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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Torus tubarius

Torus tubarius or cushion of the auditory canal is a mucosal elevation in the lateral aspect of the nasopharynx, formed by the underlying pharyngeal end of the cartilaginous portion of the Eustachian tube. The opening of the Eustachian tube is anterior to the torus tobarius. Immediately posterio...
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Trachea

The trachea, known colloquially as the windpipe, connects the upper respiratory tract to the lungs via the tracheobronchial tree, enabling gas exchange. Gross anatomy The trachea is a tube-shaped structure consisting of 15-to-20 D-shaped cartilage rings anterolaterally bridged by annular ligam...
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Transsphenoidal hypophysectomy

Transsphenoidal hypophysectomy is a commonly used surgical approach for pituitary region masses, with many significant advantages over open craniotomy.  History The transsphenoidal approach was first described in 1907 by Schloffer, modified by Halstead and subsequently popularized by Harvey Cu...
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Transverse cervical artery

The transverse cervical artery, also known as the cervicodorsal trunk, is 1 of the 4 branches of the thyrocervical trunk (off the first part of the subclavian artery). It is a short artery that bifurcates into the superficial and deep branches, both which course superficially and laterally acro...
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Transverse cervical nerve

The transverse cervical nerve, also known as the superficial cervical nerve, cutaneous cervical nerve or anterior cutaneous cervical nerve of the neck, is a cutaneous branch of the cervical plexus that innervates the skin covering the anterior cervical region. Gross anatomy Origin The transve...
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Transverse muscle of the tongue

The transverse 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 attach prox...
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Transverse temporal bone fractures

Transverse temporal bone fractures are oriented perpendicular to the long axis of the petrous temporal bone, with the line of force running roughly anterior to posterior. Although more current classifications of the extent of temporal bone fractures focus on the integrity of the otic capsule rat...
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Trapdoor fracture

A trapdoor fracture is a fracture of the orbital floor where the inferiorly displaced blowout fracture recoils back to its original position and potentially entraps contents of the orbit. It is seen in children and young adults due to the elasticity of the orbital floor. These fractures may be s...
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Trapezius muscle

The trapezius muscle is a large, broad superficial muscle of the posterior neck and back. It gains its name from its diamond shape. Along with sternocleidomastoid muscle, it is invested by the superficial layer of the deep cervical fascia, which splits around it.  Summary origin: superior nuch...
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Treacher Collins syndrome

Treacher Collins syndrome, also known as mandibulofacial dysostosis, is an autosomal dominant genetic abnormality and results from bilateral malformations of 1st and 2nd branchial arches.  Epidemiology The incidence is estimated at approximately 1 in 50,000 live births, with 60% of cases being...
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Triangles of the neck

The triangles of the neck are surgically focused divisions of the neck, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on cross-sectional imaging (see deep spaces of the neck). The neck can be divided into anterior and ...
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Trigeminal ganglion

The trigeminal ganglion, also known as the Gasser, Gasserian or semilunar ganglion, is the large crescent-shaped sensoryganglion of the trigeminal nerve located in the trigeminal cave (Meckel cave) surrounded by cerebrospinal fluid. The ganglion contains the cell bodies of the sensory root of t...
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Trigeminal nerve

The trigeminal nerve is the fifth cranial nerve and its primary role is relaying sensory information from the face and head, although it does provide motor control to the muscles of mastication. It is both large and complicated and has multiple brainstem nuclei (sensory and motor) as well as man...
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Trigeminal nerve branches (mnemonic)

A mnemonic for remembering the names of the skull foramina that the division of the trigeminal nerve (CN V) pass through is: Standing Room Only Mnemonic standing: superior orbital fissure (ophthalmic division of trigeminal nerve) room: foramen rotundum (maxillary division of trigeminal nerve...
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Trigeminal neuralgia

Trigeminal neuralgia or tic douloureux corresponds to a clinical manifestation of sudden severe paroxysms of excruciating pain on one side of the face which usually lasts a few seconds to a few minutes, involving one or more branches of the trigeminal nerve (CN V). Vascular compression is the mo...
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Trochlear apparatus calcification

