Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

1,481 results found
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Granulomatosis with polyangiitis (orbital manifestations)

Ophthalmologic manifestations of granulomatosis with polyangiitis (GPA) (previously known as Wegener granulomatosis), both ocular and orbital, have been reported in 40-50% of GPA patients 1-3 and can occur in either the classic or limited form of the disease.4 Ophthalmologic disease occasionally...
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Granulomatosis with polyangiitis (upper respiratory tract manifestations)

The upper respiratory tract manifestations of granulomatosis with polyangiitis (GPA) (previously known as Wegener granulomatosis) are common and affect most patients. . Granulomatosis with polyangiitis is a multisystem systemic necrotizing non-caseating granulomatous vasculitis affecting small t...
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Granulomatous invasive fungal sinusitis

Granulomatous invasive fungal sinusitis, sometimes termed granulomatous invasive fungal sinusitis, is a form of invasive fungal sinusitis. Reports describing the imaging findings have been uncommon 1. Epidemiology It is rare and been mainly reported in Sudan, India, Pakistan and sometimes in t...
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Graves disease

Graves disease (in mainland Europe it is called Basedow disease 9) is an autoimmune thyroid disease and is the most common cause of thyrotoxicosis (up to 85%). Epidemiology There is a strong female predilection with an F:M ratio of at least 5:1. It typically presents in middle age. Clinical p...
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Greater auricular nerve

The greater auricular nerve is a cutaneous branch of the cervical plexus that innervates the skin of the auricle as well as skin over the parotid gland and mastoid process. The greater auricular nerve also supplies branches that innervate the deep layer of the parotid fascia.   Gross anatomy O...
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Greater (descending) palatine artery

The greater (descending) palatine artery is a branch of the third part of the maxillary artery which passes through the greater palatine foramen to supply most of the hard palate. Gross anatomy After branching off from the third (pterygopalatine) part of the maxillary artery, the greater palat...
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Greater occipital nerve

The greater occipital nerve is a cutaneous nerve, the thickest in the body, that innervates the skin from the upper neck, over the occiput, up to the vertex of the scalp 1-3.  Gross anatomy Origin The greater occipital nerve arises from the medial branch of the dorsal ramus of C2 1-3. By cont...
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Greater palatine nerve

The greater palatine nerve, also known as the anterior palatine nerve, is a branch of the maxillary division of the trigeminal nerve and contributes to the pterygopalatine ganglion. Gross anatomy The greater palatine nerve divides off the maxillary division just after emerging from the foramen...
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Greater wing of sphenoid

The greater wing or ali-sphenoid of the sphenoid bone is a process which projects from either side of the lower part of the sphenoid body, at a common junction with the pterygoid process. 1 It is a paired structure, which curves upward, backward and laterally from each side of the sphenoid body,...
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Griesinger sign (mastoid)

Griesinger sign, named after Wilhelm Griesinger, a German psychiatrist and neurologist (1817-1868) 3 refers to edema of the postauricular soft tissues overlying the mastoid process as a result of thrombosis of the mastoid emissary vein. It is a complication of acute otomastoiditis and may be ass...
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Guardsman fracture

A guardsman fracture, also referred to as parade ground fracture, is one of the common forms of mandibular fracture which is caused by a fall on the midpoint of the chin resulting in fracture of the symphysis as well as both condyles. It is usually seen in epileptics, elderly patients and occas...
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Guttman test (larynx)

The Guttman test is a clinical test relating to the function of the larynx. In normal subjects, frontal pressure on the thyroid cartilage lowers the tone of voice produced and lateral pressure produces a higher tone of voice. The opposite is true with paralysis of the cricothyroid muscle.
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Hemotympanum

Hemotympanum is the presence of blood in the middle ear cavity. It is usually secondary to trauma. Clinical presentation Typically on otoscopy a bulging red to purple to dark blue colored tympanic membrane is visible, color varying with age of the hemorrhage.  Pathology The hemorrhage has us...
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Halitosis

