The lateralized piston syndrome is a one of the complications that may occur as a result of migration of a stapes prosthesis. It may be present in around 18% of stapes revision surgeries. It is characterized by lateral piston extrusion out of the oval window and is often associated with incus ne...
The laryngeal paraganglia are tiny specialized neuroendocrine tissues located within and near the larynx. Their function is uncertain but they may play a role in regulating blood flow and responding to changes in oxygen and carbon dioxide levels.
Although nomenclature is variable...
Myoepithelial carcinomas, also known as malignant myoepitheliomas, are rare malignant salivary gland tumors. Myoepithelial carcinoma makes up <2% of all salivary gland malignancies 1,3.
Myoepithelial carcinoma affects males and females at an equal rate. The mean age at presentat...
Orbital blastomycosis, less commonly known as Gilchrist disease, is an orbital infection from the fungus Blastomyces dermatidis. Blastomycosis is typically acquired via inhalation of conidia (spores). Blastomycosis is a systemic pyogranulomatous infection.
Even in endemic areas, b...
Episcleritis describes inflammation of the thin outer layer of the sclera. The episcleral layer is present in between the conjunctiva and sclera and can become acutely inflamed unilaterally or bilaterally.
Clinically, patients may present with:
Hypermetropia, also known as long-sightedness or hyperopia, is a refractive disorder. Though it can happen in any age group, it usually starts from mid-late adulthood.
In this condition, distant objects are seen better than close objects.
The blurriness of nea...
Acrodysotosis, also known as Arkless-Graham syndrome, Maroteaux-Malamut syndrome or acrodysplasia, is a rare genetic disorder affecting bone growth.
The true incidence is not known. There is no known gender predilection. The condition is often detected in early childhood.
Crural cisterns, also known as cisterna cruralis, are paired cerebrospinal fluid-filled subarachnoid cisterns located at the level of the cerebral peduncles between the uncus and the optic tract 1.
The boundaries of the crural cisterns are 2:
ventral: communicates with the oculomot...
Cervicofacial actinomycosis is the most frequent manifestation of Actinomyces infection 1,2.
Although the prevalence of cervicofacial actinomycosis cases varies with geographical regions, the disease has male gender predilection. Risk factors including poor oral hygiene, oral trau...
Sinonasal seromucinous hamartomas (SSH) are benign sinonasal neoplasms.
Sinonasal seromucinous hamartomas are rare, with approximately 25 cases reported since 1974 1. They are more common in middle-aged adults with a mean in the 6th decade and a slight female predilection (1.5:1) ...
The circle of Zinn is an arterial anastomotic ring surrounding the optic nerve head in the sclera formed by branches of the short posterior ciliary arteries. Multiple small branches from the circle of Zinn supply the anterior pia of the optic nerve, the optic disc and contribute to the blood sup...
The posterior ciliary arteries are usually paired branches arising from the ophthalmic artery, one medial and one lateral, each giving off a number of branches that supply the uvea 1.
Close to the optic nerve, are the short posterior ciliary arteries, usually numbering 16-20; these supply the ...
The short posterior ciliary arteries are branches of the posterior ciliary arteries which are, in turn, branches of the ophthalmic artery.
Each eye has multiple small short posterior ciliary arteries (16-20) which pierce the sclera adjacent to the optic nerve. Within the sclera, they anastomose...
The long posterior ciliary arteries are branches of the posterior ciliary arteries which are in turn branches of the ophthalmic artery. They supply the anterior part of the choroid of the ocular globe as well as the iris and ciliary muscle 1,2.
Each eye has a number of long ciliary arteries. T...
Glaucoma is a group of slow progressive eye diseases that is defined as an optic neuropathy. Although there are up to eight types described, there are two main types:
closed angle glaucoma (interchangeably referred to as angle-closure or narrow-angle)
Glaucoma is one ...
The incisivus labii superioris muscle, situated in the facial region, serves primarily in retracting the upper and lower lips. 'Incisivus' derives from the Latin 'incidere' meaning 'to cut through.'
origin: incisive fossa of the maxilla
insertion: orbicularis oris muscle
The posterior auricular muscle, located posterior to the auricle, plays a role in repositioning the ear. It originates from the mastoid process of the temporal bone, with insertion at the root of the posterior auricle.
origin: mastoid process
insertion: posterior auricle root
The superior auricular muscle, an extrinsic muscle of the ear, originates from the epicranial aponeurosis and plays a pivotal role in adjusting the position of the auricle.
origin: epicranial aponeurosis
insertion: superior surface of the auricle
blood Supply: branches of the facial ...
