The fissula ante fenestram (plural: fissula ante fenestras) is a small connective tissue-filled cleft in the otic capsule of the temporal bone, not typically visible on CT. The area around the fissula ante fenestram is the usual origin of fenestral otosclerosis.
The fissula ante ...
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 or singular canal, is a thin channel within the petrous temporal bone that carries the singular nerve from the internal auditory canal. It is a normal structure that may be mistaken for a temporal bone fracture (i.e., it is a pseudofractu...
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) ...
The fossula post fenestram is a saclike evagination of connective tissue within the otic capsule just posterior to the oval window. The region around the fossula is one of the less common areas of predilection for otosclerosis.
It arises from the vestibule and is thus one of three extensions of...
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 su...
The fovea ethmoidalis is an extension of the orbital plate of the frontal bone and forms the lateral part of the ethmoid roof.
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 foo...
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...
A frontal mucocele is a paranasal sinus mucocele in a frontal sinus and is the most common location of all the paranasal sinus mucoceles1.
Mucocoeles in the frontal sinus may be asymptomatic with insidious onset or present with headaches 2 and facial pain. Forehead (supra...
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.
The frontal recess is an opening in the inferior aspect of the frontal sinuses that allows drainage of the sinus.
The frontal recess is also known as the nasofrontal duct. However, since it does not have bony walls of its own, it is more appropriately referred to as a recess rather...
Frontal recess cells are anterior ethmoid air cells that pneumatize the frontal recess. Their clinical relevance lies in their potential to obstruct the frontal recess outflow. As such, they should be reported by the radiologist preoperatively, especially in cases of frontal sinusitis.
The frontal sinuses are the paranasal sinuses within the frontal bone. They are lined with mucosa and are most often two in number.
location: anterior frontal bones on either side of the midline behind the brow ridges
blood supply: supratrochlear, supraorbital and anterior ethmoidal a...
Frontal sinus fractures are facial fractures that involve the frontal sinus, either in isolation or more commonly as part of more complex facial fractures. They can result in cosmetic deformity, functional impairment, CSF leak, and/or intracranial infection (e.g. meningitis).
Frontoethmoidal encephaloceles are second only to occipital encephaloceles in terms of frequency, representing approximately 15% of all encephaloceles. They represent meninges or brain tissue herniating through a cranial defect in the anterior cranial fossa and typically result in facial deformi...
A frontoethmoidal mucocele is a paranasal sinus cyst-like lesion (mucocele) lined with respiratory mucosa. The frontal and frontoethmoidal regions are reportedly the most common locations for paranasal sinus mucocele formation 1. They are thought to arise from obstruction of normal sinus drainag...
The frontoethmoidal suture is a short cranial suture located in the anterior cranial fossa, between the orbital process of frontal and orbital plate of ethmoid bones. It forms part of the medial wall of the orbit.
The anterior and posterior ethmoidal foramina are seen just superior to it, throu...
The frontolacimal suture is the cranial suture between the frontal and lacrimal bones.
The frontomaxillary suture is the suture where the nasal process of frontal bone joins the frontal process of the maxilla.
Frontonasal dysplasia, also known as median cleft face syndrome, is a rare disorder characterized by midline defects involving the face, head, and central nervous system.
Frontonasal dysplasia is considered to be a very rare condition, with approximately 100 cases having been repo...
The frontonasal suture is the cranial suture between the frontal bone and the two nasal bones. This suture meets the internasal suture at the nasion.
The frontozygomatic suture, also known as the zygomaticofrontal suture, is between the frontal process of the zygomatic bone and the zygomatic process of the frontal bone.
Functional endoscopic sinus surgery (FESS) is a type of paranasal sinus surgery performed intranasally using a rigid endoscope. Its primary objective is to restore physiological ventilation and mucociliary transport 1.
Paranasal sinus imaging is crucial in preoperative planning and is also incr...