Trochlear apparatus calcification in the orbit is a common incidental finding on CT of the head, found in ~12.5% of patients. There is no association with diabetes mellitus but an association has been demonstrated with autoimmune disease and elevated ALP 1,2. 
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Trousseau sign

Trousseau sign of latent tetany (not to be confused with Trousseau syndrome) is highly specific for hypocalcemia 1. It may be elicited by placing a blood pressure cuff over the upper arm and inflating to above systolic pressure for 2-3 minutes. This reduces arterial supply to the forearm. The is...
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True vocal cords

The true vocal cords are the thickened, free edge of the cricovocal membrane, the cricovocal ligament, lined by mucous membrane 1. Together they form part of the glottis, the V-shaped aperture through which air passes. Their primary role is in phonation where vibration of the adducted vocal cord...
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Trumpeted internal acoustic meatus sign

A trumpeted internal acoustic meatus (IAM) is an indirect sign of an acoustic schwannoma and is useful in helping to differentiate between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend into the meatus and is more often associated with...
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Tuberculous cervical lymphadenitis

Tuberculous cervical lymphadenitis, also known as scrofula and King's evil, continues to be seen in endemic areas and in the industrialised world particularly among the immunocompromised. Epidemiology Tuberculous cervical lymphadenitis is the most common manifestation of extrapulmonary tubercu...
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Tuberculous otomastoiditis

Tuberculous otomastoiditis is an uncommon form of acute otomastoiditis that occurs secondary to tuberculosis infection, although its frequency is increasing as a result of greater population of immunocompromised patients. Clinical presentation Classically it is described as presenting with pa...
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Tuberculum sellae

The tuberculum sellae is the ridged process of the sphenoid bone which forms the anterior wall of the sella turcica. Gross anatomy Relations The tuberculum sellae forms the anterior wall of the sella turcica, which houses the pituitary gland. It is an elongated ridge located immediately poste...
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Tullio phenomenon

The Tullio phenomenon describes the precipitation of vertigo and nystagmus by a loud noise. Pathology Etiology The tympanic membrane and ossicular chain must be intact with a mobile footplate. It may be seen in several situations: Ménière disease superior semicircular canal dehiscence syndr...
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Tumors of the base of skull (differential diagnosis)

Tumors of the base of skull are histologically varied and are often challenging to preoperatively diagnose and treat. Exactly which tumors are considered to be tumors of the base of skull is debatable. The broadest definition would include any tumor that involves or abuts the base of skull, thu...
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Tunica (disambiguation)

Tunica is a word used in anatomy to refer to a type of covering.  tunica adventitia (also known as tunica externa) tunica albuginea tunica albuginea (ovary) tunica albuginea (penis) tunica albuginea (testis) tunica intima tunica media tunica vaginalis tunica vaginalis (ovary) tunica va...
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Tympanic annulus

The tympanic annulus is the thickened edge of the pars tensa of the tympanic membrane, anchoring it in the tympanic sulcus 3. Gross anatomy The tympanic annulus is formed by a fibrocartilaginous thickening of the edge of the pars tensa and has a horseshoe-shaped configuration. It is deficient ...
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Tympanic membrane

The tympanic membrane is a thin membrane that separates the external ear from the middle ear. It acts to transmit sound waves from air in the external auditory canal (EAC) to the ossicles of the middle ear. Gross anatomy The tympanic membrane is shaped like a flat cone pointing into the middle...
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Tympanic membrane retraction

Tympanic membrane retraction usually occurs when a portion of the tympanic membrane becomes weakened and is pulled inwards by the negative pressure within the middle ear.  Pathology As the tympanic membrane is pulled inwards (medially), it can become draped over the ossicles, resulting in a va...
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Tympanic part of temporal bone

The tympanic part of the temporal bone is situated inferiorly to the squamous part and anteriorly to the mastoid part. The tympanic part surrounds the external auditory meatus, forming the anterior wall, floor and some of the posterior wall of the bony external acoustic meatus. The lateral bord...
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Tympanosquamosal suture