The anterior auricular muscle, the smallest of three auricular muscles, is a thin, fan-shaped structure originating from the epicranial aponeurosis and inserting into the front of the helix.
origin: epicranial aponeurosis
insertion: anterior helix
blood Supply: superficial temporal ...
Buccal exostoses are a rare form of exostoses. They are broad-based, non-malignant surface growth occurring on the buccal/facial/outer surfaces of the maxilla and/or mandible, found usually in the premolar and molar regions.
They often occur as bilateral, smooth bony grow...
Parotid gland tumors include a variety of benign and malignant entities that are also found in other salivary glands (see salivary gland tumors). The frequency of different tumors varies considerably among the salivary glands with the parotid gland hosting the majority of all salivary gland tumo...
Parathyroid lipoadenomas are extremely rare tumors that are often considered a variant of a parathyroid adenoma.
There may be slight female predilection based on limited studies 2.
Patients may present with primary hyperparathyroidism.
Cauliflower ear, also known as perichondrial hematoma or wrestler's ear, is a deformity of the outer ear that occurs as a result of repeated blunt trauma or injury. It is most commonly seen in participants in contact sports such as wrestling, boxing, rugby, and martial arts.
Bridging vein thrombosis describes thrombosis of the fragile bridging veins that cross the subarachnoid and subdural spaces. The presence of bridging vein thrombosis on imaging has a strong association with non-accidental injury and can hint towards a traumatic etiology behind subdural hematoma ...
Listeria monocytogenes meningoencephalitis is a relatively common cause of bacterial meningoencephalitis and is more common in the elderly and immunocompromised 2.
Listeria meningoencephalitis can occur sporadically or in the setting of foodborne epidemics 1. Where meningoencephal...
The helicis minor muscle is a small, intrinsic auricular muscle responsible for shaping the anterior margin of the ear.
origin: base of the helix of the ear
insertion: anterior helix
blood supply: branches of the facial arteries
innervation: posterior and temporal auricular nerves o...
Internal auditory canal atresia, or internal auditory canal stenosis, is characterized by partial or complete bony atresia of the internal auditory canal, often in association with hypoplasia/aplasia of the vestibulocochlear nerve.
This is a very rare entity with few cases reporte...
Mental spines are small, midline, paired, bony protuberances (or eminences) of the posterior lingual surface of the mandible. There are usually two superior and two inferior spines. They represent the anchor points of origin of the superior genioglossus and the inferior geniohyoid muscles 1,2. C...
The ligaments of the larynx can be considered as two groups based on whether they attach components of the larynx together internally or externally.
median thyrohyoid ligament
lateral thyrohyoid ligament
The rima vestibuli is the V-shaped space formed between the false vocal cords, which allows the passage of air through the larynx. It is larger and located superior to the rima glottidis.
It should not be confused for the laryngeal vestibule, which is the entire open space of the supraglottis b...
The rima glottidis is the V-shaped opening formed between the true vocal cords, which permits the passage of air through the larynx. Abduction or adduction of the vocal cords can open or close the rima glottidis. The rima glottidis constitutes part of the glottic region of the larynx.
Submandibular gland agenesis, also known as aplasia, is the absence of one or both of the submandibular glands and is rare.
Only forty cases of submandibular gland agenesis had been reported in the English literature up to 2014 3.
It has been found that aplasia of m...
The inferior tympanic artery is a small branch of the ascending pharyngeal artery that supplies the tympanic cavity.
origin: proximal neuromeningeal trunk of ascending pharyngeal artery
course: passage through tympanic canaliculus
termination: anastomosis with caroticotympanic arter...
Numb chin syndrome describes a sensory neuropathy occurring in the distribution of either the mental nerve or inferior alveolar nerve. While numb chin syndrome has a multitude of causes, it is considered an ominous entity due to its strong association with heralding advanced malignancy 1.
Glottic webs are focal narrowings of the airway due to the formation of a membranous connection at the level of the true vocal folds 1.
Symptoms include exercise intolerance, dysphonia, hoarseness, stridor, respiratory distress and airway obstruction7.
Infants may also p...
Garcin syndrome, also known as hemibasal syndrome or Guillain-Alajouanine-Garcin syndrome, is characterized by progressive ipsilateral cranial neuropathies of at least seven cranial nerves, with no evidence of raised intracranial pressure, long-tract signs, or cerebellar signs, classically attri...
A tracheoesophageal voice prosthesis is a medical device that connects the trachea and esophagus to restore voice and speech communication following a total laryngectomy. It allows patients to generate the most natural and intelligible sound and voice compared to other laryngeal speech technique...