A mnemonic to remember the potential anatomic variants to report on pre-functional endoscopic sinus surgery studies is 1:
C: cribriform plate
L: lamina papyracea
O: Onodi cell
S: sphenoid sinus pneumatization
E: ethmoidal artery (anterior)
ostiomeatal complex nar...
Fungal sinusitis is a collective term referring to a number of entities, which can be divided into two groups, depending on the presence of fungal hyphae within or beyond the mucosa 1:
non-invasive: hyphae do not invade the mucosa
allergic fungal sinusitis
sinus fungal mycetoma
The galea aponeurotica (also called the galeal or epicranial aponeurosis or the aponeurosis epicranialis) is a tough fibrous sheet of connective tissue that extends over the cranium, forming the middle (third) layer of the scalp.
Gardner fibromas are benign fibrous plaque-like soft tissue masses formed by a haphazard arrangement of collagen fibers.
An acceptable alternative term for Gardner fibroma is Gardner associated fibroma, the term desmoid precursor lesion is now discouraged 1.
Garrington sign is thickening of the periodontal ligament/membrane space of involved teeth in the setting of gnathic osteosarcoma. Symmetrical widening of the space can be seen early in the disease process due to infiltration of tumor cells.
The abbreviation GCA can refer to:
giant cell arteritis
global cortical atrophy scale
A gene expression classifier (GEC) test is a developing technology in the analysis of indeterminate thyroid nodules, using cells from a fine needle aspiration. The most common commercially available GEC in the United States is known as AFIRMA.
The test is designed to use molecular markers to he...
The genioglossus muscle is a fan-shaped extrinsic muscle of the tongue which makes up the bulk of the tongue.
origin: superior mental spine of the symphysis menti (posterior surface of midline mandible)
insertion: entire tongue mass and body of the hyoid bone
nerve supply: hypoglossa...
The geniohyoid muscle is one of the suprahyoid muscles of the neck that is innervated by the ventral ramus of C1. Geniohyoid draws the hyoid bone up and forward during mastication and assists the opening of the mandible.
origin: inferior mental spine of the mandible also known as the g...
Genioplasty or in more simple terms chin augmentation refers to a surgical procedure performed to improve facial balance and/or rejuvenate the lower facial third - mandible. An osseous genioplasty refers to surgery which is performed by creating an osteotomy and then mobilizing an inferior segme...
A geographic skull is a radiographic appearance which is seen in eosinophilic granuloma (EG) and characterized by destructive lytic bone lesions, the edges of which may be bevelled, scalloped or confluent.
A ghost image is a commonly observed artifact in an orthopantomogram whereby a dense, often metallic object is located between the source of x-ray and the focal center, resulting in a duplicate 'ghost' image at the contralateral aspect of the image.
Real image vs ghost image
In panoramic imag...
Gillespie syndrome is a rare genetic condition presenting as a mydriasis, secondary to an omnipresent partial aniridia. The abnormal iris is bilateral, with a highly-specific scalloped inner margin, due to hypoplasia of the central constrictor pupillae fibers. Associated features include an unch...
Giraffe pattern (also known as the pseudonodular appearance) is a distinctive ultrasound appearance characteristic of Hashimoto thyroiditis. Bonavita originally described a thyroid gland with multiple echogenic nodules, separated from one another by bands of hypoechogenicity, reminiscent of a gi...
The glabella is the smooth midline bony prominence between the supraciliary arches of the frontal bone, representing the most anterior part of the forehead when standing erect and looking straight ahead. The metopic suture traverses the glabella, between the two frontal bones. Just below it is t...
Globe rupture is an ophthalmologic emergency. A ruptured globe or an open-globe injury must be assessed in any patient who has suffered orbital trauma because open-globe injuries are a major cause of blindness.
In blunt trauma, ruptures are most common at the insertions of the intraocular muscl...
Globus pharyngeus is the subjective feeling of a lump in the throat which can have a variety of causes, it is not a diagnosis in its own right. In modern practice globus is often evaluated by flexible nasoendoscopy in the first instance since many patients present to otorhinolaryngology services...
