Thickening of the insertion of the lateral pterygoid muscle can mimic an anterior displaced temporomandibular disc. When both thickening of the inferior belly insertion and an anteriorly displaced disc are present, as in temporomandibular joint dysfunction, the two structures parallel each other...
The doughnut sign can refer to a variety of different signs:
doughnut sign (bone scan)
doughnut sign (bowel)
crescent in a doughnut sign (bowel)
doughnut sign (chest)
doughnut sign (orbit)
The doughnut sign of optic nerve sheath meningioma refers to the appearance of this tumor on coronal CT/MRI. The meningioma forms a thick cuff of enhancing tumor around the central non-enhancing optic nerve, mimicking the appearance of a ring doughnut. It is the coronal equivalent of the tram-tr...
Down syndrome (or trisomy 21) is the most common trisomy and also the commonest chromosomal disorder. It is a major cause of intellectual disability, and also has numerous multisystem manifestations.
The approximate worldwide incidence is approximately 1 in 800 live births 15. The...
The duct of Rivinus connects the sublingual gland to the floor of the mouth.
Despite its name, it is not a single duct, but numerous small ducts all of which open into the floor of the mouth and are collectively termed the duct of Rivinus.
The largest of these little ductules is the major duct...
The ducts of the salivary glands allow the passage of salivary juice from the glands to the oral cavity:
parotid duct (Stenson duct): connects the parotid gland to the buccal mucosa, adjacent to maxillary second molar
submandibular duct (Wharton duct): connects the submandibular gland to the f...
A useful mnemonic to remember differential diagnoses associated with a dural tail sign is:
My Scary Dog Likes To Stand Guard
D: dural metastases
Dysphagia refers to subjective awareness of difficulty or obstruction during swallowing. It is a relatively common and increasingly prevalent clinical problem. Odynophagia is the term for painful swallowing.
Fluoroscopy is the mainstay of imaging assessment but manometry can help evaluate the e...
Eagle syndrome refers to symptomatic elongation of the styloid process or calcified stylohyoid ligament 1,2. It is often bilateral. In most cases, the cause is unknown; however, the condition is sometimes associated with disorders causing heterotopic calcification such as abnormal calcium/phosph...
The ear refers to the entire vestibulocochlear organ and is divided anatomically into:
Epstein-Barr virus-associated smooth muscle tumors (EBV-SMT) are rare and encountered in immunocompromised individuals.
These tumors are generally exceedingly rare, and only seen with any frequency in the setting of immunosuppression, particularly in HIV/AIDS patients, but also po...
Ectodermal dysplasia (ED) refers to a heterogeneous group of genetic disorders that cause abnormal ectoderm development. The effect is a non-progressive defect in the development of two or more tissues derived from embryonic ectoderm.
ED is rare with an estimated prevalence of 1:...
Ectopia lentis refers to subluxation or dislocation of the lens of the eye secondary to dysfunction or disruption of zonular fibers. It is most commonly due to trauma. The commonest atraumatic etiologies are Marfan syndrome and homocystinuria.
systemic and syndromic...
An ectopic thyroid gland is one which is located in a location other than the normal position anterior to the laryngeal cartilages.
Ectopic tissue refers to the gland located outside its normal anatomical position whereas accessory tissue refers to extra tissue located remote from ...
Edentulism (or edentulousness) means absence of dentition and can have a significant impact on a patient's quality of life in addition to the negative cosmetic effects.
When edentulism is used as a standalone term it usually means that all the teeth are absent, i.e. complete edentu...
Emissary veins (also known as the vena emissaria) are veins which pass through foramina in the skull to provide a venous communication between the dural venous sinuses and veins of the scalp or veins inferior to the skull base (cranial-cerebral anastomosis).
They are thin-walled and valveless. ...
The empty nose syndrome refers to a paradoxical sensation of nasal obstruction despite objectively patent nasal airways following inferior and/or middle turbinate resection.
The condition is rare, occuring in a minority of patients who have undergone prior turbinate resection.
Endolymph is one of the two types of cochlear fluids, the other being perilymph. It is located in the scala media of the cochlea.
It is secreted by the stria vascularis (also colloquially called the 'battery of the cochlea') on the outer wall of the scala media. It has a high level of potassium...
The endolymphatic duct is a small epithelial-lined channel, part of the membranous labyrinth that passes through the vestibular aqueduct in the bony labyrinth of the petrous temporal bone. It arises from the utricle and saccule via the utriculosaccule duct and drains endolymph. The distal end is...
