 ]  Some causes of ear pain require a procedure or surgery. [ 7 ] [ 8 ] [ 9 ]


83 percent of children have at least one episode of a middle ear infection by three years of age. [ 10 ]


Ear pain can present in one or both ears. It may or may not be accompanied by other symptoms such as  fever ,  sensation of the world spinning , ear itchiness, or a sense of fullness in the ear. The pain may or may not worsen with chewing. [ 3 ]  The pain may also be continuous or intermittent. [ 11 ]


Ear pain due to an infection is the most common in children and can occur in babies. [ 10 ]  Adults may need further evaluation if they have hearing loss, dizziness or ringing in the ear. [ 6 ]  Additional red flags include diabetes, a weakened immune system, swelling seen on the outer ear, or swelling along the jaw. [ 12 ]


Ear pain has a variety of causes, the majority of which are not  life-threatening . [ 3 ] [ 4 ]  Ear pain can originate from a part of the ear itself, known as primary ear pain, or from an anatomic structure outside the ear that is perceived as pain within the ear, known as secondary ear pain. [ 3 ]  Secondary ear pain is a type of  referred pain , meaning that the source of the pain differs from the location where the pain is felt. Primary ear pain is more common in children, whereas secondary (referred) pain is more common in adults. [ 13 ]


Primary ear pain is most commonly caused by  infection  or injury to one of the parts of the ear. [ 3 ]


Many conditions involving the external ear will be visible to the naked eye.  Because the external ear is the most exposed portion of the ear, it is vulnerable to trauma or environmental exposures. [ 14 ]   Blunt trauma, such as a blow to the ear, can result in a  hematoma , or collection of blood between the cartilage and  perichondrium  of the ear. This type of injury is particularly common in contact sports such as wrestling and boxing. [ 15 ]  Environmental injuries include  sunburn ,  frostbite , or  contact dermatitis . [ 14 ]


Less common causes of external ear pain include: [ 14 ] [ 16 ]


Otitis externa , also known as "swimmer's ear", is a  cellulitis  of the external ear canal. In North America, 98% of cases are caused by bacteria, and the most common causative organisms are  Pseudomonas  and  Staph aureus . [ 18 ]  Risk factors include exposure to excessive moisture (e.g. from swimming or a warm climate) and disruption of the protective  cerumen  barrier, which can result from aggressive ear cleaning or placing objects in the ear. [ 19 ]


Malignant otitis externa is a rare and potentially life-threatening complication of otitis externa in which the infection spreads from the ear canal into the surrounding skull base, hence becoming an  osteomyelitis . [ 16 ]  It occurs largely in diabetic patients. [ 20 ]  It is very rare in children, though can be seen in  immunocompromised  children and adults. [ 19 ]   Pseudomonas  is the most common causative organism. [ 20 ]  The pain tends to be more severe than in uncomplicated otitis externa, and laboratory studies often reveal elevated inflammatory markers ( ESR  and/or  CRP ). The infection may extend to  cranial nerves , or rarely to the  meninges  or brain. [ 20 ]  Examination of the ear canal may reveal  granulation tissue  in the inferior canal. It is treated with several weeks of IV and oral antibiotics, usually  fluoroquinolones . [ 20 ]


Acute  otitis media  is an infection of the middle ear. More than 80% of children experience at least one episode of otitis media by age 3 years. [ 23 ]   Acute otitis media is also most common in these first 3 years of life, though older children may also experience it. [ 19 ]  The most common causative bacteria are  Streptococcus pneumoniae ,  Haemophilus influenzae , and  Moraxella catarrhalis . [ 19 ]   Otitis media often occurs with or following  cold  symptoms. [ 14 ]  The diagnosis is made by the combination of symptoms and examination of the  tympanic membrane  for redness, bulging, and/or a middle ear effusion (collection of fluid within the middle ear). [ 5 ]


Complications of otitis media include  hearing loss , facial nerve paralysis, or extension of infection to surrounding anatomic structures, including: [ 24 ]


A variety of conditions can cause irritation of one of the nerves that provides sensation to the ear.


Conditions causing irritation the trigeminal nerve (cranial nerve V): [ 3 ]


Conditions causing irritation of the facial nerve (cranial nerve VII) or glossopharyngeal nerve (cranial nerve IX): [ 3 ]


Conditions causing irritation of the vagus nerve (cranial nerve X): [ 3 ]


Conditions causing irritation of cervical nerves C2-C3: [ 3 ] [ 14 ]


The ear can be anatomically divided into the  external ear , the  external auditory canal , the middle ear, and the  inner ear . [ 30 ]  These three are indistinguishable in terms of the pain experienced. [ 2 ]


Many different nerves provide sensation to the various parts of the ear, including cranial nerves V ( trigeminal ), VII ( facial ), IX ( glossopharyngeal ), and X ( vagus ), and the  great auricular nerve  (cervical nerves C2-C3). [ 30 ] [ 32 ]  These nerves also supply other parts of the body, from the mouth to the chest and abdomen. Irritation of these nerves in another part of the body has the potential to produce pain in the ear. [ 30 ]  This is called referred pain. Irritation of the trigeminal nerve (cranial nerve V) is the most common cause of referred ear pain. [ 3 ]


While some disorders may require specific imaging or testing, most etiologies of ear pain are diagnosed clinically. Because the differential for ear pain is so broad, there is no consensus on the best diagnostic framework to use. One approach is to differentiate by time course, as primary causes of ear pain are typically more acute in nature, while secondary causes of ear pain are more chronic.


Acute causes may be further distinguished by the presence of fever (indicating an underlying infection) or the absence of fever (suggesting a structural problem, such as such as trauma or other injury to the ear). Etiologies leading to chronic pain may be broken down by the presence or absence of worrisome clinical features, also known as red flags.


One red flag is the presence of one or multiple risk factors including smoking, heavy alcohol use (greater than 3.5 drinks per day), diabetes, coronary artery disease, and older age (greater than 50). [ 3 ]  These factors increase the risk of having a serious cause of ear pain, like cancer or a serious infection. In particular, second hand smoke may increase risk of acute otitis media in children. [ 33 ]  In addition, swimming is the most significant risk factor for otitis externae, though other risk factors include high humidity in the ear canal,  eczema  and/or ear trauma. [ 34 ]


If red flags are present it may be necessary to do additional workup such as a  CT scan  or  biopsy  to rule out a more dangerous diagnosis. Such diagnoses include malignant (or necrotizing) otitis externa, mastoiditis,  temporal arteritis , and cancer. While the presence of a red flag does raise suspicion for one of these four disease, it does not guarantee a diagnosis as any one symptom can be seen in a variety of situations. For example, jaw claudication can be seen in temporal arteritis, but also in  TMJ dysfunction . [ 4 ]


If there are no red flags, other sources of referred ear pain become more likely and are reasonable to pursue.


(otitis media with effusion)


otitis externa*


*Indicates a "Can't Miss" diagnosis or a red flag.


Management of ear pain depends on the underlying cause.


While not all causes of ear pain are treated with antibiotics, those caused by bacterial infections of the ear are usually treated with antibiotics known to cover the common bacterial organisms for that type of infection. Many bacterial ear infections are treated with cleaning of the area, topical or systemic antibiotics, and oral analgesics for comfort. [ 7 ] [ 35 ] [ 9 ]  Some types of bacterial ear infections can benefit from warm compresses included in the treatment. [ 7 ]  Some of the causes of ear pain that are typically treated with either a topical or systemic antibiotic include:


Some bacterial infections may require a more advanced treatment with evaluation by  otorhinolaryngology , IV antibiotics, and hospital admission.


Some causes of ear pain require procedural management alone, by a health professional, or in addition to antibiotic therapy.


Given the variety of causes of ear pain, some causes require treatment other than antibiotics and procedures.


2/3 of people presenting with ear pain were diagnosed with some sort of primary otalgia and 1/3 were diagnosed with some sort secondary otalgia. [ 5 ]


A common cause of primary otalgia is ear infection called otitis media, meaning an infection behind the eardrum. [ 3 ]  The peak age for children to get acute otitis media is ages 6–24 months. One review paper wrote that 83% of children had at least one episode of acute otitis media by 3 years of age. [ 10 ]  Worldwide, there are 709 millions cases of acute otitis media every year. [ 36 ]  Hearing loss globally due to ear infection is estimated to be 30 people in every 10,000. [ 36 ]  Around the world there is around 21,000 to 28,000 deaths due to complications from ear infections. [ 36 ]  These complications include brain abscesses and meningitis.


Otitis externae peaks at age 7–12 years of age and around 10% of people has had it at least once in their lives. [ 10 ]


Cerumen impaction occurs in 1 out of every 10 children, 1 in every 20 adults and 1 in every 3 elderly citizens. [ 10 ]


Barotrauma occurs around 1 in every 1000 people. [ 5 ]


Of people presenting with ear pain, only 3% was diagnosed with eustachian tube dysfunction. [ 3 ]


Not much was known about ear pain and acute otitis media before the 17th century. It was a common phenomenon with no treatment. [ 37 ]  That changed when the  otoscope  was invented in the 1840s by  Anton von Troeltsh  in Germany. [ 37 ]   Another shift came with the invention of antibiotics. Before antibiotics was introduced there used to be a high rate of ear infections spreading to the bone around the ear, but that is now considered a rare complication. [ 5 ]


There was previously a strong tradition of treating acute otitis media with amoxicillin. [ 5 ]  One quote from the 1980s shows this sentiment by saying "any child with an earache has an acute amoxicillin deficiency". [ 5 ]  However, people started realizing that using antibiotics too much can cause bacteria to gain resistance. [ 38 ]  Increasing resistance makes antibiotics less effective. The term  antibiotic stewardship  is then used to describe the systematic effort to educate antibiotic prescribers to only give these medications when they are warranted. In particular to children, most ear pain resolves by itself with no complications. [ 36 ]  There are  guidelines  in place to help determine when antibiotics for ear pain are needed in children.


