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.

1,245 results found
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Multiple cystic neck lesions (differential)

The differential diagnosis for multiple cystic neck lesions is different to that for a solitary cystic neck mass. Differential diagnosis Cystic neck lesions are seen in: necrotic metastatic SCC nodes: older patient, M>F papillary thyroid carcinoma metastases: usually a younger patient, F>M ...
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Multiple endocrine neoplasia syndromes

Multiple endocrine neoplasia (MEN) syndromes are a collection of syndromes characterised by the presence of, as the name would suggest, multiple endocrine tumours. They are autosomal dominant in inheritance. MEN1 (Wermer syndrome) MEN2 (multiple endocrine adenomatosis) MEN2a (Sipple syndrome)...
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Multiple endocrine neoplasia type I

Multiple endocrine neoplasia type I (MEN1) is also known as Wermer syndrome. Clinical presentation Primary hyperparathyroidism is one of the commonest presentations. Pathology The abnormality is related to a tumour suppressor gene located in chromosome 11q13. MEN type I is an autosomal domin...
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Multiple endocrine neoplasia type II

Multiple endocrine neoplasia type II (MEN2) is also known as mucosal neuroma syndrome or multiple endocrine adenomatosis. It is a collection of syndromes characterised by the presence of multiple endocrine tumours.  They are autosomal dominant in inheritance, and share medullary thyroid carcino...
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Multiple endocrine neoplasia type IIa

Multiple endocrine neoplasia (MEN) type IIa, also known as Sipple syndrome, accounts for most cases of MEN2 and is characterised by: pheochromocytomas: in 50% of patients, often bilateral, and can be extra-adrenal medullary thyroid cancer: 100% of patients, aggressive, and may secrete calciton...
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Multiple endocrine neoplasia type IIb

Multiple endocrine neoplasia (MEN) type IIb, also known as MEN type 3 (MEN3) 3 or mucosal neuroma syndrome 2, accounts for only 5% cases of MEN2 and is characterised by: pheochromocytoma(s): in 50% of patients, often bilateral, and can be extra-adrenal medullary thyroid cancer: 100% of patient...
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Multiple endocrine neoplasia type IV

Multiple endocrine neoplasia type IV (MEN4), previously known as MENX, is a rare type of MEN with clinical overlap with MEN1 but is due to a Cdkn1b mutation. It is characterised by 1,2: parathyroid adenoma primary hyperparathyroidism in 80% anterior pituitary adenoma neuroendocrine tumours (...
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Mumps

Mumps is a (usually) self-limited viral infection that often occurs in epidemics among children. Its incidence has markedly diminished in countries with childhood vaccination programs, but can still be seen in patient who have not received vaccinations or who have waning immunity. Clinical feat...
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Muscle of the uvula

The muscle of the uvula or musculus uvulae is one of the 5 paired muscles of the soft palate. Summary origin: posterior border of the hard palate and the posterior nasal spine of the horizontal plate of the palatine bone insertion: palatine aponeurosis and mucosa of the uvula action: alters ...
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Muscles of mastication

The muscles of mastication can be divided into primary and secondary groups according to whether they connect the mandible directly to the skull or if they attach to other structures in the neck, e.g. hyoid, thyroid cartilage. Primary temporalis muscle masseter muscle medial pterygoid muscle...
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Muscles of the soft palate

There are five paired muscles of the soft palate that are collectively referred to as the muscles of the soft palate or the palatal muscles: tensor veli palatini levator veli palatini ​palatopharyngeus palatoglossus muscle of the uvula All of them are innervated by the pharyngeal plexus ap...
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Muscles of the tongue

The muscles of the tongue are divided into 2 groups each comprising 4 muscles. They are classified as intrinsic (to the tongue) and extrinsic muscles. They allow for the complex movements of the tongue and are all innervated by the hypoglossal nerve (CN XII) except one:​ intrinsic muscles of th...
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Muscular attachments of the hyoid bone (mnemonic)

A handy mnemonic to recall the muscle attachments of the hyoid bone. The first sentence is for six muscles attaching superiorly, the second sentence is for three muscles attaching inferiorly. Both sentences are in order from lateral to medial: Christopher, He Didn't Screw Girls Much. That's Obv...
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Muscular triangle

The muscular triangle is one of the paired triangles in the anterior triangle of the neck. The triangles of the neck are surgically focussed, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces of ...
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Mylohyoid boutonniere