Halitosis, also known as fetor oris, refers to the symptom of foul oral odor, commonly termed "bad breath". This may be a complaint in the context of dental services. Pathology Etiology It is thought to be caused by the presence of volatile sulfur compounds that are produced by bacteria. The ...
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Haller cells

Haller cells, also known as infraorbital ethmoidal air cells, are ethmoid air cells located lateral to the maxillo-ethmoidal suture along the inferomedial orbital floor.  Epidemiology They are present in ~20% (range 2-45%) of patients, depending on their exact definition 1-3. Clinical present...
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Hamburger thyrotoxicosis

Hamburger thyrotoxicosis refers to ingestion of thyroid hormone from contaminated meat. It is a very rare cause of thyrotoxicosis. Pathology It is most commonly due to the practice of "gullet trimming" whereby muscles from the larynx of the slaughtered animal are ground into other cuts of meat...
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Hanging and strangulation (trauma)

Hanging and strangulation are injuries involving constricting pressure applied to the neck. The vast majority are sustained as a result of attempted suicide. Epidemiology In America, hangings are the second most common form of suicide after firearm use. In other parts of the world due to the r...
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Hard palate

The hard palate is the anterior horizontal bony part of the palate that forms the roof of the oral cavity and floor of the nasal cavity. Most of the hard palate is formed by the palatine processes of the maxillae, the horizontal plates of the palatine bones complete it posteriorly. On its inferi...
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Harlequin eye deformity

The harlequin eye deformity may be seen in unilateral (plagiocephaly) or bilateral (brachycephaly) coronal suture synostosis, and refers to the elevation of the superolateral corner of the orbit. The term harlequin eye derives from the appearance of the eyes on a harlequin mask with their exagg...
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Harvard scoring system for rhinosinusitis

The Harvard scoring system for rhinosinusitis is, as the name implies, a scoring system based on CT-scan assessment for grading of rhinosinusitis. Scoring 0: normal (< 2 mm mucosal thickening on any sinus wall) 1: all unilateral disease or anatomic abnormality 2: bilateral disease limited to...
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Hashimoto thyroiditis

Hashimoto thyroiditis, also known as lymphocytic thyroiditis or chronic autoimmune thyroiditis, is a subtype of autoimmune thyroiditis. It is one of the most common thyroid disorders.  Epidemiology Typically affects middle-aged females (30-50 year age group with an F:M ratio of 10-15:1).  Cli...
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Head and neck anatomy

Head and neck anatomy is important when considering pathology affecting the same area. In radiology, the 'head and neck' refers to all the anatomical structures in this region excluding the central nervous system, that is, the brain and spinal cord and their associated vascular structures and en...
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Head and neck cancer therapy response interpretation (Hopkins criteria)

The head and neck cancer therapy response interpretation (Hopkins criteria) is a qualitative system of interpretation for therapy response assessment using PET-CT. Background Widely used options for therapy response assessment are clinical examination, histopathology, CT  and MR imaging, howev...
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Head and neck squamous cell carcinoma (overview)

Head and neck squamous cell carcinomas (SCC) are common, being the sixth most common cancer. They can have a cutaneous or mucosal origin. As such there is a wide array of clinical and radiographic manifestations, and are separated into: squamous cell carcinoma of the skin of the head and neck ...
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Head and neck squamous cell carcinomas

Head and neck squamous cell carcinomas (HNSCC) refer to squamous cell carcinoma (SCC) of the aerodigestive tract of the head and neck, as opposed to cutaneous SCC. They are the most common tumor of the head and neck region, and can arise from any structure with squamous cell mucosa.  HNSCC is c...
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Heerfordt syndrome

Heerfordt syndrome, also known as Heerfordt-Waldenström syndrome or uveoparotid fever, is a variant of sarcoidosis, comprising of: fever parotid enlargement facial palsy ocular involvement (anterior uveitis) Epidemiology The exact prevalence is unknown, as only isolated case reports exist....
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Helicotrema