Parotid liposubstitution is a fatty degeneration of the parotid gland, sometimes increasing in volume.
Parotid liposubstitution is physiological with age but which may be associated with local or systemic conditions that include:
hypertriglyceridemia may be associated with fat...
Otalgia refers to the clinical symptoms of ear pain. It is broadly divided in two categories which are
primary otalgia (~ 50% 3) - ear pain originating from causes within or near to the ear itself
secondary otalgia / referred otalgia (~50% 3)- ear pain due to causes remote from the ear
Root dilaceration is a dental deformity presenting as an acute angulation, deviation or curvature of the crown-root axis.
Possible causes include:
trauma during root development
adjacent dentigerous cyst or tumor can lead to an abnormal angle in a developing tooth
Retropharyngeal pseudothickening is a mimic of retropharyngeal soft tissue thickening caused by neck flexion (which may also exacerbate airway obstruction), swallowing, or expiration.
It is important to consider when evaluating lateral cervical radiographs and sagittal cross-sectional imaging ...
An accessory transverse foramen, also known as a double transverse foramen, are a second, smaller foramen in the transverse process of typical cervical vertebrae 1. They are smaller than the transverse foramen, and may be unilateral or bilateral. Small studies have suggested a prevalence of 8-...
Congenital infiltrating lipomatosis of the face is a very rare congenital, non-hereditary disease manifesting with prominent unilateral facial overgrowth and deformity.
Facial asymmetry is always noted at birth. Other findings on the affected side include:
Nasal dermoids (or nasal dermoid sinus cysts) are the most common congenital midline nasal lesion typically presenting in early childhood.
Nasal dermoids are rare and account for only 4-12% of all dermoid cysts of the head and neck, far less common than angular dermoids 1,2. They ...
Cri du chat syndrome is a rare congenital disorder caused by the deletion of the short arm of chromosome 5. A high-pitched monotonous cry is the significant characteristic finding 1.
Cri du chat syndrome is rare with an incidence of 1 in 15,000-50,000 births 1.
The axiolateral oblique mandible view allows for visualization of the mandibular body, mandibular ramus, condylar process and mentum.
This projection is useful in identifying structural changes and displaced fractures of the mandible in a trauma setting, and in neoplastic or inflam...
CT orbits (computed tomography of the orbits) involves the visualization of bony and soft tissue structures of the orbits. This examination is most commonly performed as a non-contrast scan or reconstructed from other examinations such as a CT head/face. Contrast-enhanced scans are utilized depe...
The CT neck chest-abdomen-pelvis protocol aims to evaluate the neck, thoracic and abdominal structures using contrast in trauma imaging. The use of contrast facilitates the assessment of pathologies globally whilst minimizing dose by potentially disregarding a non-contrast scan.
Note: This art...
The foramen cecum of the tongue is the remnant of thyroglossal duct located between the anterior two-thirds and posterior third of the tongue.
The foramen cecum is located in the midline on the surface of the tongue, at the apex of the terminal sulcus, the groove that marks the ...
Tympanosclerosis is a descripitve terms which refers to deposition of hyalinised collagen +/- calcium in the tympanic cavity. If it occurs in solely tympanic membrane, it is termed myringosclerosis 1.
It can often be associated with chronic otomastoiditis is which instance it is termed chronic...
A metopic ridge refers to a variation in skull shape, characterized by a midline forehead ridge, which may occur either due to the physiological closure of the metopic suture or as a result of craniosynostosis of this suture 1-3. It is essential to differentiate between the two conditions becaus...
Thyroid atrophy can arise in a number of situations and most with certain chronic thyroiditides such as:
atrophic thyroiditis 1
It can also occur with conditions such as:
prior treatment (e.g. I-131) of hyperactive conditions such as Graves disease 3
The ciliary body is the continuation of the uveal layer of the eye and functions in the production of aqueous humor and the process of lens accommodation.
location: between the vitreous body and posterior chamber of the globe
function: aqueous humor production and accommodation...
The posterior meningeal artery is the largest artery supplying the dura of the posterior cranial fossa. It may arise from the ascending pharyngeal artery, or less commonly, the occipital artery. The artery may enter the cranial vault through the jugular foramen, foramen magnum or the hypoglossal...
The inferior cervical ganglion (plural: ganglia) is the second largest ganglion of the cervical sympathetic trunk and provides autonomic innervation to the head and neck region.
The inferior cervical ganglion is formed by embryologically fused C7 and C8 sympathetic ganglia. It ha...
The middle cervical ganglion (plural: ganglia) is the smallest ganglion of the cervical sympathetic trunk and providing autonomic innervation to the head and neck region.
