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 loc...
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 innervation to the head and neck region 1.
The superior cervical ganglion is formed by embryologically fused C1 to C4 sympathetic ganglia. It is elongated, cylind...
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 - late cong...
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.
Trichilemmal cysts, also known as pilar cysts, are benign accumulations of keratin along the outer hair root sheath, most commonly on the scalp. They are the most common subcutaneous nodule incidentally found on head imaging and are of no clinical relevance when asymptomatic 1. Uncommonly, they ...
Cacosmia refers to a form of olfactory dysfunction where the patient has an inability to "recognize" smells. It can arise from a number of pathologies and can include peripheral sinonasal and central sensorineural components. In this situation, the patient knows there is a smell but cannot disti...
The suboccipital cavernous sinuses are paired venous plexuses that surround the horizontal (distal V3) portion of the vertebral arteries at the craniocervical junction. Its name derives from its resemblance to the cavernous sinus as it is a venous cushion surrounding a large arterial loop at the...
Intraparotid nodal metastases refer to metastatic involvement of intraparotid lymph nodes from either a primary parotid tumor or an extraparotid tumor in the head and neck (e.g. nasopharyngeal carcinoma).
There may be a predilection towards the superficial lobe or tail regi...
Age-related macular degeneration (AMD) is an eye disease that affects central vision. It occurs when aging causes damage to the macula. The macula is responsible for fine detailed vision also known as central vision.
Lobular capillary hemangioma of the nasal cavity, also known as nasal pyogenic granuloma, is an uncommon benign, rapidly growing vascular neoplasm of the nasal cavity.
The term “pyogenic granuloma” is a misnomer due to its lack of infectious origin according to histological and mic...
The nasal septal cartilage, also known as quadrangular cartilage, forms most of the anterior portion of the nasal septum, and is one of five named nasal cartilaginous components supporting the external nose.
Most of the anterior one-third of the nasal septum is formed by the sept...
Submandibular gland enlargement refers to an increase in the volume of the submandibular gland, exceeding "normal" values of 7.4 ± 1.8 mL 1.
submandibular duct stenosis (e.g. tumor, granulomatous disease)
acute sialadenitis: following ...
The salt and pepper sign has been used to describe the MRI appearance of the parotid gland in Sjögren syndrome. This pertains to a combination of punctate regions of calcification (pepper) and fatty replacement (salt) 1.
The salt and pepper sign is used to describe a typical MRI appearance of some highly vascular tumors which contain foci of hemorrhage, typically a paraganglioma 1-3. The appearance is on T1-weighted sequences, and is made up of:
punctate regions of hyperintensity = salt
small flow voids = pepp...
The neurocranium (plural: neurocrania) is the name given to the portion of the skull that encloses the brain. It comprises the skull base and the skull vault. The neurocranium and facial bones (viscerocranium) together form the skull.
Hypervascular head and neck lesions are findings that enhance avidly after biphasic injection, on contrast-enhanced CT or MRI of the neck.
ectopic thyroid gland
hyperdense soft tissue mass on non contrast-CT
intense homogeneous enhancement after contrast injection
The nasolacrimal canal is the short bony passage along which the nasolacrimal duct courses in the face.
lacrimal groove of the medial maxilla
lacrimal hook of the lacrimal bone
superiorly: lacrimal bone
inferiorly: lacrimal process of the inferior n...
Chronic otitis media is a form of otitis media where there is a prolonged phase of inflammation in the middle with resultant tympanic membrane perforation.
There are a few types of chronic otitis media 1-5:
benign/inactive chronic otitis media: dry tympanic membrane perforation
The oropharyngeal isthmus, a.k.a. isthmus of fauces, is the relative constriction of the anterior oropharynx that borders the oral cavity. The isthmus is sometimes described as the passage that transitions between the oral cavity and pharynx, but strictly speaking, it is part of the oropharynx.
Fibrosing inflammatory pseudotumors are an inflammatory process with histology showing a polymorphous infiltrate with plasma cells, lymphocytes and eosinophils as well as a significant reactive fibrovascular component.
They can occur at various sites of the body including: ...
The modiolus (plural: modioli) may refer to one of two different anatomical structures, both in the head and neck region:
History and etymology
The Latin word, "modiolus" means hub of a wheel, and is well-named, as in both the cochlea and at the angle of t...
The modiolus (plural: modioli), also known as the modiolus anguli oris or commissural modiolus, is a small fibromuscular structure at the corner of the mouth where fibers from multiple facial muscles converge, and helps coordinate the action of these muscles.
