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...
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.
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.
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...
The globes or simply, the eyes are paired spherical sensory organs, located anteriorly on the face within the orbits, which house the visual apparatus.
The globe is suspended by the bulbar sheath in the anterior third of the bony orbit.
Each globe is an approxim...
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 a blunt trauma, ruptures are most common at the insertions of the intraocular mus...
Globus pharyngeus is the subjective feeling of a lump in the throat which can have a variety of causes. In modern practice globus is often evaluated by flexible nasoendoscopy in the first instance since many patients present to otolaryngology services. If no cause is identified or if nasoendosco...
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 p...
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.
The sensory ganglion cells lie in the supe...
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 are often classified as benign or malignant using the Fanburg-Smith criteria (especially for soft tissue lesion) 3,4.
Ophthalmologic manifestations of granulomatosis with polyangiitis (GPA) (previously known as Wegener granulomatosis), both ocular and orbital, have been reported in 40-50% of GPA patients 1-3 and can occur in either the classic or limited form of the disease.4 Ophthalmologic disease occasionally...
The upper respiratory tract manifestations of granulomatosis with polyangiitis (GPA) (previously known as Wegener granulomatosis) are common and affect most patients. Granulomatosis with polyangiitis is a multisystem systemic necrotizing non-caseating granulomatous vasculitis affecting small to ...
Granulomatous invasive fungal sinusitis, sometimes termed granulomatous invasive fungal sinusitis, 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 in t...
Graves disease (in mainland Europe it is called Basedow disease 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...
Hair artifact and hair-product artifacts are artifacts produced by the presence of the patient's hair across the field of view during acquisition of an image, which can affect all modalities to varying degrees. For example, in mammography, hair may appear as curvilinear white lines or may simula...
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...
The Harvard scoring system for rhinosinusitis is, as the name implies, a scoring system based on CT-scan assessment for grading of rhinosinusitis.
0: normal (< 2 mm mucosal thickening on any sinus wall)
1: all unilateral disease or anatomic abnormality
2: bilateral disease limited to...
Hashimoto thyroiditis, also known as lymphocytic thyroiditis or chronic autoimmune thyroiditis, is a subtype of autoimmune thyroiditis. It is one of the most common thyroid disorders.
Typically affects middle-aged females (30-50 year age group with an F:M ratio of 10-15:1).
Head and neck anatomy is important when considering pathology affecting the same area. In radiology, the 'head and neck' refers to all the anatomical structures in this region excluding the central nervous system, that is, the brain and spinal cord and their associated vascular structures and en...
The head and neck cancer therapy response interpretation (Hopkins criteria) is a qualitative system of interpretation for therapy response assessment using PET-CT.
Widely used options for therapy response assessment are clinical examination, histopathology, CT and MR imaging, howeve...
Head and neck squamous cell carcinomas (SCC) are common, being the sixth most common cancer. They can have a cutaneous or mucosal origin. As such there is a wide array of clinical and radiographic manifestations, and are separated into:
squamous cell carcinoma of the skin of the head and neck
Head and neck squamous cell carcinomas (HNSCC) are the most common histologic type of head and neck cancer. While the term may include any squamous cell carcinoma of the head and neck, common usage focuses on those of mucosal origin, i.e., squamous cell carcinoma of the upper aerodigestive tract...
Heerfordt syndrome, also known as Heerfordt-Waldenström syndrome or uveoparotid fever, is a variant of sarcoidosis, comprising of:
ocular involvement (anterior uveitis)
The exact prevalence is unknown, as only isolated case reports exist....
The helicotrema (plural: helicotremas or helicotremata) is a part of the cochlear apex where the scala tympani and scala vestibuli meet. It is located at the termination of the spiral lamina.
Hemifacial hyperplasia or hemifacial hypertrophy is a rare developmental anomaly characterized by asymmetric growth of hard and soft tissues of the face 1.
These asymmetries are often noted at birth and are usually accentuated with increasing age, especially around puberty 2.
Hemifacial microsomia (HFM) is the second most common congenital facial anomaly after cleft lip/palate. The condition may vary from mild to severe. Goldenhar syndrome has been described as a variant of HFM, in which vertebral anomalies and epibulbar dermoids were present.
HFM is al...
Hemifacial spasm is characterized by episodic facial spasms due to irritation of the facial nerve (CN VII).
Often the condition begins insidiously with painless spasm of the orbicularis oculi gradually spreading in extent and severity to involve the majority of the face, ...
The Hennebert sign describes a positive fistula test without clinical evidence of middle ear or mastoid disease. It is associated with congenital syphilis and may also be present in Ménière disease.
It has been postulated that the vestibular stimulation is mediated by fibrous bands between foot...
Hernias (or herniae) are a common pathological entity, in which an anatomical structure passes into an abnormal location via an opening.
The opening may be a normal physiological aperture (e.g. hiatus hernia: stomach passes through the diaphragmatic esophageal hiatus) or pathological. Iatrogeni...