Endolymphatic sac tumors are very rare, locally invasive tumors of endolymphatic sac. Early detection of these tumors is critical, because early surgical intervention may prevent further hearing loss. Endolymphatic sac tumors do not metastasize but are highly locally aggressive.
Endophthalmitis (plural: endophthalmitides) is a potentially sight-threatening condition that involves intraocular inflammation of any cause. It is distinguished from panophthalmitis in that it does not extend beyond the sclera. It is either infectious or non-infectious in etiology, but in clini...
There is a short list of causes for enlarged extraocular muscles. The differential can be narrowed by the clinical history, known systemic illness, pattern of specific muscles involved, the muscle morphology, as well as concurrent findings outside the muscles 3:
inflammatory, infectious, and de...
Enophthalmos refers to the posterior displacement of the globe in the orbit. It implies that the globe itself is normal and is caused by either one or a combination of 1:
structural alterations in the bony orbit
orbital fat atrophy
Specific causes include 2:
orbital blowout fract...
Epiglottic enlargement is often seen on lateral neck radiographs and it's accepted to confirm clinical suspicion of acute epiglottitis only on this finding 1. However, an enlarged epiglottitis has a wide range of differentials that should be considered.
The epiglottis is a single midline leaf-shaped fibrocartilaginous structure that forms part of the supraglottic larynx and defines the division of the hypopharynx from the larynx.
The epiglottis projects posterosuperiorly from its stem-like base, which is attached to the thyroid...
Epiglottitis, also known as supraglottitis, is a life-threatening condition caused by inflammation of the epiglottis and aryepiglottic folds 1, which can lead to acute airway obstruction.
The traditional age of presentation is in children of 3 to 6 years, although this has been c...
Epignathus is a term given to a very rare form of teratoid tumor that arises from the oropharyngeal region.
There may be a slight female predilection ref. The estimated incidence is ~ 1 in 35,000 to 200,000 births.
The tumor classically presents in utero or...
Epiphora (plural: epiphoras) represents excessive tearing of the eye and is a common clinical presentation to ophthalmological practice. It is most frequently due to an obstruction of the nasolacrimal drainage apparatus. Less commonly, overproduction of tears may be responsible.
Epistaxis (plural: epistaxes) is the medical term for a nosebleed, and is very common in clinical practice with a broad differential diagnosis. Anterior epistaxes mainly bleed from Kiesselbach's plexus and posterior epistaxes (5% of all epistaxis) from Woodruff's plexus.
The epitympanum, also known as the attic or epitympanic recess, is the most superior portion of the tympanic cavity. It is that portion of the tympanic cavity superior to the axial plane between the tip of the scutum and the tympanic segment of the facial nerve 1,3.
Posteriorly the epitympanum ...
Ethmocephaly refers to a rare type of midline cranio-facial anomaly that is characterized by the presence of extreme hypotelorism, arhinia and a midline proboscis.
holoprosencephaly 1,2: particularly alobar holoprosencephaly
The ethmoidal air cells, also known less commonly as the ethmoidal sinuses, form one of the four pairs of paranasal sinuses. They are located within the single, midline ethmoid bone.
location: between the orbit and the nasal cavity, within the ethmoid labyrinth of the ethmoid bone
The ethmoid bone is a single midline facial bone that separates the nasal cavity from the brain and is located at the roof of the nose and between the orbits. It is a cubical shape and is relatively lightweight because of its spongy construction. It contributes to the anterior cranial fossa.
The ethmoid bulla, also known as bulla ethmoidalis, is the largest and most consistent air cell of the anterior ethmoid air cells.
It is located posterior to the frontal recess and enclosed laterally by the lamina papyracea. It forms the roof of the middle meatus.
It can be clas...
The ethmoid infundibulum is a curved cleft of the ethmoid bone which leads into the anterior portion of the hiatus semilunaris. It is bordered medially by the uncinate process and laterally by the orbital plate of the ethmoid. The infundibulum is often continuous with the frontal recess into whi...
An ethmoid mucocele is a form of a paranasal sinus mucocele involving the ethmoid air cells. Depending on its anterior and/or posterior location, they can also include nasoethmoid and sphenoethmoid mucoceles. Ethmoid mucoceles are considered the second most commonest in location 2.
EU-TIRADS is a reporting system designed by the European Thyroid Association for ultrasound assessment of thyroid nodules and stratification of requirement for FNA and malignancy. This system was based on an established French system, with validated results 2,3.
This is a five stage system usin...