The ear itself played a role in treatment via  acupuncture , also known as  auriculotherapy . It was believed that acupuncture of the ear could be used to correct other pain or disorders in the body. Such practices may have started as far back as the  Stone Age . The first documentation of auriculotherapy in Europe was in the 1600s. One physician described stimulating the ear by burning or scarring to treat sciatic pain, while another physician applied this treatment for toothache. Paul Nogier is known as the father of ear acupuncture for his theory that parts of the ear corresponds to other areas of the body in a reliable fashion. [ 39 ]


There are currently studies going on delivering antibiotics directly into the middle ear. [ 36 ]


In the  anatomy  of humans and various other  tetrapods , the  eardrum , also called the  tympanic membrane  or  myringa , is a thin, cone-shaped  membrane  that separates the  external ear  from the  middle ear . Its function is to transmit changes in  pressure  of  sound  from the air to the  ossicles  inside the middle ear, and thence to the  oval window  in the fluid-filled  cochlea . The ear thereby converts and amplifies vibration in the air to vibration in cochlear fluid. [ 1 ]  The  malleus  bone bridges the gap between the eardrum and the other ossicles. [ 2 ]


Rupture or  perforation of the eardrum  can lead to  conductive hearing loss . Collapse or  retraction  of the eardrum can cause conductive hearing loss or  cholesteatoma .


The tympanic membrane is oriented obliquely in the  anteroposterior , mediolateral, and superoinferior planes. Consequently, its superoposterior end lies lateral to its anteroinferior end. [ citation needed ]


Anatomically, it relates superiorly to the  middle cranial fossa , posteriorly to the  ossicles  and  facial nerve , inferiorly to the  parotid gland , and anteriorly to the  temporomandibular joint . [ citation needed ]


The eardrum is divided into two general regions: the  pars flaccida  and the  pars tensa . [ 3 ]  The relatively fragile pars flaccida lies above the lateral  process  of the  malleus  between the  Notch of Rivinus  and the anterior and posterior malleal folds. Consisting of two layers and appearing slightly pinkish in hue, it is associated with [ vague ]   Eustachian tube  dysfunction and  cholesteatomas . [ 4 ]


The larger pars tensa consists of three layers:  skin ,  fibrous tissue , and  mucosa . Its thick periphery forms a  fibrocartilaginous ring  called the  annulus tympanicus  or Gerlach's ligament. [ 5 ]  while the central  umbo  tents inward at the level of the tip of malleus. The middle fibrous layer, containing radial, circular, and parabolic fibers, encloses the handle of malleus. Though comparatively robust, the pars tensa is the region more commonly associated with [ vague ]  perforations. [ 6 ]


The manubrium (Latin for "handle") of the  malleus  is firmly attached to the medial surface of the membrane as far as its center, drawing it toward the  tympanic cavity . The lateral surface of the membrane is thus concave. The most depressed aspect of this concavity is termed the umbo (Latin for " shield boss "). [ 7 ]


Sensation of the outer surface of the tympanic membrane is supplied mainly by the  auriculotemporal nerve , a branch of the  mandibular nerve  ( cranial nerve   V 3 ), with contributions from the  auricular branch of the vagus nerve  ( cranial nerve X ), the  facial nerve  (cranial nerve VII), and possibly the  glossopharyngeal nerve  (cranial nerve IX). The inner surface of the tympanic membrane is innervated by the glossopharyngeal nerve. [ 8 ]


When the eardrum is illuminated during a  medical examination , a  cone of light  radiates from the tip of the malleus to the periphery in the anteroinferior quadrant, this is what is known clinically as 5 o'clock. [ citation needed ]


Unintentional  perforation  (rupture) has been described in  blast injuries [ 9 ]  and  air travel , typically in patients experiencing  upper respiratory   congestion  or general  Eustachian tube dysfunction  that prevents equalization of pressure in the middle ear. [ 10 ]  It is also known to occur in  swimming ,  diving  (including  scuba diving ), [ 11 ]  and  martial arts . [ 12 ]


Patients with tympanic membrane rupture may experience bleeding,  tinnitus ,  hearing loss , or disequilibrium ( vertigo ). However, they rarely require medical intervention, as between 80 and 95 percent of ruptures recover completely within two to four weeks. [ 13 ] [ 14 ] [ 15 ]  The prognosis becomes more guarded as the force of injury increases. [ 15 ]


In some cases, the pressure of fluid in an infected middle ear is great enough to cause the eardrum to rupture naturally. Usually, this consists of a small hole (perforation), from which fluid can drain out of the middle ear. If this does not occur naturally, a  myringotomy  (tympanotomy, tympanostomy) can be performed. A myringotomy is a  surgical  procedure in which a tiny incision is created in the eardrum to relieve pressure caused by excessive buildup of fluid, or to drain  pus  from the  middle ear . The fluid or pus comes from a middle ear infection ( otitis media ), which is a common problem in children. A  tympanostomy tube  is inserted into the eardrum to keep the middle ear aerated for a prolonged time and to prevent reaccumulation of fluid.  Without the insertion of a tube, the incision usually heals spontaneously in two to three weeks.  Depending on the type, the tube is either naturally extruded in 6 to 12 months or removed during a minor procedure. [ 16 ]


Those requiring myringotomy usually have an obstructed or dysfunctional  Eustachian tube  that is unable to perform drainage or ventilation in its usual fashion.  Before the invention of antibiotics, myringotomy without tube placement was also used as a major treatment of severe acute otitis media. [ 16 ]


The  Bajau  people of the  Pacific  intentionally rupture their eardrums at an early age to facilitate diving and hunting at sea. Many older Bajau therefore have difficulties hearing. [ 17 ]


This article incorporates text in the  public domain  from  page 1039  of the 20th edition of   Gray's Anatomy   (1918)


Epiglottitis  is the  inflammation  of the  epiglottis —the flap at the base of the  tongue  that prevents food entering the  trachea  (windpipe). [ 7 ]  Symptoms are usually rapid in onset and include trouble swallowing which can result in drooling, changes to the voice, fever, and an increased breathing rate. [ 1 ] [ 2 ]  As the epiglottis is in the  upper airway , swelling can interfere with  breathing . [ 7 ]  People may  lean forward  in an effort to open the airway. [ 1 ]  As the condition worsens,  stridor  and  bluish skin  may occur. [ 1 ]


Epiglottitis was historically mostly caused by infection by  H. influenzae type b  (commonly referred to as "Hib"). [ 1 ]  With vaccination, it is now more often caused by other bacteria, most commonly  Streptococcus pneumoniae ,  Streptococcus pyogenes , or  Staphylococcus aureus . [ 1 ]  Predisposing factors include  burns  and trauma to the area. [ 1 ]  The most accurate way to make the diagnosis is to look directly at the epiglottis. [ 3 ]  X-rays of the neck from the side may show a "thumbprint sign" but the lack of this sign does not mean the condition is absent. [ 1 ]


An effective vaccine, the  Hib vaccine , has been available since the 1980s. [ 4 ]  The  antibiotic   rifampicin  may also be used to prevent the disease among those who have been exposed to the disease and are at high risk. [ 5 ]  The most important part of treatment involves securing the airway, which is often done by  endotracheal intubation . [ 1 ]  Intravenous antibiotics such as  ceftriaxone  and possibly  vancomycin  or  clindamycin  is then given. [ 2 ] [ 4 ]   Corticosteroids  are also typically used. [ 1 ]  With appropriate treatment, the risk of death among children with the condition is about one percent and among adults is seven percent. [ 3 ]


With the use of the Hib vaccine, the number of cases of epiglottitis has decreased by more than 95%. [ 8 ]  Historically, young children were mostly affected, but it is now more common among older children and adults. [ 4 ]  In the United States, it affects about 1.3 per 100,000 children a year. [ 1 ]  In adults, between 1 and 4 per 100,000 are affected a year. [ 6 ]  It occurs more commonly in the  developing world . [ 9 ]  In children the risk of death is about 6%; however, if they are  intubated  early, it is less than 1%. [ 5 ]


Epiglottitis is associated with  fever , throat pain,  difficulty in swallowing , drooling, hoarseness of voice, and  stridor . [ 10 ]  Onset is typically over a day. [ 10 ]  The throat itself may appear normal. [ 10 ]


Stridor is a sign of upper airway obstruction and is a surgical emergency. The child often appears acutely ill, anxious, and will have very quiet shallow breathing often keeping the head held forward and insisting on sitting up in bed, commonly called the " tripod position ." [ 11 ]  The early symptoms are usually insidious but rapidly progressive, and swelling of the throat may lead to  cyanosis  and  asphyxiation . [ 12 ]


Adults commonly present with less dramatic breathing symptoms than children due to them having wider airways to begin with, so their main symptoms are usually a severe sore throat and difficulty swallowing. [ 11 ]  The back of the throat appears normal in 90% of adult patients, so epiglottitis should considered when there is pain out of proportion to exam or when pain is caused by pressing on the external windpipe. [ 11 ]  Adult epiglottitis is often referred to as supraglottitis. In contrast to children, the symptoms are non-specific, sub-acute and can be unpredictable.  [ 13 ]


Epiglottitis is primarily caused by an acquired  bacterial   infection  of the epiglottis. [ 1 ]  Historically it was most often caused by  Haemophilus influenzae type B , but with the availability of immunization this is no longer the case. [ 1 ]   H. influenzae type B  contains a  capsule  which helps it avoid being destroyed by  macrophages  and also contains surface proteins that allow it to stick to the lining of the upper respiratory tract. [ 14 ]  Presently, the bacteria most often causing infection are other encapsulated organisms including  Streptococcus pneumoniae ,  Streptococcus pyogenes , and  Staphylococcus aureus . [ 1 ]  These bacteria spread in  respiratory droplets  or  aerosols  produced from coughing and sneezing. [ 15 ] [ 16 ]  While the overall incidence of epiglottitis has decreased, the incidence of cases caused by Streptococcus pneumoniae has increased in adults. [ 17 ]  The exact  strains  of  Streptococcus pneumoniae  are often those that are covered by the  PPV-23 vaccine , [ 17 ]  but there is no evidence that this vaccine prevents epiglottitis.