The convergence of t...
A gomphosis (plural: gomphoses), also known as the dentoalveolar syndesmosis, is the specific name for the fibrous joint between the teeth and the alveolar bone of the maxilla/mandible 1,2.
The incisivus labii inferioris muscle (TA: pars labialis musculi orbicularis oris) is one of the facial muscles. It acts as a supplementary muscle to the orbicularis oris muscle.
The incisivus labii inferioris muscle is often omitted from major anatomical texts or articles on the f...
Osseointegrated implants (OI) are endosteal implants characterized by porous surfaces that allow a direct structural connection between bone and implant without interposed soft tissue and ingrowth and interdigitation of the newly formed lamellar bone.
Osseointegration has been defined as direct...
A commissure (TA: commissura) is a location at which two anatomical structures are united. Though the term most commonly refers to the commissures in the brain, there are a number which exist in the human body:
central nervous system
Non-pulsatile tinnitus is a form of tinnitus where there is a continuous ringing sensation of the ears. It is thought to have a considerable subjective component in many individuals.
Many factors have been postulated, inclusive of 1-4:
middle ear infection
Auriculocondylar syndrome is a rare congenital syndrome primarily characterized by malformed ears and mandibular condyle aplasia/hypoplasia.
This is an autosomal dominant genetic disease resulting from GNAI3 or PLCB4 gene defects. This affects facial development especially the 1st an...
The pes anserinus (rare plural: pedes anserini) is the name given to two different anatomical structures:
pes anserinus (facial nerve): a.k.a. parotid plexus
pes anserinus (knee)
Both structures are so named due to their similarity to a goose's foot, which is what 'pes anserinus' means in Lat...
The marginal mandibular nerve (TA: ramus marginalis mandibularis nervi facialis) is a branch of the extratemporal (terminal) segment of the facial nerve. It supplies the depressor anguli oris, depressor labii inferioris and mentalis muscles. It is of greater clinical importance than the other fa...
Odynophagia is the term given for painful swallowing.
It can arise from a number of causes which include
esophageal inflammation - esophagitis
dysphagia: difficulty swallowing.
The mentalis muscles (TA: musculus mentalis) are paired muscles, one on each side of the mouth, important as elevators of the chin and lower lip; the muscles are one of the facial muscles.
origin: incisive fossa of the mandible
insertion: skin of the chin
innervation: facial nerve
Auricular perichondritis, also known as perichondritis of the ear or pinna, is an infection or inflammation of the cartilage-bearing part of the external ear.
The term perichondritis, strictly speaking, refers to inflammation involving the perichondrium. However, a distinction is o...
The buccolabial muscles form a subgroup of the facial muscles.
Elevators, retractors and evertors of the upper lip:
levator labii superioris alaeque nasalis (LLSAN) muscle
levator labii superioris muscle
zygomaticus major muscle
zygomaticus minor muscle
levator anguli oris...
A thyrolinguofacial trunk is a very rare pattern of branching of the anterior branches of the external carotid artery. Rather than the facial artery, lingual artery, and superior thyroid artery having their own distinct origins, all three vessels originate from a common trunk of the external car...
A linguofacial trunk is a rare variation of the anterior branches of the external carotid artery. The lingual artery and facial artery share a common trunk rather than branching independently from the external carotid artery 1. Unlike the thyrolingual or thyrolinguofacial variations in which the...
A thyrolingual trunk is an anatomical variant in which the superior thyroid artery and lingual artery share a common trunk 1. This is in contrast to the typical pattern of both vessels emerging independently from the external carotid artery. Other variations of origin include a linguofacial trun...
The submental artery is the largest branch of the facial artery. The vessel supplies the floor of the mouth and sublingual gland while also connecting the circulation of the tongue and the floor of the mouth 1,3.
origin: facial artery 2
course: emerges from the facial artery at the s...
The submasseteric space, also known as the masseteric space, is the inferolateral subcompartment of the masticator space located between the mandible and masseter muscle.
Relations and/or Boundaries
The submasseteric space has the following boundaries 1:
medially: mandible (ram...
The pterygomandibular space is the inferomedial subcompartment of the masticator space located between the mandible and pterygoid muscles.
The pterygomandibular space contains loose areolar tissue, the sphenomandibular ligament, and the following named neurovascular str...
