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 sagittal plane and ...
Eustachian tube dysfunction (ETD) is considered by many to be the underlying cause of chronic otomastoiditis, although both the exact pathogenesis and role of ETD in chronic middle ear infections is unclear.
Eustachian tube dysfunction is estimated to be present in ~1% of the adul...
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 (EAM) is variably used to refer to the canal or the porus acusticus externus (the round late...
External auditory canal atresia (EACA) is characterized by complete or incomplete bony atresia of the external auditory canal (EAC) and, especially when seen in the setting of an associated syndrome, a dysplastic auricle and an abnormal middle ear cavity.
The incidence is 1 in 10,...
External auditory canal cholesteatomas are uncommon locations for cholesteatomas, which are usually in the middle ear or petrous apex. When they occur lateral to the tympanic membrane, they are referred to as external auditory canal cholesteatomas.
The external acoustic canal i...
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 pectoral 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
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 eyelid covers the eye and is covered in front with loose skin and behind with adherent conjunctiva. The lower lid possesses very little mobility; lids are closed gently by palpebral fibers and forcefully by orbicularis oculi.
The eyelid comprises of a number of key features ...
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.
FIRES has received several names in the literature:
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...
The fissula ante fenestram (FAF), also known as the cochlear cleft, is a small connective tissue-filled cleft located where the tendon of the tensor tympani muscle turns laterally toward the malleus. It is situated immediately anterior to the oval window, and posterior to the cochleariform proce...
The fistula test is used when examining a patient with recurrent vertigo.
A finger is abruptly applied to the external meatus which causes a pulse of air-transmitted pressure. If nystagmus is induced in association with vertigo, it indicates bony destruction within the inner ear e.g. cholesteat...
Floating teeth is the description given to the appearances on imaging of teeth that appear to be floating as a result of alveolar bone destruction around their roots.
They are uncommonly encountered, with a wide differential diagnosis - albeit that the underlying cause ...
The floor of mouth is an oral cavity subsite and is a common location of oral cavity squamous cell carcinoma.
The floor of mouth is a U-shaped space which extends (and includes) from the oral cavity mucosa superiorly, and the mylohyoid muscle sling 2,3.
Florid cemento-osseous dysplasia is a subtype of cemento-osseous dysplasia. It is a rare condition presenting in the jaw refers to a group of fibro-osseous (cemental) exuberant lesions with multi-quadrant involvement.
There may be an increased female predilection and tends to be ...
Focal calvarial thinning can result from a number of causes. They include:
bilateral thinning of the parietal bones (normal variant) most common
mega cisterna magna
peripherally located tumors (e.g. oligodendroglioma)
Follicular thyroid adenoma is a commonly found benign neoplasm of the thyroid consisting of differentiated follicular cells. It cannot be differentiated from follicular carcinoma on cytologic, sonographic or clinical features alone 1.
Follicular thyroid adenoma is more commonly fo...
Follicular thyroid carcinoma (FTC) is the second most frequent malignancy of the thyroid gland after papillary cancer and accounts for ≈10-20% of all thyroid neoplasms.
It typically occurs in women and in an older age group than papillary (i.e. 40-60 years of age).
The foramen cecum represents a primitive tract between the anterior cranial fossa and the nasal space. It is located along the anterior cranial fossa, anterior to the cribriform plate of the ethmoid bone and posterior to the frontal bone, within the frontoethmoidal suture. It lies at a variable ...
Foramen cecum can refer to a number of different anatomical structures:
foramen cecum (tongue)
foramen cecum (anterior cranial fossa)
The foramen lacerum (plural: foramina lacera) is a triangular opening located in the middle cranial fossa formed by the continuation of the petrosphenoidal and petroclival fissures. Thus, it is a gap between bones, alternatively termed the sphenopetroclival synchondrosis, rather than a true for...
A mnemonic to remember foramen ovale contents is:
O: otic ganglion (inferior)
V: V3 cranial nerve (mandibular division of the trigeminal nerve)
A: accessory meningeal artery
L: lesser petrosal nerve
E: emissary veins
Foramen ovale (plural: foramina ovalia) is an oval shaped opening in the middle cranial fossa located at the posterior base of the greater wing of the sphenoid bone, lateral to the lingula. It transmits the mandibular division of the trigeminal nerve (CN V3), accessory meningeal artery, emissary...
