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.

1,476 results found
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Base of the skull

The base of the skull (or skull base) forms the floor of the cranial cavity and separates the brain from the structures of the neck and face. Gross anatomy The base of the skull is a bony diaphragm composed of a number of bones - from anterior to posterior: frontal bone ethmoid bone sphenoi...
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Basion

The basion is the median (midline) point of the anterior margin of the foramen magnum. The apical ligament attaches to it. It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement. Clinical importance Various lines and measurements using the ...
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Basion-axial interval

The basion-axial interval (BAI), as the name suggests, is the horizontal distance between the basion and the posterior cortex of the axis, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance (in mm) between the basion and the superior extension of the posterior ...
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Basion-dens interval

The basion-dens interval (BDI), as the name suggests, is the distance between the basion and the tip of the dens, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance from the most inferior portion of the basion to the closest point of the superior aspect of the ...
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Battle sign (base of skull fracture)

Battle sign is an eponymous term given to mastoid ecchymosis (bruising of the scalp overlying the mastoid process) and is strongly suggestive of a base of skull fracture, most commonly a petrous temporal bone fracture.  History and etymology Mr William Henry Battle (1855-1936) was an English s...
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Behavioral changes in obstructive sleep apnea (mnemonic)

A mnemonic used to remember the behavioral changes of obstructive sleep apnea (OSA) is: APRIL Mnemonic A: aggression P: poor school performance R: restlessness I: irritability L: lack of concentration
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Behçet disease

Behçet disease is a multisystemic and chronic inflammatory vasculitis of unknown etiology. Epidemiology The mean age at which Behçet disease occurs is 20-30 years. The disease is most prevalent in the Mediterranean region, Middle East and East Asia. The highest incidence has been reported in T...
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Benign enhancing foramen magnum lesion

Benign enhancing foramen magnum lesions have been anecdotally seen by radiologists for years but only recently described as an incidental finding in a typical location in the foramen magnum just behind the vertebral artery. Although the precise nature of this finding has not been entirely elucid...
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Benign lymphoepithelial lesions

Benign lymphoepithelial lesions (BLL or BLEL), also misleadingly known as AIDS-related parotid cysts (ARPC), are mixed solid and cystic lesions that enlarge the parotid glands, and are usually associated with cervical lymph node enlargement, and nasopharyngeal lymphofollicular hyperplasia. Term...
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Benign metastasizing tumors

There are a number of benign metastasizing tumors: benign metastasizing meningioma 1,2 benign metastasizing leiomyoma 3 primary adenoma of thyroid 4 giant cell tumor of bone 5
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Benign minor salivary gland pathology

Benign minor salivary gland pathology is a broad term that encompasses a number of relatively uncommon pathologies that affect the minor salivary glands of the head and neck: salivary retention cysts benign neoplasms pleomorphic adenoma
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Benign paroxysmal positional vertigo

Benign paroxysmal positional vertigo (BPPV) is one of the most common causes of vertigo. It occurs secondary to change in posture and typically is associated with nystagmus. The etiology is thought to be due to changes of position of the otoliths in the inner ear, most commonly into the posterio...
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Bezold abscess

A Bezold abscess is a complication of acute otomastoiditis where the infection erodes through the cortex medial to the attachment of sternocleidomastoid, at the attachment site of the posterior belly of the digastric muscle, and extends into the infratemporal fossa. Due to it being deep to the i...
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Biffl scale for blunt cerebrovascular injury

The Biffl scale or grade illustrates the spectrum of blunt cerebrovascular injury (BCVI) seen on angiography (both CTA and DSA). Some authors refer to the grading scale as the Denver scale, which is not to be confused with the Denver criteria, a series of clinical indications and risk factors fo...
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Bifid premolar root

A bifid premolar root is a normal variant there are two roots involving a premolar tooth. It is thought to present in aprroximately 2.5 % of population 1. They are mostly located in the buccal and lingual directions. In a very small proportion of people the premolar teeth can contain more than 2...
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Bilateral thinning of the parietal bones

Bilateral thinning of the parietal bones, also known as biparietal osteodystrophy, is an uncommon, slowly progressive acquired disease of middle-aged people with slight female predilection. It is typically an incidental finding.  Pathology The etiology is unknown but is thought to be an age-re...
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Bill bar