There have been many cases of epiglottitis reported in  immunocompromised  patients, including those undergoing cancer treatment and those who are  HIV  positive. [ 18 ]  While a variety of different bacteria can cause disease in these patients, cases often involve the  Candida  species of fungus, though it is unknown if the fungus causes significant disease on its own. [ 18 ]


Alternate risk factors and causes associated with infection include  burns  and other trauma to the area. [ 1 ]  Medical research has also identified a link between epiglottitis and  crack cocaine  usage. [ 19 ]   Underlying disorders of the immune system, such as  graft-versus-host disease  and  lymphoproliferative disorders , have also been identified as contributors of increased risk for developing the infection . [ 4 ]


Diagnosis may be confirmed by direct inspection using a  laryngoscope , although this may provoke airway  spasm . [ 20 ]  If epiglottitis is suspected, attempts to visualize the epiglottis using a  tongue depressor  are discouraged for this reason; therefore, diagnosis is made on basis of  indirect fiberoptic laryngoscopy  carried out in a controlled environment like an operating room. [ 20 ]  An infected epiglottis appears swollen and is described as having a "cherry-red" appearance. [ 21 ]  Imaging is rarely useful, and treatment should not be delayed for this test to be carried out. [ 20 ]


On  lateral   C-spine   X-ray , the  thumbprint sign  describes a swollen, enlarged epiglottis. [ 10 ]  A normal X-ray, however, does not exclude the diagnosis. [ 10 ]  An  ultrasound  may be helpful if specific changes are present, but its use (as of 2018) is in the early stages of study. [ 10 ]


On  CT imaging , the "Halloween sign" describes an epiglottis of normal thickness. It can safely exclude the acute epiglottitis. Furthermore, CT imaging can help to diagnose other conditions such as  peritonsillar abscess  or  retropharyngeal abscess  which have similar clinical features. [ 22 ]


If there is visual or radiologic evidence that the infection has caused tissue destruction, the disease is called "necrotizing epiglottitis" (NE). [ 23 ]  The feared complication of NE is the bacteria spreading to the surrounding neck muscles and causing cervical  necrotizing fasciitis  which is a surgical emergency. [ 23 ]


The differential diagnosis includes other infectious causes of acute airway obstruction, as well as acute or subacute mechanical causes. It includes, but is not limited to, the conditions below. [ 24 ] [ 25 ]


An effective vaccine, the  Hib vaccine , has been available since the 1980s. [ 4 ]  Modern Hib vaccines are mainly  conjugate vaccines , with the key component being the  polysaccharide  found in the bacteria's  capsule  which is its primary  virulence factor . [ 26 ]  Currently, the CDC recommends that children receive a two or three-dose primary series with an additional booster dose. [ 27 ]  The countries of the world who have included the Hib vaccine in their immunization schedules typically begin the series at the age of two or three months with subsequent doses administered at four or eight week intervals. [ 28 ]  Routine vaccination in these nations has led to a dramatic decrease in the  incidence  of invasive diseases caused by  H. influenzae type b  such as epiglottitis,  meningitis  and  pneumonia . [ 28 ]  It has been reported that epiglottitis cases have decreased by 95% since the 1980s following the introduction of the first Hib vaccine. [ 8 ]


The  antibiotic   rifampicin  may also be used to prevent the disease among those who have been exposed to the disease and are at high risk. [ 5 ] [ 21 ]


The most important part of treatment involves securing the airway. [ 1 ]  Nebulized  epinephrine  may be useful to improve the situation temporarily. [ 10 ]   Corticosteroids  are also typically used. [ 1 ]  However, there is poor evidence for whether steroids actually improve patient outcomes. [ 10 ]  Epiglottitis may require urgent  tracheal intubation  to protect the airway. [ 1 ]  Tracheal intubation can be difficult due to distorted anatomy and profuse secretions. Spontaneous respiration is ideally maintained until tracheal intubation is successful. [ 10 ]  A surgical airway opening ( cricothyrotomy ) may be required if intubation is not possible. [ 10 ]  The management of epiglottitis is different in adults compared to children. [ 13 ]  Emergent tracheal intubation with general anesthesia (inhalational induction to preserve spontaneous ventilation) in the operating theater is standard. [ 13 ]  However only 10% of adults require airway intervention, which means a selective approach is required. [ 13 ]  Tracheal intubation is a high risk scenario with a 1 in 25 failure rate in adults. [ 13 ]  Multiple airway management techniques have described for adults and include: awake tracheostomy, awake fibreoptic intubation, general anesthesia with spontaneous breathing preserved or ablated with paralysis. [ 13 ]  The optimal technique is controversial and likely determined by contextual factors such as the severity of epiglottitis and the clinical location (ie emergency department or intensive care or the operating room). [ 13 ]  Ideally airway intervention should occur in the operating room with an otolaryngology surgeon present to perform an emergency tracheostomy in the event of complete airway obstruction or failed intubation. [ 13 ]


Intravenous antibiotics such as  ceftriaxone  and possibly  vancomycin  or  clindamycin  are given once the airway is secure. [ 2 ] [ 4 ]  A  third-generation cephalosporin  such as ceftriaxone is usually sufficient since it is usually effective against  H. influenzae  and  S. pneumoniae . [ 29 ]  If  S. aureus  is suspected to be causing the disease, then the treatment should include  ceftaroline  or clindamycin as these would provide coverage against antibiotic resistant strains of that bacteria ( MRSA ). [ 29 ]  Vancomycin can also be considered for its MRSA coverage, but it may be less safe than ceftaroline in children older than two months. [ 29 ]  If the patient has a penicillin allergy,  trimethoprim/sulfamethoxazole ,  clindamycin , or  levofloxacin  may be appropriate choices. [ 29 ] [ 11 ]


Necrotizing epiglottitis is treated similarly to uncomplicated epiglottitis, but usually requires intubation in addition to standard IV antibiotic therapy. [ 23 ]  If the tissue damage continues to spread and necrotizing fasciitis of the neck is suspected, patients are taken to the operating room for emergency  debridement . [ 23 ]


With appropriate treatment, the risk of death among children with the condition is about one percent and among adults is seven percent. [ 3 ]  Elsewhere, it has been reported that only one percent of adults diagnosed with epiglottitis die from the disease. [ 11 ]  Some people may develop  pneumonia ,  lymphadenopathy , or  septic arthritis . [ 30 ]


Between 1998 and 2006, there were an average of 36 deaths per year in the United States attributed to epiglottitis, giving a case-fatality rate of 0.89% during that time period. [ 31 ]


Patients who recover from necrotizing epiglottitis often regain their ability to swallow foods and liquids despite the tissue damage. [ 23 ]


While, historically, young children were mostly affected, it is now more common among older children and adults. [ 4 ]  Before  Haemophilus influenzae  (Hib) immunization children of two to four were most commonly affected. [ 1 ]  With immunization about 1.3 per 100,000 children are affected a year. [ 1 ]  It has been reported that only 0.5 per 100,000 American children are diagnosed every year, while the incidence in American adults is about 1 to 4 per 100,000. [ 11 ]  A 2010 retrospective study revealed the average age of patients admitted to American hospitals for epiglottitis was about 45, but patients under the age of 1 and over the age of 85 are also particularly vulnerable. [ 31 ]


Bill Bixby 's 6-year-old son Christopher died of the condition in 1981. [ 32 ]


Jeannie Mai  spent some time in an  ICU  with epiglottitis. [ 33 ]


Sarah Silverman  spent a week in the ICU at  Cedars Sinai Hospital  with epiglottitis. [ 34 ] [ 35 ] [ 36 ]


George Washington  is thought to have died of epiglottitis. [ 37 ]  The treatments given to Washington, such as severe  bloodletting , an  enema , vinegar, sage, molasses, butter, blistering his throat with  Spanish fly , requiring him to swallow mercurous chloride and antimony potassium tartrate, and applying wheat poultices to various parts of the body, are no longer used. [ 38 ]


Jin  announced in a 2022 video that he had been diagnosed with epiglottitis. [ 39 ]


Wes Moore 's father died of epiglottitis when Moore was four years old. [ 40 ]


Epignathus  is a rare  teratoma  of the  oropharynx . [ 1 ]  Epignathus is a form of oropharyngeal teratoma that arises from the  palate  and, in most cases, results in death. The pathology is thought to be due to unorganized and uncontrolled differentiation of  somatic cells  leading to formation of the teratoma; sometimes it is also referred to as  fetus  in fetu , which is an extremely rare occurrence of an incomplete but  parasitic  fetus located in the body of its twin. [ 2 ] [ 3 ]  This tumor is considered benign (non- cancerous ) but life-threatening because of its atypical features (size, location, and rate of development) and high risk of  airway obstruction , which is the cause of death in 80-100% of the cases at the time of delivery. [ 1 ]


Despite the high mortality rate, the most important factor in improving survival probability is to detect and diagnose the lesion before birth using  ultrasound  and  MRI  scans. [ 4 ]  If undetected prenatally, the epignathus will be apparent immediately after birth, but prognosis will be poor due to lack of preparation and treatment plans. [ 1 ]  Most babies with epignathus have a poor prognosis due to late diagnosis and, subsequently, complications in securing the airway. [ 2 ]  However, with early detection and multidisciplinary healthcare teams, an adequate treatment plan to secure the baby's airway and surgically remove the lesion may improve the prognosis. [ 2 ]  Treatment options for this rare condition prioritize managing the risk of  asphyxiation  prior to deciding on an appropriate plan for the teratoma resection. [ 5 ]


Teratomas , which are generally benign tumors, originate from  stem cells , with the oropharynx (epignathus) region being the second most common location for head and neck teratomas. [ 2 ]  The tumor arises from the palato-pharyngeal region around the  basisphenoid  ( Rathke's pouch ), or most commonly the base of the skull. [ 6 ]  Epignathi are present from birth and has been shown to affect all three germ layers (ectodermal, mesodermal, and endodermal layers) and can include cartilage, bone, and fat. [ 1 ] [ 2 ]  Case reports describe the possibility for an epignathus to present as an incompletely formed and parasitic fetal twin, which is called fetus  in fetu . [ 7 ]  Many case reports about babies with epignathus have reported common malformations of  cleft palate , and bifid tongue and/or  nose . [ 1 ] [ 2 ]  The tumor can grow within the oral cavity and protrude out of the mouth, causing obstruction of the airway and therefore mortality. [ 8 ]  This lesion may be associated with  polyhydramnios  – excessive amniotic fluid around the fetus – and typically prevents the fetus from swallowing the amniotic fluid. In rare cases, the tumor may extend into the  cranial cavity , including into the brain, or it may become encapsulated in the cranial cavity and not enter the brain at all. [ 9 ]  Most neonates and young children who present with epignathus have exhibited benign tumors, in comparison to older children and adults who have presented with more malignant teratomas. [ 2 ]


