The causes of obstructive sleep apnea are complex and individualized, but typical risk factors include narrow pharyngeal anatomy and craniofacial structure. [ 15 ]  When anatomical risk factors are combined with non-anatomical contributors such as an ineffective pharyngeal dilator muscle function during sleep, unstable control of breathing (high loop gain), and premature awakening to mild airway narrowing, the severity of the OSA rapidly increases as more factors are present. [ 15 ]  When breathing is paused due to upper airway obstruction, carbon dioxide builds up in the bloodstream.  Chemoreceptors  in the bloodstream note the high carbon dioxide levels. The brain is signaled to awaken the person, which clears the airway and allows breathing to resume. Breathing normally will restore oxygen levels and the person will fall asleep again. [ 35 ]  This carbon dioxide build-up may be due to the decrease of output of the brainstem regulating the chest wall or pharyngeal muscles, which causes the pharynx to collapse. [ 36 ]  People with sleep apnea experience reduced or no  slow-wave sleep  and spend less time in  REM sleep . [ 36 ]


Central sleep apnea


There are two main mechanism that drive the disease process of CSA, sleep-related hypoventilation and post-hyperventilation hypocapnia. [ 18 ]  The most common cause of CSA is post-hyperventilation hypocapnia secondary to heart failure. [ 18 ]  This occurs because of brief failures of the ventilatory control system but normal alveolar ventilation. [ 18 ]  In contrast, sleep-related hypoventilation occurs when there is a malfunction of the brain's drive to breathe. [ 18 ]  The underlying cause of the loss of the wakefulness drive to breathe encompasses a broad set of diseases from strokes to severe kyphoscoliosis. [ 18 ]


OSA is a serious medical condition with systemic effects; patients with untreated OSA have a greater mortality risk from cardiovascular disease than those undergoing appropriate treatment. [ 37 ]  Other complications include hypertension, congestive heart failure, atrial fibrillation, coronary artery disease, stroke, and type 2 diabetes. [ 37 ]  Daytime fatigue and sleepiness, a common symptom of sleep apnea, is also an important public health concern regarding transportation crashes caused by drowsiness. [ 37 ]  OSA may also be a risk factor of  COVID-19 . People with OSA have a higher risk of developing severe complications of COVID-19. [ 38 ]


Alzheimer's disease  and severe obstructive sleep apnea are connected [ 39 ]  because there is an increase in the protein  beta-amyloid  as well as  white-matter  damage.  These are the main indicators of Alzheimer's, which in this case comes from the lack of proper rest or poorer sleep efficiency resulting in  neurodegeneration . [ 3 ] [ 40 ] [ 41 ]  Having sleep apnea in mid-life brings a higher likelihood of developing Alzheimer's in older age, and if one has Alzheimer's then one is also more likely to have sleep apnea. [ 9 ]  This is demonstrated by cases of sleep apnea even being misdiagnosed as  dementia . [ 42 ]  With the use of treatment through CPAP, there is a reversible risk factor in terms of the amyloid proteins.  This usually restores brain structure and f cognitive impairment. [ 43 ] [ 44 ] [ 45 ]  Evidence continues to be found supporting there is an association between BMI and Alzheimer's. [ 46 ]  There is also evidence of increased risk of developing Alzheimer's for those with a higher BMI in women ages 70 and above. [ 47 ]  While continuous positive airway pressure (CPAP) wasn't found to significantly improve cognitive performance, it was found to benefit other symptoms like depression, anxiety, etc. [ 48 ]


There are three types of sleep apnea. OSA accounts for 84%, CSA for 0.9%, and 15% of cases are mixed. [ 49 ]


In a systematic review of published evidence, the  United States Preventive Services Task Force  in 2017 concluded that there was uncertainty about the accuracy or clinical utility of all potential screening tools for OSA, [ 50 ]  and recommended that evidence is insufficient to assess the balance of benefits and harms of screening for OSA in asymptomatic adults. [ 51 ]


The diagnosis of OSA syndrome is made when the patient shows recurrent episodes of partial or complete collapse of the upper airway during sleep resulting in apneas or hypopneas, respectively. [ 52 ]  Criteria defining an apnea or a hypopnea vary. The  American Academy of Sleep Medicine (AASM)  defines an apnea as a reduction in airflow of ≥ 90% lasting at least 10 seconds. A hypopnea is defined as a reduction in airflow of ≥ 30% lasting at least 10 seconds and associated with a ≥ 4% decrease in pulse oxygenation, or as a ≥ 30% reduction in airflow lasting at least 10 seconds and associated either with a ≥ 3% decrease in pulse oxygenation or with an arousal. [ 53 ]


To define the severity of the condition, the Apnea-Hypopnea Index (AHI) or the Respiratory Disturbance Index (RDI) are used. While the AHI measures the mean number of apneas and hypopneas per hour of sleep, the RDI adds to this measure the respiratory effort-related arousals (RERAs). [ 54 ]  The OSA syndrome is thus diagnosed if the AHI is > 5 episodes per hour and results in daytime sleepiness and fatigue or when the RDI is ≥ 15 independently of the symptoms. [ 55 ]  According to the American Association of Sleep Medicine, daytime sleepiness is determined as mild, moderate and severe depending on its impact on social life. Daytime sleepiness can be assessed with the Epworth Sleepiness Scale (ESS), a self-reported questionnaire on the propensity to fall asleep or doze off during daytime. [ 56 ]  Screening tools for OSA itself comprise the STOP questionnaire, the Berlin questionnaire and the STOP-BANG questionnaire which has been reported as being a very powerful tool to detect OSA. [ 57 ] [ 58 ]


According to the  International Classification of Sleep Disorders , there are 4 types of criteria. [ 59 ] [ 60 ]  The first one concerns sleep – excessive sleepiness, nonrestorative sleep, fatigue or insomnia symptoms. The second and third criteria are about respiration – waking with breath holding, gasping, or choking; snoring, breathing interruptions or both during sleep. The last criterion revolved around medical issues as hypertension, coronary artery disease, stroke, heart failure, atrial fibrillation, type 2 diabetes mellitus, mood disorder or cognitive impairment. Two levels of severity are distinguished, the first one is determined by a polysomnography or home sleep apnea test demonstrating 5 or more predominantly obstructive respiratory events per hour of sleep and the higher levels are determined by 15 or more events. If the events are present less than 5 times per hour, no obstructive sleep apnea is diagnosed. [ 60 ]


A considerable night-to-night variability further complicates diagnosis of OSA. In unclear cases, multiple nights of testing might be required to achieve an accurate diagnosis. [ 61 ]  Since sequential nights of testing would be impractical and cost prohibitive in the sleep lab, home sleep testing for multiple nights can not only be more useful, but more reflective of what is typically happening each night. [ 62 ]


Nighttime in-laboratory Level 1 polysomnography (PSG) is the gold standard test for diagnosis. Patients are monitored with EEG leads,  pulse oximetry , temperature and pressure sensors to detect nasal and oral airflow, respiratory impedance plethysmography or similar resistance belts around the chest and abdomen to detect motion, an ECG lead, and EMG sensors to detect muscle contraction in the chin, chest, and legs. A hypopnea can be based on one of two criteria. It can either be a reduction in airflow of at least 30% for more than 10 seconds associated with at least 4% oxygen desaturation or a reduction in airflow of at least 30% for more than 10 seconds associated with at least 3% oxygen desaturation or an arousal from sleep on EEG. [ 63 ]


An "event" can be either an apnea, characterized by complete cessation of airflow for at least 10 seconds, or a  hypopnea  in which airflow decreases by 50 percent for 10 seconds or decreases by 30 percent if there is an associated decrease in the oxygen saturation or an arousal from sleep. [ 64 ]  To grade the severity of sleep apnea, the number of events per hour is reported as the  apnea-hypopnea index  (AHI). An AHI of less than 5 is considered normal. An AHI of 5–15 is mild; 15–30 is moderate, and more than 30 events per hour characterizes severe sleep apnea.


The diagnosis of CSA syndrome is made when the presence of at least 5 central apnea events occur per hour. [ 11 ]  There are multiple mechanisms that drive the apnea events. In individuals with heart failure with Cheyne-Stokes respiration, the brain's respiratory control centers are imbalanced during sleep. [ 65 ]   This results in ventilatory instability, caused by chemoreceptors that are hyperresponsive to CO2 fluctuations in the blood, resulting in high respiratory drive that leads to apnea. [ 11 ]  Another common mechanism that causes CSA is the loss of the brain's wakefulness drive to breathe. [ 11 ]


CSA is organized into 6 individual syndromes: Cheyne-Stokes respiration, Complex sleep apnea, Primary CSA, High altitude periodic breathing, CSA from medication, CSA from comorbidity. [ 11 ]  Like in OSA, nocturnal polysomnography is the mainstay of diagnosis for CSA. [ 18 ]   The degree of respiratory effort, measured by esophageal pressure or displacement of the thoracic or abdominal cavity, is an important distinguishing factor between OSA and CSA. [ 18 ]


Some people with sleep apnea have a combination of both types; its prevalence ranges from 0.56% to 18%. The condition, also called treatment-emergent central apnea, is generally detected when obstructive sleep apnea is treated with CPAP and central sleep apnea emerges. [ 18 ]  The exact mechanism of the loss of central respiratory drive during sleep in OSA is unknown but is most likely related to incorrect settings of the CPAP treatment and other medical conditions the person has. [ 66 ]


The treatment of obstructive sleep apnea is different than that of central sleep apnea. Treatment often starts with behavioral therapy and some people may be suggested to try a  continuous positive airway pressure  device. Many people are told to avoid alcohol, sleeping pills, and other sedatives, which can relax throat muscles, contributing to the collapse of the airway at night. [ 67 ]  The evidence supporting one treatment option compared to another for a particular person is not clear. [ 68 ]


More than half of people with obstructive sleep apnea have some degree of positional obstructive sleep apnea, meaning that it gets worse when they sleep on their backs. [ 69 ]   Sleeping on their sides is an effective and cost-effective treatment for positional obstructive sleep apnea. [ 69 ]


For moderate to severe sleep apnea, the most common treatment is the use of a  continuous positive airway pressure  (CPAP) or automatic positive airway pressure (APAP) device. [ 67 ] [ 70 ]  These splint the person's airway open during sleep by means of pressurized air. The person typically wears a plastic facial mask, which is connected by a flexible tube to a small bedside CPAP machine. [ 67 ]


Although CPAP therapy is effective in reducing apneas and less expensive than other treatments, some people find it uncomfortable. Some complain of feeling trapped, having chest discomfort, and skin or nose irritation. Other side effects may include dry mouth, dry nose, nosebleeds, sore lips and gums. [ 71 ]


Whether or not it decreases the risk of death or heart disease is controversial with some reviews finding benefit and others not. [ 22 ] [ 72 ] [ 68 ]  This variation across studies might be driven by low rates of compliance—analyses of those who use CPAP for at least four hours a night suggests a decrease in cardiovascular events. [ 73 ]


Excess body weight is thought to be an important cause of sleep apnea. [ 74 ]  People who are overweight have more tissues in the back of their throat which can restrict the airway, especially when sleeping. [ 75 ]  In weight loss studies of overweight individuals, those who lose weight show reduced apnea frequencies and improved apnoea–hypopnoea index (AHI). [ 74 ] [ 76 ]  Weight loss effective enough to relieve obesity hypoventilation syndrome (OHS) must be 25–30% of body weight. For some obese people, it can be difficult to achieve and maintain this result without  bariatric surgery . [ 77 ]


In children, orthodontic treatment to expand the volume of the nasal airway, such as nonsurgical rapid  palatal expansion  is common. The procedure has been found to significantly decrease the AHI and lead to long-term resolution of clinical symptoms. [ 78 ] [ 79 ]


Since the palatal suture is fused in adults, regular RPE using tooth-borne expanders cannot be performed. Mini-implant assisted rapid palatal expansion (MARPE) has been recently developed as a non-surgical option for the transverse expansion of the maxilla in adults. This method increases the volume of the nasal cavity and nasopharynx, leading to increased airflow and reduced respiratory arousals during sleep. [ 80 ] [ 81 ]  Changes are permanent with minimal complications.


