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.

1,194 results found
Article

Thyroid malignancies

Thyroid malignancies are most commonly primary thyroid cancers but can rarely be metastatic deposits. Pathology Classification Thyroid malignancies can be categorised into the following key subtypes: primary thyroid cancers ​papillary thyroid carcinoma: 60-80% of carcinomas follicular thyr...
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Thyroid mass (mnemonic)

A mnemonic for thyroidal mass differential diagnosis is: CATCH Mnemonic C: carcinoma A: adenoma  T: thyroiditis C: colloid cyst H: hyperplasia (parathyroid gland)
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Thyroid scan (I-123)

Thyroid scan (thyroid scintigraphy) is a nuclear medicine examination used to evaluate thyroid tissue.  Clinical indications functional status of a thyroid nodule thyrotoxicosis: differential diagnosis thyroid cancer whole body scan for distant metastases estimation of local residual thyro...
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Thyroid-associated orbitopathy

Thyroid-associated orbitopathy (TAO) is the most common cause of proptosis in adults and is most frequently associated with Graves disease. On imaging, it is characterised by enlargement of the extraocular muscles' bellies (frequently: inferior rectus > medial rectus  > superior rectus) sparing...
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Thyroidea ima artery

The thyroidea ima artery is an uncommon variant of the blood supply to the inferior aspect of the thyroid gland. It is reported in ~7.5% (range 1.5-12.2%) of individuals and can arise from: brachiocephalic trunk right common carotid artery aortic arch internal thoracic artery The thyroidea ...
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Thyrotoxicosis

Thyrotoxicosis is a hypermetabolic clinical syndrome caused by a pathological excess of circulating free T4 (thyroxine) and/or free T3 (triiodothyronine). Terminology Although commonly done, thyrotoxicosis should not be confused nor synonymized with hyperthyroidism, the latter of which is a gr...
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Tinnitus

Tinnitus refers to a  sensation of “sound in one ear or both ears, such as buzzing, ringing, or whistling, occurring without an external stimulus” 1. It can be subjective or objective. Epidemiology It is thought that as many as 40 million people in the United States may have tinnitus. The repo...
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Tobey-Ayer-Queckenstedt sign

Tobey-Ayer-Queckenstedt sign is used in the diagnosis of unilateral and bilateral lateral sinus thrombophlebitis. In cases where the lateral sinus is obstructed on one side, compression of the jugular vein on the intact side causes a rise in CSF pressure, whereas compression of the obstructed si...
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Tolosa-Hunt syndrome

Tolosa-Hunt syndrome (THS) is an idiopathic inflammatory condition that involves the cavernous sinus and orbital apex, and is essentially a clinical diagnosis of exclusion. Clinical presentation Clinically it refers to the presence of a painful ophthalmoplegia secondary to surrounding cavernou...
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Tongue

The tongue is a complex, principally muscular, structure that extends from the oral cavity to the oropharynx. It has important roles in speech, swallowing and taste.  Gross anatomy The tongue has a tip, ventral surface, dorsal surface and root. The tongue is made of a midline lingual septum an...
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Tonsillitis

Tonsillitis refers to inflammation of any of the tonsils and is one of the most common head and neck infections in adolescents and young adults. Clinical presentation Patients may present with a variety of symptoms including painful throat (may be unilateral), dysphagia, fevers, tender cervica...
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Tonsillolith

Tonsilloliths, also known as tonsil (or tonsillar) stones or calculi, are clusters of calcifications that form in tonsillar crypts, within the tonsils or around them. Although they are uncommon and benign, they may be symptomatic (pain, halitosis, etc). Radiographic features Small foci of calc...
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Tornwaldt cyst

Tornwaldt cyst (also spelled as a Thornwaldt cyst or Thornwald cyst) is a common incidental benign midline nasopharyngeal mucosal cyst. Epidemiology The lesion is developmental and usually asymptomatic. In most cases it is found incidentally and as such age of diagnosis represents age of imagi...
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Torticollis

Torticollis (wryneck) is a clinical finding of head tilt with or without rotational spinal malalignment. It is not a diagnosis in itself and there are a wide range of underlying conditions. It is most common in the paediatric age group.  Pathology Torticollis can be acute (<1 week) or chronic ...
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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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Towne projection

The Towne projection is an fronto-occipital projection with the central ray angle laying 40 degrees cranially in the midline to the  patient. The projection is used to visualize the petrous part of the pyramids, the dorsum sellae and the posterior clinoid processes, which are visible in the shad...
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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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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 fibres attach prox...
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Transverse temporal bone fractures