Recent findings have shown some genetic abnormalities associated with epignathi. [ 9 ]  There have been case reports noting chromosomal irregularities such as a  49,XXXXY  karyotype, [ 10 ]  duplication of 1q and 19p, [ 11 ]  and ring X chromosome mosaicism. [ 12 ]  However, this theory is still inconclusive, as there have been other studies that have shown no chromosomal abnormalities. [ 13 ]


Teratomas develop in the head and neck region with a  live birth  (fetus shows signs of life after leaving mother's womb) incidence of 1:20,000 to 40,000. [ 14 ]  Due to the rarity of epignathus, the information gathered regarding incidence and prevalence is sourced from case reports. The occurrence of epignathus, a teratoma of the oropharynx, is extremely rare, with a live birth incidence found to be 1:35,000 to 1:200,000. [ 1 ]  Of the reported cases, epignathus was found to be more common in females than in males (3:1 ratio); however, there is a lack of evidence demonstrating that an individual's genetic makeup will increase the likelihood of developing this form of teratoma. [ 15 ]  The studies have shown having one child with epignathus does not increase the chances of having pregnancies with this disease in the future. [ 16 ]  An estimated 10% of most epignathus diagnoses also report various epignathus-related abnormalities and deformities, such as the formation of a  cleft palate  (split in the mouth's roof due to abnormal fusing of the hard palate during fetal development),  hemangiomas  (pathological development of extra blood vessels). [ 17 ] [ 2 ]


Epignathus occurs at a critical location, which makes this tumor extremely dangerous and not resectable in newborn children. One of the primary modalities that can be used for diagnosing teratoma and epignathus is  ultrasound . Diagnosis of epignathus may be made before the birth of the child by using ultrasound. Sonography evaluation is essential during pregnancy for diagnosing epignathus and, in some cases, surgically removing the teratoma while the child is still in the womb. [ 3 ]  One of the main characteristics of epignathus in the sonography evaluation is a relatively large mass that can be seen in the anterior or front side of the neck. [ 3 ] [ 8 ]


For diagnosing epignathus,  radiography , which is an imaging tool for bones and skeleton, might not be beneficial, as no skeletal abnormalities have been noted in several cases of epignathus. Microscopic examination of the tumor may be of benefit. The microscopic examination focuses on the pattern of cell growth ( histology ). Because epignathus is a type of teratoma, it has a unique histological structure. Hence, the pattern found in microscopic examination can show a growth pattern consistent with teratoma. [ 4 ]  Another method that can be used to diagnose epignathus is  karyotyping , which shows genetic abnormalities in the fetus. However, the parents' chromosomes are healthy, and there is no evidence of it being inherited genetically. [ clarification needed ] [ 16 ]


Epiganthus is a very rare condition that results in the studies on it to primarily be  case studies . In some of these case reports, it was seen that the diagnosis of epignathus occurred as early as 17 weeks from conception. [ 16 ]  However, in other case studies, the ultrasound was normal at 17 weeks. If the tumor is small enough, it might appear at the delivery unpredicted or even later on, in a child. [ 16 ]  For example, in one case, epignathus was detected at week 28, which caused change in the structure of the face and airways, and the child was born in week 34 with Caesarean section and needed assistance for breathing. [ 18 ]  If the diagnosis of epignathus does not happen during pregnancy, and the baby survives to birth, even though it becomes immediately apparent, there is a low chance for survival. [ 8 ]  Other clinical features include  dyspnoea ,  cyanosis , and difficulty in breathing, sucking and swallowing due to the presence of the tumor. [ 8 ]


The main priority for treating epignathus is to establish a usable airway free of obstruction, and then to feed the baby. [ 19 ] [ 20 ]  This is frequently difficult because there are often complications due to the large mass of the tumor, its location, the complex progression and required corrective modifications. [ 1 ]  These tumors, characterized as unusual masses or lumps of tissue, are often the result of abnormal tissue growth and may remain localized in one area or spread to other parts of the body.


However, diagnostic imaging tools such as 3-D ultrasonography and magnetic resonance imaging (MRI) have been essential in early detection of tumors in the head and neck region of the fetus. [ 2 ]  Although few cases have been treated successfully, early prenatal detection and intervention prior to birth has proven to be key in order to have a chance to save the baby's life. [ 9 ]


3-D ultrasonography  works to create an image by producing high frequency sound waves throughout the body in order to detect and receive echo sound. These echoes are then interpreted to form an image depending on how strong the echo was and how long the echo was received after the sound waves were transmitted. Compared to other imaging techniques that use radioactive dyes or ionizing radiation, ultrasounds have been considered safe. [ 21 ]  The use of 3-D ultrasonography has allowed surgeons to pinpoint the exact position of organs and tissues within the body and has been proven vital for surgical guidance especially when treating transplant and cancer. [ 22 ]  Magnetic resonance imaging (MRI) is another medical imaging technique that uses strong magnetic fields and radio waves to create images of organs and tissues within the body. [ 23 ]  MRI does not involve  x-rays  or  ionizing radiation , which makes it a better and safer choice for medical imaging compared to  CT  and  PET  scans. [ 23 ]  The use of these diagnostic tools during fetal development are important for early detection of any abnormal masses that may turn out to be tumors.


If tumors are detected early using the featured diagnostic tools, the baby should be stabilized before surgical removal is conducted to repair the abnormalities. [ 5 ]  In order to stabilize the baby, the umbilical cord is kept intact to provide oxygen to the fetus in case of airway obstruction. [ 5 ]  This is important in the case that a  tracheostomy  – operation required to allow air to enter the lungs – is required in order to save the baby's life. [ 5 ]  Only after the airway is secured should the umbilical cord be clamped and the baby can proceed with surgery. [ 5 ]  During surgery, a complete repair and removal procedure of the diseased tissues, especially those that may spread throughout the body, is necessary in order to prevent any chance of reoccurrence after a period of improvement. [ 2 ]  Following surgery,  chemotherapy  may be used to promote residual tumor regression. [ 9 ]


In some cases, because of the complications of the epignathus tumor, termination of the pregnancy might be an option that needs to get discussed. [ 16 ] [ why? ]


Epignathus diagnoses have a very poor prognosis or outcome with a death rate of 80–100% in newborn babies (either before delivery or shortly after delivery), primarily due to  asphyxiation  or suffocation from the tumor blocking the baby's airway. [ 15 ] [ 3 ]  The course of the disease and outcome are dependent on many factors including size, location, and rate of development of the teratoma, all of which affect the magnitude of airway obstruction. [ 24 ]  Other complications such as the deformation of facial structure or deformation of jaw structure may impact the baby's ability to swallow and breathe, which may also negatively impact the prognosis as well. [ 15 ]  If the tumors are large, they might cause changes in the structure of face, nose and upper lips, to the point that they cannot be identified. [ 16 ]  Factors that may improve survival rates include early diagnosis of epignathus before birth, multidisciplinary management in preventing obstruction in the airways, and feasibility in surgical removal of the teratoma. [ 25 ] [ 26 ]  The prognosis can result in broad range of outcomes. In some cases, pregnancies were terminated after the fetus was diagnosed with epignathus for different complications. The most common reason was that the tumor was continuing to spread even further in the head and mouth area. [ 16 ]


Very few long term survivors have been reported, so the prognosis past the neonatal period is unclear. [ 27 ]


The  epitympanic recess  is the portion of the  tympanic cavity  (of the middle ear) situated superior to the  tympanic membrane . [ 1 ] : 414   The recess lodges the  head of malleus , and the  body of incus . [ 1 ] : 416


The  mastoid antrum  is situated posterior to the recess and opens into the recess at the posterior wall of the recess via the  aditus to mastoid antrum . [ 1 ] : 416   The  ampulla  of the  lateral semicircular canal  creates a prominence upon the medial wall of the recess. [ 1 ] : 420


This recess is a possible route of spread of infection to the  mastoid air cells  located in the  mastoid process  of the  temporal bone  of the skull.  Inflammation  which has spread to the mastoid air cells is very difficult to drain and causes considerable pain. Before the advent of  antibiotics , it could only be drained by drilling a hole in the mastoid bone, a process known as  mastoidectomy . [ 2 ]


This  anatomy  article is a  stub . You can help Wikipedia by  expanding it .


The  ethmoid bone  ( / ˈ ɛ θ m ɔɪ d / ; [ 1 ] [ 2 ]  from  Ancient Greek :  ἡθμός ,  romanized :  hēthmós ,  lit.   'sieve') is an unpaired  bone  in the  skull  that separates the  nasal cavity  from the  brain . It is located at the roof of the  nose , between the two  orbits . The cubical bone is lightweight due to a spongy construction. The ethmoid bone is one of the bones that make up the orbit of the eye.


The ethmoid bone is an anterior cranial bone located between the eyes. [ 3 ]  It contributes to the medial wall of the orbit, the nasal cavity, and the nasal septum. [ 3 ]  The ethmoid has three parts:  cribriform plate ,  ethmoidal labyrinth , and  perpendicular plate . The cribriform plate forms the roof of the nasal cavity and also contributes to formation of the  anterior cranial fossa , [ 4 ]  the ethmoidal labyrinth consists of a large mass on either side of the perpendicular plate, and the perpendicular plate forms the superior two-thirds of the nasal septum. [ 3 ]  Between the  orbital plate  and the  nasal conchae  are the  ethmoidal sinuses  or ethmoidal air cells, which are a variable number of small cavities in the lateral mass of the ethmoid. [ 5 ] [ 6 ]


The ethmoid  articulates  with thirteen bones:


The ethmoid is  ossified  in the cartilage of the nasal capsule by three centers: one for the perpendicular plate, and one for each labyrinth.


The labyrinths are first developed, ossific granules making their appearance in the region of the  lamina papyracea  between the fourth and fifth months of  fetal  life, and extending into the  conchæ .


At birth, the bone consists of the two labyrinths, which are small and ill-developed. During the first year after birth, the perpendicular plate and  crista galli  begin to ossify from a single center, and are joined to the labyrinths about the beginning of the second year.


