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.
1,739 results found
Article
Fissula ante fenestram
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.
Gross anatomy
The fissula ante ...
Article
Fistula test
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...
Article
Floating teeth
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.
Differential diagnosis
They are uncommonly encountered, with a wide differential diagnosis - albeit that the underlying cause ...
Article
Floor of mouth
The floor of mouth is an oral cavity subsite and is a common location of oral cavity squamous cell carcinoma.
Gross anatomy
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.
Boundaries
superiorly:...
Article
Florid cemento-osseous dysplasia
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.
Epidemiology
There may be an increased female predilection and tends to be ...
Article
Focal calvarial thinning
Focal calvarial thinning can result from a number of causes. They include:
bilateral thinning of the parietal bones (normal variant) most common
arachnoid cyst
mega cisterna magna
peripherally located tumors (e.g. oligodendroglioma)
See also
calvarial thinning
calvarial thickening
Article
Follicular thyroid adenoma
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.
Epidemiology
Follicular thyroid adenoma is more commonly fo...
Article
Follicular thyroid cancer
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.
Epidemiology
It typically occurs in women and in an older age group than papillary (i.e. 40-60 years of age).
Pathology
Unl...
Article
Foramen cecum
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 ...
Article
Foramen cecum (disambiguation)
Foramen cecum can refer to a number of different anatomical structures:
foramen cecum (tongue)
foramen cecum (anterior cranial fossa)
Article
Foramen lacerum
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...
Article
Foramen ovale contents (mnemonic)
A mnemonic to remember foramen ovale contents is:
OVALE
Mnemonic
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
Article
Foramen ovale (skull)
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...
Article
Foramen rotundum
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...
Article
Foramen singulare
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...
Article
Foramen tympanicum
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).
Epidemiology
Various studies have reported on the occurrence of a f...
Article
Foramen Vesalii
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...
Article
Fossa of Rosenmüller
The fossa of Rosenmüller, also known as the posterolateral pharyngeal recess, is the most common site of origin for nasopharyngeal carcinoma.
Gross anatomy
It is located superior and posterior to the torus tubarius (the posterior projection of the cartilaginous portion of the Eustachian tube) ...
Article
Fossula post fenestram
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...
Article
Fourth branchial cleft cyst
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...
Article
Fovea ethmoidalis
The fovea ethmoidalis is an extension of the orbital plate of the frontal bone and forms the lateral part of the ethmoid roof.
Article
Frenulum (disambiguation)
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 (clitoris)
frenulum (ileocecal valve)
frenulum (labia minora)
frenulum (penis)
frenulum (tongue)
History and etymology
Frenulum derives from ...
Article
Frey syndrome
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...
Article
Frontal bone
The frontal bone is a skull bone that contributes to the cranial vault. It contributes to form part of the anterior cranial fossa.
Gross anatomy
The frontal bone has two portions:
vertical portion (squama): has external/internal surfaces
horizontal portion (orbital): has superior/inferior su...
Article
Frontal bossing
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.
Pathology
This feature can be seen in many conditions (in alphabetical order):
18q syndrome
acromegaly
achondroplasia
ß-tha...
Article
Frontal bullar cells
The frontal bullar cells are a subset of variably present frontal recess cells located above the ethmoid bulla.
Terminology
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...
Article
Frontal cells
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.
See also
functional endoscopic si...
Article
Frontal infundibulum
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.
Article
Frontal intersinus septal cells
Frontal intersinus septal cells, also known as interfrontal sinus septal cells, are a subtype of medial frontal recess cells.
Gross anatomy
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...
Article
Frontal mucocele
A frontal mucocele is a paranasal sinus mucocele in a frontal sinus and is the most common location of all the paranasal sinus mucoceles1.
Clinical presentation
Mucocoeles in the frontal sinus may be asymptomatic with insidious onset or present with headaches 2 and facial pain. Forehead (supra...
Article
Frontal nerve
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...
Article
Frontal ostium
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.
Article
Frontal recess
The frontal recess is an opening in the inferior aspect of the frontal sinuses that allows drainage of the sinus.
Terminology
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...
Article
Frontal recess cells
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.
Named fr...
Article
Frontal sinus
The frontal sinuses are the paranasal sinuses within the frontal bone. They are lined with mucosa and are most often two in number.
Summary
location: anterior frontal bones on either side of the midline behind the brow ridges
blood supply: supratrochlear, supraorbital and anterior ethmoidal a...
Article
Frontal sinus fracture
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).
Epidemiology
Fron...
Article
Frontoethmoidal encephalocele
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...
Article
Frontoethmoidal mucocele
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...
Article
Frontoethmoidal suture
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...
Article
Frontolacrimal suture
The frontolacimal suture is the cranial suture between the frontal and lacrimal bones.
Article
Frontomaxillary suture
The frontomaxillary suture is the suture where the nasal process of frontal bone joins the frontal process of the maxilla.
Article
Frontonasal dysplasia
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.
Epidemiology
Frontonasal dysplasia is considered to be a very rare condition, with approximately 100 cases having been repo...
Article
Frontonasal suture
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.
Article
Frontozygomatic suture
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.
Article
Functional endoscopic sinus surgery
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...
