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 frnotal 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.
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 doesn't 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 pneumatise 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 site where the nasal process of frontal bone meets the frontal process of the maxilla.
Frontonasal dysplasia, also known as median cleft face syndrome, is a rare disorder characterised 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 (or 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 variants to report on pre-functional endoscopic sinus surgery studies is 1:
Sphenoid sinus pneumatisation
Ethmoidal artery (anterior)
ostiomeatal complex narrowing due to anatomical variations
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 mucosa
allergic fungal sinusitis
sinus fungal mycetoma
invasive: hyphae ...
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 tumour cells.
The genioglossus muscle is a fan-shaped extrinsic muscles 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: hypogloss...
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 mobilising an inferior segme...
A geographic skull is a radiographic appearance which is seen in eosinophilic granuloma (EG) and characterised by destructive lytic bone lesions, the edges of which may be bevelled, scalloped or confluent.
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 look straight ahead. The metopic suture traverses the glabella, between the two frontal bones. Just below it is the ...
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 tumour, it is the most common of the jugular fossa tumours.
The relative prevalence of glomus jugulare with respect to other head and neck 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...
Glomus tympanicum paragangliomas (chemodectomas) are the most common middle ear tumour.
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 tumours are glomus tumours that occur along the path of the vagus nerve (CN X). They are a subset of extra-adrenal neuroendocrine tumours that are derived from the nonchromaffin paraganglion cells.
Typically presents as a painless mass behind the carotid ar...
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.
Goitre (rarely thyromegaly) refers to enlargement of the thyroid gland. It can occur from multiple conditions.
The definition of a goitre depends on age and sex; below are the upper limits of normal for thyroid gland volume 1:
adult males: 25 mL
adult females: 18 mL
13-14 years: 8-10 mL
Goldenhar syndrome (also known as oculo-auriculo-vertebral spectrum (OAVS), Goldenhar-Gorlin syndrome or facio-auriculo-vertebral dysplasia) is a complex congenital anomaly characterised by abnormalities of the ears, eyes and vertebrae.
The estimated incidence is at 1 in 3000-500...
Gorlin-Goltz syndrome, also known as the basal cell naevus syndrome, is a rare phakomatosis characterised by multiple odontogenic keratocysts (KOT), multiple basal cell carcinomas (BCC), and other abnormalities.
The condition is thought to occur in ~1 in 60,000 live births while 0...
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...
Granulocytic sarcoma (also called myeloid sarcoma and chloroma) is a rare neoplasm comprised of myeloid precursor cells.
It is typically seen is in children with ~60% occurring in individuals less than 15 years of age. There is no recognised gender predilection.
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 t...
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 spinal nerve that innervates the skin of the occiput and upper neck.
The greater occipital nerve arises from the medial branch of the dorsal ramus of C2.
The greater occipital nerve emerges between axis (C2) and the obliquus capit...
The greater palatine nerve (or 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 rotundum to en...
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,...
Griesinger sign, named after Wilhelm Griesinger, a German psychiatrist and neurologist (1817-1868) refers to oedema 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 asso...
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.
Halitosis (or fetor oris) refers to the symptom of foul oral odour, commonly termed "bad breath", that patients can present with, usually to dental services.
It is thought to be caused by the presence of volatile sulphur compounds that are produced by bacteria. Although the underlyin...
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.
In America hangings are the second most common form of suicide after firearm use. In other parts of the world due to the relative difficulty in accessing firearms, hangings are the most com...
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. It is formed by the palatine processes of the maxillae and the horizontal plates of the palatine bones. On its inferior oral surface it is lined by oral mucosa...
The harlequin eye deformity may be seen in unilateral (plagiocephaly) or bilateral (brachycephaly) coronal suture synostosis, and refers to the elevation of the superolateral corner of the orbit.
The term harlequin eye derives from the appearance of the eyes on a harlequin mask with their exagg...
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 (HT), 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, howev...
Head and neck squamous cell carcinomas (HNSCC) refer to SCCs of the aerodigestive tract of the head and neck rather than cutaneous SCCs. SCC is the most common tumour of the mucosa of the upper aerodigestive tract, and can occur anywhere there is squamous cell mucosa.
Epidemiology, risk factor...
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. Neurologic involvement may occur...
Hemifacial hyperplasia or hemifacial hypertrophy is a rare developmental anomaly characterised 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 characterised 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...
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, 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 experienced by ...
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 jugular bulb is distinguished from an asymmetrically large jugular bulb by its dome (roof) reaching above the internal acoustic meatus (IAM). It need not be larger than the contralateral bulb, but usually is.
A run of the mill high riding jugular bulb has an intact sigmoid plate -...
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...
Hockey stick sign has been used to describe the appearance of the thyroid gland in cases of thyroid hemiagenesis, when investigated with 99m technetium pertechnetate thyroid scan 1. The unilateral lobe and isthmus make a shape reminiscent of a hockey stick.
hockey stick sign (Creutzf...
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...
The Hutchinson sign can refer to two 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) and thu...
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, sesamoids aside. It is a place of convergence of multiple small neck muscles that permit the pharyngeal phase of s...
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 haemorrhage into sinus (haemosinus)
In some situations can consider early calcification within the sinus.
Hyperostosis of the skull has many causes, broadly divided into focal or diffuse.
Paget's disease of bone
metastatic disease, especially prostate carcinoma
chronic, severe anaemia
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...
Hypertelorism refers to an abnormal increase in distance between any two organs although some authors use the term synonymously with orbital hypertelorism meaning an abnormal increase in distance between the two eyes. The article mainly focuses on the latter. The abnormality is similar to teleca...
Hypodontia refers to the congenital absence of one or more teeth.
Hypodontia is common, affecting ~15% of the population with a recognised variations in ethnicities, e.g. prevalence of 1% in indigenous Australians through to 30% in Japanese populations. There is a female preponder...
Hypoglobus refers to the inferior displacement of the globe into the orbit. It may or may not be associated with enophthalmos.
Hypoglobus is most commonly caused by fracture of the orbital floor but may be due to other causes:
silent sinus syndrome
orbital foreign bodies
The hypoglossal canal is located between the occipital condyle and jugular tubercle and runs obliquely forwards (posteromedial to anterolateral) allowing the hypoglossal nerve (12th cranial nerve) to exit the posterior cranial fossa.
Its proximal portion is often divided by a fibrous (sometime...
Hypoparathyroidism results from reduced secretion of parathyroid hormone by the parathyroid glands. It results in hypocalcaemia.
tetany: peripheral paresthaesia, carpopedal spasm, seizures
emotional lability, depression and anxiety, psychosis
Squamous cell carcinoma of the hypopharynx is relatively uncommon, carries the worst prognosis of any head and neck squamous cell carcinoma (HNSCC), and is a challenge to diagnose and treat.
Hypopharyngeal carcinoma is relatively uncommon representing only 10% of all proximal aerodigestive tra...
Staging of hypopharyngeal squamous cell carcinoma is performed using the TNM staging system.
Primary tumour staging (T)
limited to 1 subsite AND
tumour size ≤ 2 cm in greatest dimension
extends into adjacent subsite or area (larynx, oropharynx) and/or
tumour size betw...