Bill bar is a bony anatomical landmark that divides the superior compartment of the internal acoustic meatus into an anterior and posterior compartment. Anterior to Bill bar, in the anterior superior quadrant, are the facial nerve (CN VII) and nervus intermedius, and posterior to it, in the post...
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Bimastoid line

The bimastoid line has been described and used to evaluate basilar invagination on frontal skull plain film and coronal reconstructed CT image. The bimastoid line is drawn between the inferior tips of the of mastoid processes bilaterally. The tip of the odontoid process of C2 normally projects ...
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Binocular distance

The binocular distance (BOD) is a measurement between the two lateral (outer) canthi of each eye. It is sometimes used as a accessory fetal biometric parameter where it is often documented on both 2nd trimester anatomy scans on axial brain scans. The largest diameter of the orbit should be used ...
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Biphenotypic sinonasal sarcoma

Biphenotypic sinonasal sarcoma, initially named low-grade sinonasal sarcoma with neural and myogenic features,  is a rare and only recently described low-grade sarcoma of the nasal and paranasal sinuses. The tumor exhibits both neural and myogenic differentiation and thus can be problematic to d...
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Black eyebrow sign

Black eyebrow sign is the description given on plain facial radiographs to intra-orbital air 1. Air rises into the most superior aspect of the orbit, almost always in the context of a facial fracture, in a linear fashion, giving the appearance of an eyebrow. The fracture is usually an orbital b...
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Black turbinate sign (nasal cavity)

The black turbinate sign refers to an area of non-enhancing mucosa on MRI in a patient with angioinvasive fungal sinus infection / rhinocerebral mucormycosis. Mucormycosis is caused by fungi that include Mucor, Rhizopus, and Absidia species.  It is seen in diabetic and immunocompromised patient...
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Blepharophimosis

Blepharophimosis is dysplasia of the eyelids, where there is horizontal shortening of palpebral fissure. It is often associated with ptosis. Blepharophimosis is a feature of Dubowitz syndrome and Smith Lemli Opitz syndrome. Blepharophimosis, ptosis, and epicanthus inversus syndrome (BPES) is c...
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Blunt traumatic neck injury

Blunt traumatic neck injury is uncommon because it is usually protected by the head, shoulders, and chest. This term is generally used to refer to injuries of the neck besides to cervical spine injuries, which are common.  Pathology Blunt injury to the neck is most commonly from motor vehicle ...
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Body of sphenoid

The body of the sphenoid bone is the midline cubical portion of the sphenoid bone, hollowed by the sphenoid air sinuses.  Gross anatomy The body has superior, inferior, anterior, posterior, and lateral surfaces. The superior surface features: ethmoidal spine: prominent spine that articulates...
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Bogorad syndrome

Bogorad syndrome also known as the syndrome of crocodile tears, is characterized by residual facial paralysis with profuse lacrimation during eating. This phenomenon is also known as paroxysmal lacrimation or the gustolachrymal reflex. It is caused by a misdirection of the regenerating autonomic...
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Bolger classification of maxillary sinus hypoplasia

The Bolger classification of maxillary sinus hypoplasia proposed by Bolger et al. in 1990 1 takes into account associated anomalies of the uncinate process, which are of utmost importance for planning functional endoscopic sinus surgery (FESS). Maxillary sinus hypoplasia in itself is asymptomat...
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Bony orbit

The bony orbit refers to the bones that constitute the margins of the orbits, that is the roof, medial and lateral walls and floor. The orbital margin or rim refers to the anterior circular margin of the orbit. The orbital apex refers to the posterior confluence of the orbit, where the optic can...
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Boogard's angle

Boogard's angle is measured by drawing a line from basion to opisthion and another line along the plane of the clivus to the basion intersecting the first line - the angle between these two lines is measured . The normal angle is 126° +/- 6°. If the angle measures more than 136° it is indicativ...
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Bouthillier classification of internal carotid artery segments

Bouthillier et al. described (in 1996) 1 a seven segment internal carotid artery (ICA) classification system. It remains the most widely used system for describing ICA segments at the time of writing (mid-2016). There are a few other classifications systems including those proposed by Fisher (1...
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Brachycephaly

Brachycephaly refers to a calvarial shape where the bi-parietal diameter to fronto-occipital diameter approaches the 95th percentile. It can result from a  craniosynostosis involving the coronal and lambdoid sutures. Pathology Associations Brachycephaly can be associated with numerous syndrom...
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Branches of maxillary artery (mnemonic)