The  cribriform plate  is ossified partly from the perpendicular plate and partly from the labyrinths.


The development of the ethmoidal cells begins during fetal life.


Some  birds  and other migratory animals have deposits of biological  magnetite  in their ethmoid bones which allow them to sense the direction of the Earth's  magnetic field . Humans have a similar magnetite deposit (ferric iron), but it is believed to be  vestigial . [ 7 ]


Fracture of the  lamina papyracea , the lateral plate of the ethmoid labyrinth bone, permits communication between the  nasal cavity  and the orbit on the same side of the body through the inferomedial orbital wall, resulting in  orbital emphysema .  Increased pressure within the nasal cavity, as seen during sneezing, for example, leads to temporary  exophthalmos .


The porous fragile nature of the ethmoid bone makes it particularly susceptible to fractures.  The ethmoid is usually fractured from an upward force to the nose. This could occur by hitting the dashboard in a car crash or landing on the ground after a fall.  The ethmoid fracture can produce bone fragments that penetrate the  cribriform plate .  This trauma can lead to a leak of  cerebrospinal fluid  into the nasal cavity.  These openings let opportunistic bacteria in the nasal cavity enter the sterile environment of the central nervous system (CNS).  The CNS is usually protected by the  blood–brain barrier , but holes in the cribriform plate let bacteria get through the barrier.  The blood–brain barrier makes it extremely difficult to treat such infections, because only certain drugs can cross into the CNS.


An ethmoid fracture can also sever the olfactory nerve.  This injury results in  anosmia  (loss of smell).  A reduction in the ability to taste is also a side effect because it is based so heavily on smell.  This injury is not fatal, but can be dangerous, as when a person fails to smell smoke, gas, or spoiled food. [ 3 ]  In fact, people with anosmia were more than four times as likely to die in five years compared to those with a healthy sense of smell. [ 8 ]


The  ethmoid bulla  (or  ethmoidal bulla ) is a rounded elevation upon the lateral wall of the  middle nasal meatus [ 1 ] [ 2 ] : 377   ( nasal cavity  inferior to the  middle nasal concha ) produced by one or more of the underlying middle  ethmoidal air cells  (which open into the nasal cavity upon or superior to the ethmoidal bulla [ 2 ] : 374  [ 3 ] ). [ 2 ] : 377   It varies significantly based on the size of the underlying air cells. [ 4 ]


The ethmoid bulla is formed by is the largest and least variable of the middle ethmoidal air cells. [ 3 ]  The size of the bulla varies with that of its contained cells. The bulla may be a pneumatised cell or a bony prominence found in middle meatus. [ citation needed ]


The  hiatus semilunaris  is situated (sources differ) inferior [ 5 ] [ 6 ] [ 1 ] /anterior [ 2 ] : 374   to the ethmoid bulla. The  maxillary sinus  also opens below the bulla. [ 5 ] [ 6 ]


The ethmoid bulla begins to develop between 8 weeks and 12 weeks of  gestation . [ 6 ]


The  ethmoid sinuses  or  ethmoid air cells  of the  ethmoid bone  are one of the four paired  paranasal sinuses . [ 1 ]  Unlike the other three pairs of paranasal sinuses which consist of one or two large cavities, the ethmoidal sinuses entail a number of small air-filled cavities ("air cells"). [ 2 ]  The cells are located within the  lateral mass (labyrinth)  of each ethmoid bone and are variable in both size and number. [ 1 ]  The cells are grouped into anterior, middle, and posterior groups; the groups differ in their drainage modalities, [ 2 ]  though all ultimately drain into either the  superior  or the  middle nasal meatus [ 3 ]  of the lateral wall of the nasal cavity.


The ethmoid air cells consist of numerous thin-walled cavities in the  ethmoidal labyrinth [ 4 ]  that represent invaginations of the mucous membrane of the nasal wall into the ethmoid bone. [ 3 ]  They are situated between the superior parts of the  nasal cavities  and the  orbits , and are separated from these cavities by thin bony lamellae. [ 4 ]


There are 5-15 air cells in either ethmoid bone in the adult, with a combined volume of 2-3mL. [ 5 ]


The ethmoidal cells (sinuses) and  maxillary sinuses  are present at birth. [ 6 ]  At birth, 3-4 air cells are present, with the number increasing to 5-15 by adulthood. [ 5 ]


The ethmoidal labyrinth is divided by multiple obliquely oriented, parallel lamellae. The first lamellae is equivalent to the  uncinate process of ethmoid bone , the second corresponds the  ethmoid bulla , and the third is the basal lamella, and the fourth is equivalent to the  superior nasal concha . [ 5 ]


The anterior and posterior ethmoid cells are separated by the  basal lamella [ 7 ] [ 5 ]  (also known as the  ground lamella ). [ 5 ]  It is one of the bony divisions of the ethmoid bone and is mostly contained inside the  ethmoid labyrinth . The basal lamella is continuous medially with the bony  middle nasal concha . [ 7 ]  Anteriorly, it vertically inserts into the  ethmoid crest ; the middle part attaches obliquely into the  orbital lamina of ethmoid bone (lamina papyricea)  while the posterior part attaches into the orbital lamina horizontally. [ 5 ]


The ethmoidal air cells receive sensory innervation from the  anterior  and the  posterior ethmoidal  nerve (which are ultimately derived from the  ophthalmic branch (CN V 1 )  of the  trigeminal nerve (CN V) ), [ 3 ]   and the orbital branches of the  pterygopalatine ganglion , which carry the postganglionic parasympathetic nerve fibers for mucous secretion from the  facial nerve . [ clarification needed ] [ citation needed ]


Haller cells are air cells situated beneath the  ethmoid bulla  along the roof of the  maxillary sinus  and the most inferior portion of the  lamina papyracea , including air cells located within the  ethmoid infundibulum . [ 8 ]  These may arise from the anterior or posterior ethmoidal sinuses. [ citation needed ]


Also known as a sphenoethmoidal air cell, an Onodi cell is a posterior ethmoidal air cell that lies superolateral to the  sphenoid sinus , often extending into the  anterior clinoid process . [ 9 ]  Onodi cells are clinically significant because they lie in close proximity to the  optic nerve  and  internal carotid artery , so surgeons should be aware of their existence when performing surgery on the sphenoid sinus so as not to damage these important structures.


A central Onodi air cell is a variation in which a posterior ethmoid cell lies superior to the sphenoid sinus in a midline position with at least one optic canal bulge. [ 10 ]


Acute ethmoiditis in childhood and ethmoidal carcinoma may spread superiorly causing meningitis and cerebrospinal fluid leakage or it may spread laterally into the orbit causing  proptosis  and  diplopia . [ 11 ]


This article incorporates text in the  public domain  from  page 154  of the 20th edition of   Gray's Anatomy   (1918)


The  ethmoidal infundibulum  is a funnel-shaped [ 1 ] /slit-like [ 2 ] : 690  /curved [ 3 ]  opening [ 1 ] /passage [ 4 ] /space [ 2 ] : 690  /cleft [ 3 ]  upon the anterosuperior portion of the  middle nasal meatus [ 1 ]  (and thus of the lateral wall of [ 2 ]  the  nasal cavity [ 1 ] ) at the  hiatus semilunaris [ 3 ] [ 5 ]  (which represents the medial extremity of the infundibulum [ 2 ] ). The  anterior ethmoidal air cells , [ 4 ] [ 2 ] : 612   and (usually [ 2 ] : 612, 690  ) the  frontonasal duct  (which drains the  frontal sinus [ 1 ] [ 4 ] ) [ 1 ] [ 4 ] [ 2 ] : 690   open into the ethmoidal infundibulum. [ 1 ]  The ethmoidal infundibulum extends anterosuperiorly from its opening into the nasal cavity. [ 3 ] [ 2 ] : 612


The ethmoidal infundibulum is bordered medially by the  uncinate process of the ethmoid bone , and laterally by the orbital plate of the ethmoid bone. [ 3 ]


The ethmoid infundibulum leads towards the  maxillary hiatus . [ 2 ] : 690  The  anterior ethmoidal cells  open into the anterior part of the infundibulum. [ 6 ]


The frontonasal duct may or may not drain into the ethmoidal infundibulum - this is determined by the place of attachment of the  uncinate process of the ethmoid bone : if the uncinate process is attached to the lateral nasal wall, the frontonasal duct will open directly into the middle nasal meatus; if otherwise, it will drain into the infundibulum. [ 2 ] : 690   In slightly over 50% of subjects, it is directly continuous with the frontonasal duct. When the anterior end of the uncinate process fuses with the anterior part of the bulla, however, this continuity is interrupted and the frontonasal duct then drains directly into the anterior end of the  middle meatus . [ 6 ]


The  ethmoidal labyrinth  or  lateral mass  of the  ethmoid bone  consists of a number of thin-walled cellular cavities, the  ethmoid air cells , arranged in three groups, anterior, middle, and posterior, and interposed between two vertical plates of bone; the lateral plate forms part of the orbit, the medial plate forms part of the  nasal cavity . In the disarticulated bone many of these cells are opened into, but when the bones are articulated, they are closed in at every part, except where they open into the nasal cavity. [ 1 ]


The upper surface of the labyrinth presents a number of half-broken cells, the walls of which are completed, in the articulated skull, by the edges of the  ethmoidal notch  of the frontal bone. Crossing this surface are two grooves, converted into two openings by articulation with the frontal; they are the  anterior  and  posterior ethmoidal foramina , and open on the inner wall of the orbit. The posterior surface presents large irregular cellular cavities, which are closed in by articulation with the  sphenoidal concha  and  orbital process of palatine bone . The lateral surface is formed of a thin, smooth, oblong plate, the  lamina papyracea  (os planum), which covers in the middle and posterior ethmoidal cells and forms a large part of the medial wall of the orbit; it articulates above with the orbital plate of the frontal bone, below with the maxilla and orbital process of the palatine, in front with the lacrimal, and behind with the sphenoid. [ 1 ]


In front of the lamina papyracea are some broken air cells which are overlapped and completed by the lacrimal bone and the frontal process of the maxilla. A curved lamina, the  uncinate process , projects downward and backward from this part of the labyrinth; it forms a small part of the medial wall of the  maxillary sinus , and articulates with the ethmoidal process of the inferior  nasal concha . [ 1 ]