Glomus jugulare paraganglioma is a paraganglioma of the head and neck that is confined to the jugular fossa. While it is a rare tumor, it is the most common of the jugular fossa tumors.
The relative prevalence of glomus jugulare with respect to other head and neck paraganglioma va...
Glomus jugulotympanicum paraganglioma is a glomus jugulare paraganglioma that has spread superiorly to involve the middle ear cavity. The term can also be used clinically when a suspected glomus tympanicum paraganglioma involves the hypotympanum as its inferior extent cannot be established clini...
Glomus tympanicum paragangliomas (chemodectomas) are the most common middle ear tumor.
There is a female predominance (M: F = 1:3); presentation is most common when patients are more than 40 years old 1,2.
May be incidental but symptomatic masses produce ...
Glomus vagale tumors are paragangliomas that occur along the path of the vagus nerve (CN X). They are a subset of extra-adrenal neuroendocrine tumors that are derived from the nonchromaffin paraganglion cells.
Typically presents as a painless mass behind the carotid arte...
The glossopharyngeal nerve is the ninth (IX) of the twelve pairs of cranial nerves. It exits the brainstem out from the sides of the upper medulla, just rostral to the vagus nerve and has sensory, motor, and autonomic components.
There are four cranial nerve nuclei in the...
Glossopharyngeal neuralgia is due to irritation of the glossopharyngeal nerve and presents with repeated episodes of severe pain in the tongue, throat, ear, and tonsils, which can last from a few seconds to a few minutes. It is far less common than trigeminal neuralgia.
The glottis is an anatomic subsite of the larynx, between the supraglottis and subglottis.
The glottic larynx includes the true vocal cords, where they come together at the anterior commissure, and where they meet the laryngeal cartilages at the interarytenoid region or posterio...
Goiter (rarely thyromegaly) refers to enlargement of the thyroid gland. It can occur from multiple conditions. Clearly the absence of thyroid enlargement does not preclude significant thyroid pathology.
The definition of a goiter depends on age and sex; below are the upper limits of normal for ...
Goldenhar syndrome, also known as oculo-auriculo-vertebral spectrum (OAVS), Goldenhar-Gorlin syndrome or facio-auriculo-vertebral dysplasia, is a complex congenital anomaly characterized by abnormalities of the ears, eyes and vertebrae.
The estimated incidence is at 1 in 3000-5000...
Gorlin-Goltz syndrome (also known as the basal cell nevus syndrome, nevoid basal cell carcinoma syndrome, or just Gorlin syndrome) is a rare phakomatosis characterized by multiple odontogenic keratocysts (OKC), multiple basal cell carcinomas (BCC) and other abnormalities.
Gradenigo syndrome consists of the triad of:
abducens nerve palsy, secondary to involvement of the nerve as it passes through Dorello canal
retro-orbital pain, or pain in the cutaneous distribution of the frontal and maxillary divisions of the trigeminal nerve, due to extensi...
Granular cell tumors (GrCTs) are uncommon soft tissue tumors with the vast majority being benign (approximately 0.5-2.0% have been reported as malignant).
They have been reported in all organ systems, but most prominently are found in these sites 2,5:
breast (granular cell tumor of...
Ophthalmologic manifestations of granulomatosis with polyangiitis (GPA) is not uncommon and can occur in either the classic or limited form of the disease.
For a general discussion of the condition, please refer to the main article on granulomatosis with polyangiitis (GPA). For other organ-spec...
The upper respiratory tract manifestations of granulomatosis with polyangiitis (GPA) are common and affect most patients.
For a general discussion of the condition, please refer to the main article on granulomatosis with polyangiitis (GPA). For other organ-specific radiographic features, pleas...
Granulomatous invasive fungal sinusitis, sometimes termed granulomatous invasive fungal rhinosinusitis, is a form of invasive fungal sinusitis. Reports describing the imaging findings have been uncommon 1.
It is rare and been mainly reported in Sudan, India, Pakistan and sometimes...