Mylohyoid boutonniere is a normal focal discontinuity in the mylohyoid muscle, which may permit the sublingual salivary gland, fat or vessels - or a combination thereof - to protrude out from the sublingual space into the submandibular space. Epidemiology The finding has been observed in up to...
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Mylohyoid muscle

The mylohyoid muscles form a paired muscular sling that forms part of the floor of the mouth. It also separates the sublingual space (and oral cavity) from the submandibular space.  Summary origin: mylohyoid line/ridge on the medial surface of the mandible insertion: midline raphe that extend...
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Myoepithelioma

Myoepitheliomas and malignant myoepitheliomas were considered a variant of pleomorphic adenomas until 1991. However, these are also found in breast and bronchus and have gained recognition as separate entities. They account for less than 1% of salivary gland tumours, only rarely undergo malignan...
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Myofascial cone

The myofascial cone is a structure within the orbit involved in the movement and support of the globe, or more simply the eye. It also serves as the physical division between the intraconal and extraconal compartments, but the cone itself is included in the contents of the intraconal space 1.  ...
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Myokymia

Myokymia refers to a fine undulating fascicular tremor of facial musculature which should be distinguished from hemifacial spasm which involves entire muscles rather than individual fascicles. The two conditions may co-exist.
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Nasal bone

The nasal bones are paired oblong upper central facial bones placed side by side between the frontal processes of the maxilla, jointly forming the nasal ridge. Gross anatomy The nasal bone has two surfaces: external surface attaches the procerus and nasalis muscles internal, which is transve...
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Nasal bone fracture

Nasal bone fractures are the most common type of facial fractures, accounting for ~45% of facial fractures, and are often missed when significant facial swelling is present.  Clinical presentation Unsurprisingly, nasal bone fractures occur when the nose impacts against a solid object (e.g. fis...
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Nasal cavity

The nasal cavity forms part of the aerodigestive tract. Gross anatomy The nasal cavity is formed by 1: anteriorly: nasal aperture laterally: inferior, middle and superior nasal conchae or turbinates superiorly: cribiform plate of the ethmoid bone inferiorly: palatal processes of the maxill...
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Nasal concha

The nasal conchae or turbinates are long, narrow curled shelves of bone that protrude into the nasal cavity. The superior, middle and inferior conchae divide the nasal cavity into four groove-like air passages. Their position and relationship to other important anatomic landmarks are extremely i...
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Nasal encephalocele

Nasal encephaloceles are in most cases a form of neural tube defect particularly common in Southeast asia. They are are herniation of cranial content through a bony defect in the anterior skull base into the nasal area. The term is variably used, but generally encompasses both frontoethmoidal e...
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Nasal glioma

Nasal gliomas, also know as nasal glial heterotopia, are a rare congenital lesion composed of dysplastic glial cells which have lost their intracranial connections and present as an extranasal or intranasal mass.  Epidemiology Nasal gliomas are rare congenital lesions. These masses occur spora...
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Nasal septal perforation

Nasal septal perforation may affect either the bony, or cartilaginous septum. Most commonly it affects the anterior septal cartilaginous area although with syphilis it characteristically affects the bony septum. Clinical presentation Symptoms include a nasal discharge, nasal congestion (loss o...
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Nasal septum

The nasal septum (Latin: septum nasi) separates the left and right nasal cavities. It extends from the nares anteriorly to the choanae posteriorly and is covered by squamous epithelium. Structure The vertical midline nasal septum is comprised primarily of a single cartilage and two bones. Ante...
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Nasal septum perforation (mnemonic)

A not-very-useful mnemonic for the causes of nasal septum perforation is: Say Water Coke Syrup Sugarwater Lemonade or Say Nothing  Mnemonic S: sarcoidosis W: Wegener granulomatosis C: cocaine S: syphilis S: surgery L: leprosy or say N: non-Hodgkin T-cell lymphoma (NHL)
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Nasal sill

The nasal sill is the soft tissue ridge forming the posterior margin of the anterior naris. It also forms the caudal margin of the nasal vestibule. The nasal sill forms part of the nasal base, which is defined as the inferior third of the nose when viewing the nose from below with the neck exte...
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Nasal vestibule

The nasal vestibule forms the small area just inside the anterior naris. It is formed by the columella medially, the nasal ala lateral and anteriorly and the nasal sill posteriorly.
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Nasion