The medial surface of the labyrinth forms part of the lateral wall of the corresponding nasal cavity. It consists of a thin  lamella , which descends from the under surface of the cribriform plate, and ends below in a free, convoluted margin, the middle nasal concha. It is rough, and marked above by numerous grooves, directed nearly vertically downward from the cribriform plate; they lodge branches of the olfactory nerves, which are distributed to the  mucous membrane  covering the superior nasal concha. The back part of the surface is subdivided by a narrow oblique fissure, the superior meatus of the nose, bounded above by a thin, curved plate, the superior nasal concha; the posterior ethmoidal cells open into this meatus. Below, and in front of the  superior meatus , is the convex surface of the middle nasal concha; it extends along the whole length of the medial surface of the labyrinth, and its lower margin is free and thick. The lateral surface of the middle concha is concave, and assists in forming the middle meatus of the nose. The middle ethmoidal cells open into the central part of this  meatus , and a sinuous passage, termed the  infundibulum , extends upward and forward through the labyrinth and communicates with the anterior ethmoidal cells, and in about 50% of skulls is continued upward as the frontonasal duct into the frontal sinus. [ 1 ]


The  ethmoidal nerves , which arise from the  nasociliary nerve , supply the  ethmoidal cells ; the posterior branch leaves the  orbital cavity  through the  posterior ethmoidal foramen  and gives some filaments to the  sphenoidal sinus . There are two ethmoidal nerves on each side of the face:


This article incorporates text in the  public domain  from  page 888  of the 20th edition of   Gray's Anatomy   (1918)


The  Eustachian tube  ( / j uː ˈ s t eɪ ʃ ən / ), also called the  auditory tube  or  pharyngotympanic tube , [ 1 ]  is a tube that links the  nasopharynx  to the  middle ear , of which it is also a part.  In adult humans, the Eustachian tube is approximately 35 mm (1.4 in) long and 3 mm (0.12 in) in diameter. [ 2 ]  It is named after the sixteenth-century Italian anatomist  Bartolomeo Eustachi . [ 3 ]


In humans and other  tetrapods , both the middle ear and the  ear canal  are normally filled with air. Unlike the air of the ear canal, however, the air of the middle ear is not in direct contact with the atmosphere outside the body; thus, a pressure difference can develop between the atmospheric pressure of the ear canal and the middle ear. Normally, the Eustachian tube is collapsed, but it gapes open with  swallowing  and with  positive pressure , allowing the middle ear's pressure to adjust to the atmospheric pressure. When taking off in an aircraft, the ambient air pressure goes from higher (on the ground) to lower (in the sky). The air in the middle ear  expands  as the plane gains altitude, and pushes its way into the back of the nose and mouth; on the way down, the volume of air in the middle ear shrinks, and a slight vacuum is produced. Active opening of the Eustachian tube (through actions like swallowing or the  Valsalva maneuver ) is required to equalize the pressure between the middle ear and the ambient atmosphere as the plane descends. A  diver  also experiences this change in pressure, but with greater rates of pressure change;  active opening of the Eustachian tube  is required more frequently to  equalize pressure  as the diver goes deeper, into higher pressure.


The Eustachian tube extends from the anterior wall of the middle ear to the lateral wall of the  nasopharynx , approximately at the level of the  inferior nasal concha . It consists of a bony part and a  cartilaginous  part.


The bony part ( 1 ⁄ 3 ) nearest to the middle ear is made of  bone  and is about 12 mm in length. It begins in the  anterior wall of the tympanic cavity , below the  septum canalis musculotubarius , and, gradually narrowing, ends at the angle of junction of the  squamous  and the  petrous parts  of the  temporal bone , its extremity presenting a jagged margin which serves for the attachment of the cartilaginous part. [ 5 ]
The vestibule of the Eustachian tube is known as the  protympanum , [ 6 ]  The protympanum is also known as the anterior part of the bony part of the tube. [ 7 ]


The cartilaginous part of the Eustachian tube is about 24 mm in length and is formed of a triangular plate of  elastic fibrocartilage , the apex of which is attached to the margin of the medial end of the bony part of the tube, while its base lies directly under the  mucous membrane  of the nasal part of the  pharynx , where it forms an elevation, the  torus tubarius  or cushion, behind the pharyngeal opening of the auditory tube.


The upper edge of the  cartilage  is curled upon itself, being bent laterally so as to present on  transverse section  the appearance of a hook; a groove or furrow is thus produced, which is open below and laterally, and this part of the canal is completed by fibrous membrane. The cartilage lies in a groove between the  petrous part of the temporal bone  and the  great wing of the sphenoid ; this groove ends opposite the middle of the  medial pterygoid plate . The cartilaginous and bony portions of the tube are not in the same plane, the former inclining downward a little more than the latter. The diameter of the tube is not uniform throughout, being greatest at the pharyngeal opening, least at the junction of the bony and cartilaginous portions, and again increased toward the  tympanic cavity ; the narrowest part of the tube is termed the isthmus.


The position and relations of the pharyngeal opening are described with the  nasal part of the pharynx . The mucous membrane of the tube is continuous in front with that of the nasal part of the pharynx, and behind with that of the tympanic cavity; it is covered with  ciliated pseudostratified columnar epithelia  and is thin in the osseous portion, while in the cartilaginous portion it contains many  mucous glands  and near the pharyngeal orifice a considerable amount of  adenoid  tissue, which has been named by Gerlach the tube tonsil.


There are four muscles associated with the function of the Eustachian tube:


The tube is opened during swallowing by contraction of the tensor veli palatini and levator veli palatini, muscles of the  soft palate . [ 1 ]  The tensor veli palatini makes the largest contribution to active opening of the tube. [ 9 ] [ 10 ]


Since 2015, two developments have enhanced our understanding of the anatomy of the eustachian tube: Valsalva computerized tomography and endoscopic ear surgery. [ 11 ]


The Eustachian tube is derived from the dorsal part of the first  pharyngeal pouch  and second endodermal pouch, which during  embryogenesis  forms the  tubotympanic recess . The distal part of the tubotympanic sulcus gives rise to the  tympanic cavity , while the proximal tubular structure becomes the Eustachian tube. It helps transformation of sound waves.


Under normal circumstances, the human Eustachian tube is closed, but it can open to let a small amount of air through to prevent damage by equalizing pressure between the middle ear and the atmosphere. Pressure differences cause temporary  conductive hearing loss  by decreased motion of the  tympanic membrane  and  ossicles  of the ear. [ 13 ]  Various methods of  ear clearing  such as  yawning , swallowing, or  chewing gum  may be used to intentionally open the tube and equalize pressures. When this happens, humans hear a small popping sound, an event familiar to aircraft passengers, scuba divers, or drivers in mountainous regions. Devices assisting in pressure equalization include an  ad hoc  balloon applied to the nose, creating inflation by positive air pressure. [ 14 ]
Some people learn to voluntarily 'click' their ears, together or separately, performing a pressure equalizing routine by opening their Eustachian tubes when pressure changes are experienced, as in ascending/descending in aircraft, mountain driving, elevator lift/drops, etc. Some are even able to deliberately keep their Eustachian tubes open for a brief period, and even increase or decrease air pressure in the middle ear. The 'clicking' can actually be heard by putting one's ear to another's while performing the clicking sound. This voluntary control may be first discovered when yawning or swallowing, or by other means (above). Those who develop this ability may discover that it can be done deliberately without force even when there are no pressure issues involved.


The Eustachian tube also drains mucus from the middle ear. Upper respiratory tract infections or allergies can cause the Eustachian tube, or the membranes surrounding its opening to become swollen, trapping fluid, which serves as a growth medium for bacteria, causing  ear infections . This swelling can be reduced through the use of decongestants such as  pseudoephedrine ,  oxymetazoline , and  phenylephrine . [ 15 ]  Ear infections are more common in children because the tube is horizontal and shorter, making bacterial entry easier, and it also has a smaller diameter, making the movement of fluid more difficult. In addition, children's developing immune systems and poor hygiene habits make them more prone to upper respiratory infections.


Otitis media , or  inflammation  of the  middle ear , commonly affects the Eustachian tube.  Children under 7 are more susceptible to this condition, one theory being that this is because the Eustachian tube is shorter and at more of a horizontal angle than in the adult ear.  Others argue that susceptibility in this age group is related to immunological factors and not Eustachian tube anatomy. [ citation needed ]


Barotitis, a form of  barotrauma , may occur when there is a substantial difference in air or water pressure between the outer and the middle ear – for example, during a rapid ascent while  scuba diving , or during sudden decompression of an aircraft at high altitude.


Some people are born with a dysfunctional Eustachian tube [ 16 ]  that is much slimmer than usual. The cause may be genetic, but it has also been posited as a condition in which the patient did not fully recover from the effects of pressure on the middle ear during birth (retained birth compression). [ 17 ] [ unreliable medical source ]  It is suggested that Eustachian tube dysfunction can result in a large amount of mucus accumulating in the middle ear, often impairing hearing to a degree. This condition is known as  otitis media with effusion .


A  patulous Eustachian tube  is a rare condition in which the Eustachian tube remains intermittently open, causing an echoing sound of the person's own heartbeat, breathing, and speech. This may be temporarily relieved by holding the head upside down.


Smoking can also cause damage to the  cilia  that protect the Eustachian tube from mucus, which can result in the clogging of the tube and a buildup of bacteria in the ear, leading to a middle ear infection. [ 18 ]


Recurring and chronic cases of  sinus infection  can result in Eustachian tube dysfunction caused by excessive mucus production which, in turn, causes obstruction to the openings of the Eustachian tubes.


In severe cases of childhood middle ear infections and Eustachian tube blockage, ventilation can be provided by a surgical puncturing of the eardrum to permit air equalization, known as  myringotomy . The eardrum would normally naturally heal and close the hole, so a tiny plastic rimmed grommet is inserted into the hole to hold it open. This is known as a  tympanostomy tube . As a child grows, the tube is eventually naturally expelled by the body. Longer-lasting vent grommets with larger flanges have been researched, but these can lead to permanent perforation of the eardrum.