Article
Functional endoscopic sinus surgery preoperative variants (mnemonic)
A mnemonic to remember the potential anatomic variants to report on pre-functional endoscopic sinus surgery studies is 1:
CLOSE
Mnemonic
C: cribriform plate
L: lamina papyracea
O: Onodi cell
S: sphenoid sinus pneumatization
E: ethmoidal artery (anterior)
See also
ostiomeatal complex nar...
Article
Fungal sinusitis
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
invasive: hyp...
Article
Galea aponeurotica
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.
Gross anatomy
Attachments
anteriorly: frontalis
posteriorly
o...
Article
Gardner fibroma
Gardner fibromas are benign fibrous plaque-like soft tissue masses formed by a haphazard arrangement of collagen fibers.
Terminology
An acceptable alternative term for Gardner fibroma is Gardner associated fibroma, the term desmoid precursor lesion is now discouraged 1.
Epidemiology
Gardner ...
Article
Garrington sign (teeth)
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.
Article
GCA (disambiguation)
The abbreviation GCA can refer to:
giant cell arteritis
global cortical atrophy scale
Article
Gene expression classifier
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...
Article
Genioglossus muscle
The genioglossus muscle is a fan-shaped extrinsic muscle of the tongue which makes up the bulk of the tongue.
Summary
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...
Article
Geniohyoid muscle
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.
Summary
origin: inferior mental spine of the mandible also known as the g...
Article
Genioplasty
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...
Article
Geographic skull
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.
See also
geographic appearance
Article
Ghost image (orthopantomogram)
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...
Article
Gillespie syndrome
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...
Article
Giraffe pattern
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...
Article
Glabella
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...
Article
Globe rupture
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...
Article
Globus pharyngeus
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...
Article
Glomus jugulare paraganglioma
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.
Epidemiology
The relative prevalence of glomus jugulare with respect to other head and neck paraganglioma va...
Article
Glomus jugulotympanicum paraganglioma
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...
Article
Glomus tympanicum paraganglioma
Glomus tympanicum paragangliomas (chemodectomas) are the most common middle ear tumor.
Epidemiology
There is a female predominance (M: F = 1:3); presentation is most common when patients are more than 40 years old 1,2.
Clinical presentation
May be incidental but symptomatic masses produce ...
Article
Glomus vagale tumor
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.
Clinical presentation
Typically presents as a painless mass behind the carotid arte...
Article
Glossopharyngeal nerve
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.
Gross anatomy
Origin
There are four cranial nerve nuclei in the...
Article
Glossopharyngeal neuralgia
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.
Epidemiology
Glossophar...
Article
Glottis
The glottis is an anatomic subsite of the larynx, between the supraglottis and subglottis.
Gross anatomy
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...
Article
Goiter
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 ...
Article
Goldenhar syndrome
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.
Epidemiology
The estimated incidence is at 1 in 3000-5000...
Article
Gorlin-Goltz syndrome
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.
Epidemiology
The cond...
Article
Gradenigo syndrome
Gradenigo syndrome consists of the triad of:
petrous apicitis
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...
Article
Granular cell tumor
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).
Pathology
They have been reported in all organ systems, but most prominently are found in these sites 2,5:
breast (granular cell tumor of...
Article
Granulomatosis with polyangiitis (orbital manifestations)
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...
Article
Granulomatosis with polyangiitis (upper respiratory tract manifestations)
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...
Article
Granulomatous invasive fungal sinusitis
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.
Epidemiology
It is rare and been mainly reported in Sudan, India, Pakistan and sometimes...
Article
Graves disease
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%).
Epidemiology
There is a strong female predilection with an F:M ratio of at least 5:1. It typically presents in middle age.
Clinical ...
Article
Greater auricular nerve
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.
Gross anatomy
O...
Article
Greater (descending) palatine artery
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.
Gross anatomy
After branching off from the third (pterygopalatine) part of the maxillary artery, the greater palat...
Article
Greater occipital nerve
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.
Terminology
The greater occipital nerve has also been known in the past - confusingly - as the nerve of Arnold. But as...
Article
Greater palatine nerve
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.
Gross anatomy
The greater palatine nerve divides off the maxillary division just after emerging from the foramen...
Article
Greater wing of sphenoid
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,...
Article
Griesinger sign (mastoid)
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...
Article
Guardsman fracture
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...
Article
Guttman test (larynx)
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.
Article
Hemotympanum
Hemotympanum is the presence of blood in the middle ear cavity. It is usually secondary to trauma.
Clinical presentation
Typically on otoscopy a bulging red to purple to dark blue colored tympanic membrane is visible, color varying with age of the hemorrhage.
Pathology
The hemorrhage has us...
Article
Halitosis
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.
Pathology
Etiology
It is thought to be caused by the presence of volatile sulfur compounds that are produced by bacteria. The ...
Article
Haller cells
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.
Epidemiology
They are present in ~20% (range 2-45%) of patients, depending on their exact definition 1-3.
Clinical present...
Article
Hamburger thyrotoxicosis
Hamburger thyrotoxicosis refers to ingestion of thyroid hormone from contaminated meat. It is a very rare cause of thyrotoxicosis.
Pathology
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...
Article
Hanging and strangulation (trauma)
Hanging and strangulation are injuries involving constricting pressure applied to the neck. The vast majority are sustained as a result of attempted suicide.
Epidemiology
In America, hangings are the second most common form of suicide after firearm use. In other parts of the world due to the r...
Article
Hard palate
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...
Article
Harlequin eye deformity
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...