The levator anguli oris muscle, also known as caninus or triangularis labii superioris muscles, is a buccolabial muscle, a subdivision of the facial muscles.
origin: canine fossa of the maxilla
insertion: modiolus and merges with depressor anguli oris muscle
The lesser palatine artery is a small branch of the descending palatine artery (branch of the 3rd part of the maxillary artery). The vessel supplies the soft palate with small branches to the palatine tonsils 1,2. The vessel emerges through the lesser palatine foramen before traveling posterior ...
The descending palatine artery is a branch of the maxillary artery that supplies both the soft palate and hard palate as well as the palatine tonsils 1.
origin: 3rd part of the maxillary artery
course: descending through the pterygopalatine fossa before its branches enter either the ...
The CT paranasal sinus protocol serves as an examination for the assessment of the study of the mucosa and bone system of the sinonasal cavities. It is usually performed as a non-contrast study. In certain situations, it might be combined or simultaneously acquired with a
Note: This article aim...
The ascending palatine artery is a branch of the facial artery that supplies part of the soft palate. In addition, the vessel also supplies the tensor veli palatini, uvular muscle, palatine tonsils, and palatopharyngeus 1,2. The posterior branch supplies the posterior and inferior soft palate es...
The frontalis muscle (TA: musculus frontalis) is a paired muscle extending from the supraorbital region to the level of the coronal suture. Flat and quadrilateral in shape, it is one of the facial muscles. Along with the occipitalis muscle, it forms the occipitofrontalis muscle due to a common t...
The solitary fibrous tumor of the orbit is a rare spindle-cell neoplasm originating from mesenchymal fibroblast-like cells histologically identical to solitary fibrous tumors found elsewhere
Solitary fibrous tumors occur in a wide age range reported from 9 to 76 years without a co...
The risorius muscle (TA: musculus risorius) is one of the muscles of the mouth, a subset of the facial muscles. It is often absent and has been described as an accessory muscle.
origin: fascia overlying the parotid, masseter and/or platysma muscles
insertion: modiolus at the angle of...
A mastoid bowl or mastoid cavity refers to a post surgical cavity that is created from the resection of mastoid air cells and intervening septae, usually during complex mastoidectomies such as canal wall up or canal wall down mastoidectomies, or other surgeries such as cochlear implantations. Th...
The levator labii superioris (LLS) muscle (TA synonym: musculus levator labii superioris) is one of the elevators of the upper lip, a subset of the facial muscles.
It is not to be confused with the levator labii superioris alaeque nasalis muscle, which has a very similar name, at least partiall...
Barrett's index (BI) is used to assess for dysthyroid optic neuropathy, a severe complication of thyroid-associated orbitopathy that can lead to permanent blindness 1.
Measurement is calculated on coronal CT or MRI imaging of the orbits at a point halfway between the posterior glob...
Exophytic sinonasal papillomas (ESP) or fungiform sinonasal papillomas are a form of Schneiderian papillomas and benign sinonasal tumors arising from the Schneiderian epithelium of the nasal septum.
Exophytic sinonasal papillomas are the second most common form of sinonasal papill...
Oncocytic sinonasal papillomas (OSP) or cylindrical cell papillomas are a rare form of Schneiderian papillomas and benign epithelial sinonasal tumors arising from the Schneiderian epithelium of the nasal cavity and paranasal sinuses.
Oncocytic sinonasal papillomas are the least fr...
Primary intraosseous carcinomas NOS (PIOC) are malignant epithelial odontogenic neoplasms of the jawbones with no clear benign analog.
Primary intraosseous carcinomas are rare tumors 1-4. They occur in a wide age range with the mean in the sixth decade of life. Men are more freque...
A mnemonic to remember the nerve supply to the scalp is:
G: greater occipital nerve / greater auricular nerve
L: lesser occipital nerve
A: auriculotemporal nerve
S: supratrochlear nerve
S: supraorbital nerve
Please note that other nerves also contribute, see anatomy articl...
A mnemonic to remember the commonest causes of tinnitus is:
A: anemia / acoustic neuroma
M: migraine / Menière's disease
M: medication (quinine, NSAIDs, streptomycin)
E: ear pathology (wax, foreign body, otitis media)
R: rare (temporomandibular joint ...
Glandular odontogenic cysts (GOC) are developmental odontogenic cysts with glandular differentiation of the epithelium.
Glandular odontogenic cysts are rare 1,2 and account for about 0.5% of odontogenic cysts 3. They are slightly more frequent in men and show a peak in the fifth a...
Gingival cysts or dental lamina cysts are developmental oral mucosal cysts growing from the remnants of the dental lamina in the gingival or alveolar tissue. In newborns, they are transient appearances.
Gingival cysts are very common and transient in newborns and are seen within t...