The nasion is the midline bony depression between eyes where the frontal and two nasal bones meet, just below the glabella. It is also known as the bridge of the nose. It is one of the skull landmarks, craniometric points for radiological or anthropological skull measurement.
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Nasociliary nerve

The nasociliary nerve is the intermediate branch of the ophthalmic division of the trigeminal nerve. Gross anatomy The nasociliary nerve divides off the ophthalmic division just before entering the orbit through the superior orbital fissure and through the tendinous ring between the inferior a...
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Nasolabial cyst

Nasolabial cyst (also known as nasoalveolar cyst or Klestadt`s cyst) is a rare non-odontogenic, soft-tissue, developmental cyst occurring inferior to the nasal alar region. The cyst is derived from epithelial cells retained in the mesenchyme after fusion of the medial and lateral nasal processes...
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Nasolacrimal drainage apparatus

The nasolacrimal (drainage) apparatus consists of: lacrimal canaliculi lacrimal sac nasolacrimal duct Tears produced by the lacrimal gland, accessory lacrimal glands of Krause Wolfring and Zeis, and Meibomian glands track medially along the eyelid margins and collect at the lacrimal lake at ...
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Nasolacrimal duct

The nasolacrimal duct is the terminal part of the nasolacrimal apparatus. Gross anatomy The nasolacrimal duct is the inferior continuation of the lacrimal sac and is ~17 mm in length in total. There are two parts to the nasolacrimal duct: intraosseous part (12 mm): lies within the nasolacrima...
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Nasolacrimal tumours

Nasolacrimal tumours, in other words tumours involving the nasolacrimal drainage apparatus, are uncommon, and have a variety of histologies. Clinical presentation Clinical presentation of nasolacrimal tumours are typically fairly non-specific, often resulting in delayed diagnosis 1. Typical pr...
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Nasomaxillary suture

This suture forms the fissure between the frontal process of maxilla and the lateral border of the nasal bone. The nasomaxillary sutures are paried.
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Naso-orbital-ethmoid region

The naso-orbital-ethmoid (NOE) region or interorbital region simply refers to the space between the orbits.  Gross anatomy Boundaries anterior: frontal process of the maxilla, nasal process of frontal bone, nasal bone posterior: sphenoid sinus lateral: medial orbital wall superior: cribrif...
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Naso-orbitoethmoid (NOE) complex fracture

Naso-orbitoethmoid (NOE) fractures (also known as orbitoethmoid or nasoethmoidal complex fractures) are fractures which involve the central upper midface. Pathology Naso-orbitoethmoid fractures are caused by a high-impact force applied anteriorly to the nose and transmitted posteriorly through...
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Nasopalatine nerve

The nasopalatine nerve (also known as the long sphenopalatine nerve) is a branch of the maxillary division of the trigeminal nerve and contributes to the pterygopalatine ganglion. Gross anatomy The nasopalatine nerve divides off the maxillary division just after emerging from the foramen rotun...
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Nasopharyngeal carcinoma

Nasopharyngeal carcinomas (NPC) are the most common primary malignancy of the nasopharynx. It is of squamous cell origin, some types of which are strongly associated with the Epstein-Barr virus (EBV). Epidemiology Nasopharyngeal carcinoma accounts for ~70% of all primary malignancies of the na...
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Nasopharyngeal carcinoma (staging)

Nasopharyngeal carcinoma staging uses the TNM staging system with derived stage groupings.  TNM staging Primary tumour (T) Tx: primary tumour cannot be assessed T0: no evidence of primary tumour Tis: carcinoma in situ T1: tumour is confined to the nasopharynx T2: tumour extends to soft ti...
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Nasopharyngeal choristoma

A nasopharyngeal choristoma is a rare, non-neoplastic mass (type of choristoma) typically located in the lateral aspect of the nasopharynx without intracranial extension. These lesions are composed of fibrovascular tissue and fat. Resection is curative. Differential diagnosis nasopharyngeal ca...
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Nasopharyngeal mass (mnemonic)

A mnemonic for causes of nasopharyngeal masses is: SAIL Mnemonic S: squamous cell carcinoma A: antrachoanal polyp I: inverted papilloma L: lethal midline granuloma
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Nasopharynx

The nasopharynx forms the superior-most part of the pharynx, in continuity with the inferior oropharynx, and the posterior continuation of the anterior nasal cavity. Gross anatomy Boundaries anteriorly: posterior nares and posterior margin of nasal septum 1,2 inferiorly: soft palate 2 super...
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Neck dissection classification