The Eustachian tube, also known as the pharyngotympanic tube or auditory tube, is the channel via which the tympanic cavity communicates with the nasopharynx.
It is ~36 mm in length and is directed downward, forward, and medially, forming an angle of about 45 degrees with the sag...
Eustachian tube dysfunction refers to the failure of the Eustachian tube to open or close properly. Therefore, it encompasses a spectrum from patulous to obstructive pathophysiology. Eustachian tube dysfunction predisposes to chronic otitis media.
Eustachian tube dysfunction is es...
The external auditory canal (EAC) or external auditory meatus (EAM) extends from the lateral porus acusticus externus medially to the tympanic membrane.
As the term external auditory meatus is variably used to refer to the canal itself or the porus acusticus externus (the round lat...
External auditory canal atresia, also known as congenital aural atresia, is characterized by complete or incomplete bony atresia of the external auditory canal (EAC), often in association with a dysplastic auricle and an abnormal middle ear cavity or ossicles.
The incidence is 1 i...
External auditory canal cholesteatomas (EACCs) are rare, the external auditory canal is an unusual site for cholesteatoma, which are usually in the middle ear or petrous apex.
The external acoustic canal is a rare location for a cholesteatoma with an estimated incidence of around...
Exostosis of the external auditory canal (also known as surfer's ear), is a benign bony overgrowth of the bony external auditory canal brought about by exposure to cold wind and water combined.
broad-based or more focal circumferential bony overgrowth of the osseous exter...
External auditory canal osteomas are rare focal pedunculated bony overgrowths of the osseous external auditory canal.
solitary pedunculated bony overgrowth of the external auditory canal usually at the bony cartilaginous junction
large lesions may be associat...
The external carotid artery (ECA) is one of the two terminal branches of the common carotid artery. The other terminal branch is the internal carotid (ICA), which is somewhat larger than the ECA.
origin: bifurcation of the common carotid artery
course: under the submandibular gland an...
The external ear (or outer ear) comprises the auricle (or pinna), the external auditory meatus, and the tympanic membrane ("eardrum"). The auricle concentrates and amplifies sound waves and funnels them through the outer acoustic pore into the external auditory meatus to the tympanic membrane.
The external jugular vein (EJV) drains the head, face and part of the scapular region.
The posterior division of the retromandibular vein and posterior auricular vein unite within the parotid gland to form the external jugular vein, at the angle of the mandible.
A mnemonic to remember external jugular vein (formed by the retromandibular and posterior auricular veins) tributaries is:
P: posterior external jugular vein
A: anterior jugular vein
S: suprascapular vein
T: transverse cervical vein
The external laryngeal nerve is one of the two branches of the superior laryngeal nerve and supplies the cricothyroid muscle.
origin: arises as the smaller of the two branches of the superior laryngeal nerve at the level of the greater cornu of the hyoid bone
The extraconal orbital compartment or extraconal space is the space within the orbit outside the musculofascial cone. The base of which is anterior and is formed by the orbital septum that surrounds the equator of the globe. The external sides are formed by the bones of the orbit and their perio...
Extraconal orbital lesions include lesions which arise from structures within the extraconal orbital space and those extending from adjacent structures into the orbits.
dermoid cyst: most common lesion in pediatrics
lacrimial gland lesions
Extracorporeal shock wave lithotripsy (ESWL) is a common non-invasive treatment for urolithiasis, and less commonly for pancreatic or salivary ductal stones 4. It is less successful in obese patients and with stones >2 cm. Children respond equally well or better to ESWL than adults 5.
Extracranial meningiomas, also known as primary extradural meningiomas are a form of ectopic meningioma, are a rare location-specific type of meningioma that arise outside the dural covering of the brain and spinal cord. They are essentially extracranial tumors, most often occurring in the head ...
Extramedullary plasmacytoma, also known as extraosseous plasmacytoma, are the less common form of solitary plasmacytoma, manifesting as isolated plasma cell tumors located at a non-osseous site. In contrast to multiple myeloma (MM), solitary plasmacytoma have little or no systemic bone marrow in...
An extramural air cell is one that is not contained within its named parent bone. So, the infraorbital ethmoidal air cells that lie within the maxilla rather than the ethmoidal bone are an example of extramural air cells.
A mnemonic to remember the order in which extraocular muscles are involved in thyroid-associated orbitopathy (TAO) is:
I: inferior rectus
M: medial rectus
S: superior rectus
L: lateral rectus
O: obliques muscles (superior oblique and inferior oblique)
There is some deba...