A mnemonic for remembering the branches of the maxillary artery is: DAM I AM Piss Drunk But Stupid Drunk I Prefer, Must Phone Alcoholics Anonymous Mnemonic D: deep auricular artery A: anterior tympanic artery M: middle meningeal artery I: inferior alveolar artery A: accessory meningeal ar...
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Branches of the external carotid artery (mnemonic)

Mnemonics for the branches of the external carotid artery abound. A few colorful examples include:  Some American Ladies Found Our Pyramids Most Satisfactory Some Anatomists Like Freaking Out Poor Medical Students She Always Likes Friends Over Papa, Sister, and Mama There are many many many ...
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Branches of the thoracoacromial artery (mnemonic)

Useful mnemonics to remember the four branches of the thoracoacromial artery are: ABCD CAlifornia Police Department Cadavers Are Dead People PACkeD Mnemonics ABCD A: acromial B: breast (pectoral) C: clavicular D: deltoid CAlifornia Police Department C: clavicular A: acromial  P: pe...
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Branchial cleft anomalies

Branchial cleft anomalies comprise of a spectrum of congenital defects that occur in the head and neck. Pathology The anomalies result from branchial apparatus (six arches; five clefts), which are the embryologic precursors of the ear and the muscles, blood vessels, bones, cartilage, and mucos...
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Branchio-oto-renal dysplasia

Branchio-oto-renal (BOR) dysplasia is a rare syndromic disorder characterized by: otic malformations can involve the outer, middle, and inner ear associated with conductive, sensorineural, or mixed hearing impairment preauricular pits branchial fistulae and branchial cleft cysts renal malfo...
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Bregma

The bregma is the midline bony landmark where the coronal and sagittal sutures meet, between the frontal and two parietal bones. It is the anterior fontanelle in the neonate and closes in the second 2 (typically around 18 months after birth). It is one of the skull landmarks, craniometric poin...
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Broken heart sign

The broken heart sign describes the appearances of incudomalleolar disarticulation. This sign is identified on CT in the coronal plane, being formed by the widening of the incudomalleolar joint and lateral displacement of the short process of the incus relative to the head of the malleus 1,2.
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Brown syndrome (orbit)

The Brown syndrome refers to an inability of a patient to perform an upward gaze while the eye is adducted due to an abnormality of the superior oblique tendon sheath complex. History and etymology It was first described by Allan Brown in 1950 1. See also Brown-Sequard syndrome
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Buccal nerve

The buccal nerve is the only purely sensory branch of the anterior division of the mandibular division of the trigeminal nerve. It is not to be confused with the buccal branch of the facial nerve. Gross anatomy The buccal nerve divides off the anterior division and passes with the paired nerve...
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Buccal space

The buccal space, also known as the buccinator space, is one of the seven suprahyoid deep compartments of the head and neck. Gross anatomy  The buccal spaces are paired fat contained spaces on each side of the face forming cheeks. Each space is enveloped by the superficial (investing) layer of...
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Buccinator artery

The buccinator artery is a small branch from the second part of the maxillary artery. It runs obliquely forward, between the medial pterygoid and the insertion of the temporalis, to the outer surface of the buccinator, to which it is distributed, anastomosing with branches of the facial artery a...
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Bulla lamella

The bulla lamella is a structure that, when intact, forms the posterior boundary of the frontal recess. When pneumatized, it forms the ethmoid bulla. Gross anatomy It is frequently incomplete and often does not reach the roof of the ethmoid at the skull base. Under these circumstances, the fro...
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Buphthalmos

Buphthalmos is a descriptive term which simply means an enlarged eyeball or ocular globe due to increased intraocular pressure (glaucoma), without deformation or and intrinsic mass lesion. Epidemiology It typically manifests in infants and young children. Pathology It usually indicates the p...
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Calcification of the external ear (differential)

Calcification of the external ear (auricular cartilage) may arise from a number of causes, including: hyperparathyroidism gout and pseudogout relapsing polychondritis frostbite trauma ochronosis sarcoidosis diabetes mellitus adrenal insufficiency
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Calcification of the globe (differential)

Calcification of the globe has many causes, varying from the benign to malignant. When calcification is seen of the posterior half of the globe, it could relate to any of the layers (scleral, choroidal or retinal), as it is not possible to separate them out on CT. Retinal drusen: 1% population...
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Calcific tendinitis of the longus colli muscle