There are several types of neck dissections which can classified as follows: Radical neck dissection Radical neck dissection is considered to be the standard basic procedure for cervical lymphadenectomy. All other procedures represent one or more alterations of this procedure. The dissection i...
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Necrotising otitis externa

Necrotising otitis externa (NOE), also known as malignant otitis externa, is a severe invasive infection of the external auditory canal (EAC) which can spread rapidly to involve the surrounding soft tissue, adjacent neck spaces and skull base.  Pathology Predisposing conditions for NOE include...
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Necrotising sialometaplasia

Necrotising sialometaplasia is a benign inflammatory condition of the salivary gland remnants or elements, which is usually self-limiting.  It is most commonly found in the palate.  Epidemiology Most patients are more than 40 years of age, with a male:female ratio of 2:1. It is rarely seen in ...
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Nerve to medial pterygoid

The nerve to medial pterygoid or medial pterygoid nerve is a branch of the mandibular division of the trigeminal nerve. Gross anatomy The nerve to medial pterygoid divides off the mandibular division just below the foramen ovale and just before it branches into anterior and posterior divisons....
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Nerve to mylohyoid

The nerve to mylohyoid or mylohyoid nerve is a motor branch of the inferior alveolar nerve, a branch of the mandibular division of the trigeminal nerve. Gross anatomy The nerve to mylohyoid arises from the inferior alveolar nerve just before it enters the mandibular foramen. It does not enter ...
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Nerve to stapedius

The nerve to stapedius arises from the facial nerve to supply the stapedius muscle. The branch is given off in the facial nerve's mastoid segment, as it passes posterior to the pyramidal process. Damage to this branch with resulting paralysis of stapedius leads to hypersensitivity to loud noise...
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Nervus intermedius neuralgia

Nervus intermedius neuralgia, or geniculate neuralgia, corresponds to a clinical manifestation of sudden paroxysms of excruciating otalgia which usually lasts a few seconds to a few minutes, involving the nervus intermedius (intermediate nerve of Wrisberg). Epidemiology Nervus intermedius neur...
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Nervus spinosus

The nervus spinous (also known as the meningeal branch of the mandibular nerve) is a branch of the mandibular division of the trigeminal nerve which innervates the dura of the middle cranial fossa. Gross anatomy The nervus spinosus divides off the mandibular division just below the foramen ova...
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Neuroblastoma (craniocerebral metastases)

Craniocerebral neuroblastoma metastases usually involve the calvaria, orbits, skull base and the dura. Please refer to the article neuroblastoma for a general discussion on this entity.  Clinical presentation proptosis periorbital ecchymosis "raccoon eyes" palpable calvarial masses Radiogr...
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Neurofibromatosis type 1 (orbital manifestations)

Orbital manifestations of neurofibromatosis type 1 (NF1) reflects a mix of CNS, musculoskeletal and ocular disease. Usually only one orbit is affected, commonly associated with ipsilateral extracranial disease. Pathology NF1 manifests in the orbit in the following ways 1-5: plexiform neurofib...
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Neurosyphilis

Neurosyphilis results from infection of the central nervous system by the spirochete Treponema pallidum, subspecies pallidum. The disease has a heterogeneous spectrum of early and late manifestations. For a general discussion, and for links to other system specific manifestations, please refer ...
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NEXUS criteria

NEXUS (National Emergency X-Radiography Utilization Study) is a set of validated criteria used to decide which trauma patients do not require cervical spine imaging. Trauma patients who do not require cervical spine imaging: alert and stable no focal neurologic deficit no altered level of co...
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Node of Rouviere

The node of Rouviere is the most superior of the lateral group of the retropharyngeal lymph nodes. It is found at the base of the skull. History and etymology Henri Rouvière (1876–1952) was an anatomy professor from Le Bleymard in France.  His seminal work, "Anatomy of the Human Lymphatic Syst...
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Non-decussating retinal-fugal fibre syndrome

Non-decussating retinal-fugal fibre syndrome (NRFFS), also referred to as achiasma, is the isolated congenital absence of optic chiasm with unremarkable rest of the optic pathway and midline structures. Clinically, it typically presents as seesaw nystagmus since childhood. Diagnosis is usually m...
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Nonsteroidal anti-inflammatory drug (NSAID) exacerbated respiratory disease

Nonsteroidal anti-inflammatory drug (NSAID) exacerbated respiratory disease or previously known as Samter syndrome or aspirin or analgesic-induced asthma refers to the constellation of 1-2: allergy to aspirin nasal polyposis / rhinosinusitis asthma Epidemiology In adults, prevalence can ran...
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Normal bone marrow signal of the clivus