The helicotrema is a part of the cochlear apex where the scala tympani and scala vestibuli meet. It is located at the termination of the spiral lamina. See also cochlear anatomy
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Hemifacial hypertrophy

Hemifacial hyperplasia or hemifacial hypertrophy is a rare developmental anomaly characterized by asymmetric growth of hard and soft tissues of the face 1. Epidemiology These asymmetries are often noted at birth and are usually accentuated with increasing age, especially around puberty 2. The...
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Hemifacial microsomia

Hemifacial microsomia (HFM) is the second most common congenital facial anomaly after cleft lip/palate. The condition may vary from mild to severe. Goldenhar syndrome has been described as a variant of HFM, in which vertebral anomalies and epibulbar dermoids were present. Terminology HFM is al...
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Hemifacial spasm

Hemifacial spasm is characterized by episodic facial spasms due to irritation of the facial nerve (CN VII). Clinical presentation Often the condition begins insidiously with painless spasm of the orbicularis oculi gradually spreading in extent and severity to involve the majority of the face, ...
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Hennebert sign (inner ear)

The Hennebert sign describes a positive fistula test without clinical evidence of middle ear or mastoid disease. It is associated with congenital syphilis and may also be present in Ménière disease. It has been postulated that the vestibular stimulation is mediated by fibrous bands between foot...
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Heterogeneous thyroid echotexture

Heterogeneous echogenicity of the thyroid gland is a non-specific finding and is associated with conditions diffusely affecting the thyroid gland. These include: Hashimoto thyroiditis Graves disease
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Hiatus semilunaris

The hiatus semilunaris is a semicircular shaped opening located on the lateral wall of the nasal cavity. It is a component of the ostiomeatal complex and serves as the opening for the frontal and maxillary sinuses and the anterior ethmoid air cells. It is inferior to the ethmoid bulla and the un...
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Hiccups

Hiccups (or hiccoughs), medical term singultus (rarely used), are an unpleasant phenomenon, experienced by everyone on occasion, and usually self-limiting. However the much rarer intractable chronic form can be extremely debilitating. Epidemiology Hiccups are a symptom that has probably been e...
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High arched palate

High arched palates are a facial feature of many syndromes, although the classic association is Marfan syndrome. There are hundreds of conditions associated with high arched palates, with some of the radiologically-more important including: Down syndrome Apert syndrome Rubinstein-Taybi syndro...
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High riding jugular bulb

A high riding jugular bulb indicates the dome (roof) of the jugular bulb extends more superiorly in the petrous temporal bone than is typical. The transverse level above which a jugular bulb is considered high riding has been variably defined as the following 1,6,8: floor of the internal acoust...
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High-velocity penetrating brain injury

High-velocity penetrating brain injuries, in practical terms most often due to cranial gunshot injuries, are a form of penetrating traumatic brain injuries, which are much less common than blunt traumatic brain injuries and distinguished from low-velocity penetrating brain injuries (such as stab...
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Hockey stick sign (disambiguation)

The hockey stick sign can refer to a variety of different signs and appearances: hockey stick sign (thyroid hemiagenesis) hockey stick sign (Creutzfeldt-Jakob disease) hockey stick sign (ureters)
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Hockey stick sign (thyroid hemiagenesis)

Hockey stick sign has been used to describe the appearance of the thyroid gland in cases of thyroid hemiagenesis, when investigated with 99m technetium pertechnetate thyroid scan 1. The unilateral lobe and isthmus make a shape reminiscent of a hockey stick.  See also hockey stick sign (Creutzf...
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Holman-Miller sign (maxillary sinus)

The Holman-Miller sign (also called the antral sign) is seen in juvenile nasopharyngeal angiofibroma; it refers to the anterior bowing of the posterior wall of the maxillary antrum as seen on a lateral skull radiograph or cross-sectional imaging 1,2. This is a non-specific sign that can be prod...
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Hutchinson sign (disambiguation)