Calcific tendinitis of the longus colli muscles is an inflammatory/granulomatous response to the deposition of calcium hydroxyapatite crystals in the tendons of the longus colli muscle. Epidemiology This condition typically occurs in adults in middle age (20-50 years of age) with a slight pred...
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Calcifying epithelial odontogenic tumor

Calcifying epithelial odontogenic tumor (CEOT), also known as a Pindborg tumor, (previously has been called adenoid adamintoblastoma, unusual ameloblastoma and cystic odontoma) is typically located in the premolar and molar region of the mandible, although up to a third are found in the maxilla....
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Calcifying odontogenic cyst

Calcifying odontogenic cyst (COC) is a form of odontogenic cyst. There is some disagreement on the terminology and classification of this lesion. Epidemiology It may represent around 0.3-0.8% of all odontogenic cysts 2. Pathology It can show extreme diversity in its clinical and histopatholo...
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Caldwell-Luc operation

The Caldwell-Luc operation uses an external approach for surgical treatment of the severely diseased maxillary sinus. It is an alternative to middle meatal antrostomy done via endonasal endoscopic surgery and was the primary approach used for accessing the maxillary sinus before the advent of en...
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Canadian C-spine rules

Canadian C-spine rules are a set of guidelines that help a clinician decide if cervical spine imaging is not appropriate for a trauma patient in the emergency department. The patient must be alert and stable. There are three rules: is there any high-risk factor present that requires cervical s...
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Capillary hemangioma of the orbit

Capillary hemangiomas of the orbit, also known as strawberry hemangiomas, on account of its coloring, or orbital infantile hemangiomas, are the most common orbital tumors of infancy, and unlike orbital cavernous hemangiomas, they are neoplasms rather than vascular malformations. Clinical presen...
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Capps triad

The Capps triad refers to the constellation of clinical and imaging findings in patients with spontaneous retropharyngeal hematomas, and consists of: tracheal and esophageal compression anterior displacement of the trachea subcutaneous bruising over the neck and anterior chest History and et...
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Carcinoembryonic antigen

Serum carcinoembryonic antigen (CEA) is a cell-adhesive glycoprotein that was discovered in colorectal cancer in 1965, and is hence one of the oldest and most used tumor markers. Its name derives from its normal expression in fetoembryonic liver, gut and pancreas tissue. Normal range of CEA is ...
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Carcinogens

Carcinogens are substances known to cause cancer. They include: Brain vinyl chloride Nasopharynx / nasal passage nickel wood dust chromium Thyroid ionising radiation (not technically a substance) Skin arsenic coal tars polyaromatic hydrocarbons (PAH) Lungs arsenic asbestos chloro...
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Carcinoma ex pleomorphic adenoma

Carcinoma ex pleomorphic adenoma is the most common of three malignant mixed tumors of salivary glands, and are thought to arise from pre-existing pleomorphic adenomas (or benign mixed tumors) 1. Epidemiology These tumors usually occur in older patients (6th to 8th decade), who have had a pleo...
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Carcinosarcoma

Carcinosarcomas are highly malignant biphasic tumors with both carcinomatous (epithelial) and sarcomatous (bone, cartilage, or skeletal muscle) components.  Pathology It can arise in many organs: lung 5: pulmonary carcinosarcoma esophagus 1: esophageal carcinosarcoma genitourinary tract 2 ...
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Caroticocavernous fistula

Caroticocavernous fistulas (CCF) represent abnormal communication between the carotid circulation and the cavernous sinus. They can be classified as direct or indirect which are separate conditions with different etiologies.   Epidemiology Direct CCFs are often secondary to trauma, and as such...
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Caroticotympanic artery

The caroticotympanic branch (tympanic branch) is a small branch from the C2 segment of the internal carotid artery. It is a vestigial remnant of the hyoid artery. It passes posterolaterally into the middle ear cavity and anastomoses with the inferior tympanic artery (a branch of the external ca...
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Carotid bifurcation

The carotid bifurcation is the point at which the common carotid artery terminates. As it does so, it forms the internal and external carotid arteries which go on to supply the head and neck. It is closely related anatomically to the carotid body, a small group of chemoreceptors and supporting ...
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Carotid body

The carotid body is located within the neck, and in close proximity to the carotid bifurcation. It is composed of a number of chemoreceptor cells and supporting matrix and detects changes in the composition of blood in the common carotid as it forms the internal and external carotid arteries. I...
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Carotid body tumor