A mnemonic to remember the nerve supply to the extraocular muscles:
LR6SO4O3 (mock 'chemical formula')
The letters represent the extraocular muscles and numbers represent their respective cranial nerve supply:
LR6: lateral rectus, innervated by the 6th (abducens) nerve
The extraocular muscles are the six muscles that insert onto the eye and hence control eye movements:
superior rectus: elevation
superior oblique: intorsion
medial rectus: adduction
lateral rectus: abduction
inferior oblique: extorsion
inferior rectus: depression
The extrinsic muscles of the tongue are a group of 4 muscles of the tongue. They all arise outside the tongue, which is in comparison to the intrinsic muscles of the tongue which are entirely within the tongue with no external attachments. They act to alter the position of the tongue where as th...
The extrinsic muscles of the tongue can be remembered with the following mnemonic:
Paris St Germain's Hour
Paris St. Germain's Hour
Exudative retinitis, also known as retinal telangiectasis or Coats disease, is a rare congenital disease affecting the eyes and is a cause of leukocoria.
It occurs predominantly in young males, with the onset of symptoms generally appearing in the first decade of life with a peak ...
The eyebrows may refer either to:
horizontal ridge where the forehead meets the superior eyelid consisting of the five layers of the scalp, i.e. skin, subcutaneous soft tissue, intertwined fibers of the orbicularis oculi and occipitofrontalis muscles, areolar layer and lastly the pericranium of...
The eyelids cover the eyes, with an upper and lower eyelid on each side, and are covered in front with loose skin and behind with adherent conjunctiva. The lower lids possess very little mobility; lids are closed gently by levator palpebrae superioris muscle fibers and forcefully by the orbicula...
Eye movements are a complex set of movements of the globe that are performed by the extraocular muscles that are grouped by the muscles that perform particular movements:
ocular internal rotators
ocular external rotators
Facial angiofibroma, also known as fibrous papule, is a fairly common skin lesion seen in males and females after puberty.
They represents a focal vascular and collagen growth.
This lesion is usually solitary and located on the nose skin, measuring 1-5 mm.
There is no hereditary p...
The facial artery is one of the branches of the external carotid artery and supplies blood to the structures of the face.
origin: branch of the external carotid artery a little above the level of the lingual artery, in the carotid triangle of the neck
course: passes deep to the poster...
The facial bones comprise a set of bones that make up the face:
inferior nasal concha
zygoma (zygomatic bone)
A suture is formed where two or more of the bones ar...
The acanthioparietal or reverse water's view modified Water's view used in trauma. It can be used to assess for facial fractures, as well as for acute sinusitis. Skull radiographs, in general, are rapidly becoming obsolete, being replaced by much more sensitive CT scans.
The facial-cavernous anastomoses are the communications of the facial and deep facial veins with the cavernous sinus.
At the medial canthus of the eye there is a communication with the ophthalmic veins, which drain into the cavernous sinus. Blood from the frontal scalp normally f...
Facial clefts comprise a wide spectrum of pathologies that result from failure of fusion in the facial region during the embryonic/early fetal period. The result is a gap in the fetal face. These clefts can affect the lip, philtrum, alveolus, and hard and soft palate to varying degrees.
Facial fractures are commonly caused by blunt or penetrating trauma at moderate or high levels of force. Such injuries may be sustained during a fall, physical assault, motor vehicle collision, or gunshot wound. The facial bones are thin and relatively fragile making them susceptible to injury.
The facial muscles (also known as the muscles of facial expression or mimetic muscles) enable facial expression and serve as sphincters and dilators of the orifices of the face. These muscles differ from those of other regions in the body as there is no fascia deep to the skin of the face; many ...
The facial nerve is one of the key cranial nerves with a complex and broad range of functions.
Although at first glance it is the motor nerve of facial expression which begins as a trunk and emerges from the parotid gland as five branches (see facial nerve branches mnemonic), it has taste and p...
There are many mnemonics to recall the branches of the facial nerve (superior to inferior) as they exit the anterior border of the parotid gland. Examples include:
Tall Zulus Bear Many Children
Two Zebras Bit My Coccyx
Ten Zebras Buggered My Car
To Zanzibar By Motor Car
Two Zombies Buggered...
Helpful mnemonics for remembering the segments of the facial nerve include:
I Love Going To Makeover Parties 1
I Love Grinning, Then Making Pouts
both grinning and pouting are performed by muscles which are innervated by the facial nerve
I Must Learn To Make (facial) Expressions
Facial palsy refers to the neurological syndrome of facial paralysis. It can result from a broad range of physiological insults to the facial nerve or its central nervous system origins. The most common causes of this is Bell palsy.