The Hutchinson sign can refer to two signs.  Hutchinson sign (ophthalmology) Relates to involvement of the tip of the nose from facial herpes zoster. It implies involvement of the external nasal branch of the nasociliary nerve (branch of the ophthalmic division of the trigeminal nerve) and thu...
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Hutchinson teeth

Hutchinson teeth are smaller and more widely spaced than normal and are notched on their biting surfaces. It is a sign of congenital syphilis and should not be confused with: Hutchinson triad Hutchinson pupil Hutchinson freckle Hutchinson sign Hutchinson syndrome History and etymology Na...
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Hyoglossus muscle

The hyoglossus muscle is a thin, quadrilaterally shaped muscle in the upper neck and the floor of the mouth. It is one of the extrinsic muscles of the tongue. The submandibular ganglion suspended from the lingual nerve sits on it. Summary origin: hyoid bone: from the entire length of the great...
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Hyoid bone

The hyoid is a "horseshoe-shaped" bone that serves as a structural anchor in the mid-neck. It is the only bone in the human body that does not directly articulate with another bone (other than sesamoids). It is a place of convergence of multiple small neck muscles that permit the pharyngeal phas...
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Hyoid elevation

Hyoid elevation on a modified barium swallow study indicates that the pharyngeal muscles are contracting appropriately. Radiographic features Modified barium swallow With real time fluoroscopy (or videofluoroscopy) during the act of swallowing, the larynx moves upward and forward when there i...
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Hyperattenuating paranasal sinus opacification

Hyperattenuating paranasal sinus opacification can arise in a number of situations: fungal sinus disease inspissated secrections acute hemorrhage into sinus (hemosinus) Differential diagnosis In some situations can consider early calcification within the sinus - intrasinus calcification.
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Hyperostosis of the skull (differential)

Hyperostosis of the skull has many causes, broadly divided into focal or diffuse. Diffuse Paget's disease of bone metastatic disease, especially prostate carcinoma chronic, severe anemia hyperparathyroidism acromegaly osteopetrosis hyperostosis frontalis interna long-term phenytoin use ...
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Hyperparathyroidism

Hyperparathyroidism is the effect of excess parathyroid hormone in the body. It can be primary, secondary, or tertiary. There are many characteristic imaging features, predominantly involving the skeletal system. Pathology Increased levels of the parathyroid hormone lead to increased osteoclas...
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Hyperparathyroidism-jaw tumor syndrome

Hyperparathyroidism-jaw tumor syndrome is an extremely rare condition where a gene mutation results in hyperparathyroidism in association with both benign and malignant tumors, most notably, tumors in the mandible or maxilla 2. Epidemiology Approximately 200 cases have been reported in the med...
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Hypertelorism

Hypertelorism refers to an abnormal increase in distance between any two organs although some authors use the term synonymously with orbital hypertelorism meaning an abnormal increase in distance between the two eyes. The article mainly focuses on the latter. The abnormality is similar to teleca...
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Hyperthyroidism

Hyperthyroidism refers to increased production and secretion of thyroid hormone from the thyroid gland. Terminology Hyperthyroidism is not synonymous with thyrotoxicosis, the latter referring to a clinical syndrome of excess thyroid hormone.   Clinical presentation Hyperthyroidism may be acc...
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Hypodontia

Hypodontia refers to the congenital absence of one or more teeth. Epidemiology Hypodontia is common, affecting ~15% of the population with a recognized variations in ethnicities, e.g. prevalence of 1% in indigenous Australians through to 30% in Japanese populations. There is a female preponder...
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Hypoglobus

Hypoglobus refers to the inferior displacement of the globe into the orbit. It may or may not be associated with enophthalmos. Hypoglobus is most commonly caused by fracture of the orbital floor but may be due to other causes: silent sinus syndrome orbital masses orbital foreign bodies thyr...
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Hypoglossal canal