The foramen rotundum (plural: foramina rotunda) is located in the middle cranial fossa, inferomedial to the superior orbital fissure at the base of greater wing of the sphenoid bone. Its medial border is formed by lateral wall of sphenoid sinus. It runs downwards and laterally in an oblique path...
The foramen singulare, also known as the singular foramen, is a small opening at the posteroinferior aspect of the fundus of the internal auditory canal (IAC) 2,3. It carries the singular or posterior ampullary nerve, a branch of the inferior vestibular nerve which carries afferent information f...
The foramen tympanicum (plural: foramina tympanica), also known as foramen of Huschke, is an anatomical variation in the external acoustic canal (EAC), where a bony defect connects the EAC to the temporomandibular joint (TMJ).
Various studies have reported on the occurrence of a f...
The foramen Vesalii (plural: foramina Vesalii), also known as the foramen of Vesalius, sphenoidal emissary foramen, foramen venosus or canaliculus sphenoidal, is a tiny variably present foramen in the greater wing of the sphenoid bone. It transmits a sphenoidal emissary vein linking the pterygoi...
The fossa of Rosenmüller, also known as the posterolateral pharyngeal recess, is the most common site of origin for nasopharyngeal carcinoma.
It is located superior and posterior to the torus tubarius (the posterior projection of the cartilaginous portion of the Eustachian tube) ...
Fourth branchial cleft cysts are very rare, and parallel the course of the recurrent laryngeal nerve. They are most commonly on the left side (80%) and usually form a sinus which extends from the apex of the piriform sinus, as do third branchial cleft sinuses, but passes inferiorly rather than s...
The fovea ethmoidalis is a portion of the ethmoid bone and represents its superior portion (part of the ethmoid roof) which is seen as a continuation of the superior orbital roof to the cribriform plate.
A foveola pharyngica recess is one of the variants of the inferior median clival canal, thought to represent a remnant of the notocord. It represents a blind ending recess in the anteroinferior surface (nasopharyngeal) surface of the clivus 1,2.
Frenulum (plural: frenula) is an anatomical term and refers to a small fold of soft tissue that checks the movement of an anatomical part.
frenulum (ileocecal valve)
frenulum (labia minora)
History and etymology
Frenulum derives from ...
Frey syndrome (also known as Baillarger syndrome, Dupuy syndrome and auriculotemporal syndrome) is a complication of parotid surgery. It clinically manifests as sweating and reddening in the region of the face supplied by the auriculotemporal nerve. The symptoms typically occur when tasting food...
The frontal bone is a skull bone that contributes to the cranial vault. It contributes to form part of the anterior cranial fossa.
The frontal bone has two portions:
vertical portion (squama): has external/internal surfaces
horizontal portion (orbital): has superior/inferior su...
Frontal bossing is a calvarial radiographic feature where the front of the skull appears protruding anteriorly. It is best appreciated on a sagittal or lateral image.
This feature can be seen in many conditions (in alphabetical order):
The frontal bullar cells are a subset of variably present frontal recess cells located above the ethmoid bulla.
They are nearly identical to suprabullar cells. The distinguishing features with the latter are that the frontal bullar cells are located above the frontal ostium and ext...
Frontal cells are anterior ethmoid air cells located along the anterior aspect of the frontal recess. They are a subset of frontal recess cells and are classified into four types according to Kuhn's classification.
They are seen on CT in 20-33% of patients 1.
functional endoscopic si...
The frontal infundibulum is a term that refers to the funnel-shaped inferior narrowing of the frontal sinus. Together with the frontal ostium and frontal recess, it forms the frontal sinus outflow tract.
Frontal intersinus septal cells, also known as interfrontal sinus septal cells, are a subtype of medial frontal recess cells.
The frontal intersinus septal cells lie within the intersinus septum between the frontal sinuses. They usually drain in the medial aspect of the frontal r...
The frontal nerve is the largest and main branch of the ophthalmic division of the trigeminal nerve. It divides off the ophthalmic division just before entering the orbit through the superior orbital fissure outside and superolateral to the tendinous ring, where it lies between the lacrimal nerv...
The frontal ostium is an opening of the frontal sinus below the frontal infundibulum that drains into the frontal recess. Together with the frontal infundibulum and recess, it forms the frontal sinus outflow tract.