Several surgical procedures ( sleep surgery ) are used to treat sleep apnea, although they are normally a third line of treatment for those who reject or are not helped by CPAP treatment or dental appliances. [ 22 ]  Surgical treatment for obstructive sleep apnea needs to be individualized to address all anatomical areas of obstruction. [ 10 ]


Often, correction of the nasal passages needs to be performed in addition to correction of the  oropharynx  passage.  Septoplasty  and turbinate surgery may improve the nasal airway, [ 82 ]  but has been found to be ineffective at reducing respiratory arousals during sleep. [ 83 ]


Tonsillectomy  and  uvulopalatopharyngoplasty  (UPPP or UP3) are available to address pharyngeal obstruction. [ 10 ]


The "Pillar" device is a treatment for snoring and obstructive sleep apnea; it is thin, narrow strips of polyester. Three strips are inserted into the roof of the mouth (the  soft palate ) using a modified syringe and local anesthetic, in order to stiffen the soft palate. This procedure addresses one of the most common causes of snoring and sleep apnea — vibration or collapse of the soft palate. It was approved by the FDA for snoring in 2002 and for obstructive sleep apnea in 2004. A 2013 meta-analysis found that "the Pillar implant has a moderate effect on snoring and mild-to-moderate obstructive sleep apnea" and that more studies with high level of evidence were needed to arrive at a definite conclusion; it also found that the polyester strips work their way out of the soft palate in about 10% of the people in whom they are implanted. [ 84 ]


Base-of-tongue advancement by means of advancing the genial tubercle of the mandible, tongue suspension, or  hyoid suspension  (aka hyoid myotomy and suspension or hyoid advancement) may help with the lower pharynx. [ 10 ]


Other surgery options may attempt to shrink or stiffen excess tissue in the mouth or throat, procedures done at either a doctor's office or a hospital. Small shots or other treatments, sometimes in a series, are used for shrinkage, while the insertion of a small piece of stiff plastic is used in the case of surgery whose goal is to stiffen tissues. [ 67 ]


Maxillomandibular advancement  (MMA) is considered the most effective surgery for people with sleep apnea, because it increases the posterior airway space (PAS). [ 85 ]  However, health professionals are often unsure as to who should be referred for surgery and when to do so: some factors in referral may include failed use of CPAP or device use; anatomy which favors rather than impedes surgery; or significant craniofacial abnormalities which hinder device use. [ 86 ]


Several inpatient and outpatient procedures use sedation. Many drugs and agents used during surgery to relieve pain and to depress consciousness remain in the body at low amounts for hours or even days afterwards. In an individual with either central, obstructive or mixed sleep apnea, these low doses may be enough to cause life-threatening irregularities in breathing or collapses in a patient's airways. [ 87 ]  Use of analgesics and sedatives in these patients postoperatively should therefore be minimized or avoided. [ 10 ]


Surgery on the mouth and throat, as well as dental surgery and procedures, can result in postoperative swelling of the lining of the mouth and other areas that affect the airway. Even when the surgical procedure is designed to improve the airway, such as tonsillectomy and adenoidectomy or tongue reduction, swelling may negate some of the effects in the immediate postoperative period. Once the swelling resolves and the palate becomes tightened by postoperative scarring, however, the full benefit of the surgery may be noticed. [ 10 ]


A person with sleep apnea undergoing any medical treatment must make sure their doctor and  anesthetist  are informed about the sleep apnea. Alternative and emergency procedures may be necessary to maintain the airway of sleep apnea patients. [ 88 ]


Diaphragm pacing , which involves the rhythmic application of electrical impulses to the diaphragm, has been used to treat central sleep apnea. [ 89 ] [ 90 ]


In April 2014, the U.S. Food and Drug Administration granted pre-market approval for use of an upper airway stimulation system in people who cannot use a continuous positive airway pressure device. The Inspire Upper Airway Stimulation system is a  hypoglossal nerve stimulator  that senses respiration and applies mild electrical stimulation during inspiration, which pushes the tongue slightly forward to open the airway. [ 91 ]


There is currently insufficient evidence to recommend any medication for OSA. [ 92 ]  This may result in part because people with sleep apnea have tended to be treated as a single group in clinical trials. Identifying specific physiological factors underlying sleep apnea makes it possible to test drugs specific to those causal factors: airway narrowing, impaired muscle activity, low arousal threshold for waking, and unstable breathing control. [ 93 ] [ 94 ]
Those who experience low waking thresholds may benefit from  eszopiclone , a sedative typically used to treat insomnia. [ 93 ] [ 95 ]  The  antidepressant  desipramine  may stimulate upper airway muscles and lessen pharyngeal collapsibility in people who have limited muscle function in their airways. [ 93 ] [ 96 ]


There is limited evidence for medication, but 2012 AASM guidelines suggested that  acetazolamide  "may be considered" for the treatment of central sleep apnea;  zolpidem  and  triazolam  may also be considered for the treatment of central sleep apnea, [ 97 ]  but "only if the patient does not have underlying risk factors for respiratory depression". [ 92 ] [ 70 ]
Low doses of oxygen are also used as a treatment for hypoxia but are discouraged due to side effects. [ 98 ] [ 99 ] [ 100 ]


In December 2024, the FDA approved  tirzepatide , an anti-diabetic and weight loss medication, as a component in the combination treatment of adults with obesity suffering from moderate to severe obstructive sleep apnea. Other components of the therapy are a reduced-calorie diet and increased physical activity. [ 101 ]


An oral appliance, often referred to as a  mandibular advancement splint , is a custom-made mouthpiece that shifts the lower jaw forward and opens the bite slightly, opening up the airway. These devices can be fabricated by a general dentist. Oral appliance therapy (OAT) is usually successful in patients with mild to moderate obstructive sleep apnea. [ 102 ] [ 103 ]  While CPAP is more effective for sleep apnea than oral appliances, oral appliances do improve sleepiness and quality of life and are often better tolerated than CPAP. [ 103 ]


Nasal EPAP  is a bandage-like device placed over the nostrils that uses a person's own breathing to create positive airway pressure to prevent obstructed breathing. [ 104 ]


Oral pressure therapy  uses a device that creates a vacuum in the mouth, pulling the soft palate tissue forward. It has been found useful in about 25 to 37% of people. [ 105 ] [ 106 ]


Death could occur from untreated OSA due to lack of oxygen to the body. [ 71 ]


There is increasing evidence that sleep apnea may lead to liver function impairment, particularly  fatty liver  diseases (see  steatosis ). [ 107 ] [ 108 ] [ 109 ] [ 110 ]


It has been revealed that people with OSA show tissue loss in brain regions that help store memory, thus linking OSA with memory loss. [ 111 ]  Using  magnetic resonance imaging  (MRI), the scientists discovered that people with sleep apnea have  mammillary bodies  that are about 20% smaller, particularly on the left side. One of the key investigators hypothesized that repeated drops in oxygen lead to the brain injury. [ 112 ]


The immediate effects of central sleep apnea on the body depend on how long the failure to breathe endures. At worst, central sleep apnea may cause sudden death. Short of death, drops in blood oxygen may trigger  seizures , even in the absence of  epilepsy . In people  with  epilepsy, the hypoxia caused by apnea may trigger seizures that had previously been well controlled by medications. [ 113 ]  In other words, a seizure disorder may become unstable in the presence of sleep apnea. In adults with  coronary artery disease , a severe drop in blood oxygen level can cause  angina ,  arrhythmias , or heart attacks ( myocardial infarction ). Longstanding recurrent episodes of apnea, over months and years, may cause an increase in carbon dioxide levels that can change the pH of the blood enough to cause a  respiratory acidosis . [ medical citation needed ]


The Wisconsin Sleep Cohort Study estimated in 1993 that roughly one in every 15 Americans was affected by at least moderate sleep apnea. [ 114 ] [ 115 ]  It also estimated that in middle-age as many as 9% of women and 24% of men were affected, undiagnosed and untreated. [ 74 ] [ 114 ] [ 115 ]


The costs of untreated sleep apnea reach further than just health issues. It is estimated that in the U.S., the average untreated sleep apnea patient's annual health care costs $1,336 more than an individual without sleep apnea. This may cause $3.4 billion/year in additional medical costs. Whether medical cost savings occur with treatment of sleep apnea remains to be determined. [ 116 ]


Sleep disorders including sleep apnea have become an important health issue in the United States. Twenty-two million Americans have been estimated to have sleep apnea, with 80% of moderate and severe OSA cases undiagnosed. [ 117 ]


OSA can occur at any age, but it happens more frequently in men who are over 40 and overweight. [ 117 ]


A type of CSA was described in the German  myth  of  Ondine's curse  where the person when asleep would forget to breathe. [ 118 ]  The clinical picture of this condition has long been recognized as a character trait, without an understanding of the disease process. The term " Pickwickian syndrome " that is sometimes used for the syndrome was coined by the famous early 20th-century physician  William Osler , who must have been a reader of  Charles Dickens . The description of Joe, "the fat boy" in Dickens's novel  The Pickwick Papers , is an accurate clinical picture of an adult with obstructive sleep apnea syndrome. [ 119 ]


The early reports of obstructive sleep apnea in the medical literature described individuals who were very severely affected, often presenting with severe  hypoxemia ,  hypercapnia  and  congestive heart failure . [ medical citation needed ]


The management of obstructive sleep apnea was improved with the introduction of  continuous positive airway pressure  (CPAP), first described in 1981 by Colin Sullivan and associates in  Sydney , Australia. [ 120 ]  The first models were bulky and noisy, but the design was rapidly improved and by the late 1980s, CPAP was widely adopted. The availability of an effective treatment stimulated an aggressive search for affected individuals and led to the establishment of hundreds of specialized clinics dedicated to the diagnosis and treatment of  sleep disorders . Though many types of sleep problems are recognized, the vast majority of patients attending these centers have sleep-disordered breathing. Sleep apnea awareness day is 18 April in recognition of Colin Sullivan. [ 121 ]


In  surgery , a  sling  is an implant that is intended to provide additional support to a particular tissue. It usually consists of a synthetic mesh material in the shape of a narrow ribbon but sometimes a biomaterial (bovine or porcine) or the patient’s own tissue. The ends are usually attached to a fixed body part such as the  skeleton .