Bone marrow signal of the clivus changes predictably with age and is well assessed with midline T1 non-fat-saturated, non-contrast images. As is seen in the rest of the body the proportion of yellow (fatty) marrow increases with age. Knowledge of these changes allows diagnosis of the abnormal cl...
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Normal head and neck imaging examples

This article lists examples of normal imaging of the head and neck and surrounding structures, divided by region and modality. Neck For normal spinal imaging, please see: normal spinal imaging Plain radiographs soft tissue: example 1 soft tissue: example 2 CT soft tissue contrast: exampl...
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Norrie disease

Norrie disease is a rare X-linked inherited cause of congenital bilateral blindness. It can present with a retinal mass (pseudoglioma) and cataracts. It is associated with developmental delay and hearing loss. 
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Nose

The nose, sometimes referred to as the external nose, is a feature of the face and is composed of soft tissues that extend externally from the skull. It is continuous posteriorly with the nasal cavity. Blood supply arterial supply facial artery (from external cartoid artery) with anastomoses ...
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Nystagmus (mnemonic)

A helpful mnemonic to remember the expected direction of nystagmus during a caloric test is: COWS Mnemonic Cold-Opposite Warm-Same Following ear stimulation with water (left ear): cold water (cooler than body temperature), a right-beating nystagmus (directed toward the opposite ear) result...
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Obelion

The obelion refers to the skull landmark along the sagittal suture intersected by an imaginary line connecting the two parietal foramina, where both are present. It is said to represent the site of commencement of sagittal suture closure 1. It is one of the skull landmarks, craniometric points ...
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Obstruction of nasolacrimal drainage apparatus

Obstruction of nasolacrimal drainage apparatus results in epiphora and can be primary or secondary, congenital or acquired. Obstruction can occur in canaliculi, lacrimal sac, or nasolacrimal duct (post saccular) levels. Congenital obstruction is usually secondary to persistence of the membrane ...
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Occipital artery

The occipital artery, a posterior branch of the external carotid artery, opposite the external maxillary, near the lower margin of the posterior belly of the digastic muscle, and ends in the posterior part of the scalp. Summary origin: branch of the external carotid artery at the level of the ...
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Occipital bone

The occipital bone is a trapezoid skull bone that contributes to the posteroinferior part of the cranial vault. It is pierced by the foramen magnum, permitting communication from the cranial cavity to the vertebral canal Gross anatomy The occipital bone is composed of four parts: squamous par...
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Occipital condyle

The occipital condyles are two large protuberances on the undersurface of the occipital bone, located besides the front half of the foramen magnum. It forms the connection between the skull and the vertebral coloumn. Articulations atlas (C1) at the atlanto-occipital joint See Also  third co...
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Occipital plagiocephaly

Occipital plagiocephaly is a type of plagiocephaly. It is used to describe the shape of the skull which is a result of an early fusion of the lambdoid suture. The premature fusion may occur either on one side or both sides of the suture. Epidemiology It is one of the rarest craniosynostosis, a...
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Occipital triangle

The occipital triangle is one of the paired triangles in the posterior triangle of the neck. The triangles of the neck are surgically focussed, first described from early dissection-based anatomical studies which predated cross-sectional anatomical description based on imaging (see deep spaces o...
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Occipitotemporal suture

The occipitotemporal/occipitomastoid suture is the obliquely oriented articulation of the anterior border of the squamous occipital bone and the mastoid portion of the temporal bone. A mastoid foramen is occasionally located near or in it. The occipitotemporal suture and the parietotemporal sut...
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Ocular abductors

The ocular abductors are the extra-ocular muscles responsible for abduction of the globe: lateral rectus (primary function) superior oblique (tertiary function) inferior oblique (tertiary function)
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Ocular adductors

The ocular adductors are the extra-ocular muscles responsible of adduction of the globe: medial rectus (primary function) inferior rectus (tertiary function) superior rectus (tertiary function)
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Ocular depressors

The ocular depressors are the extra-ocular muscles responsible for depression of the globe: inferior rectus (primary function) superior oblique (secondary function)
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Ocular elevators

The ocular elevators are the extra-ocular muscles responsible for elevation of the globe: superior rectus (primary function) inferior oblique (secondary function)
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Ocular external rotators