The hypoglossal canal is located between the occipital condyle and jugular tubercle and runs obliquely forwards (posteromedial to anterolateral) allowing the hypoglossal nerve (12th cranial nerve) to exit the posterior cranial fossa.  Its proximal portion is often divided by a fibrous (sometime...
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Hypoparathyroidism

Hypoparathyroidism results from reduced secretion of parathyroid hormone by the parathyroid glands. It results in hypocalcemia.  Clinical presentation tetany: peripheral paresthaesia, carpopedal spasm, seizures emotional lability, depression and anxiety, psychosis short stature Pathology T...
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Hypopharyngeal squamous cell carcinoma

Squamous cell carcinoma of the hypopharynx is relatively uncommon, carries the worst prognosis of any head and neck squamous cell carcinoma (HNSCC), and is a challenge to diagnose and treat.  Hypopharyngeal carcinoma is relatively uncommon representing only 10% of all proximal aerodigestive tra...
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Hypopharyngeal squamous cell carcinoma (staging)

Staging of hypopharyngeal squamous cell carcinoma is performed using the TNM staging system. TNM staging Primary tumor staging (T) T1: limited to 1 subsite AND tumor size ≤ 2 cm in greatest dimension T2: extends into adjacent subsite or area (larynx, oropharynx) and/or tumor size between...
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Hypopharynx

The hypopharynx or laryngopharynx forms the most inferior portion of the pharynx, being the continuation of the oropharynx superiorly and both the larynx and esophagus inferiorly.  Gross anatomy The hypopharynx begins as the continuation of the oropharynx at the pharyngoepiglottic fold (which ...
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Hypotelorism

Hypotelorism refers to an abnormal decrease in distance between any two organs although some authors use the term synonymously with orbital hypotelorism meaning an abnormal decrease in the distance between the two eyes (the eyes appear too close together). The article mainly focuses on the latte...
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Hypothyroidism

The clinical syndrome of hypothyroidism is marked by inadequate thyroid hormone production, resulting in a decreased rate of cellular metabolism. It may be primary, in which the dysfunction pertains to the thyroid gland itself, or secondary, due to hypothalamic or pituitary dysfunction 1. Epide...
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Hypotympanum

The hypotympanum refers to the portion of the tympanic cavity lying inferior to the level of the inferior margin of the external acoustic canal (EAC). Gross anatomy The hypotympanum is the smallest of the three compartments that make up the tympanic cavity and is a shallow depression in the fl...
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Hyrtl’s fissure

Hyrtl's fissure (also known as tympanomeningeal fissure) is a congenital infralabyrinthic fissure. It is a very rare cause of spontaneous CSF ottorhoea and meningitis. Development This fissure is present in the developing fetal petrous temporal bone and is typically ossified by 24 weeks. Radi...
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Ice cream cone sign (disambiguation)

The ice cream cone sign may refer to: the appearance of the head of malleus and the body and short process of the incus on axial CT scan: failure of this normal configuration suggests incudomalleolar dysarticulation the ball of the ice cream is formed by the head of the malleus and cone is for...
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Idiopathic orbital inflammation

Idiopathic orbital inflammation (IOI), also known as orbital pseudotumour and nonspecific orbital inflammation, is an idiopathic inflammatory condition that most commonly involves the extraocular muscles. Less commonly there is inflammatory change involving the uvea, sclera, lacrimal gland, and ...
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IgG4-related disease

IgG4-related disease (IgG4-RD) is a systemic disease that is characterized by extensive IgG4-positive plasma cells and T-lymphocyte infiltration of various organs. Terminology This condition has been known by many other names in the past, such as IgG4-related sclerosing disease, IgG4-related s...
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Incisive canal

The maxillary incisive canal runs through the maxilla in the midline. It connects the inferior nasal cavity with the superior oral cavity, opening at the incisive foramen posterior to the central maxillary incisor teeth. It contains the descending palatine artery and the nasopalatine nerve.  Re...
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Incisive canal cyst