In  stress incontinence , a sling is a potential method of treatment, and is placed under the urethra through one vaginal incision and two small abdominal incisions. The idea is to replace the deficient pelvic floor muscles and provide a backboard of support under the urethra.


For this purpose, Pelvicol (a porcine dermal sling) implant sling had a comparable patient-determined success rate with TVT. [ 1 ]


Slings can also be used in the surgical management of  female genital prolapse .


A  chin sling  is a  synthetic  lining used in  chin augmentation  to lift the tissues under the  chin  and  neck . The sling is surgically implanted under the skin of the chin and hooked behind the ears, giving a more youthful appearance, and reversing the effects of aging such as accumulated fat, lost skin elasticity and stretched muscle lining, all of which cause the neck to droop and sag.


Sore throat , also known as  throat pain , is pain or irritation of the  throat . [ 1 ]  The majority of sore throats are caused by a virus, for which  antibiotics  are not helpful. [ 2 ]


For sore throat caused by bacteria (GAS), treatment with antibiotics may help the person get better faster, reduce the risk that the bacterial infection spreads, prevent  retropharyngeal abscesses  and  quinsy , and reduce the risk of other complications such as  rheumatic fever  and  rheumatic heart disease . [ 2 ]  In most  developed countries , post-streptococcal diseases have become far less common. For this reason, awareness and  public health  initiatives to promote minimizing the use of antibiotics for viral infections have become the focus. [ 2 ]


Approximately 35% of childhood sore throats and 5–25% of cases in adults are caused by a bacterial infection from group A streptococcus. [ 2 ]  Sore throats that are "non-group A streptococcus" are assumed to be caused by a viral infection. Sore throat is a common reason for people to visit their primary care doctors and the top reason for antibiotic prescriptions by primary care practitioners such as family doctors. [ 2 ]  In the United States, about 1% of all visits to the hospital emergency department, physician office and medical clinics, and outpatient clinics are for sore throat (over 7 million visits for adults and 7 million visits for children per year). [ 2 ]


Causes of sore throat include:


A sore throat is pain felt anywhere in the throat. [ 3 ]


Symptoms of sore throat include:


The most common cause (80%) is  acute   viral  pharyngitis, a viral  infection  of the throat. [ 3 ]   Other causes include other bacterial infections (such as group A streptococcus or  streptococcal pharyngitis ), trauma, and  tumors . [ 3 ]   Gastroesophageal (acid) reflux disease  can cause  stomach acid  to back up into the throat and also cause the throat to become sore. [ 5 ]  In children, streptococcal pharyngitis is the cause of 35–37% of sore throats. [ 6 ] [ 2 ]


The symptoms of a viral infection and a bacterial infection may be very similar. Some clinical guidelines suggest that the cause of a sore throat is confirmed prior to prescribing antibiotic therapy and only recommend antibiotics for children who are at high risk of non- suppurative  complications. [ 7 ] [ 8 ]  A group A streptococcus infection can be diagnosed by  throat culture  or a rapid test:


Clinicians often also make treatment decisions based on the person's signs and symptoms alone. In the US, approximately two-thirds of adults and half of children with sore throat are diagnosed based on symptoms and do not have testing for the presence of GAS to confirm a bacterial infection. [ 2 ]


Numerous clinical scoring systems ( decision tools ) have also been developed to support clinical decisions. Scoring systems that have been proposed include  Centor's , McIsaac's, and the feverPAIN. [ 2 ]  A clinical scoring system is often used along with a rapid test. [ 2 ]  The scoring systems use observed signs and symptoms in order to determine the likelihood of a bacterial infection. [ 2 ]


Sore or  scratchy  throat can temporarily be relieved by  gargling  a solution of 1/4 to 1/2 teaspoon (1.3 to 2.5 milliliters)  salt  dissolved in an 8-US-fluid-ounce (240 ml) glass of water. [ 9 ]


Pain medications such as  non-steroidal anti-inflammatory drugs  (NSAIDs) and  paracetamol  (acetaminophen) help in the  management of pain . [ 10 ] [ 11 ]  The use of  corticosteroids  seems to increase slightly the likelihood of resolution and the reduction of pain, but more analysis is necessary to ensure that  this minimal benefit outweighs the risks. [ 11 ] [ 12 ]  Antibiotics probably reduce pain, diminish headaches and could prevent some sore throat complications, but as these effects are small they must be balanced with the threat of antimicrobial resistance. [ 13 ]   It is not known whether antibiotics are effective for preventing  recurrent  sore throat. [ 14 ]


There is only limited evidence that a hot drink can help alleviate a sore throat, and other  common cold  and  influenza  symptoms. [ 15 ]  If the sore throat is unrelated to a cold and is caused by, for example,  tonsillitis , a cold drink may be helpful. [ 16 ]


There are also other medications such as  lozenges  which can help soothe irritated tissues of the throat.


Without active treatment, symptoms usually last two to seven days. [ 17 ]


In the United States, there are about 2.4 million  emergency department  visits with throat-related complaints per year. [ 3 ]


The  sphenoid bone [ note 1 ]  is an unpaired  bone  of the  neurocranium . It is situated in the middle of the  skull  towards the front, in front of the  basilar part of the occipital bone . The sphenoid bone is one of the seven bones that articulate to form the  orbit . Its shape somewhat resembles that of a  butterfly ,  bat  or  wasp  with its wings extended. The name presumably originates from this shape, since  sphekodes  ( σφηκώδης ) means  ' wasp-like '  in  Ancient Greek .


It is divided into the following parts:


Two  sphenoidal conchae  are situated at the anterior and inferior part of the body.


The more important of these are:


These ligaments occasionally  ossify , though the incidence of ligamentous ossification (both partial and complete) varies according to the ligament type, with the interclinoid ligament being most commonly identified as having ossified and the  pterygoalar ligament  least commonly identified. [ 6 ]


The sphenoid articulates with the  frontal ,  parietal ,  ethmoid ,  temporal ,  zygomatic ,  palatine ,  vomer , and  occipital  bones and helps to connect the  neurocranium  to the  facial skeleton .


Articulates with  ethmoid bone  anteriorly and basilar part of  occipital bone  posteriorly.
It shows:


Sphenoidal crest articulates with the perpendicular plate of  ethmoid  leading to formation of a part of the septum of nose.


Basilar part of occipital bone


Carotid sulcus  lodging  cavernous sinus  and  internal carotid artery


Sphenoidal or  sphenoid sinuses  are asymmetrical air sinuses in the body of the sphenoid, closed by  sphenoidal conchae .


This forms the floor of the  middle cranial fossa .  It presents (starting from the front):


This is divided into (by  infratemporal crest ):


Foramen  pierce it:


This forms the posterior wall of the  orbit [ 4 ]


These are two triangular wings projecting laterally from anterosuperior part of the body.  Each consists of:


Until the seventh or eighth month of  fetal development , the body of the sphenoid consists of two parts: one in front of the  tuberculum sellae , the presphenoid, with which the small wings are continuous; the other, consisting of the  sella turcica  and  dorsum sellae , the postsphenoid, with which are associated the great wings, and pterygoid processes.


The greater part of the bone is ossified in cartilage. There are fourteen centers in all, six for the presphenoid and eight for the postsphenoid.


By about the ninth week of  fetal development  an ossific center appears for each of the  small wings  (orbito-sphenoids) just lateral to the  optic foramen ; this is followed by the appearance of two nuclei in the  presphenoid  part of the body.


The sphenoidal conchae are each developed from a center that makes its appearance about the fifth month; at birth they consist of small triangular laminae, and it is not until the third year that they become hollowed out and coneshaped; about the fourth year they fuse with the labyrinths of the  ethmoid bone , and between the ninth and twelfth years they unite with the sphenoid bone.


The first ossific nuclei are those for the great wings ( alisphenoids ). One makes its appearance in each wing between the  foramen rotundum  and  foramen ovale  about the eighth week. The orbital plate and that part of the sphenoid, which is found in the temporal fossa, as well as the lateral pterygoid plate, are ossified in membrane (Fawcett).


Soon after, the centers for the  postsphenoid part of the body  appear, one on either side of the sella turcica, and become blended together about the middle of fetal life.


Each  medial pterygoid plate  (except its hamulus) is ossified in membrane, and its center probably appears about the ninth or tenth week; the hamulus becomes chondrified during the third month, and almost at once ossifies (Fawcett).


The medial joins the lateral pterygoid plate about the sixth month.


About the fourth month, a center appears for each lingula and speedily joins the rest of the bone.


The  presphenoid  is united to the postsphenoid about the eighth month, and at birth the sphenoid is in three pieces [Fig. 4]: a central, consisting of the body and small wings, and two lateral, each comprising a great wing and pterygoid process.


In the first year after birth the great wings and body unite, and the small wings extend inward above the anterior part of the body, and, meeting with each other in the middle line, form an elevated smooth surface, termed the jugum sphenoidale.


By the twenty-fifth year the sphenoid and occipital are completely fused.


Between the pre- and postsphenoid there are occasionally seen the remains of a canal, the canalis cranio-pharyngeus, through which, in early fetal life, the hypophyseal diverticulum of the buccal  ectoderm  is transmitted.


The sphenoidal sinuses are present as minute cavities at the time of birth (Onodi), but do not attain their full size until after puberty.


This bone assists with the formation of the base and the sides of the skull, and the floors and walls of the orbits. It is the site of attachment for most of the muscles of  mastication . Many foramina and fissures are located in the sphenoid that carry nerves and blood vessels of the head and neck, such as the  superior orbital fissure  (with  ophthalmic nerve ),  foramen rotundum  (with  maxillary nerve ) and  foramen ovale  (with  mandibular nerve ). [ 7 ]


The sphenoid bone of humans is  homologous  with a number of bones that are often separate in other animals, and have a somewhat complex arrangement.