More recently, dilation of the eustachian tube using balloon catheter has gained attention as a method of treating eustachian tube obstruction. There are two methods of performing this procedure depending on the route of the catheter introduction and the area of the Eustachian tube to be dilated. Dennis Poe popularized the transnasal introduction and the dilation  of the nose side of the eustachian tube. [ 19 ]  Muaaz Tarabichi pioneered the transtympanic (ear) introduction of the balloon catheter and the dilatation of the proximal part (the ear side) of the cartilaginous eustachian tube. [ 20 ] [ 21 ] [ 22 ]


In the  equids  (horses) and some rodent-like species such as the desert  hyrax , an  evagination  of the Eustachian tube is known as the  guttural pouch  and is divided into medial and lateral compartments by the stylohyoid bone of the  hyoid  apparatus. This is of great importance in equine medicine as the pouches are prone to infections, and, due to their intimate relationship to the cranial nerves (VII, IX, X, XI) and the internal and external carotid artery, various syndromes may arise relating to which is damaged.  Epistaxis  (nosebleed) is a very common presentation to veterinary surgeons and this may often be fatal unless a balloon catheter can be placed in time to suppress bleeding.


The  external carotid artery  is the major  artery  of the head and upper neck. It arises from the  common carotid artery . It terminates by splitting into the  superficial temporal  and  maxillary artery  within the  parotid gland . [ 1 ]


The external carotid artery arises from the  common carotid artery  just inferior to the upper border of the  thyroid cartilage . [ 1 ]


At its origin, this artery is closer to the skin and more medial than the internal carotid, and is situated within the  carotid triangle .


It curves to pass anterosuperiorly before inclining posterior-ward to reach the space posterior the neck of the  mandible , where it divides into the  superficial temporal  and  maxillary artery  within the  parotid gland .


It rapidly diminishes in size as it travels up the neck, owing to the number and large size of its branches.


At the origin, external carotid artery is more medial than  internal carotid artery . When external carotid artery ascends the neck, it lies more lateral than internal carotid artery. [ 2 ]


The external carotid artery is covered by the skin, superficial fascia,  platysma muscle , deep fascia, and anterior margin of the  sternocleidomastoid ; it is crossed by the  hypoglossal nerve , by the  lingual ,  ranine ,  common facial , and  superior thyroid veins ; and by the  digastricus  and  stylohyoideus muscles ; higher up it passes deeply into the substance of the  parotid gland , where it lies deep to the  facial nerve  and the junction of the temporal and internal maxillary veins.


Medial to it are the  hyoid bone , the wall of the  pharynx , the  superior laryngeal nerve , and a portion of the  parotid gland .


Posterior to it, near its origin, is the  superior laryngeal nerve ; and higher up, it is separated from the  internal carotid  by the  styloglossus  and  stylopharyngeus muscles , the  glossopharyngeal nerve , the pharyngeal branch of the  vagus , and part of the parotid gland.


As the artery travels upwards, it gives the following branches:


The external carotid artery terminates as two branches:


The superior thyroid artery anastomoses with  inferior thyroid artery , where the latter arises from  thyrocervical trunk  of the  subclavian artery . [ 2 ]


Terminal branch of facial artery anastomose with  ophthalmic artery  of  internal carotid artery . [ 2 ]


Posterior auricular artery anastomose with occipital artery, another branch of external carotid artery. [ 2 ]


One of the branches of superficial temporal artery anastomose with lacrimal and palpebral branches of ophthalmic artery. [ 2 ]


In children, the external carotid artery is smaller than the  internal carotid ; but in the adult, the two vessels are of nearly equal size.


The condition and health of the external carotid arteries is usually evaluated using  Doppler ultrasound ,  CT angiogram  or  phase contrast magnetic resonance imaging  (PC-MRI). Typically, blood flow velocities in the external carotid artery are measured as peak systolic velocity (PSV) and end diastolic velocity (EDV). [ 4 ]


PSV values greater than 200 cm/s are considered to be predictive of more than 50% of external  carotid artery stenosis . [ 5 ]


The  facial artery , formerly called the  external maxillary artery,  is a branch of the  external carotid artery  that supplies blood to superficial structures of the medial regions of the face.


The facial artery arises in the  carotid triangle  from the  external carotid artery , [ 1 ] [ 2 ]  a little above the  lingual artery , and sheltered by the  ramus of the mandible . It passes obliquely up beneath the  digastric  and  stylohyoid  muscles, over which it arches to enter a groove on the posterior surface of the  submandibular gland . [ 3 ]


It then curves upward over the body of the mandible at the antero-inferior angle of the  masseter  ( the antegonial notch ); [ 1 ] [ 2 ] [ 4 ]  passes forward and upward across the cheek to the angle of the mouth, then ascends along the side of the nose, and ends at the medial commissure of the eye, under the name of the  angular artery . [ 5 ]


The facial artery is remarkably tortuous.  This is to accommodate itself to neck movements such as those of the  pharynx  in  swallowing ; and facial movements such as those of the  mandible ,  lips , and  cheeks .


In the neck, its origin is superficial, being covered by the integument,  platysma , and fascia; it then passes beneath the  digastric  and  stylohyoid  muscles and part of the  submandibular gland , but superficial to the  hypoglossal nerve .


It lies upon the  middle pharyngeal constrictor  and the  superior pharyngeal constrictor , the latter of which separates it, at the summit of its arch, from the lower and back part of the tonsil.


On the face, where it passes over the body of the mandible, it is comparatively superficial, lying immediately beneath the dilators of the mouth. In its course over the face, it is covered by the integument, the fat of the cheek, and, near the angle of the mouth, by the  platysma ,  risorius , and  zygomaticus major . It rests on the  buccinator  and  levator anguli oris , and passes either over or under the infraorbital head of the  levator labii superioris .


The  anterior facial vein  lies lateral/posterior to the artery, [ 2 ]  and takes a more direct course across the face, where it is separated from the artery by a considerable interval. In the neck it lies superficial to the artery.


The branches of the  facial nerve  cross the artery from behind forward.


The facial artery anastomoses with (among others) the  dorsal nasal artery  of the  internal carotid artery .


The branches of the facial artery are: [ 5 ]


Muscles supplied by the facial artery include:


The facial artery may be punctured during  maxillofacial surgery , and is likely to  haemorrhage  significantly. [ 6 ]


This article incorporates text in the  public domain  from  page 553  of the 20th edition of   Gray's Anatomy   (1918)


The  facial canal  (also known as the  Fallopian canal ) is a Z-shaped canal in the  temporal bone  of the  skull . It extends between the  internal acoustic meatus  and  stylomastoid foramen . It transmits the  facial nerve (CN VII)  (after which it is named).


The facial canal gives passage to the  facial nerve (CN VII)  (hence the name). [ 1 ] [ verification needed ] [ better source needed ]  Its proximal opening is at the  internal auditory meatus ; its distal opening is the  stylomastoid foramen . In humans, the canal is approximately 3 cm long, making it the longest bony canal of a nerve in the human body. [ 2 ] [ verification needed ] [ better source needed ]  It is located within the middle ear region. [ verification needed ] [ better source needed ]


The facial nerve gives rise to three nerves while passing through the canal: the  greater petrosal nerve ,  nerve to stapedius , and the  chorda tympani . [ 3 ]


The proximal portion of the facial canal is termed the  horizontal part . It commences at the  introitus of facial canal  at the distal end of the internal auditory meatus. The horizontal part is further subdivided into two crura: the proximal/medial [ 4 ]  anteriolaterally [ 5 ]  directed  medial crus  (or  labyrinthine segment [ 5 ] ), and the distal/lateral [ 4 ]  posteriolaterally [ 5 ]  directed  lateral crus  (or  tympanic segment [ 5 ] ); the two crura meet at a sharp angle at the  genu of facial canal  ( geniculum canalis facialis [ 6 ] ) where the  geniculate ganglion  is situated (at the genu, the  greater petrosal nerve  leaves the facial canal through the hiatus of the facial canal). [ 4 ]


The lateral crus of horizontal part ends by turning sharply inferior-ward, commencing the distal-most  descending part  (or  mastoid segment [ 5 ] ) of facial canal which passes vertically inferior-ward, ending distally at the  stylomastoid foramen . The descending part presents two openings through each of which a branch of the facial nerve passes: the  nerve to stapedius  enters the  canaliculus for nerve to stapedius , and the  chorda tympani  enters the  posterior canaliculus of chorda tympani  ( canaliculus chordae tympani , or  iter chordae posterius [ 7 ] ). [ 8 ]


The labyrinthine segment is situated superior to  cochlea . [ 5 ]


The canal traverses the  medial wall  of the  tympanic cavity  superior to the  oval window ; [ citation needed ]  here, the  prominence of the facial canal  (or  prominence of the aqueduct of Fallopius ) upon the medial wall indicates the position of the superior portion of the facial canal. [ 9 ] : 745   The canal then curves nearly vertically inferior-ward along the  posterior wall . [ citation needed ]  The tympanic segment is closely related to the posterior and medial walls of the  tympanic cavity ; it passes superior to the  oval window  and inferior to the  lateral semicircular canal . [ 5 ]


The facial canal may be interrupted in some people. This may lead to the  facial nerve  being split into 2 or 3 fibres, or it may be poorly formed or congenitally absent on one side. [ 2 ]


The facial canal was first described by  Gabriele Falloppio . [ 10 ]  This is why it may also be known as the Fallopian canal. [ 10 ]


Facial feminization surgery  ( FFS ) is a set of reconstructive [ 1 ]   surgical procedures  that alter typically male facial features to bring them closer in shape and size to typical female facial features. FFS can include various bony and soft tissue procedures such as  brow lift ,  rhinoplasty ,  cheek implantation , and  lip augmentation . [ 2 ]


Faces contain  secondary sex characteristics  that make male and female faces readily distinguishable, including the shape of the forehead, nose, lips, cheeks, chin, and jawline; the features in the upper third of the face seem to be the most important, and subtle changes in the lips can have a strong effect.