Incisive canal cysts, also known as nasopalatine duct cysts (NPDC), are developmental, non-neoplastic cysts arising from degeneration of nasopalatine ducts. These ducts usually regress in fetal life. The persistence of ductal epithelium leads to formation of cyst. It is considered the most comm...
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Incisive foramen

The incisive foramen (also known as nasopalatine foramen or anterior palatine foramen) is the oral opening of the nasopalatine canal. It is located in the maxilla in the incisive fossa, midline in the palate posterior to the central incisors, at the junction of the medial palatine and incisive s...
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Incisive nerve

The incisive nerve is one of the two terminal branches of the inferior alveolar nerve, a branch of the posterior division of the mandibular division of the trigeminal nerve. It continues running anteriorly in the medullary cavity of the mandible after the mental nerve branches off and exits via ...
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Incus

The incus is the middle of the ossicles articulating with the head of the malleus anteromedially and the stapes inferomedially. Parts include: a body which articulates with the head of the malleus, and to which the superior ligament of the incus is attached (to the roof of the middle ear cavit...
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Infantile cervical ligament edema

Infantile cervical ligament edema can typically be seen when infants have suffered accidental or abusive head and neck trauma. The finding is best seen on sagittal STIR images. Terminology The posterior ligamentous complex refers to the ligamentum flavum and interspinous ligaments. The anterio...
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Infantile hemangioma

Infantile hemangiomas are benign vascular neoplasms that are the most common head and neck tumors of infancy. They can occur virtually anywhere, but the majority are found in the head and neck regions. This article aims to be a generic discussion of the condition, for detailed and more specific...
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Inferior alveolar artery

The inferior alveolar artery is a branch of the maxillary artery. It runs with the inferior alveolar nerve as it descends through the infratemporal fossa and enters the mandibular canal and supplies mandibular teeth. In the region of the first premolar it bifurcates into the incisive and mental ...
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Inferior alveolar nerve

The inferior alveolar nerve or inferior dental nerve is a mixed sensory and motor branch of the posterior division of the mandibular division of the trigeminal nerve, located in the pteryogomandibular space of the oral cavity/masticator space. Gross anatomy The inferior alveolar nerve divides ...
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Inferior alveolar nerve injury

Inferior alveolar nerve injuries are most common iatrogenic post third mandibular molar extraction although they can occur post dental implant or in mandibular fractures. This article is focused on iatrogenic injuries.  Epidemiology The incidence of inferior alveolar nerve injuries after third...
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Inferior labial artery

Inferior labial artery (old name: inferior coronary artery) is one of the facial branches of the facial artery. It is smaller than the superior labial artery. It supplies the lower lip, including its labial glands, mucous membranes and muscles. Summary origin: facial branch of the facial arter...
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Inferior longitudinal muscle of the tongue

The inferior longitudinal muscle of the tongue is one of the 4 intrinsic muscles of the tongue which alters the shape of the tongue mass, being entirely confined to the tongue without an attachment outside the tongue (like the extrinsic muscles of the tongue). Gross anatomy The muscles fibers ...
Article

Inferior meatus

The inferior meatus is an air passage of the lateral nasal cavity located between the inferior nasal concha and lateral nasal wall. The nasolacrimal duct drains into the inferior meatus. Terminology The plural of meatus is meatus (Latin noun of the fourth declension) or meatuses. Meati is inco...
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Inferior median clival canal

The inferior median clival canal also known as the canalis basilaris medianus is a rare anatomical variant of the clivus, which passes in the sagittal plane from the intracranial surface of the clivus to its retropharyngeal surface. It is generally thought to represent a remnant of the notocord....
Article

Inferior nasal concha

The inferior nasal conchae or turbinates are one of the pairs of conchae in the nose. Gross anatomy It extends horizontally along the lateral wall of the nasal cavity and consists of a lamina of spongy bone, curled upon itself like a scroll. The inferior nasal conchae are considered a pair of ...
Article