In the early  lobe-finned fishes  and  tetrapods , the pterygoid bones were flat, wing-like bones forming the major part of the roof of the mouth.  Above the pterygoids were the epipterygoid bones, which formed part of a flexible joint between the braincase and the palatal region, as well as extending a vertical bar of bone towards the roof of the skull. Between the pterygoids lay an elongated, narrow parasphenoid bone, which also spread over some of the lower surface of the braincase, and connected, at its forward end, with a  sphenethmoid  bone helping to protect the  olfactory nerves . Finally, the basisphenoid bone formed part of the floor of the braincase and lay immediately above the parasphenoid. [ 8 ]


Aside from the loss of the flexible joint at the rear of the palate, this primitive pattern is broadly retained in  reptiles , albeit with some individual modifications. In  birds , the epipterygoids are absent and the pterygoids considerably reduced. Living  amphibians  have a relatively simplified skull in this region; a broad parasphenoid forms the floor of the braincase, the pterygoids are relatively small, and all other related bones except the sphenethmoid are absent. [ 8 ]


In  mammals , these various bones are often (though not always) fused into a single structure; the sphenoid. The basisphenoid forms the posterior part of the base, while the pterygoid processes represent the pterygoid bones. The epipterygoids have extended into the wall of the cranium; they are referred to as  alisphenoids  when separate in mammals, and form the greater wings of the sphenoid when fused into a larger structure. The sphenethmoid bone forms as three bones: the lesser wings and the anterior part of the base. These two parts of the sphenethmoid may be distinguished as  orbitosphenoids  and  presphenoid , respectively, although there is often some degree of fusion. Only the parasphenoid appears to be entirely absent in mammals. [ 8 ]


In the  dog  the sphenoid is represented by eight bones: basisphenoid, alisphenoids, presphenoid, orbitosphenoids, pterygoids. These bones remain separate and are the:


This article incorporates text in the  public domain  from  page 147  of the 20th edition of   Gray's Anatomy   (1918)


The  sphenoid sinus  is a paired  paranasal sinus  in the  body  of the  sphenoid bone . It is one pair of the four paired paranasal sinuses. [ 1 ]  The two sphenoid sinuses are separated from each other by a septum. Each sphenoid sinus communicates with the  nasal cavity  via the opening of sphenoidal sinus. [ 2 ] : 500   The two sphenoid sinuses vary in size and shape, and are usually asymmetrical. [ 3 ]


On average, a sphenoid sinus measures 2.2 cm vertical height, 2 cm in transverse breadth; and 2.2 cm antero-posterior depth. [ 3 ]


Each spehoid sinus is in the  body of sphenoid bone , just under the  sella turcica . The sphenoid sinuses are separated from each other medially by the septum of sphenoidal sinuses, which is usually asymmetrical. [ 2 ] : 500


An opening of sphenoidal sinus forms a passage between each sphenoidal sinus [ 2 ] : 500   and the nasal cavity. Posteriorly, an opening of sphenoidal sinus opens into the sphenoidal sinus by an aperture high on the anterior wall the sinus; anteriorly, an opening of sphenoidal sinus opens into the roof of the nasal cavity via an aperture on the posterior wall of the  sphenoethmoidal recess , just over the  choana . [ 4 ]


The mucous membrane receives sensory [ citation needed ]  innervation from the  posterior ethmoidal nerve  (branch of the  ophthalmic nerve (CN V 1 ) ) and from branches of the  maxillary nerve (CN V 2 ) . [ 5 ]


Postganglionic   parasympathetic  fibers of the  facial nerve  that  synapsed  at the  pterygopalatine ganglion  control  mucus   secretion . [ citation needed ]


Nearby structures include the  optic canal , the  optic nerve , the  internal carotid artery , the  cavernous sinus , the  trigeminal nerve , the  pituitary gland , and the  anterior ethmoidal cells . [ 2 ] : 500   One study found that  carotid canal  protrudation into the sphenoid sinus wall was present in 23.9–32.1% of males and 35.5–36.2% of females, dehiscence in carotid canal was detected more in females (34%) than in males (22%),  optic canal  protrudation was 33.3 and 30.5% in males and females, and optic canal dehiscence was detected in 11.3% of males and 9.9% of females. [ 6 ]


The sphenoid sinuses vary in size and shape; because of the lateral displacement of the intervening  septum  of sphenoid sinuses, the pair rarely is symmetrical. [ 3 ]


When exceptionally large, the sphenoid sinuses may extend into the roots of the  pterygoid processes  or  greater wings of sphenoid bone , and may invade the  basilar part  of the  occipital bone . [ 3 ]


The septum of the sphenoidal sinuses may be partly or completely absent. Other septa also may be incomplete. [ 2 ] : 500


The sphenoidal sinuses are minute at birth; [ 3 ] [ 4 ]  their main development takes place after puberty. [ 4 ]


The sphenoid sinuses cannot be palpated on physical examination. [ 1 ]  However, patients with isolated  sphenoid sinusitis  may complain of  occipital  or vertex headache, retro-orbital pain,  otalgia , drowsiness, or  meningitis -like symptoms. [ 7 ]


A potential complication of sphenoidal  sinusitis  is  cavernous sinus thrombosis . [ 7 ]


If a fast-growing tumor erodes the floor of the sphenoidal sinus, the  vidian nerve  may be in danger. [ citation needed ]  If the tumor spreads laterally, the  cavernous sinus  and all its constituent nerves may be in danger. [ 8 ]


Sphenoidotomy, a form of endonasal surgery, may be done to enlarge the sphenoid sinus, usually in order to drain it. [ 8 ]


The sphenoid sinus should be distinguished from an  Onodi cell , an anatomic variant that is the rearmost  ethmoidal air cell . Onodi cells typically extend back to lie superolateral to the sphenoid sinus and thus near the  optic nerve  and  internal carotid artery . [ 9 ]  Failure to recognize an Onodi cell on  CT scan  before surgery may put these structures at risk. One study found that an Onodi cell was present in 26.6% of males and 19.1% of females. [ 6 ]


Because only thin shelves of bone separate the sphenoidal sinuses from the nasal cavities, below, and from the  hypophyseal fossa , above, the  pituitary gland  can be reached surgically through the roof of the nasal cavities by passage through the anterioinferior aspect of the sphenoid bone and into the sinuses, followed by entry through the top of the sphenoid bone into the hypophyseal fossa. [ citation needed ]


The  sphenopalatine artery  ( nasopalatine artery ) is an  artery  of the head, commonly known as the  artery of  epistaxis . [ 1 ]  It passes through the  sphenopalatine foramen  to reach the  nasal cavity . It is the main artery of the nasal cavity. [ 2 ]


The sphenopalatine artery is a branch of the  maxillary artery  which passes through the  sphenopalatine foramen  into the cavity of the  nose , at the back part of the  superior meatus . Here it gives off its  posterior lateral nasal branches .


Crossing the under surface of the sphenoid, the sphenopalatine artery ends on the  nasal septum  as the  posterior septal branches .  Here it will  anastomose  with the branches of the  greater palatine artery .


The sphenopalatine artery is the artery commonly responsible for epistaxis (difficult to control bleeding of the nasal cavity, especially the posterior nasal cavity). [ 3 ]  In severe nose bleed cases which do not stop after intense packing of anti-clotting agents, the sphenopalatine artery can be ligated (clipped and then cut) during open surgery or embolized (blocked with surgical glue or tiny microparticles). [ 4 ]  Embolization is typically done under  fluoroscopic  guidance with minimally invasive techniques (e.g. via small  microcatheters  inserted into arteries in the wrist or groin) by interventional radiologists.


This article incorporates text in the  public domain  from  page 562  of the 20th edition of   Gray's Anatomy   (1918)


The  splenius capitis  ( / ˈ s p l iː n i ə s   ˈ k æ p ɪ t ɪ s / ) (from  Greek    splēníon  'bandage' and  Latin    caput  'head' [ 1 ] [ 2 ] ) is a broad, straplike muscle in the back of the neck. It pulls on the  base of the skull  from the  vertebrae   in the neck  and upper  thorax . It is involved in movements such as shaking the head.


It arises from the lower half of the  nuchal ligament , from the  spinous process  of the  seventh cervical vertebra , and from the spinous processes of the upper three or four  thoracic vertebrae .


The fibers of the muscle are directed upward and laterally and are inserted, under cover of the  sternocleidomastoideus , into the  mastoid process  of the  temporal bone , and into the rough surface on the  occipital bone  just below the lateral third of the  superior nuchal line . The splenius capitis is deep to  sternocleidomastoideus  at the mastoid process, and to the  trapezius  for its lower portion. It is one of the muscles that forms the floor of the posterior triangle of the neck.


The splenius capitis muscle is innervated by the  posterior ramus of spinal nerves   C3  and  C4 .


The splenius capitis muscle is a prime mover for head extension. The splenius capitis can also allow lateral flexion and rotation of the  cervical spine .


This article incorporates text in the  public domain  from  page 397  of the 20th edition of   Gray's Anatomy   (1918)


The  stapedius  is the smallest  skeletal muscle  in the  human  body. [ 1 ]  At just over one millimeter in length, its purpose is to stabilize the smallest bone in the body, the  stapes  or stirrup bone of the middle ear.


The stapedius emerges from a pinpoint  foramen  or opening in the apex of the  pyramidal eminence  (a hollow, cone-shaped prominence in the posterior wall of the  tympanic cavity ), and inserts into the neck of the stapes. [ 2 ]   : 863


The stapedius is supplied by the  nerve to stapedius , a branch of the  facial nerve . [ 2 ]   : 863


The stapedius dampens the vibrations of the stapes by pulling on the neck of that bone. [ 2 ]   : 863   As one of the muscles involved in the  acoustic reflex  it prevents excess movement of the  stapes , helping to control the amplitude of  sound waves  from the general external environment to the inner  ear . [ 3 ]


Paralysis  of the stapedius allows wider  oscillation  of the stapes, resulting in heightened reaction of the  auditory ossicles  to sound vibration. This condition, known as  hyperacusis , causes normal sounds to be perceived as very loud. Paralysis of the stapedius muscle may result when the  nerve to the stapedius , a branch of the  facial nerve , is damaged, or when the facial nerve itself is damaged before the nerve to stapedius branches. In cases of  Bell's palsy , a unilateral paralysis of the facial nerve, the stapedius is paralyzed and hyperacusis may result. [ 3 ]


Like the  stapes  bone to which it attaches, the stapedius muscle shares evolutionary history with other vertebrate structures.


The mammalian stapedius evolved from a muscle called the  depressor mandibulae  in other tetrapods, the function of which was to open the jaws (this function was taken over by the  digastric muscle  in mammals). The depressor mandibulae arose from the  levator operculi  in bony fish, and is equivalent to the  epihyoidean  in sharks. Like the stapedius, all of these muscles derive from the  hyoid arch  and are innervated by  cranial nerve VII . [ 4 ]


Rodríguez-Vázquez JF. Development of the stapedius muscle and pyramidal eminence in humans. J Anat. 2009 Sep;215(3):292-9. doi: 10.1111/j.1469-7580.2009.01105.x


The  stapes  or  stirrup  is a  bone  in the  middle ear  of humans and other tetrapods which is involved in the conduction of sound vibrations to the  inner ear . This bone is connected to the  oval window  by its  annular ligament , which allows the footplate (or base) to transmit sound energy through the  oval window  into the inner ear. The  stapes  is the smallest and lightest bone in the  human body , and is so-called because of its resemblance to a  stirrup  ( Latin :  Stapes ).