The tympanosquamosal suture or fissure separates the tympanic part of the temporal bone from the squamous part. It is parallel and anterior to the bony external auditory meatus and medially continuous with the petrotympanic fissure and petrosquamous fissure.
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Ultrasound-guided FNA of the thyroid

Ultrasound-guided fine needle aspiration (FNA) of the thyroid refers to a minimally invasive procedure where in which tissue samples are collected from a thyroid nodule or other suspicious thyroid lesion. It is usually done on a outpatient basis and generally complications are very minimal. Pro...
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Ultrasound "U" classification of thyroid nodules

The ultrasound "U" classification of thyroid nodules has been developed by the British Thyroid Association (BTA) as part of their 2014 guidelines on the management of thyroid cancer 1. It allows for stratifying thyroid nodules as benign, suspicious or malignant based on ultrasound appearances t...
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Uncinate process

The uncinate process of the ethmoid bone is a thin hook-like osseous structure of the wall of the lateral nasal cavity. Gross anatomy Together with the ethmoid bulla, it forms the boundaries of the hiatus semilunaris and ethmoid infundibulum. The course of the free edge of the uncinate proces...
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Utricle (disambiguation)

The utricle may refer to: utricle of the inner ear utricle of the prostatic urethra
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Utricle (ear)

The utricle is a small membranous sac (part of the membranous labyrinth) and paired with the saccule lies within the vestibule of the inner ear. It has an important role in orientation and static balance, particularly in horizontal tilt. Gross anatomy The vestibule is located within the bony l...
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Uvea

The uvea (also called the uveal layer or vascular tunic) is the middle of the three layers that make up the eye. It is the pigmented layer and its main function is of nutrition and gas exchange. It sits between the retina (innermost layer) and sclera.  It is traditionally split up into three an...
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Vagal nerve stimulator

A vagal nerve stimulator (VNS) is an implantable device used in patients with intractable epilepsy. It is considered to be an adjunctive therapy in the treatment of refractory seizure disorders. The device is somewhat similar in appearance to a pacemaker with the 'box' typically inserted into t...
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Vallecula

The valleculae are depressions in the oropharynx located anterior to the epiglottis and posterior to the base of tongue. Etymology Vallecula is Latin for "small valley", a combination of valles (valley) and cula (diminutive suffix).
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Valsalva maneuver

The Valsalva maneuver is the forced expiration of air against a closed airway, resulting in increased intra-abdominal, intrathoracic and pharyngeal pressure. It can be performed against a closed glottis or by one closing the mouth and pinching the nose while forcibly exhaling. It is commonly us...
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Van der Woude syndrome

van der Woude syndrome (VWS) is characterized by the association of congenital lower lip fistulae/pits with cleft lip and/or palate. It is one of the most common clefting syndromes in humans 1 and affected individuals have a high prevalence of hypodontia. Pathology Genetics It carries an aut...
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Ventral cord syndrome

Ventral cord syndrome (also known as anterior cord syndrome) is one of the incomplete cord syndromes and affects the anterior parts of the cord resulting in a pattern of neurological dysfunction dominated by motor paralysis and loss of pain, temperature and autonomic function. Anterior spinal ar...
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Vernet syndrome

Vernet syndrome, also known as jugular foramen syndrome, is a constellation of cranial nerve palsies due to compression from a jugular foramen lesion, such as a glomus jugulare tumor, schwannoma, or metastasis 2. Clinical presentation It consists of motor paralysis of: glossopharyngeal nerve ...
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Vertebral artery

The vertebral arteries (VA) are paired arteries, each arising from the respective subclavian artery and ascending in the neck to supply the posterior fossa and occipital lobes, as well as provide segmental vertebral and spinal column blood supply. Summary origin: branches off the 1st part of t...
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Vertebral artery dissection

Vertebral artery dissection, like arterial dissection elsewhere, is a result of blood entering the media through a tear in the intima. It is potentially lethal and can be difficult to diagnose clinically and radiologically. Epidemiology Vertebral artery dissections have an incidence of 1-5 per...
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Vertebral artery ectasia