Orthokeratinized odontogenic cysts (OOC) are developmental odontogenic cysts arising from the remnants of the dental lamina and form a separate new entity in the WHO classification of odontogenic and maxillofacial bone tumors since 2017.
Orthokeratinized odontogenic cysts are rare...
Rosenbach sign may refer to several different clinical signs:
Rosenbach sign (AV regurgitation)
Rosenbach sign (eye)
Rosenbach sign (hemiplegia)
History and etymology
Ottomar Ernst Felix Rosenbach (1851-1907), a German physician born in Prussian County in Silesia, graduated from medicine in...
Lateral periodontal odontogenic cysts are developmental cysts arising adjacent or lateral to the roots of vital teeth and botryoid odontogenic cysts are multilocular variants of lateral periodontal odontogenic cysts.
Lateral periodontal and botryoid odontogenic cysts are rare, wit...
Ameloblastic carcinomas or malignant ameloblastoma are malignant epithelial odontogenic neoplasms with histologic features ameloblastoma.
Ameloblastic carcinomas are rare tumors approximately accounting for 1% of jaw tumors 1,2. They have been found in a wide age range and are mor...
Tobacco abuse, most commonly by smoking cigarettes, is a legal drug habit of many throughout the world. It is a significant risk factor for many malignancies, respiratory and cardiovascular diseases and is a major cause of premature mortality throughout the world.
It has been esti...
A non-recurrent laryngeal nerve is an uncommon anatomical variant in which the recurrent laryngeal nerve takes a course that is deviant to its usual descent into the thorax. The non-recurrent laryngeal nerve rather enters the larynx directly from the cervical Vagus nerve instead of coursing infe...
Dentinogenic ghost cell tumors (DGCT) are benign mixed epithelial and mesenchymal odontogenic tumors with locally aggressive behavior.
It is also known as the 'solid' or 'neoplastic form of calcifying odontogenic cyst’, since the 4th WHO classification of head and neck tumors in 20...
Odontogenic fibromas are benign mesenchymal odontogenic tumors with varying amounts of fibrous connective tissue.
Odontogenic fibromas are rare tumors and are more common in women. Central odontogenic fibromas occur in a wide age range and peripheral odontomas have a peak between ...
The Rosenbach sign of the eyes is a clinical sign of Graves disease. It consists of fine tremors of the eyelids when gently closed 1,2.
History and etymology
Ottomar Ernst Felix Rosenbach (1851-1907), a German physician born in Prussian County in Silesia, graduated from medicine in Breslau in ...
The "white knight" nodule is regarded as a benign lesion of the thyroid gland 1.
Follicular cells, Hurthle cells, numerous small and large lymphocytes and colloid are seen on fine needle aspiration cytology of white knight nodules, which is consistent with Hashimoto thyroiditis 2,3.
Secondary osteosarcomas are osteosarcomas growing on abnormal bone in the setting of various underlying osseous disorders.
Other acceptable terms include Paget sarcoma, osteosarcoma in Paget disease of bone or radiation-associated osteosarcoma, if applicable. The terms postirradiat...
Godtfredsen syndrome is a rare syndrome of abducens and hypoglossal nerve palsies that localizes to a clival mass.
The classic clinical presentation includes 1-3:
abducens nerve palsy: diplopia worse when horizontal gaze is directed towards the affected side
The CT neck protocol serves as a radiological examination of the head and neck. This protocol is usually performed as a contrast study and might be acquired separately or combined with a CT chest or CT chest-abdomen-pelvis. On rare occasions, it will be performed as a non-contrast study. Dependi...
Cartilage or cartilaginous tissue is a resilient and type of connective tissue of mesodermal origin that forms an integral part within the musculoskeletal system and as a structural component in other organs.
Cartilage can be generally classified into the following main types:
Periodontal ligament widening can be a finding which can present on OPG and facial bone CT imaging and can occur in several situations.
The normal width range is usually between 0.15-0.21 mm (may decrease with age).
Conditions associated with widening are varied and can include:
Periodontal ligaments are structures holding teeth in their sockets. They are seen as a thin radiolucent space between the surface of the tooth root and the lamina dura, the lining of the tooth socket. The lamina dura serves as a periodontal ligament attachment site.
They comprise soft connect...
Dentomaxillofacial Radiology (DMFR) is the official journal of the International Association of Dentomaxillofacial Radiology (IADMFR) and is published by the British Institute of Radiology (BIR); it was first published in 1972. Its primary focus is head and neck imaging and oral radiology.