The  stapes  is the third bone of the three  ossicles  in the  middle ear  and the smallest in the human body. It measures roughly  2 to 3 mm , greater along the head-base span. [ 1 ]  It rests on the  oval window , to which it is connected by an  annular ligament  and articulates with the  incus , or anvil through the  incudostapedial joint . [ 2 ]  They are connected by anterior and posterior limbs ( Latin :  crura ). [ 3 ] : 862


The  stapes  develops from the second  pharyngeal arch  during the sixth to eighth week of  embryological life . The central cavity of the  stapes , the  obturator foramen , is due to the presence embryologically of the  stapedial artery , which usually regresses in humans during normal development. [ 2 ] [ 4 ]


The  stapes  is one of three ossicles in mammals. In non-mammalian  tetrapods , the bone  homologous  to the  stapes  is usually called the  columella ; however, in  reptiles , either term may be used. In fish, the homologous bone is called the  hyomandibular , and is part of the  gill arch  supporting either the  spiracle  or the jaw, depending on the species. The equivalent term in  amphibians  is the  pars media plectra . [ 2 ] [ 5 ] : 481–482


The  stapes  appears to be relatively constant in size in different ethnic groups. [ 6 ]  In 0.01–0.02% of people, the stapedial artery does not regress, and persists in the central foramen. [ 7 ]  In this case, a pulsatile sound may be heard in the affected ear, or there may be no symptoms at all. [ 8 ]  Rarely, the  stapes  may be completely absent. [ 9 ] [ 10 ] : 262


Situated between the incus and the inner ear, the  stapes  transmits sound vibrations from the incus to the oval window, a membrane-covered opening to the inner ear. The  stapes  is also stabilized by the  stapedius  muscle, which is innervated by the  facial nerve . [ 3 ] : 861–863


Otosclerosis  is a congenital or spontaneous-onset disease characterized by abnormal  bone remodeling  in the inner ear. Often this causes the  stapes  to adhere to the oval window, which impedes its ability to conduct sound, and is a cause of  conductive hearing loss . Clinical otosclerosis is found in about 1% of people, although it is more common in forms that do not cause noticeable hearing loss. Otosclerosis is more likely in young age groups, and females. [ 11 ]  Two common treatments are  stapedectomy , the surgical removal of the  stapes  and replacement with an artificial prosthesis, and  stapedotomy , the creation of a small hole in the base of the  stapes  followed by the insertion of an artificial prosthesis into that hole. [ 12 ]   : 661   Surgery may be complicated by a  persistent stapedial artery ,  fibrosis -related damage to the base of the bone, or obliterative otosclerosis, resulting in obliteration of the base. [ 7 ] [ 10 ]   : 254–262


The  stapes  is commonly described as having been discovered by the professor  Giovanni Filippo Ingrassia  in 1546 at the  University of Naples , [ 13 ]   although this remains the nature of some controversy, as Ingrassia's description was published posthumously in his 1603 anatomical commentary  In Galeni librum de ossibus doctissima et expectatissima commentaria . Spanish anatomist  Pedro Jimeno  is first to have been credited with a published description, in  Dialogus de re medica  (1549). [ 14 ]  The bone is so-named because of its resemblance to a stirrup ( Latin :  stapes ), an example of a  late Latin  word, probably created in  mediaeval  times from "to stand" ( Latin :  stapia ), as stirrups did not exist in the early Latin-speaking world. [ 15 ]


The  sternocleidomastoid muscle  is one of the largest and most superficial cervical muscles. The primary actions of the muscle are rotation of the head to the opposite side and  flexion  of the neck. [ 3 ]  The sternocleidomastoid is innervated by the  accessory nerve . [ 3 ]


It is given the name  sternocleidomastoid  because it originates at the  manubrium  of the  sternum  ( sterno- ) and the  clavicle  ( cleido- ) and has an  insertion  at the  mastoid process  of the  temporal bone  of the  skull . [ 4 ]


The sternocleidomastoid muscle originates from two locations: the  manubrium  of the  sternum  and the  clavicle . [ 4 ]  It travels obliquely across the side of the neck and inserts at the  mastoid process  of the  temporal bone  of the  skull  by a thin  aponeurosis . [ 4 ] [ 5 ]  The sternocleidomastoid is thick and narrow at its center, and broader and thinner at either end.


The sternal head is a round  fasciculus , tendinous in front, fleshy behind, arising from the upper part of the front of the  manubrium sterni . It travels superiorly, laterally, and posteriorly.


The clavicular head is composed of fleshy and  aponeurotic  fibers, arises from the upper, frontal surface of the medial third of the  clavicle ; it is directed almost vertically upward.


The two heads are separated from one another at their origins by a triangular interval ( lesser supraclavicular fossa ) but gradually blend, below the middle of the neck, into a thick, rounded muscle which is inserted, by a strong tendon, into the lateral surface of the  mastoid process , from its apex to its superior border, and by a thin  aponeurosis  into the lateral half of the  superior nuchal line  of the  occipital bone .


The sternocleidomastoid is innervated by  accessory nerve  of the same side. [ 6 ] [ 7 ]  It supplies only motor fibres. The cervical plexus supplies sensation, including  proprioception , from the  ventral primary rami  of  C2  and  C3 . [ 6 ]


The clavicular origin of the sternocleidomastoid varies greatly: in some cases the clavicular head may be as narrow as the sternal; in others it may be as much as 7.5 millimetres (0.30 in) in breadth.


When the clavicular origin is broad, it is occasionally subdivided into several slips, separated by narrow intervals. More rarely, the adjoining margins of the sternocleidomastoid and  trapezius  are in contact. This would leave no  posterior triangle .


The  supraclavicularis muscle  arises from the manubrium behind the sternocleidomastoid and passes behind the sternocleidomastoid to the upper surface of the clavicle.


The function of this muscle is to rotate the head to the opposite side or obliquely rotate the head. [ 4 ]  It also flexes the neck. [ 4 ]  When both sides of the muscle act together, it  flexes  the neck and extends the head. When one side acts alone, it causes the head to rotate to the opposite side and flexes laterally to the same side (ipsilaterally).


It also acts as an  accessory muscle of respiration , along with the  scalene muscles  of the neck.


The signaling process to contract or relax the sternocleidomastoid begins in Cranial Nerve XI, the  accessory nerve . The accessory nerve nucleus is in the  anterior horn of the spinal cord  around C1-C3, where lower motor neuron fibers mark its origin. The fibers from the accessory nerve nucleus travel upward to enter the cranium via the foramen magnum. The internal carotid artery to reach both the sternocleidomastoid muscles and the  trapezius . After a signal reaches the accessory nerve nucleus in the anterior horn of the spinal cord, the signal is conveyed to  motor endplates  on the muscle fibers located at the clavicle.  Acetylcholine  (ACH) is released from vesicles and is sent over the synaptic cleft to receptors on the postsynaptic bulb. The ACH causes the resting potential to increase above -55mV, thus initiating an action potential which travels along the muscle fiber. Along the muscle fibers are t-tubule openings which facilitate the spread of the action potential into the muscle fibers. The t-tubule meets with the  sarcoplasmic reticulum  at locations throughout the muscle fiber, at these locations the sarcoplasmic reticulum releases calcium ions that results in the movement of  troponin  and  tropomyosin  on thin filaments. The movement of troponin and tropomyosin is key in facilitating the myosin head to move along the thin filament, resulting in a contraction of the sternocleidomastoid muscle. [ 8 ]


The sternocleidomastoid is within the  investing fascia  of the neck, along with the  trapezius muscle , with which it shares its nerve supply (the  accessory nerve ). It is thick and thus serves as a primary  landmark  of the neck, as it divides the neck into anterior and posterior cervical triangles (in front and behind the muscle, respectively) which helps define the location of structures, such as the lymph nodes for the head and neck. [ 9 ]


Many important structures relate to the sternocleidomastoid, including the  common carotid artery , accessory nerve, and  brachial plexus .


Examination of the sternocleidomastoid muscle forms part of the  examination of the cranial nerves . It can be felt on each side of the neck when a person moves their head to the opposite side. [ 9 ]


The triangle formed by the clavicle and the sternal and clavicular heads of the sternocleidomastoid muscle is used as a landmark in identifying the correct location for  central venous catheterization . [ 10 ]


Contraction of the muscle gives rise to a condition called  torticollis  or  wry neck , and this can have a number of causes.  Torticollis gives the appearance of a tilted head on the side involved. Treatment involves physiotherapy exercises to stretch the involved muscle and strengthen the muscle on the opposite side of the neck.  Congenital torticollis  can have an unknown cause or result from  birth trauma  that gives rise to a mass or tumor that can be palpated within the muscle.


This article incorporates text in the  public domain  from  page 390  of the 20th edition of   Gray's Anatomy   (1918)


The  stomatognathic system  is an anatomical system comprising the  teeth ,  jaws , and associated soft tissues. It was formerly called the  stomognathic system .


Stomatognathic diseases  are treated by  dentists ,  maxillofacial surgeons ,  ear, nose, and throat specialists ,  speech therapists ,  occupational therapists ,  myofunctional therapists , and  physical therapists .


The  stylohyoid muscle  is one of the  suprahyoid muscles . [ 1 ]  Its originates from the styloid process of the  temporal bone ; it inserts onto hyoid bone. It is innervated by a branch of the  facial nerve . It acts draw the  hyoid bone  upwards and backwards.


The stylohyoid is a  slender   muscle . [ 2 ]  It is directed inferoanteriorly from its origin towards its insertion. [ 3 ]


It is perforated near its insertion by the intermediate  tendon  of the  digastric muscle . [ 3 ]


The muscle arises from the posterior surface of the  temporal styloid process ; it arises near the base of the process. It arises by a small tendon of origin. [ 3 ]


The muscle inserts onto the  body of hyoid bone  at the junction of the body and  greater cornu . [ 3 ]


The site of insertion is situated immediately superior to that of the superior belly of  omohyoid muscle . [ 3 ]


The stylohyoid muscle receives arterial supply branches of the  facial artery ,  posterior auricular artery , and  occipital artery . [ 3 ]


The stylohyoid muscle receives motor innervation from the  stylohyoid branch  of  facial nerve (CN VII) . [ 3 ]


The muscle is situated  antero superior  to the posterior belly of the  digastric muscle . [ 2 ]


It may be absent or doubled. It may be situated medial to the  carotid artery . It may insert suprahyoid muscles of infrahyoid muscles. [ 3 ]


The stylohyoid muscle elevates and retracts the hyoid bone (i.e. draws it superiorly and posteriorly). [ 3 ]


The stylohyoid muscle elongates the floor of the mouth. [ 3 ]  It initiates a swallowing. [ citation needed ]


This article incorporates text in the  public domain  from  page 392  of the 20th edition of   Gray's Anatomy   (1918)


Anatomy figure: 34:02-04  at Human Anatomy Online, SUNY Downstate Medical Center


The  stylomastoid foramen  is a  foramen  between the  styloid  and  mastoid  processes of the  temporal bone  of the  skull . It is the termination of the  facial canal , and transmits the  facial nerve , and  stylomastoid artery . Facial nerve  inflammation  in the stylomastoid foramen may cause  Bell's palsy .