The middle cervical ganglion is formed by embryologically fused C5 and C6 sympathetic ganglia. It has superio...
The autonomic ganglia and plexuses are a collection of ganglia where autonomic preganglionic neurons arising from the CNS synapse with postganglionic neurons outside the CNS, i.e. in the peripheral nervous system. Many of the ganglia contain nerves of the sympathetic and parasympathetic nervous ...
This article lists examples of normal imaging divided by body region and system.
head and neck
Sinonasal carcinomas are a broad group of sinonasal malignant tumors that are of epithelial cell origin/lineage.
Sinonasal carcinomas can be classified into various histological and etiological subgroups:
sinonasal squamous cell carcinoma: considered the most common histological sub...
Protrusion of the infraorbital canal into the maxillary sinus is a type of variant anatomy where the infraorbital canal traverses below the level of the orbital floor and often through the maxillary sinus to varying degrees. It can be detected on sinus CT and cone beam computed tomography and it...
The superior alveolar arteries is a collective term for the following arteries:
posterior superior alveolar artery: branch of the maxillary artery in the pterygopalatine fossa
middle superior alveolar artery: small branch of the infraorbital artery
anterior superior alveolar artery: branch of...
The suspensory ligaments of the middle ear ossicles are ligaments within the middle ear which attach the ossicles to the walls of the mesotympanum 1. The ligaments help the ossicles transmit sound from the tympanic membrane to the oval window.
Origins and insertions of the suspen...
Lacrimal gland prolapse, also known as lacrimal gland displacement or lacrimal gland dislocation, is defined as significant herniation of the lacrimal gland outside the lacrimal fossa. It is an underrecognized clinical condition that needs to be differentiated from mass lesions in the preseptal ...
Pseudoproptosis is a situation where the eye can have a proptotic anatomic appearance but without any mass effect from a lesion displacing the globe or any underlying pathology. Instances where this can occur include
buphthalmos: as a result of congenital glaucoma or severe myopia
Elfin facies refers to a characteristic facial appearance seen in certain rare congenital syndromes.
Elfin facies is sometimes used synonymously with Williams syndrome and the latter is occasionally called elfin facies syndrome. However elfin facies is seen with other rare genetic ...
Saturday night retinopathy is an acute ischemic retinopathy, choroidopathy, and orbitopathy secondary to prolonged ocular pressure during a drug-induced stupor.
While monocular blindness as a complication of prolonged headrest use in prone neurosurgical procedures has been widely ...
The bright tongue sign is a radiological sign most commonly described in amyotrophic lateral sclerosis with bulbar involvement 1,2. However, this sign is not pathognomonic, and may be seen with other myopathies or neuropathies with tongue or bulbar involvement (e.g. Kennedy disease, Pompe diseas...
Spontaneous retropharyngeal hemorrhage, also known as spontaneous retropharyngeal hematoma, describes an accumulation of blood in the retropharyngeal space. It is a rare but potentially fatal entity due to potential for acute airway obstruction and/or rapid internal bleeding.
The scalene muscles are a group of three closely related neck muscles.
anterior scalene muscles
middle scalene muscles
posterior scalene muscles
origin: transverse processes of mid to lower cervical vertebrae (C2-C7).
insertion: first or second ribs. The anterior and middle insert...
Oral tori (singular torus) are benign bony outgrowths from the maxilla and mandible:
maxillary tori a.k.a. torus palatinus
mandibular tori a.k.a. torus mandibularis
Oral tori are subcategorised according to their shape 1:
Although not usually called tori, fur...
Internal auditory canal (IAC) exostoses are bony growths that can narrow the IAC lumen, sometimes causing neurological symptoms due to nerve compression.
Unlike their counterpart in the external auditory canal, IAC exostoses are uncommon and can be difficult to detect 1.
Radiation therapy has the potential to cause complications in many organ systems, many of which, especially in the thorax, are important for radiologists to be aware of.
acute radiation syndrome
complications of cranial radiation therapy
radiation-induced cerebral vasculopathy
Salivary duct carcinomas are a subtype of primary salivary gland tumor. Salivary duct carcinomas show high rates of metastasis and recurrence.
Salivary duct carcinomas represent 5-10% of salivary gland malignancies and can arise de novo or out of a pleomorphic adenoma 1,2. They t...
Impacted teeth are common with the third molars most common. Other impacted teeth (e.g. maxillary canines, maxillary second molar, mandibular second premolar, and mandibular second molar) are less common 1,2.
Cone beam CT (CBCT) allows for 1,3:
impacted tooth loca...