For some  transgender  women and non binary people, FFS is medically necessary to treat  gender dysphoria . [ 3 ] [ 4 ]  It can be just as important or even more important than genital forms of  sex reassignment surgery  (SRS) in reducing gender dysphoria and helping trans women integrate socially as women; data on these sorts of outcomes are limited by small study size and confounding variables like other feminization procedures. [ 5 ] [ 6 ]  While most FFS patients are transgender women, some  cisgender  women who feel that their faces are too masculine will also undergo FFS. [ 7 ]


FFS candidates should wait until the bones of their skull have stopped growing before undergoing FFS. The way to determine if the bones of the skull have stopped growing is to take successive  radiographs  of the  mandible  and wrist bones to make sure that bone growth has stopped. [ 8 ]


The surgical procedures most frequently performed during FFS include the following. [ 5 ] [ 9 ]


Some studies have shown that the shape of the forehead is one of the key differences between cisgender males and cisgender females. [ 5 ] [ 10 ]  Hairline correction, forehead recontouring, eye socket recontouring, and brow lift are procedures often performed at the same time, with rhinoplasty in mind. [ 5 ]


In males, the hairline is often higher than in females and usually has receded corners above the temples that give it an "M" shape. The hairline can be moved forward and given a more rounded shape, either with a procedure called a " scalp advance " wherein the scalp is lifted and repositioned, or with  hair transplantation . [ 5 ]


Cisgender males tend to have a horizontal ridge of bone running across the forehead just above eyebrow level called the  brow ridge  (or "brow bossing"), which includes the "supraorbital rims" (the lower edge, on which the eyebrows sit). Cisgender males also tend to have indented temples and a flatter forehead than females. [ 5 ]


The brow ridge is usually solid bone and can simply be ground down. The section of bossing between the eyebrows (the  glabella ) sits over a hollow area called the  frontal sinus . The frontal sinus is hollow, and thus it can be more difficult to remove bossing there. If the bone over the frontal sinus is thick enough the bossing can be removed by simply grinding down the bone. However, in some people, the wall of bone is so thin that it is not possible to grind the bossing away completely without breaking through the wall into the frontal sinus. [ 5 ]


FFS surgeons have taken two main approaches to resolving this problem. The most conservative approach is to grind down the wall of bone as far as possible without breaking through, and then build up the area around any remaining bossing with  hydroxyapatite  bone cement which can smooth out any visible step between remaining bossing and the rest of the forehead. In these cases, some additional reduction in the bossing can sometimes be achieved by thinning the soft tissues that sit over it. Alternatively, FFS surgeons can perform a procedure called a forehead reconstruction or  cranioplasty  where the  glabella  bone is taken apart, thinned and re-shaped, and reassembled in the new feminine position with small titanium wires or titanium  orthopedic plate  and screws. [ 5 ]  The data on which approach is better is limited and does not provide guidance. [ 5 ]  The risks of cranioplasty include the skull not healing properly, movement of the bone fragments, and the formation of cysts; these can usually be corrected by another procedure. [ 5 ]


Cisgender men tend to have lower eyebrows relative to the position of their  brow ridges  when compared to cisgender women. Cis men's eyebrows tend to be below their brow ridges while cis women's eyebrows tend to be above their brow ridges. Accordingly, FFS to raise the eyebrows results in a face with a more womanly appearance. [ 8 ]


In some studies, the eye shape has been shown to be the key differentiating feature between cis males and females. [ 5 ] [ 10 ]  Cis female eye sockets tend to be smaller, located higher on the face, to have more sharply angled outer edges, and to be closer together at their inner edges (the  intercanthal distance ). [ 5 ]   Some FFS alter the orbit shape; data on outcomes is limited. [ 5 ]


Cis males tend to have larger, longer, and wider noses than cis females; also, the tip of the female nose will more often visibly point slightly upwards than that of a male. Hence, the procedure involves removing bone and cartilage and remodelling what remains. [ 5 ] [ 10 ]  In most cases this is performed in an open procedure, but endonasal procedures have been used; in all cases when reducing the nose there is a risk of interfering with  nasal valve  function. [ 5 ]  Standard rhinoplasty procedures are generally used. [ 11 ]  There is limited data on outcomes. [ 5 ]


Cis females often have more forward projection in their cheekbones as well as fuller cheeks overall, with a triangle formed by the  cheekbones  and the point of the chin. Planning of cheek contouring is done while planning reshaping of the chin. [ 5 ]  The cheeks are reshaped by  cutting away bone  and repositioning the facial bones. [ 5 ]  Augmenting the cheeks with implants or with fat harvested from other parts of the body is common. Risks of implants include infection, and the implant moving and becoming asymmetrical; fat can eventually be absorbed. [ 5 ]


Subtle changes to the shape and structure of lips can have a strong influence on feminization. [ 5 ]  The distance between the base of the nose and the top of the upper lip tends to be longer in males than in females and the upper lip is longer; when a female mouth is open and relaxed, the upper incisors are often exposed by a few millimeters. [ 5 ]


An incision is usually made just under the base of the nose and a section of skin is removed. When the gap is closed it has the effect of lifting the top lip, placing it in a more feminine position and often exposing a little of the upper incisors. The surgeon can also use a lip lift to roll the top lip out a little, making it appear fuller. [ 5 ]


Cis females often have fuller lips than cis males, so  lip filling  is often used in feminization. Injectable fillers are low-risk but tend to be absorbed after six months or so, and many implants have higher complication rates like infection or rejection. [ 5 ]  Use of fat harvested from the person can result in lumps and does not last long. [ 5 ]  The longest lasting and least risky results appear to arise from use of  acellular dermis  products. [ 5 ]


The chins of cis males tend to be longer and wider than those of cis females, with a more square base, and to project outward more than female chins. [ 10 ]  Cis male jawlines tend to extend outward from the chin at a wider angle than those of cis females, and to have a sharp corner at the back. [ 5 ]


The  chin can be reduced  in length either by bone shaving or with a procedure called a " sliding genioplasty ", where a section of bone is removed. The jaw can be reshaped through  jaw reduction  surgery; sometimes this is done through the mouth. The  chewing muscles  can also be reduced to make the jaw appear narrower. [ 5 ]


The biggest risk in these procedures is damage to the  mental nerve  that runs through the chin and jaw; other risks include damage to tooth roots, infection, nonunion, and damage to the  mentalis muscle  that controls the lower lip and is at the edges of the chin. [ 5 ]


Males tend to have a much more prominent  Adam's apple  than females following puberty. [ 5 ] [ 10 ]  The Adam's apple can be reduced with a procedure called a  chondrolaryngoplasty ; the goal of the procedure is to reduce the size without leaving a scar. [ 5 ]  There are risks of damage to the vocal cords and destabilization of the  epiglottis . [ 5 ]


Beautification and rejuvenation procedures are often performed at the same time as facial feminisation. For example, it is common for eye bags and sagging eyelids to be corrected with a procedure called " blepharoplasty " and many feminization patients undergo a  face and neck lift . [ 5 ]


FFS techniques are derived from  maxillofacial ,  otolaryngology , and  plastic aesthetic and reconstructive surgery . [ 5 ] [ 8 ]


FFS began in 1982 when Darrell Pratt, a plastic surgeon who performed  sex reassignment surgeries , approached  Douglas Ousterhout  with a request from a transgender woman patient of Pratt's; the patient wanted plastic surgery to make her face appear more feminine, since people still reacted to her as though she were a man. [ 12 ]  Ousterhout's prior practice had involved reconstructing faces and skulls of people who had had birth defects, accidents, or other trauma. [ 12 ]  Ousterhout was interested in helping but knew that he did not know what a "female face" was, so he investigated by first reading the  physical anthropology  from the early 20th century to identify what features were "female", then deriving measurements defining those features from a series of  cephalograms  taken in the 1970s, and then working with a set of several hundred skulls to see if he could reliably differentiate which were females and which were males using those measurements. [ 6 ] [ 12 ]  Ousterhout then began working out what surgical techniques and materials he already used could be applied in order to transform a male face into a female face. He pioneered most of the procedures involved in FFS and was involved in their subsequent improvements as well. [ 6 ]


The  facial motor nucleus  is a  collection of neurons  in the  brainstem  that belong to the  facial nerve  ( cranial nerve  VII). [ 1 ]  These  lower motor neurons  innervate the  muscles of facial expression  and the  stapedius . [ 2 ]


The  nucleus  is situated in the caudal portion of the ventrolateral  pontine tegmentum . Its axons take an unusual course, traveling dorsally and looping around the  abducens nucleus , then traveling ventrally to exit the  ventral pons  medial to the  spinal trigeminal nucleus . These axons form the motor component of the  facial nerve , with  parasympathetic  and  sensory  components forming the  intermediate nerve .


The nucleus has a dorsal and ventral region, with neurons in the dorsal region innervating muscles of the upper face and neurons in the ventral region innervating muscles of the lower face.


Because it innervates muscles derived from  pharyngeal arches , the facial motor nucleus is considered part of the  special visceral efferent  (SVE) cell column, which also includes the  trigeminal motor nucleus ,  nucleus ambiguus , and (arguably) the  spinal accessory nucleus .


Like all lower motor neurons, cells of the facial motor nucleus receive  cortical input  from the  primary motor cortex  in the  frontal lobe  of the  brain .  Upper motor neurons  of the cortex send axons that descend through the  internal capsule  and synapse on neurons in the facial motor nucleus. This pathway from the cortex to the brainstem is called the  corticobulbar tract .


The neurons in the dorsal aspect of the facial motor nucleus receive inputs from both sides of the cortex, while those in the ventral aspect mainly receive contralateral inputs (i.e. from the opposite side of the cortex). The result is that both sides of the brain control the muscles of the upper face, while the right side of the brain controls the lower left side of the face, and the left side of the brain controls the lower right side of the face.


As a result of the corticobulbar input to the facial motor nucleus, an upper motor neuron lesion to fibers innervating the facial motor nucleus results in  central seven . The syndrome is characterized by spastic paralysis of the contralateral lower face. For example, a left corticobulbar lesion results in paralysis of the muscles that control the lower right quadrant of the face.


By contrast, a lower motor neuron lesion to the facial motor nucleus results in  paralysis of facial muscles  on the same side of the injury. If a cause, such as trauma or infection, cannot be identified (this situation is called  idiopathic  palsy) this condition is known as  Bell's palsy .  Otherwise it is described by its cause.


Any lesion occurring within or affecting the corticobulbar tract is known as an upper motor neuron lesion.  Any lesion affecting the individual branches (temporal, zygomatic, buccal, mandibular and cervical) is known as a lower motor neuron lesion.