The stylomastoid foramen is between the  styloid  and  mastoid  processes of the  temporal bone . The average distance between the opening of the stylomastoid foramen and the styloid process is around 0.7 mm or 0.8 mm in adults, but may decrease to around 0.2 mm during aging. [ 1 ]


The stylomastoid foramen transmits the  facial nerve , [ 2 ] [ 3 ]  and the  stylomastoid artery . [ 3 ]  These 2 structures lie directly next to each other. [ 3 ]


Bell's palsy  can result from  inflammation  of the  facial nerve  where it leaves the skull at the stylomastoid foramen. Patients with Bell's palsy appear with facial drooping on the affected side.


The  sublingual gland  ( glandula sublingualis ) is a seromucous polystomatic  exocrine gland . Located underneath the oral diaphragm ( diaphragma oris ), the sublingual gland is the smallest and most diffuse of the three major salivary glands of the oral cavity, with the other two being the  submandibular  and  parotid . The sublingual gland provides approximately 3-5% of the total salivary volume. [ 1 ] [ 2 ]


They lie anterior and superior to the  submandibular gland  and inferior and lateral to the  tongue , as well as beneath the  mucous membrane  of the floor of the mouth. They are bound laterally by the bone of the mandible and inferolaterally by the  mylohyoid muscle .  The glands can be felt behind each mandibular canine. Placing one index finger within the mouth and the fingertips of the opposite hand outside it, the compressed gland is manually palpated between the inner and outer fingers. [ clarification needed ] [ 3 ]


The sublingual gland is constituted by 1 major duct and approximately 20 small excretory ducts, with the latter often being referred to as  ducts of Rivinus . [ 4 ]  The largest of all, the  sublingual duct  (of Bartholin) joins the submandibular duct to drain through the  sublingual caruncle . The sublingual caruncle is a small papilla near the midline of the floor of the mouth on each side of the lingual frenum. [ 3 ]  Most of the remaining small sublingual ducts (of Rivinus) open separate into the mouth on an elevated crest of mucous membrane, the  plica sublingualis  (aka  sublingual fold ), formed by the gland and located on either side of the  frenulum linguae .


The sublingual gland consists mostly of mucous acini capped with  serous demilunes  and is therefore categorized as a mixed mucous gland with a mucous product predominating.  Striated  and  intercalated  ducts are also present. [ 1 ]


The gland receives its blood supply from the sublingual and submental arteries. [ 4 ]  Lymph from the sublingual salivary gland drains into the  submandibular lymph nodes . [ 3 ]


The  chorda tympani  nerve (from the  facial nerve  via the  submandibular ganglion ) is  secretomotor  and provides parasympathetic supply to the sublingual glands. The path of the nerve is as follows: junction between  pons  and  medulla , through  internal acoustic meatus  and  facial canal  to  chorda tympani , through middle ear cavity, out petrotympanic fissure to join the  lingual nerve , travels with lingual nerve to synapse at the  submandibular ganglion , then  postganglionic  fibers travels to the sublingual gland.


The sublingual salivary glands appear in the eighth week of prenatal development, two weeks later than the other two major salivary glands. They develop from  epithelial  buds in the sulcus surrounding the sublingual folds on the floor of the mouth, lateral to the developing submandibular gland. These buds branch and form into cords that canalize to form the sublingual ducts associated with the gland. The rounded terminal ends of the cords form  acini . [ 1 ]


Ranulas  are the most common pathologic lesion associated with the sublingual glands. [ 5 ]


The  sublingual space  is a  fascial space of the head and neck  (sometimes also termed fascial spaces or tissue spaces). It is a  potential space [ 1 ]  located below the mouth and above the  mylohyoid muscle , and is part of the suprahyoid group of fascial spaces.


The sublingual space is V-shaped, with the apex pointing to the anterior. Its boundaries are: [ 2 ]


The sublingual space communicates posteriorly around the posterior free border of the mylohyoid muscle with the  submandibular space . [ 2 ]  Infections of the sublingual space may also erode through the mylohyoid, or spread via the lymphatics to the submandibular and  submental spaces .


The sublingual space contains: [ 2 ]


This space may be created by pathology, such as the spread of  pus  in an infection, e.g.  odontogenic infections . A  periapical abscess  may spread into the sublingual space if the apex of the tooth is above the level of attachment of mylohyoid, and the infection erodes through the lingual cortical plate of the mandible.


Signs and symptoms of a sublingual space infection might include a firm, painful swelling in the anterior part of the floor of the mouth. A sublingual abscess may elevate the tongue and cause drooling or  dysphagia  (difficulty swallowing). There is usually little swelling visible on the face outside the mouth.


If the space contains pus, the usual treatment is by  incision and drainage . The site of the incision is intra-oral, made lateral to sublingual plica. Incision of the plica itself can result in a  ranula , or an incision placed medial to the plica can damage Wharton's duct, the sublingual artery and veins and the lingual nerve.


Pathology arising from the sublingual gland is rare, however, sublingual gland  neoplasms  are predominantly  malignant  and thus important to recognize.


Ludwig's angina  is a serious infection involving the submandibular, sublingual and submental spaces bilaterally. [ 3 ]  Ludwig's angina may extend into the pharyngeal and cervical spaces, and the swelling can compress the airway and cause  dyspnoea  (difficulty breathing). [ 3 ]  Collectively, the submandibular, sublingual and submental spaces are sometimes termed the perimandibular spaces, or the submaxillary space. [ 4 ]


The  submandibular ganglion  (or  submaxillary ganglion  in older texts) is part of the human  autonomic nervous system . It is one of four  parasympathetic ganglia  of the head and neck. (The others are the  otic ganglion ,  pterygopalatine ganglion , and  ciliary ganglion ).


The submandibular ganglion is small and  fusiform  in shape. It is situated above the deep portion of the  submandibular gland , on the  hyoglossus muscle , near the posterior border of the  mylohyoid muscle .


The ganglion 'hangs' by two nerve filaments from the lower border of the  lingual nerve  (itself a branch of the  mandibular nerve , CN V 3 ). It is suspended from the lingual nerve by two filaments, one anterior and one posterior. Through the posterior of these it receives a branch from the  chorda tympani  nerve which runs in the sheath of the lingual nerve.


Like other parasympathetic ganglia of the head and neck, the submandibular ganglion is the site of synapse for parasympathetic fibers and carries other types of nerve fiber that do not synapse in the ganglion. In summary, the fibers carried in the ganglion are:


The paired  submandibular glands  (historically known as  submaxillary glands ) are major  salivary glands  located beneath the  floor of the mouth . In adult humans, they each weigh about 15 grams and contribute some 60–67% of unstimulated saliva secretion; on stimulation their contribution decreases in proportion as  parotid gland  secretion rises to 50%. [ 1 ]  The average length of the normal adult human submandibular salivary gland is approximately 27 mm, while the average width is approximately 14.3 mm. [ 2 ]


Each submandibular gland is divided into a superficial lobe and a deep lobe, the two being separated by the  mylohyoid muscle : [ 3 ]


Secretions are delivered into the  submandibular duct  on the deep portion after which they hook around the posterior edge of the mylohyoid muscle and proceed on the superior surface laterally. The excretory ducts are then crossed by the  lingual nerve , and ultimately drain into the  sublingual caruncles  – small prominences on either side of the  lingual frenulum  along with the major  sublingual duct . The gland can be bilaterally  palpated  (felt) inferior and posterior to the body of the mandible, moving inward from the inferior border of the mandible near its angle with the head tilted forwards. [ 4 ]


The terminal part of the submandibular (Wharton's) duct is located in the mouth floor and opens as an orifice of the submandibular duct papilla. The position of the duct and its 0.5–1.5 mm wide ostium is invariably symmetric, but quite unpredictable; consequently, submandibular duct papillae can occasionally be challenging to recognize. Based on the macroscopic appearance of the papillae and a  sialoendoscopic  approach, Anicin et al. described four different types of submandibular gland papillae: types A, B, C, and D. [ 5 ]


Lobes contain smaller lobules, which contain  adenomeres , the secretory units of the gland. Each adenomere contains one or more  acini , or alveoli, which are small clusters of cells that secrete their products into a duct. The acini of each adenomere are composed of either  serous  or  mucous cells , with serous adenomeres predominating. [ 6 ]  Some mucous adenomeres may also be capped with a  serous demilune , a layer of  lysozyme -secreting serous cells resembling a half moon.


Like other  exocrine glands , the submandibular gland can be classified by the microscopic anatomy of its secretory cells and how they are arranged. Because the glands are branched, and because the tubules forming the branches contain secretory cells, submandibular glands are classified as  branched tubuloacinar glands . Further, because the secretory cells are of both serous and mucous types, the submandibular gland is a mixed gland, and though most of the cells are serous, the exudate is chiefly mucous.  It has long striated ducts and short intercalated ducts. [ 7 ]


The secretory acinar cells of the submandibular gland have distinct functions. The mucous cells are the most active and therefore the major product of the submandibular glands is saliva which is mucoid in nature. Mucous cells secrete mucin which aids in the lubrication of the food bolus as it travels through the esophagus. In addition, the serous cells produce salivary amylase, which aids in the breakdown of starches in the mouth. The submandibular gland's highly active acini account for most of the salivary volume. The parotid and sublingual glands account for the remaining.


The gland receives its blood supply from the facial and lingual arteries. [ 8 ]  The gland is supplied by sublingual and submental arteries and drained by common facial and lingual veins.


The lymphatics from submandibular gland first drain into submandibular lymph nodes and subsequently into jugulo - digastric lymph nodes.


Their secretions, like the secretions of other salivary glands, are regulated  directly  by the  parasympathetic nervous system  and  indirectly  by the  sympathetic nervous system .


The submandibular gland occurs within the  submandibular triangle . It is situated posteroinferior to the  ramus of mandible , [ 12 ] : 601   and between the two bellies of the  digastric muscle . [ 12 ] : 601


The submandibular salivary glands develop later than the parotid glands and appear late in the sixth week of prenatal development. They develop bilaterally from epithelial buds in the sulcus surrounding the sublingual folds on the floor of the primitive mouth. Solid cords branch from the buds and grow posteriorly, lateral to the developing tongue. The cords of the submandibular gland later branch further and then become canalized to form the ductal part. The submandibular gland acini develop from the cords’ rounded terminal ends at 12 weeks, and secretory activity via the submandibular duct begins at 16 weeks. Growth of the submandibular gland continues after birth with the formation of more acini. Lateral to both sides of the tongue, a linear groove develops and closes over to form the submandibular duct. [ 7 ]


The submandibular gland is one of the major three glands that provide the mouth with  saliva . The
two other types of  salivary  glands are  parotid  and  sublingual  glands. [ 13 ]


The submandibular gland releases a host of factors which regulate systemic inflammatory responses and modulate systemic immune and inflammatory reactions.  Early work in identifying factors that played a role in the cervical sympathetic trunk-submandibular gland (CST-SMG) axis lead to the discovery of a seven  amino acid   peptide , called the submandibular gland peptide-T.  SGP-T was demonstrated to have biological activity and thermoregulatory properties related to  endotoxin  exposure. [ 14 ]  SGP-T, an isolate of the submandibular gland, demonstrated its immunoregulatory properties and potential role in modulating the CST-SMG axis, and subsequently was shown to play an important role in the control of inflammation.