Graves disease (also known as Basedow disease in mainland Europe 9) is an autoimmune thyroid disease and is the most common cause of thyrotoxicosis (up to 85%).
There is a strong female predilection with an F:M ratio of at least 5:1. It typically presents in middle age.
The greater auricular nerve is a cutaneous branch of the cervical plexus that innervates the skin of the auricle as well as skin over the parotid gland and mastoid process. The greater auricular nerve also supplies branches that innervate the deep layer of the parotid fascia.
The greater (descending) palatine artery is a branch of the third part of the maxillary artery which passes through the greater palatine foramen to supply most of the hard palate.
After branching off from the third (pterygopalatine) part of the maxillary artery, the greater palat...
The greater occipital nerve is a cutaneous nerve, the thickest in the body, that innervates the skin from the upper neck, over the occiput, up to the vertex of the scalp 1-3.
The greater occipital nerve has also been known in the past - confusingly - as the nerve of Arnold. But as...
The greater palatine nerve, also known as the anterior palatine nerve, is a branch of the maxillary division of the trigeminal nerve and contributes to the pterygopalatine ganglion.
The greater palatine nerve divides off the maxillary division just after emerging from the foramen...
The greater wing or ali-sphenoid of the sphenoid bone is a process which projects from either side of the lower part of the sphenoid body, at a common junction with the pterygoid process 1. It is a paired structure, which curves upward, backward and laterally from each side of the sphenoid body,...
The Griesinger sign refers to edema of the postauricular soft tissues overlying the mastoid process as a result of thrombosis of the mastoid emissary vein. It is a complication of acute otomastoiditis and may be associated with dural sinus occlusive disease (DSOD). It is said to be a pathognomon...
A guardsman fracture, also referred to as parade ground fracture, is one of the common forms of mandibular fracture which is caused by a fall on the midpoint of the chin resulting in fracture of the symphysis as well as both condyles.
It is usually seen in epileptics, elderly patients and occas...
The Guttman test is a clinical test relating to the function of the larynx.
In normal subjects, frontal pressure on the thyroid cartilage lowers the tone of voice produced and lateral pressure produces a higher tone of voice. The opposite is true with paralysis of the cricothyroid muscle.
Hemotympanum is the presence of blood in the middle ear cavity. It is usually secondary to trauma.
Typically on otoscopy a bulging red to purple to dark blue colored tympanic membrane is visible, color varying with age of the hemorrhage.
The hemorrhage has us...
Halitosis, also known as fetor oris, refers to the symptom of foul oral odor, commonly termed "bad breath". This may be a complaint in the context of dental services.
It is thought to be caused by the presence of volatile sulfur compounds that are produced by bacteria. The ...
Haller cells, also known as infraorbital ethmoidal air cells, are ethmoid air cells located lateral to the maxillo-ethmoidal suture along the inferomedial orbital floor.
They are present in ~20% (range 2-45%) of patients, depending on their exact definition 1-3.
Hamburger thyrotoxicosis refers to ingestion of thyroid hormone from contaminated meat. It is a very rare cause of thyrotoxicosis.
It is most commonly due to the practice of "gullet trimming" whereby muscles from the larynx of the slaughtered animal are ground into other cuts of meat...
Hanging and strangulation are injuries involving constricting pressure applied to the neck. The vast majority are sustained as a result of attempted suicide.
In America, hangings are the second most common form of suicide after firearm use. In other parts of the world due to the r...
The hard palate is the anterior horizontal bony part of the palate that forms the roof of the oral cavity and floor of the nasal cavity. Most of the hard palate is formed by the palatine processes of the maxillae, the horizontal plates of the palatine bones complete it posteriorly. On its inferi...
The harlequin eye deformity is characterized by elevation of the superolateral corner of the orbit. It may be seen in unilateral (plagiocephaly) or bilateral (brachycephaly) coronal suture synostosis.
History and etymology
The term harlequin eye derives from the appearance of the eyes on a har...