Vertebral artery ectasia refers to an abnormal dilatation of the vertebral artery. It is also known as a dolichoarterial loop (of Danziger). Clinical presentation Symptoms occur due to radicular compression or pathologic fracture (rare) from extensive bone erosion. Generally, patients present ...
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Vertex

The vertex is the midline bony landmark at the most superior part of the calvaria in the standard anatomical position, near the midpoint of the sagittal suture (i.e. between the bregma and lambda). It is one of the skull landmarks, craniometric points for radiological or anthropological skull m...
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Vertical muscle of the tongue

The vertical 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 attach proxim...
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Vestibular aqueduct

The vestibular aqueduct is a structure of the inner ear being part of the osseous labyrinth. It contains the endolymphatic duct and sac. It normally has a diameter of approximately 1.5 mm (similar to the posterior semicircular canal) and runs from the vestibule in a transverse direction to the l...
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Vestibular line of Lapayowker

The vestibular line of Lapayowker refers to a vertical line passing down the most lateral aspect of vestibular apparatus. The petrous part of internal carotid artery lies medial to this line but lies lateral to it in the case of an aberrant internal carotid artery which is the characteristic ang...
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Vestibule (disambiguation)

A vestibule is an anatomical term and refers to a small cavity at the proximal end of a tube. It may refer to: vestibule (aorta) vestibule (ear) vestibule (larynx) vestibule (mouth) vestibule (nose) vestibule (esophagus) vestibule (vulva) History and etymology Vestibule derives ultimate...
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Vestibule (ear)

The vestibule is an approximately 4 mm central chamber of the bony labyrinth. It is dominated by depressions housing parts of the membranous labyrinth: utricle (elliptical recess) saccule (spherical recess) basal end of the cochlear duct (cochlear recess) It is located medial to the tympanic...
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Vestibulocochlear nerve

The vestibulocochlear nerve is the eighth cranial nerve and has two roles: innervation to the cochlea for hearing innervation to the vestibule for acceleration and balance senses Gross anatomy It emerges between the pons and the medulla, lateral to the facial nerve and nervus intermedius, pa...
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Videofluoroscopic swallow study

Videofluoroscopic swallow studies (also often called modified barium swallow studies) are a variation on traditional barium swallow studies. Although typical barium swallow studies / esophagrams evaluate the pharynx, the goal in these studies is to even more closely evaluate the oral cavity, pha...
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Vidian artery

There are two arteries passing through Vidian canal from the pterygopalatine fossa to the petrous portion of the ICA. One is a branch of the internal maxillary artery (itself a branch of the ECA) and the other is from the C2 segment of the ICA. It therefore forms one of the ICA to ECA anastamoses.
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Vidian nerve

Vidian nerve, also known as the nerve of the pterygoid canal or nerve of the Vidian canal, is so named because of the canal in which is travels: the Vidian canal. It is formed by the confluence of two nerves: greater superfical petrosal nerve (from the geniculate ganglion of the facial nerve) ...
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Visceral space

The visceral space is one of the infrahyoid deep spaces of the head and neck.  Gross anatomy The visceral space extends from the hyoid bone to the superior mediastinum (level of aortic arch / T4), and is surrounded by the middle layers of the deep cervical fascia.  Contents thyroid gland pa...
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Vitreous body

The vitreous body or vitreous humor is a transparent, avascular gel that occupies ~80% of the globe and helps to maintain the position of the retina and the shape of the globe.  Gross anatomy Situated within the globe between the lens and the optic cup, its anterior surface is indented by the...
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Vitreous hemorrhage

Vitreous hemorrhage refers to bleeding into the vitreous chamber. Epidemiology Vitreous hemorrhage has an incidence of approximately 7 in 100000 1,2.   Clinical presentation The most common clinical presentation is with sudden, painless visual loss to varying degrees of severity 2. Associate...
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Vocal cord paralysis