The ocular external (lateral) rotators are the extra-ocular muscles responsible for external rotation (extorsion) of the globe: inferior oblique (primary function) inferior rectus (secondary function)
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Ocular internal rotators

The ocular internal (medial) rotators are the extra-ocular muscles responsible for internal rotation (intorsion) of the globe: superior oblique (primary function) superior rectus (secondary function)
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Ocular metastasis

Ocular metastases, also termed uveal metastases, account for over 80% of all ocular pathology, and need to be distinguished from extraocular metastasis, which are a quite different group of tumours. This article will discuss metastatic lesions affecting the orbits. For other intracranial metast...
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Ocular pathology

Ocular pathology covers a wide range of conditions and therefore represents the cause of a wide range of symptoms, signs and radiographic features. Ocular metastases account for over 80% of all ocular pathology. With regard to the remainder of ocular lesions, the primary differentiating factor ...
Article

Oculomotor nerve

The oculomotor nerve is the third of the cranial nerves and arises from the midbrain. It is responsible for the movements of four of the six extra-ocular muscles, the other two being innervated by the trochlear and abducens nerves. Gross anatomy Nucleus and cisternal portion The oculomotor nu...
Article

Oculomotor nerve palsy

An oculomotor nerve palsy results in weakness of the muscles supplied by the oculomotor nerve, namely the superior rectus, inferior rectus, medial rectus, inferior oblique, and levator palpebrae superioris muscles. This leads clinically to an eye that is "down and out". Pathology It has numero...
Article

Odontogenic myxoma

Odontogenic myxomas are rare tumours that involve the mandible or maxilla and account for 3-6% of odontogenic tumours 2. Epidemiology Typically seen in the 2nd to 3rd decades of life (slightly earlier than ameloblastomas). They are usually not painful. Pathology Arises from mesenchymal odont...
Article

Odontohypophosphatasia

Odontohypophosphatasia is the mildest form of hypophosphatasia that manifests as tooth dysplasia and/or early loss of deciduous or permanent teeth. Pathology As with all forms of hypophosphatasia, the underlying abnormality is a mutation in the ALPL gene that encodes for tissue non-specific al...
Article

Odontoma

Odontomas are one of the most common of mandibular lesions encountered and the most common odontogenic tumours of the mandible. They account for up to two-thirds of all such tumours; the next most common are ameloblastomas, making up the majority of the remaining one-third. Epidemiology They c...
Article

Oesophagus

The oesophagus is a muscular tube that conveys food and fluids from the pharynx to the stomach. Gross anatomy The oesophagus is 23-37 cm long with a diameter of 1-2 cm and is divided into three parts: cervical: continuous with the hypopharynx, commences at the lower border of cricoid cartilag...
Article

Olfactory fossa

The olfactory fossae, grooves or recesses of the cribriform plate are shallow depressions located within the ethmoid bone in the anterior cranial fossa that contains the olfactory bulb of the olfactory nerve. The floor is formed by the medial lamella of the cribriform plate, bordered laterally b...
Article

Olfactory neuroblastoma

Olfactory neuroblastomas, also known as esthesioneuroblastomas, are tumours arising from the basal layer of the olfactory epithelium in the superior recess of the nasal cavity. They usually present as a soft tissue mass in the superior olfactory recess involving the anterior and middle ethmoid ...
Article

Olfactory neuroblastoma (staging)

Olfactory neuroblastomas (or esthesioneuroblastomas) are most frequently staged using a system proposed by Kadish et al. in 1976 1. group a: limited to the nasal cavity group b: limited to the nasal cavity and paranasal sinuses group c: extends beyond the nasal cavity and paranasal sinuses: ...
Article

Olfactory neuroepithelioma

Olfactory neuroepithelioma (9523/3) is a rare tumour which mimics olfactory neuroblastomas (9500/3) in presentation and imaging features and is often used synonymously with the latter 1-2. Pathology Olfactory neuroepitheliomas differ from olfactory neuroblastomas in a number of ways 1: neura...
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Omega sign (disambiguation)

The omega sign can refer to a number of different anatomical structures or signs: omega sign (epiglottitis) omega sign (hand bump on the precentral gyrus)
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Omega sign of epiglottitis

The omega sign refers to the thickened aryepiglottic folds and epiglottis seen in epiglottitis, when the larynx is seen endoscopically or via laryngoscope, and not to the appearance on lateral plain films. CT would show the finding, but placing a child with epiglottitis supine to CT their neck i...

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