Tetanus is a rare vaccine-preventable disease caused by Clostridium tetani, a ubiquitous soil bacterium which contaminates open wounds. It secretes a powerful neurotoxin which degrades neuromuscular junction function, producing muscle spasms and, despite intensive intervention, is often fatal.
Branch retinal artery occlusion (BRAO) refers to the acute obstruction of an arteriolar branch of the central retinal artery, which can lead to retinal ischemia and transient or permanent visual loss. The distribution affecting a branch distinguishes this disease from central retinal artery occl...
Trigeminal radiofrequency ablation, also known as trigeminal radiofrequency rhizotomy, is a percutaneous interventional procedure used to treat trigeminal neuralgia. It is the most popular technique for trigeminal ablation.
trigeminal neuralgia resistant to traditional medical trea...
Non-arteritic anterior ischemic optic neuropathy (NAION) is a form of ischemic optic neuropathy.
It is considered the most common acute optic neuropathy in patients over 50 years of age (especially in those with vasculopathy risk factors (e.g. diabetes mellitus, hypertension, and ...
The depressor labii inferioris muscle, also known as quadratus labii inferioris muscle, is one of the facial muscles.
origin: oblique line of the mandible, medial to the mental foramen
modiolus at the angle of the mouth
ascends to medially insert into lower lip
Carotid artery tortuosity is the elongation of the extracranial carotid arteries with redundancy and/or altered course, which may present on imaging as kinking, coiling, and/or looping 1,2.
Carotid artery tortuosity is mostly (~80%) asymptomatic. When symptomatic (~12.5%,...
The superior cervical ganglion (plural: ganglia) is the largest ganglion of the cervical sympathetic trunk, providing autonomic innervation to the head and neck region 1.
The superior cervical ganglion is formed by embryologically fused C1 to C4 sympathetic ganglia. It is elongat...
Orbital apex syndrome, also known as Jacod syndrome, is a constellation of clinical findings, presenting as a result of several potential pathologies that compress or otherwise affect structures passing through the orbital apex.
Presentation is according to the structures...
Hypoglossal nerve palsies, or twelfth nerve palsies, result in weakness of the muscles supplied by the hypoglossal nerve, namely the intrinsic and extrinsic tongue muscles, except for palatoglossus.
The hypoglossal nucleus receives a major component of contralateral corti...
The ciliary muscle (TA: musculus ciliaris) is located within the ciliary body of the eye. It acts to facilitate lens accommodation for near vision, and receives parasympathetic innervation from short ciliary nerves, arising from the oculomotor nerve via the ciliary ganglion.
The dilator pupillae muscle is a ring of contractile cells within the iris. These cells are arranged radially, such that their contraction facilitates pupillary dilation (mydriasis). The dilator pupillae muscle receives innervation from the sympathetic nervous system.
The sphincter pupillae muscle is a circular ring of smooth muscle within the iris responsible for constriction of the pupil (miosis). The structure is stimulated by the parasympathetic nervous system causing the muscle to decrease in diameter as it contracts.
The sphincter pupill...
There are multiple pharyngeal muscles that make up the structure of the pharynx. They comprise circular and longitudinal muscles whose overall function is to propel food into the esophagus.
These muscles comprise the outer layer of musculature and act to c...
Clival fractures are uncommon skull base fractures resulting from high-energy cranial trauma and are usually associated with other skull vault fractures and brain injuries.
For a general discussion, please refer to the article on basilar fractures of the skull.
Most fractures of ...
An intracochlear schwannoma is a subtype of an intralabyrinthine schwannoma which is a schwannoma arising in relation to the 8th cranial nerve.
Patients may present with unilateral sensorineural hearing loss.
Schwannomas that are confined exclusively to the c...
Periodontitis is an inflammatory disease affecting the supporting tissues of the teeth. It is a common cause of tooth loss, particularly in the adult population.
Different forms of periodontitis are recognized. The terms 'chronic periodontitis' and 'aggressive periodontitis' have b...
A canal-wall-down mastoidectomy comprises a group of mastoidectomies which is more open and extensive than a canal-wall-up mastoidectomy. In addition to traditional forms, various modified forms are now performed (see modified canal wall down mastoidectomy).
They initially comprise the similar ...
Prognathism or mandibular prognathism refers to a type of morphological jaw positional anomaly in which the lower jaw protrudes ahead of the upper jaw. This results in an extended chin and dental malocclusion. It can be associated with certain conditions such as
syphilis - lat...
The canine space, or infraorbital space, is a paired compartment in the soft tissues of the face, overlying the maxilla near the canine tooth root and covered by the levator labii superioris muscle.
The canine space contains fat and branches of the infraorbital nerve.