The submandibular gland accounts for 80% of all  salivary duct calculi  (salivary stones or sialolith), possibly due to the different nature of the saliva that it produces and the tortuous travel of the submandibular duct to its ductal opening for a considerable upward distance. [ 16 ]


Benign and malignant tumors can also develop in the submandibular gland (see pie chart).


The  submandibular space  is a  fascial space of the head and neck  (sometimes also termed fascial spaces or tissue spaces). It is a  potential space , and is paired on either side, located on the superficial surface of the  mylohyoid muscle  between the anterior and posterior bellies of the  digastric muscle . [ 1 ]  The space corresponds to the anatomic region termed the  submandibular triangle , part of the  anterior triangle of the neck .


The anatomic boundaries of each submandibular space are: [ 2 ]


The communications of the submandibular space are:


In health, the contents of the space are:


Infections  may spread into the submandibular space, e.g.  odontogenic infections , often related to the  mandibular molar  teeth. This is due to the fact that the attachment of mylohyoid (the  mylohyoid line ) becomes more superior towards the posterior of the mandible, meaning that the roots of the posterior teeth are more likely to be below mylohyoid than above.


Signs and symptoms of a submandibular space infection might include  trismus  (difficulty opening the mouth), inability to  palpate  (feel) the inferior border of the mandible and swelling of the face over the submandibular region.


If the space contains pus, the usual treatment is by  incision and drainage . The site of the incision is extra-oral, and usually made 2–3 cm below, and parallel to, the inferior border of the mandible.


Ludwig's angina  is a serious infection involving the submandibular, sublingual and submental spaces bilaterally. [ 3 ]  Ludwig's angina may extend into the pharyngeal and cervical spaces, and the swelling can compress the airway and cause  dyspnoea  (difficulty breathing). [ 3 ]


The  submasseterric space  (also termed the  masseteric space ) is a  fascial space of the head and neck  (sometimes also termed  fascial  spaces or tissue spaces). It is a  potential space  in the face over the angle of the jaw, and is paired on each side. It is located between the lateral aspect of the mandible and the medial aspect of the  masseter muscle  and its  investing fascia . The term is derived from  sub-  meaning "under" in Latin and  masseteric  which refers to the masseter muscle. The submasseteric space is one of the four  compartments  of the  masticator space . [ 1 ]  Sometimes the submasseteric space is described as a series of spaces, created because the masseter muscle has multiple insertions that cover most of the lateral surface of the  ramus of the mandible .


The boundaries of each submasseteric space are:


The communications of each submasseteric space are:


Submasseteric abscesses are relatively rare, and may be confused with a  parotid abscess  or  parotitis . [ 2 ]  They tend to be chronic. [ 3 ]  The submasseteric space may be involved by infections that spread from the buccal space. [ 1 ]  Sometimes  mandibular fractures  in the region of the angle of the mandible may cause an infection of the submasseteric space. [ 1 ]  The signs and symptoms of a submasseteric abscess may include marked  trismus  (i.e. difficulty opening the mouth, since the masseter elevates the mandible and it becomes restricted) and swelling in the region of the masseter muscle. [ 1 ]  The treatment of a submasseteric space infection is usually by surgical  incision and drainage , and the incision is placed intra-orally (inside the mouth) or both intra and extra-orally if other parts of the masticator space are involved.


The submasseteric space is sometimes involved by the spread of  odontogenic infections , such as a  pericoronal abscess  associated with an  impacted   mandibular third molar  (lower wisdom tooth) when the apices of the tooth lie very close to or within the space. [ 4 ]


The  submental space  is a  fascial space of the head and neck  (sometimes also termed  fascial  spaces or tissue spaces). It is a  potential space  located between the  mylohyoid muscle   superiorly , the  platysma muscle   inferiorly , [ 1 ]  under the chin in the midline. The space coincides with the  anatomic  region termed the  submental triangle , part of the  anterior triangle of the neck .


The boundaries of the submental space are:


The communications of the submental space are:


Its contents are submental  lymph nodes ,  areolar connective tissue  and the  anterior jugular veins .


This space may be created by pathology, such as the spread of  pus  in an infection.  Odontogenic infection  of the mandibular anterior teeth may erode through the lingual cortical plate of the mandible. If the level at which the infection breaks out of the mandible is below the attachment of the mylohyoid, then it will spread into the submental space. [ 1 ]  However, it is more usual for odontogenic infections to spread into the submental space via first involving the submandibular space. Cutaneous infections or symphyseal/parasymphyseal  mandibular fractures  may also give rise to a submental space infection. Signs and symptoms of a severe submental  abscess  include a firm swelling below the chin and  dysphagia  (difficulty swallowing). Treatment is by surgical  incision and drainage , with the incision running transversely in a skin crease behind the chin.


Ludwig's angina  is a progressive  cellulitis  involving the submandibular, sublingual and submental spaces bilaterally. Ludwig's angina may extend into the pharyngeal and cervical spaces, and the swelling can compress the airway and cause  dyspnoea  (difficulty breathing). [ 1 ]


Superficial muscular aponeurotic system  (or  superficial musculoaponeurotic system [ 1 ] ) ( SMAS ) is a thin yet tough [ 2 ] : 438   unitary tissue plane of the face [ 3 ]  formed by facial fasciae, subcutis connective tissue, and facial muscles. [ 2 ] : 438   Its composition varies, containing muscle fibres in some areas, and fibrous or fibroaponeurotic tissue in others. [ 3 ]  It connects to the dermis via vertical septa. [ citation needed ]  It does not attach to bone. In most areas, a distinct plane can be defined deep to the SMAS (continuous with that formed between the platysma and underlying  investing layer of deep cervical fascia ). [ 3 ]


Superiorly, the SMAS extends to the  galea aponeurotica  of [ citation needed ]  the scalp, [ 2 ] : 438   becoming continuous with  temporoparietal fascia [ 1 ] [ 1 ]  (at the  zygomatic arch [ 1 ] ) and galea. [ citation needed ]  It becomes continuous with the  platysma muscle  inferiorly (inferior to the inferior border of the mandible), and indistinct laterally (inferior to the  zygomatic arch ). Anteromedially, it blends with the  epimysium  of some facial muscles; [ 3 ]  a link between facial muscles and the skin of the face is thereby established, enabling  facial expression . [ 2 ] : 429   Over the parotid gland, the SMAS is firmly united with the superficial layer of  parotid fascia . [ 4 ]


The SMAS is clinically important in  facial   plastic surgery  for  rhytidectomy (facelift procedure) . During this procedure, the SMAS is accessed through an arch-shaped incision anterior to the ear; a portion of the SMAS is then excised and the remaining SMAS is stretched by drawing it posterior-ward and suturing it, thus making the skin of the face which overlies the SMAS taut. [ 2 ] : 438


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


The  superior labial artery  ( superior labial branch of facial artery ) is larger and more egregious than the  inferior labial artery .


It follows a similar course along the edge of the  upper lip , lying between the  mucous membrane  and the  orbicularis oris , and anastomoses with the artery of the opposite side.


It supplies the upper lip, and gives off in its course two or three vessels which ascend to the nose; a septal branch ramifies on the  nasal septum  as far as the point of the  nose , and an alar branch supplies the  ala of the nose .


This article incorporates text in the  public domain  from  page 555  of the 20th edition of   Gray's Anatomy   (1918)


Surgical airway management  ( bronchotomy [ 1 ]  or  laryngotomy ) is the medical procedure ensuring an open  airway  between a patient’s  lungs  and the outside world. Surgical methods for airway management rely on making a surgical incision below the  glottis  in order to achieve direct access to the  lower respiratory tract , bypassing the  upper respiratory tract . Surgical airway management is often performed as a last resort in cases where orotracheal and nasotracheal  intubation  are impossible or  contraindicated . Surgical airway management is also used when a person will need a  mechanical ventilator  for a longer period. The surgical creation of a permanent opening in the  larynx  is referred to as laryngostomy.
Surgical airway management is a primary consideration in  anaesthesia ,  emergency medicine  and  intensive care medicine .


Surgical methods for airway management include  cricothyrotomy  and  tracheostomy


Asclepiades of Bithynia  is credited with being the first person who proposed bronchotomy as a surgical procedure, though he never attempted to perform one. [ 2 ]   Aretaeus of Cappadocia  thought the procedure dangerous even as a remedy for  choking , since the resulting incision " would not heal, as being  cartilaginous ";  Caelius Aurelianus  also rejected its usefulness. [ 2 ]


A cricothyrotomy is an incision made through the skin and  cricothyroid membrane  to establish a patent airway during certain life-threatening situations, such as airway obstruction by a foreign body,  angioedema , or massive facial trauma. [ 3 ]   A cricothyrotomy is nearly always performed as a last resort in cases where orotracheal and nasotracheal intubation are impossible or contraindicated. Cricothyrotomy is easier and quicker to perform than tracheotomy, does not require manipulation of the cervical spine and is associated with fewer complications. [ 4 ]


A needle cricothyrotomy is similar to a cricothyrotomy, but instead of making a scalpel incision, a large over-the-needle catheter is inserted (10- to 14-gauge). This is considerably simpler, particularly if using specially designed kits. This technique provides very limited airflow. The delivery of oxygen to the lungs through an over-the-needle catheter inserted through the skin into the trachea using a high pressure gas source is considered a form of conventional ventilation called  percutaneous transtracheal ventilation  (PTV).


A tracheotomy is a surgically created opening from the skin of the neck down to the trachea. [ 5 ]  A tracheotomy may be considered where a person will need to be on a mechanical ventilator for a longer period. [ 5 ]  The advantages of a tracheotomy include less risk of infection and damage to the trachea such as tracheal stenosis. [ 5 ]


The  temporal bones  are situated at the sides and base of the  skull , and lateral to the  temporal lobes  of the  cerebral cortex .


The temporal bones are overlaid by the sides of the head known as the  temples  where four of the cranial bones fuse. Each temple is covered by a  temporal muscle . The temporal bones house the structures of the  ears . The lower seven  cranial nerves  and the major vessels to and from the  brain  traverse the temporal bone.