Vocal cord paralysis/paresis (VCP), also known as vocal fold paralysis/paresis, refers to the impaired mobility of the true vocal cord or fold due to neurologic dysfunction. Clinical presentation Unilateral vocal cord paralysis usually presents with dysphonia (hoarseness), characterized as a b...
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Vogt-Koyanagi-Harada syndrome

Vogt-Koyanagi-Harada syndrome is a multisystem disorder characterized by granulomatous panuveitis with exudative retinal detachments that is often associated with neurologic and cutaneous manifestations. Epidemiology Vogt-Koyanagi-Harada usually affected those of Asian, Middle Eastern, Asian I...
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Vomer

The vomer is one of the facial bones and forms the postero-inferior part of the bony nasal septum. Variant anatomy Occasionally the sphenoid sinus may pneumatize the vomer 2.
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Von Hippel-Lindau disease

Von Hippel-Lindau (vHL) disease is characterized by the development of numerous benign and malignant tumors in different organs (at least 40 types 1) due to mutations in the VHL tumor suppressor gene on chromosome 3. Epidemiology The disease is rare with an estimated prevalence of 1:35,000-50,...
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Wackenheims line

Wackenheims line (also known as the clivus canal line or basilar line) is formed by drawing a line along the clivus and extending it inferiorly to the upper cervical canal. Normally the tip of the dens is ventral and tangential to this line. In basilar invagination odontoid process transects th...
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Waldeyer's ring

Waldeyer's ring is a ring of lymphoid tissue located in the nasopharynx and oropharynx at the entrance to the aerodigestive tract. Gross anatomy The structures composing this ring are: palatine tonsils (also called the faucial tonsils) adenoid tonsils (nasopharyngeal tonsils) the lateral ba...
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Warthin tumor

Warthin tumors, also known as lymphomatous papillary cystadenomas, are benign, sharply demarcated tumors of the salivary gland. They are of lymphoid origin and most commonly arise from parotid gland tail. They may be bilateral or multifocal in up to 20% of cases and are the most common neoplasti...
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WHO classification of head and neck tumors

The World Health Organization (WHO) classification of head and neck tumors is the most widely used pathologic classification system for such disorders. The current revision, part of the 4th edition of the WHO series, was published in 2017 and is reflected in the article below 1. Classification ...
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Widening of diploic space

Widening of diploic space refers to expansion of the spongy or cancellous bone between the inner and outer tables of the calavarium. The diploic space is the medullary cavity of the skull, and a location of normal physiologic hematopoiesis in adults. Thus, expansion of this structure most common...
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Widow's peak hair anomaly

Widow's peak hair anomaly refers to a frontal hairline projection. Epidemiology Associations Aarskog syndrome Opitz syndrome Waardenburg syndrome frontonasal dysplasia craniofrontonasal dysplasia Clinical presentation Prominent V-shaped hairline projection. Ocular hypertelorism might be...
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Williams syndrome

Williams syndrome (WS) is characterized by some or all or the following features: craniofacial dysmorphism (e.g. elfin facies) oral abnormalities short stature (50% of cases) mild to moderate mental retardation supravalvular aortic stenosis 2 pulmonary artery stenosis 3 renal insufficienc...
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Wolff-Chaikoff effect

Wolff-Chaikoff effect is an autoregulatory phenomenon, whereby a large amount of ingested iodine acutely inhibits thyroid hormone synthesis within the follicular cells, irrespective of the serum level of thyroid-stimulating hormone (TSH) 1.  Pathology The Wolff-Chaikoff effect is thought to be...
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Wormian bone

Wormian bones (a.k.a. intrasutural bones) is the name given to the additional small bones sometimes found between the cranial sutures of the bones of the skull vault, most commonly in relation to the lambdoid suture. Some reserve the term Wormian bones to just the intrasutural bones proximate to...
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Young syndrome

Young syndrome shares similar clinical and radiological findings to primary ciliary dyskinesia and cystic fibrosis, however the underlying pathogenesis yet to be fully elucidated. Obstructive azoopsermia at the level of the epididymis is thought to be the cause of infertility. The commonly refer...
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Zenker diverticulum