Inferior oblique muscle

The inferior oblique muscle is one of six extraocular muscles that control eye movements. Summary innervation: inferior branch of the oculomotor nerve (CN III) origin: orbital surface of the maxilla insertion: globe (posterior, inferolateral surface) primary function: one of two ocular exte...
Article

Inferior ophthalmic vein

The inferior ophthalmic vein (IOV) is a vein of the inferior orbit and is smaller than the more well-known superior ophthalmic vein. Gross anatomy The vein forms at the confluence of several veins within the anteroinferior orbit along the infraorbital margin from facial vein tributaries. It co...
Article

Inferior pharyngeal constrictor muscle

The inferior pharyngeal constrictor muscle is one of the pharyngeal constrictor muscles. It has a sphincteric function, and physiologically is usually in a tonic state, constricting the distal end of the pharynx (in coordination with the superior pharyngeal constrictor and the middle pharyngeal ...
Article

Inferior rectus muscle

The inferior rectus muscles is one of the 6 extraocular muscles that control eye movements. Summary innervation: inferior branch of the oculomotor nerve (CN III) origin: annulus of Zinn (tendinous ring) insertion: globe (anterior, inferior surface) primary function: one of two ocular depres...
Article

Inferior thyroid artery

The inferior thyroid artery is a branch of the thyrocervical trunk (85%) or subclavian artery (15%) and ascends to enter the thyroid gland on its posterior surface, as well as supplying both the superior and inferior parathyroid glands 1. The nerve is closely related to the ascending limb of the...
Article

Infrahyoid muscles

The infrahyoid muscles or strap muscles are a group of four paired muscles in the anterior neck below the hyoid bone, within the muscular triangle. They are responsible for depressing the hyoid during swallowing. The four muscles are: sternohyoid: superficial and medial omohyoid: superficial ...
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Infraorbital artery

The infraorbital artery is a branch of the third part of the maxillary artery. It runs through the inferior orbital fissure, orbit, infraorbital canal then the infraorbital foramen. Here it gives off the anterior superior alveolar artery which supplies the anterior teeth and the anterior part of...
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Infraorbital foramen

The infraorbital foramen is located in the maxillary bone. It is the anterior opening of the infraorbital canal, which is the anterior continuation of the infraorbital groove, which course through the floor of the orbit. The canal may reside entirely in the maxillary sinus, suspended from the si...
Article

Infraorbital nerve

The infraorbital nerve is a branch of the maxillary division of the trigeminal nerve.   Gross anatomy The infraorbital nerve divides off the maxillary division just after emerging from the foramen rotundum to enter the pterygopalatine fossa. It courses laterally over the palatine bone and maxi...
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Infratemporal fossa

The infratemporal fossa is a complex space of the face that lies posterolateral to the maxillary sinus and many important nerves and vessels traverse it.  Gross anatomy The infratemporal fossa is the space between the skull base, lateral pharyngeal wall and the ramus of mandible. The fossa is ...
Article

Infratrochlear nerve

The infratrochlear nerve is an extraconal branch of the nasociliary nerve, a branch of ophthalmic division of the trigeminal nerve. Some authors describe it as the terminal branch of the nasociliary nerve. It courses through the medial aspect of the extraconal space of the orbit inferior to the ...
Article

Ingested bones

Ingested bones that become lodged in the throat or gastrointestinal tract are a common presentation to the emergency department. Recognition is important because these cases can be potentially fatal.  Pathology Patients may present with a 'foreign body' feeling in the throat after eating fish ...
Article

Inion

The inion (plural: inia/inions)  is the tip of external occipital protuberance (EOP), the midline bony prominence in the occipital bone where the ligamentum nuchae and trapezius muscle attaches. It is usually easily palpable. It is the surface marking of the internal attachment of the tentorium...

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