The temporal bone consists of four parts—the  squamous ,  mastoid ,  petrous  and  tympanic  parts. [ 1 ] [ 2 ]  The squamous part is the largest and most superiorly positioned relative to the rest of the bone. The  zygomatic process  is a long, arched process projecting from the lower region of the squamous part and it articulates with the  zygomatic bone . Posteroinferior to the squamous is the mastoid part. Fused with the squamous and mastoid parts and between the  sphenoid  and  occipital bones  lies the  petrous part , which is shaped like a pyramid. The tympanic part is relatively small and lies inferior to the squamous part, anterior to the mastoid part, and superior to the  styloid process . The styloid, from the  Greek   stylos , is a phallic shaped pillar directed inferiorly and anteromedially between the  parotid gland  and  internal jugular vein . [ 3 ]


The temporal bone is  ossified  from eight centers, exclusive of those for the  internal ear  and the  tympanic ossicles : one for the squama including the zygomatic process, one for the tympanic part, four for the petrous and mastoid parts, and two for the styloid process. Just before the end of  prenatal development  [Fig. 6] the temporal bone consists of three principal parts:


Apart from size increase, the chief changes from birth through puberty in the temporal bone are as follows:


Glomus jugulare tumor:


Temporal bone fractures were historically divided into three main categories,  longitudinal , in which the vertical axis of the fracture paralleled the petrous ridge,  horizontal , in which the axis of the fracture was perpendicular to the petrous ridge, and  oblique , a mixed type with both longitudinal and horizontal components. Horizontal fractures were thought to be associated with injuries to the  facial nerve , and longitudinal with injuries to the  middle ear ossicles . [ 6 ]
More recently, delineation based on disruption of the  otic capsule  has been found as more reliable in predicting complications such as facial nerve injury,  sensorineural hearing loss ,  intracerebral hemorrhage , and  cerebrospinal fluid   otorrhea . [ 7 ]


In many animals some of these parts stay separate through life:


In evolutionary terms, the temporal bone is derived from the fusion of many bones that are often separate in non-human mammals:


Its exact etymology is unknown. [ 9 ]  It is thought to be from the Old French  temporal  meaning "earthly", which is directly from the Latin  tempus  meaning "time, proper time or season." Temporal bones are situated on the sides of the skull, where grey hairs usually appear early on. Or it may relate to the pulsations of the underlying superficial temporal artery, marking the time we have left here. There is also a probable connection with the Greek verb  temnion , to wound in battle. The skull is thin in this area and presents a vulnerable area for a blow from a battle axe. [ 10 ]  Another possible etymology is described at  Temple (anatomy) .


This article incorporates text in the  public domain  from  page 138  of the 20th edition of   Gray's Anatomy   (1918)


The  temporal branches of the facial nerve  ( frontal branch of the facial nerve ) crosses the  zygomatic arch  to the temporal region, supplying the  auriculares anterior  and superior, and joining with the  zygomaticotemporal branch  of the  maxillary nerve , and with the  auriculotemporal branch  of the  mandibular nerve .


The more anterior branches supply the  frontalis , the  orbicularis oculi , and  corrugator supercilii , and join the  supraorbital  and  lacrimal branches  of the  ophthalmic . The temporal branch acts as the efferent limb of the  corneal reflex .


The temporal branch of the  facial nerve  is typically found between the  temporoparietal fascia  (i.e., superficial temporal fascia) and  temporal fascia  (i.e., deep temporal fascia). This layer is also known as the innominate fascia.


There are several methods using anatomic landmarks that may be used to find the temporal branch of the  facial nerve . One method is using Pitanguy's line, which is defined as running from 0.5 cm below the  tragus  to 1.5 cm above the lateral eyebrow. [ 1 ]  Another method is to recognize that the temporal branch runs between the lines from the earlobe to the hairline and from the earlobe to the lateral eyebrow.


To test the function of the temporal branches of the facial nerve, a patient is asked to frown and wrinkle their forehead.


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


The  temporal styloid process  is a slender bony  process  of the  temporal bone  extending downward and forward from the undersurface of the  temporal bone [ 1 ]  just below the ear. [ citation needed ]  The styloid process gives attachments to several muscles, and ligaments.


The styloid process is a slender and pointed bony process of the temporal bone projecting anteroinferiorly from the inferior surface of the  temporal bone [ 1 ]  just below the ear. [ citation needed ]  Its length normally ranges from just under 3 cm to just over 4 cm. It is usually nearly straight, but may be curved in some individuals. [ 1 ]


Its  proximal  ( tympanohyal )  part  is ensheathed by the  tympanic part of the temporal bone   (vaginal process), whereas  its  distal (stylohyal)   part  gives attachment to several structures. [ 1 ]


The styloid process gives attachments to several muscles, and ligaments. [ 1 ]  It serves as an anchor point for several muscles associated with the  tongue  and  larynx . [ citation needed ]


The parotid gland is situated laterally to the styloid process, the external carotid artery passes by its apex, the facial nerve crosses its base, and the attachment of the stylopharyngeus muscle separates it from the internal jugular vein medially. [ 1 ]


The styloid process arises from  endochondral ossification  of the  cartilage  from the second  pharyngeal arch . [ citation needed ]


A small percentage of the population will suffer from an elongation of the styloid process and stylohyoid ligament  calcification . This condition is also known as  Eagle syndrome . The tissues in the throat rub on the styloid process during the act of swallowing with resulting pain along the glossopharyngeal nerve. There is also pain upon turning the head or extending the tongue. Other symptoms may include voice alteration, cough, dizziness, migraines, occipital neuralgia, pain in teeth and jaw and sinusitis or bloodshot eyes. [ citation needed ]


This article incorporates text in the  public domain  from  page 145  of the 20th edition of   Gray's Anatomy   (1918)


In  vertebrate anatomy , the  throat  is the front part of the  neck , internally positioned in front of the  vertebrae . It contains the  pharynx  and  larynx . An important section of it is the  epiglottis , separating the  esophagus  from the  trachea  (windpipe), preventing food and drinks being inhaled into the  lungs . The throat contains various  blood vessels ,  pharyngeal muscles , the  nasopharyngeal tonsil , the  tonsils , the  palatine uvula , the trachea, the  esophagus , and the  vocal cords . [ 1 ] [ 2 ]   Mammal  throats consist of two  bones , the  hyoid bone  and the  clavicle . The "throat" is sometimes thought to be synonymous for the  fauces . [ 3 ]


It works with the mouth,  ears  and  nose , as well as a number of other parts of the body. Its pharynx is connected to the mouth, allowing speech to occur, and food and liquid to pass down the throat. It is joined to the nose by the  nasopharynx  at the top of the throat, and to the ear by its  Eustachian tube . [ 4 ]  The throat's trachea carries inhaled air to the  bronchi  of the lungs. The esophagus carries food through the throat to the  stomach . [ 5 ]   Adenoids  and tonsils help prevent infection and are composed of lymph tissue. The larynx contains vocal cords, the epiglottis (preventing food/liquid inhalation), and an area known as the subglottic larynx, in children it is the narrowest section of the upper part of the throat. [ 6 ] [ 7 ]


The  jugulum  is a low part of the throat, located slightly above the breast. [ 8 ]  The term  jugulum  is reflected both by the internal and external  jugular veins , which pass through the  jugulum .


Thyroplasty  is a phonosurgical technique designed to improve the voice by altering the  thyroid cartilage  of the  larynx  (the voice box), which houses the  vocal cords  in order to change the position or the length of the vocal cords.


There are four different types of thyroplasty procedures described by Isshiki:


It is the most commonly used surgical procedure to correct unilateral vocal cord paralysis (a condition where the vocal cord of one side is paralysed).


In this type of thyroplasty, a rectangular portion of the thyroid cartilage is mobilized and pushed towards the medial side using a piece of silastic block of proper shape under local anesthesia. [ 2 ]


Earlier, the piece of the thyroid cartilage was kept along with implant and the stitches were taken, but nowadays, the piece of the thyroid cartilage is cut and removed to avoid complications.


Currently, there are four types of implant procedures which are used to perform type 1 thyroplasty.


This system was discovered after years of research and the main advantage of this implant system is that it eliminates the process of customizing the implant at the time of surgery. This system consists of different sizes and shapes of shims made of silastic. It has the most proven success rate and the duration of the procedure is slow in comparison to other implant system. The other advantage is that it does not require suturing. It has reduced incidence of trauma.


This system consists of different sizes and shapes of implants made from  hydroxyapatite  (a naturally occurring mineral form of calcium  apatite ). It helps in achieving accurate vocal fold medialization. This procedure is technically reversible. But it should be used in candidates of permanent implantation due to its biocompatible clinical use lasting for nearly a decade.


This system generally consists of two sizes of implants made out of pure titanium. It has a lot of advantages and the main one is that it reduces the operative time. Titanium is safer than other implants. It has great biocompatibility. The implants are available in only two variants and they are designed in such a way that they ensure optimal fixation. The implant can be easily made as the titanium sheet is easy to shape. The technique is relatively simple and does not require expensive instruments.


In this type of implant system, the implant is made of homopolymer of  polytetrafluoroethylene  in form of minute beads arranged in a fine fiber mesh. It is  malleable  and can be inserted through a small window. [ 3 ]


It is a surgical procedure used in conditions like adductor spasmodic dysphonia (a condition in which there is distortion of the voice due to excessively tight closure of the glottis on phonation).
Generally, lateralization thyroplasty is intended to prevent this tight closure of the glottis at the terminal stage of phonation by lateralizing the position of the vocal cord.
This is a completely mechanical process.


An incision is made at midline of the thyroid cartilage. A silicon wedge is used to fix the incised thyroid cartilage in the newly abducted position.


A specially devised titanium bridge is used instead of silicon wedge. Nowadays, instead of one titanium bridge, two titanium bridges are used for permanent fixation of the thyroid cartilage.


This procedure is generally done to lower the vocal pitch by shortening the thyroid ala.


In this thyroplasty, the relaxation of the vocal cords is done by antero-posterior shortening of the thyroid ala.


This procedure is done to elevate the vocal pitch.
This procedure consists of lengthening of the thyroid cartilage. It includes  cricothyroid approximation .


In some specific conditions, different types of thyroplasties are combined for the desired results.


The main purpose of this combination is the medialization of the entire vocal cord (anterior and posterior).


Thyrotomy  (also called  thyroidotomy ,  median laryngotomy ,  laryngofissure  or  thyrofissure ) is an  incision of the  larynx  through the  thyroid cartilage .


Tonsil stones , also known as  tonsilloliths , are mineralizations of debris within the crevices of the  tonsils . [ 1 ] [ 3 ]  When not mineralized, the presence of debris is known as  chronic caseous tonsillitis  ( CCT ). [ 1 ]  Symptoms may include  bad breath , [ 1 ]  foreign body sensation, sore throat, pain or discomfort with swallowing, and cough. [ 4 ]  Generally there is no pain, though there may be the feeling of something present. [ 1 ]  The presence of tonsil stones may be otherwise undetectable; however, some people have reported seeing white material in the rear of their throat.


Risk factors may include recurrent  throat infections . [ 2 ]  Tonsil stones contain a  biofilm  composed of a number of different  bacteria , and calcium salts, either alone or in combination with other mineral salts. [ 5 ] [ 1 ]  While they most commonly occur in the  palatine tonsils , they may also occur in the  adenoids ,  lingual tonsils  and  tubal tonsil . [ 3 ] [ 6 ] [ 7 ]  Tonsil stones have been recorded weighing from 0.3   g to 42   g, [ 3 ]   and they are typically small in size. However, there are occasional reports of large tonsilloliths. They are often discovered during  medical imaging  for other reasons and more recently, due to the impact and influence of social media platforms such as  TikTok , medical professionals have experienced an increase in patient concern and tonsillolith evaluations. [ 8 ] [ 9 ]