Carotid body tumor, also known as a chemodectoma or carotid body paraganglioma, is a highly vascular glomus tumor that arises from the paraganglion cells of the carotid body. It is located at the carotid bifurcation with characteristic splaying of the ICA and ECA.  Epidemiology Typically, caro...
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Carotid canal

The carotid canal is a passage within the petrous temporal bone and transmits the internal carotid artery and sympathetic plexus. Its inferior opening is called the carotid foramen and is situated anteriorly to the jugular fossa and medially to the carotid plate. The carotid canal is initially d...
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Carotid plate

The carotid plate, also known as the tympanic plate, is a thin (0.5 mm) bony plate that separates the carotid canal from the middle ear cavity. Gross anatomy The caroticotympanic artery perforates the carotid plate normally. Related pathology Disruption or dehiscence of the carotid plate may...
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Carotid space

The carotid space (also known as the post-styloid parapharyngeal space) is one of the seven deep compartments of the head and neck. Gross anatomy The carotid space is a roughly cylindrical space that extends from the skull base through to the aortic arch.  It is circumscribed by all three laye...
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Carotid triangle

The carotid triangle is one of the paired triangles in the anterior triangle of the neck. The triangles of the neck are surgically focused, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces of th...
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Carotid web

Carotid webs, also known as carotid intimal variant fibromuscular dysplasia, are rare vascular pathologies of the internal carotid artery that are an important cause of cryptogenic and recurrent ischemic stroke. Terminology Carotid webs have had many different names in the literature, includin...
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Carotidynia

Carotidynia, also known as Fay syndrome, is a rare syndrome characterized by neck pain in the region of the carotid bifurcation. It was classified by the International Headache Society (IHS) in 1988 as an idiopathic neck pain syndrome associated with tenderness over the carotid bifurcation with...
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Castleman disease

Castleman disease, also known as angiofollicular lymph node hyperplasia or giant lymph node hyperplasia, is an uncommon benign B-cell lymphoproliferative condition. It can affect several regions of the body although commonly described as a solitary mediastinal mass. There are two distinct subty...
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Cataract

Cataracts are an opacification or thickening of the lens within the globe and are the leading cause of blindness in the world 2.  Clinical presentation Visual deterioration occurs with increasing degrees of severity, and left untreated may present as complete blindness. The diagnosis is made c...
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Cavernous sinus thrombosis

Cavernous sinus thrombosis (CST) is a rare condition, most commonly infectious in nature, and the diagnosis on imaging is not always straightforward. It has high mortality and morbidity rates. Epidemiology CST is rare with ~4.5 cases per 1,000,000 per year 5. It is the least common dural venou...
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Cebocephaly

Cebocephaly refers to a type of rare midline craniofacial anomaly where there is a single nostril (which usually ends blindly 6-7) with proboscis-like nose 8 and hypotelorism. Pathology Associations holoprosencephaly: particularly alobar holoprosencephaly trisomy 13 See also ethmocephaly ...
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Cementoblastoma

Cementoblastoma is one of many mandibular lesions is a rare tumor of the cementum, with only approximately 100 cases reported. Key to diagnosis both radiologically and histologically is attachment to the tooth root.  Terminology Cementoblastomas have been previously described in the literature...
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Cemento-osseous dysplasia

Cemento-osseous dysplasia (COD) is a benign condition that can affect jaw. They may arise from the fibroblasts of the periodontal ligaments. Three types have been described periapical cemental dysplasia focal cemento-osseous dysplasia florid cemento-osseous dysplasia See also 2005 WHO his...
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Cemento-ossifying fibroma

Cemento-ossifying fibroma (COF) are rare, benign neoplasms that usually arise from the mandible or maxilla. They most often arise from the tooth bearing areas of these bones. Terminology In the 2005 WHO histological classification of odontogenic tumors, this tumor is referred to as "ossifying ...
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Central artery of the retina

The central artery of the retina or central retinal artery (CRA) arises from the ophthalmic artery.  Gross anatomy The central artery of the retina courses anteriorly and inferior to the optic nerve, It then pierces the dura and the arachnoid of the optic nerve. It then runs in the center of t...
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Central base of skull

The central base of skull is a region of the skull base centered on the pituitary fossa and includes surrounding structures. Despite no single universally accepted definition of this region, it is frequently used clinically and is conceptually useful particularly when considering tumors of the ...
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Central retinal artery occlusion