Transverse temporal bone fractures are orientated perpendicular to the long axis of the petrous temporal bone, with the line of force running roughly anterior to posterior. A more current classification of the extent of temporal bone fractures describes the integrity of the otic capsule rather t...
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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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Triangles of the neck

The triangles of the neck are surgically focussed divisions of the neck, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces of the neck). The neck can be divided into anterior and posterior trian...
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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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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 differentiating between one and other cerebellopontine angle entities, especially from a meningioma which typically does not extend into the meatus 1. It is characterized by widenin...
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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. Aetiology The tympanic membrane and ossicular chain must be intact with a mobile footplate. It can be present in may situations congenital syphilis, with a semicircular canal fistula post-fenestratio...
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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 to the ossicles of the middle ear. The malleus is the first bone in the ossicular chain that eventually sees the sound wave trans...
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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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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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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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Uvea

The uvea (also called the uveal layer or vascular tunic) is the middle 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 anatomica...
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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 the one of the most common clefting syndromes in humans 1.  VWS individuals have a high prevalence of hypodontia. Pathology Genetics It carries anau...
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Vernet syndrome

Vernet syndrome (also known as the jugular foramen syndrome) is a constellation of cranial nerve palsies due to compression from a jugular foramen lesion such as a glomus jugulare tumour or schwannoma. It consists of motor paralysis of: glossopharyngeal nerve (CN IX) vagus nerve (CN X) access...
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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 fibres 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 ~1.5 mm (similar to the posterior semicircular canal) and runs from the vestibule in a transverse direction to the long axis of t...
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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

The vestibule is an approximately 4 mm central chamber of the bony labyrinth. It is dominated by depressions housing the: utricle (elliptical recess) saccule (spherical recess) basal end of the cochlear duct (cochlear recess) The cribrose areas have perforations through which the nerve bundl...
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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 haemorrhage

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

Vocal cord paralysis/palsy (VCP) can cause laryngeal dysfunction ranging from slight hoarseness to life-threatening airway obstruction. Pathology Left vocal cord paralysis is twice as common than right vocal cord paralysis, and unilateral vocal cord paralysis much less common than bilateral vo...
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Vogt-Koyanagi-Harada syndrome

Vogt-Koyanagi-Harada syndrome is a multisystem disorder characterised 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 pneumatise the vomer 2.
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Von Hippel-Lindau disease

Von Hippel-Lindau (vHL) disease is characterised by the development of numerous benign and malignant tumours in different organs (at least 40 types 1) due to mutations in the VHL tumour suppressor gene on chromosome 3. Epidemiology The disease is rare with an estimated prevalence of 1:35,000-5...
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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 tumour

Warthin tumours, also known as lymphomatous papillary cystadenomas, are benign, sharply demarcated tumours 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 neoplas...
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Widening of diploic space

Widening of diploic space refers to diffuse, most commonly bilateral, calvarium widening secondary to extramedullary hematopoiesis within the skull. Causes Most commonly caused by systemic underlying pathologies such as: chronic haemolytic disorders: may be associated with vertical striations...
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Widow's peak hair anomaly

Widow's peak hair anomaly refers to a frontal hairline projection. Clinical features Prominent V shaped hairline projection. Ocular hypertelorism might be noted. On examination a bony prominence may be present. Pathology It is purported that the periorbital fields of hairless region or hairg...
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Williams syndrome

Williams syndrome (WS) is characterised 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 bones

Wormian bones are a subset of the small intrasutural bones that lie between the cranial sutures formed by the bones of the skull vault. The title Wormian bones is reserved for abnormal intrasutural bones that are typically found around the lambdoid suture. Some consider them abnormal only if gr...
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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 an outpouching at the level of the hypopharynx, just proximal to the upper oesophageal sphincter. It is located in the posterior midline at the cleavage plane between the thyropharyngeus muscle and the cricopharyngeus muscle (known as the...
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Zuckerkandl tubercle

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

The zygoma (or zygomatic 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 orbital border by the zy...
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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 a 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 ...
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Zygomaticomaxillary suture

The zygomaticomaxillary suture is between the zygomatic process of the maxilla and the maxillary margin of the zygomatic bone.
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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 fibres to the lacrimal nerve from the pterygopalatine ganglion which reach the lacrimal gland. It le...

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