Zenker diverticulum, also known as a pharyngeal pouch, is a posterior outpouching of the hypopharynx, just proximal to the upper esophageal sphincter through a weakness in the muscle layer called the Killian dehiscence. Epidemiology More than 50% of the affected patients present in 60-80 years...
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Zimmerman-Laband syndrome

Zimmerman-Laband syndrome is a rare congenital syndrome, characterized primarily by gingival hypertrophy and skeletal abnormalities.  Pathology The molecular basis of the syndrome is currently unknown. An autosomal dominant mutation with high mutation rate and rare instances of germinal mosaic...
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Zuckerkandl tubercle

Zuckerkandl tubercle is a normal variant of the thyroid and may be mistaken for a thyroid nodule, mass or lymph node. It is a projection of normal thyroid tissue from the posterior aspect of the lateral lobes of the thyroid gland.  The tubercle is also an important surgical landmark due to its ...
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Zygoma

The zygoma (also known as zygomatic bone or malar bone) is an important facial bone which forms the prominence of the cheek. It is roughly quadrangular in shape. Gross anatomy Zygoma has three surfaces, five borders, and two processes. Surfaces anterolateral surface is convex, pierced at its...
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Zygomatic arch

The zygomatic arch is formed by the union of the temporal process of the zygomatic bone and the zygomatic process of the temporal bone at the zygomaticotemporal suture.  Related pathology Le Fort type 3 fracture zygomaticomaxillary complex fracture
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Zygomatic nerve

The zygomatic nerve is a main branch of the maxillary division of the trigeminal nerve. It should not be confused with the zygomatic branch of the facial nerve. Gross anatomy The zygomatic nerve divides off the maxillary division just after emerging from the foramen rotundum to enter the ptery...
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Zygomaticofacial foramen

The zygomaticofacial foramen is a small foramen in the mid lateral surface of the zygomatic bone that transmits the zygomaticofacial nerve (a branch of the zygomatic nerve from the maxillary division of the trigeminal nerve) and zygomaticofacial vessels.
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Zygomaticofacial nerve

The zygomaticofacial nerve is the smaller of the two branches of the zygomatic nerve, from the maxillary division of the trigeminal nerve. It is sometimes referred to as the malar branch of the zygomatic nerve. It leaves the inferolateral aspect of the extraconal space of the orbit through the z...
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Zygomaticomaxillary complex fracture

Zygomaticomaxillary complex (ZMC) fractures, also known as tripod, tetrapod, quadripod, malar or trimalar fractures, are seen in the setting of traumatic injury to the face. They comprise fractures of the: zygomatic arch inferior orbital rim, and anterior and posterior maxillary sinus walls l...
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Zygomaticomaxillary suture

The zygomaticomaxillary suture is between the zygomatic process of the maxilla and the maxillary process of the zygomatic bone. They are often involved in zygomaticomaxillary complex (ZMC) fractures.
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Zygomaticotemporal foramen

The zygomaticotemporal foramen is a small foramen in the anteromediall surface of the zygomatic bone that transmits the zygomaticotemporal nerve (a branch of the zygomatic nerve from the maxillary division of the trigeminal nerve) and zygomaticotemporal vessels.
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Zygomaticotemporal nerve

The zygomaticotemporal nerve is the larger of the two branches of the zygomatic nerve, from the maxillary division of the trigeminal nerve. It is primarily sensory but also relays parasympathetic fibers to the lacrimal nerve from the pterygopalatine ganglion which reach the lacrimal gland. It le...
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Zygomaticus major

Zygomaticus major is a member of the buccolabial muscle group of the upper lip1. It joins with the fibers of levator anguli oris, orbicularis oris and the more deeply placed muscular bands to move the side of the mouth upwards and sideways during facial movements such as laughing. Summary orig...
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Zygomaticus minor

Zygomaticus minor is a member of the buccolabial muscle group. Together with levator labii superioris alaeque nasi and levator labii superioris it is one of the main elevators of the lip, exposing the maxillary teeth 1. Along with its other action of deepening and elevating the nasolabial furro...

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