Heterogeneous echogenicity of the thyroid gland is a non-specific finding and is associated with conditions diffusely affecting the thyroid gland. These include:
The hiatus semilunaris is a semicircular shaped opening located on the lateral wall of the nasal cavity. It is a component of the ostiomeatal complex and serves as the opening for the frontal and maxillary sinuses and the anterior ethmoid air cells. It is inferior to the ethmoid bulla and the un...
Hiccups (or hiccoughs), medical term singultus (rarely used), are an unpleasant phenomenon, experienced by everyone on occasion, and usually self-limiting. However the much rarer intractable chronic form can be extremely debilitating.
Hiccups are a symptom that has probably been e...
High arched palates are a facial feature of many syndromes, although the classic association is Marfan syndrome. There are hundreds of conditions associated with high arched palates, with some of the radiologically-more important including:
A high-riding brachiocephalic artery (now preferred to innominate artery) is a rare anomaly of the neck vessels in which the brachiocephalic artery passes much more superiorly than normally. It is a clinically important variant, as mistaking it for a neck lump and sampling it or neck surgery in ...
A high riding jugular bulb indicates the dome (roof) of the jugular bulb extends more superiorly in the petrous temporal bone than is typical. The transverse level above which a jugular bulb is considered high riding has been variably defined as the following 1,6,8:
floor of the internal acoust...
High-velocity penetrating brain injuries, in practical terms most often due to cranial gunshot injuries, are a form of penetrating traumatic brain injuries, which are much less common than blunt traumatic brain injuries and distinguished from low-velocity penetrating brain injuries (such as stab...
The hockey stick sign can refer to a variety of different signs and appearances:
hockey stick sign (thyroid hemiagenesis)
hockey stick sign (Creutzfeldt-Jakob disease)
hockey stick sign (ureters)
Hockey stick sign has been used to describe the appearance of the thyroid gland in cases of thyroid hemiagenesis when investigated with thyroid scan (Tc-99m) 1. The unilateral lobe and isthmus make a shape reminiscent of a hockey stick.
hockey stick sign (Creutzfeldt-Jakob disease)
The Holman-Miller sign (also called the antral sign) is seen in juvenile nasopharyngeal angiofibroma; it refers to the anterior bowing of the posterior wall of the maxillary antrum as seen on a lateral skull radiograph or cross-sectional imaging 1,2.
This is a non-specific sign that can be prod...
Human papillomavirus (HPV)-mediated oropharyngeal (p16+) cancer staging refers to TNM staging of squamous cell carcinomas of the oropharynx that test positive for p16, an immunohistochemical proxy for HPV infection. Nodal metastases of p16+ squamous cell carcinoma without an identified primary t...
Hurthle cells are a type of oncocyte arising from thyroid follicular epithelial cells.
Under microscopy, Hurthle cells are larger than typical follicular cells, with abundant mitochondria.
Cancers of Hurthle cell origin can be benign adenomas or malignant carcinomas and consist of a...
The Hutchinson sign can refer to two clinical signs.
Hutchinson sign (ophthalmology)
Relates to involvement of the tip of the nose from facial herpes zoster. It implies involvement of the external nasal branch of the nasociliary nerve (branch of the ophthalmic division of the trigeminal nerve...
Hutchinson teeth are smaller and more widely spaced than normal and are notched on their biting surfaces.
It is a sign of congenital syphilis and should not be confused with:
History and etymology
The hyoglossus muscle is a thin, quadrilaterally shaped muscle in the upper neck and the floor of the mouth. It is one of the extrinsic muscles of the tongue. The submandibular ganglion suspended from the lingual nerve sits on it.
origin: hyoid bone: from the entire length of the great...
The hyoid is a "horseshoe-shaped" bone that serves as a structural anchor in the mid-neck. It is the only bone in the human body that does not directly articulate with another bone (other than sesamoids). It is a place of convergence of multiple small neck muscles that permit the pharyngeal phas...
Hyoid elevation on a modified barium swallow study indicates that the pharyngeal muscles are contracting appropriately.
Modified barium swallow
With real time fluoroscopy (or videofluoroscopy) during the act of swallowing, the larynx moves upward and forward when there i...
Hyperattenuating paranasal sinus opacification can arise in a number of situations:
fungal sinus disease
acute hemorrhage into sinus (hemosinus)
In some situations can consider early calcification within the sinus - intrasinus calcification.
Hyperostosis of the skull has many causes, broadly divided into focal or diffuse.
Paget disease of bone
metastatic disease, especially prostate carcinoma
chronic, severe anemia
hyperostosis frontalis interna
long-term phenytoin use
Hyperparathyroidism is the effect of excess parathyroid hormone in the body. It can be primary, secondary, or tertiary. There are many characteristic imaging features, predominantly involving the skeletal system.
Increased levels of the parathyroid hormone lead to increased osteoclas...