A cause of inner retinal infarction and profound, monocular vision loss, central retinal artery occlusion (CRAO) is most commonly caused by embolic occlusion of the central retinal artery.  Epidemiology The most common etiological associations with occlusion of the central retinal artery inclu...
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Cerumen

Cerumen, also known as earwax, is a natural secretion produced by, and found within the external auditory canal (EAC). It has important roles as part of the first-line of defense of the ear from micro-organisms and optimizing function of the tympanic membrane and EAC. Secretion Cerumen is secr...
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Cervical adenitis

Cervical adenitis refers to the inflammation of lymph nodes in the neck. Epidemiology Most common cause of a pediatric neck mass following non-specific infectious/inflammatory insults. Clinical presentation In the pediatric population, a child will present with a painful cervical mass. Path...
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Cervical lymph node groups

Cervical lymph node groups describe the anatomic position of the nodes. It differs from cervical lymph node levels, covering all lymph nodes not just those relevant to head and neck surgery.  Gross anatomy Groups described in the literature include but are not limited to:  facial group parot...
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Cervical lymph node metastasis (radiologic criteria)

Cervical lymph node metastases refer to regional nodal involvement by cancer in the head and neck, most commonly due to squamous cell carcinoma originating from the aerodigestive tract or skin. Radiologic detection of cervical lymph node metastases is important for clinical staging and planning ...
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Cervical lymph node (staging)

Cervical lymph node staging refers to evaluating regional nodal metastasis from primary cancer of the head and neck. The following article reflects the 8th edition of the TNM staging system published by the American Joint Committee on Cancer, which is used for staging starting January 1, 2018 1,...
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Cervical plexus

The cervical plexus is formed by the ventral (anterior) rami of the C1 to C5 nerve roots and innervates the diaphragm, provides motor supply to some neck muscles and cutaneous sensation to the skin of the head, neck and chest. Gross anatomy Roots anterior rami of C1 to C5 nerves Course runs...
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Cervical thymus

The cervical thymus refers to the ectopic location of thymus at the cervical level above the brachiocephalic vein. Clinical presentation A cervical thymus usually presents before adolescence as a painless unilateral midline or lateral neck mass. Pathology Etiology Around the 4th to 5th week...
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Chamberlain line

Chamberlain line is a line joining the back of hard palate with the opisthion on a lateral view of the craniocervical junction. Significance It helps to recognize basilar invagination which is said to be present if the tip of the dens is >3 mm above this line. McGregor developed a modificatio...
Article

Charcot-Leyden crystals

Charcot-Leyden crystals consist of collections of bipyramidal crystalloid made up of eosinophilic membrane proteins, which occur in:  asthma other eosinophilic lung disease 2 certain cases of sinusitis (e.g. allergic fungal sinusitis) They may be detected in the sputum or sinus secretions wi...
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Cherubism

Cherubism has historically been considered a variant of fibrous dysplasia, but in reality is likely a distinct entity.  Epidemiology Cherubism is a rare disorder and the precise incidence is unknown. It is inherited in an autosomal dominant pattern 2 and has variable penetrance, with onset in ...
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Choanal atresia

Choanal atresia refers to a lack of formation of the choanal openings. It can be unilateral or bilateral. Epidemiology It frequently presents in neonates where it is one of the commonest causes of nasal obstruction in this age group. There is a recognized female predilection. The incidence is ...
Article

Cholesteatoma

Cholesteatoma is histologically-equivalent to an epidermoid cyst and is composed of desquamated keratinising stratified squamous epithelium forming a mass. They usually present with conductive hearing loss. Pathology The mass is lined by epithelium (facing inwards) which continues to grow, the...
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Cholesterol granuloma

Cholesterol granuloma (CG) is a special type of middle ear granulation tissue which is particularly prone to bleeding and is a frequent cause of a hemotympanum. Cholesterol granulomas represent the most common cystic lesion of the petrous apex.  Epidemiology Cholesterol granulomas typically af...
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Chondrosarcoma of the skull base

Chondrosarcomas of the base of the skull are rare compared with other skull base tumors but are an important differential diagnosis as surgical resection and management are affected by the preoperative diagnosis. Epidemiology Chondrosarcomas of the base of the skull make up only a small fracti...
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Chorda tympani

The chorda tympani is a nerve that arises from the mastoid segment of the facial nerve, carrying afferent special sensation from the anterior two-thirds of the tongue via the lingual nerve, as well as efferent parasympathetic secretomotor innervation to the submandibular and sublingual glands. ...

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