While facial palsy refers to the clinical presen...
The facial recess of the petrous temporal bone is a small recess in the posterior wall of the mesotympanum lateral to the pyramidal eminence and stapedius muscle origin. The upper mastoid portion of the facial nerve runs immediately posterior to it, giving it its name. Medial to the pyramidal em...
The facial vein (previously known as the anterior facial vein) is the continuation of the angular vein and joins the anterior branch of the retromandibular vein to form the common facial vein 1-3.
At the level of the lower margin of the orbit, the angular vein becomes the facial ...
Factitious hyperthyroidism or thyrotoxicosis factitia refers to precipitation of thyrotoxicosis due to exogenous ingestion of thyroid hormone (e.g. levothyroxine). It has been rarely associated with myocardial ischemia 2.
The hypervascularity which is seen wit...
The falciform crest, also known as the crista falciformis, is a horizontal ridge that divides the lateral portion of the internal acoustic meatus (IAM) into superior and inferior portions.
The facial nerve (VII) and superior vestibular nerve (SVN) travel in the superior portion of the...
The Fallopian canal or facial nerve canal refers to a bony canal through which the facial nerve traverses the petrous temporal bone, from the internal acoustic meatus to the stylomastoid foramen. There are three segments of the canal, corresponding to the segments of the facial nerve they contai...
The eponym Fallopian may refer to:
Fallopian canal (facial nerve canal)
Fallopian tube (uterine duct)
Fallopian ligament (inguinal ligament)
History and etymology
It is named after Gabriele Falloppio (also known by his Latin name Fallopius), Italian anatomist (1523-1562).
The false vocal cords (vestibular folds, ventricular folds, ventricular bands) are paired shelf-like structures located within the supraglottic larynx that divide the vestibule above from the ventricle below.
The vestibular ligaments are the ligamentous component of the false vo...
Familial medullary thyroid carcinoma (FMTC) is a genetic disorder closely related multiple endocrine neoplasia type IIa (MEN2a) and multiple endocrine neoplasia type IIa (MEN2b). It is characterized by the development of medullary thyroid cancer.
FMTC is the result of mutations in the RET (re...
Fatty nodal metaplasia in the neck occurs as a result of chronic inflammation or radiotherapy 3. The normal fatty nodal hilum enlarges, such that the lymph node appears cystic. However, its center is of fatty density. There is no surrounding stranding, and the node otherwise looks normal.
Faulty fetal packing, also known as congenital vault depression, is a congenital concave depression of the skull in a newborn.
Occurs in 1 in 10,000 births 1.
This appearance is due to external compression on the skull from 1,2:
fetal limb or twin
Febrile infection-related epilepsy syndrome (FIRES) is a severe postinfectious neurological disorder that presents with status epilepticus in a previously normal child (or less commonly adult) after a febrile illness.
In these cases, pleocytosis or elevated protein levels on CSF has been report...
The Fédération Dentaire Internationale or FDI World Dental Federation notation system is a commonly used system for the numbering and naming of teeth. The system uses a two number system for the location and naming of each tooth.
The jaw is divided into four quadrants between t...
A fetal goiter is an enlargement of the thyroid gland in utero. It can occur with either hyper- or hypothyroidism (and in isolated cases of euthyroidism 8).
The mechanism depends on whether the underlying cause is hyper- or hypothyroidism.
maternal Graves disease with...
There are four sutures in the fetal skull vault of obstetric importance:
1. frontal suture: it lies between the two frontal bones
2. sagittal suture: it lies between the two parietal bones
3. coronal suture: it lies between the parietal and frontal bones
4. lambdoid suture: it lies between t...
Fibromuscular dysplasia (FMD) is a heterogeneous group of vascular lesions characterized by an idiopathic, non-inflammatory, and non-atherosclerotic angiopathy of small and medium-sized arteries.
The prevalence is unknown 7. It is most common in young women with a female to male r...
First branchial cleft cysts are a type of branchial cleft anomaly. They are uncommon and represent only ~7% of all branchial cleft cysts.
They are usually diagnosed in middle-aged women 3-4.
Their presentation can in the form of 3:
asymptomatic, e.g. inci...
First branchial cleft fistulae are rare congenital malformations arising from the branchial apparatus during embryogenesis 1-5. They are often in close relation to the parotid gland, facial nerve, external auditory canal and the anterior neck near the angle of the mandible 1,2,5. Diagnosis can b...