The foramen Vesalii, also know as the foramen of Vesalius, sphenoidal emissary foramen, foramen venosus or canaliculus sphenoidal, is a tiny variably present foramen in the greater wing of the sphenoid bone, located between the foramen ovale and scaphoid fossa. It transmits a sphenoidal emissary...
Retinopathy of prematurity (ROP) (formerly referred to as retrolental fibroplasia) is an ocular condition seen in the infant population. It often occurs bilaterally, although usually with significant asymmetry 1.
There is often a history of premature delivery, low birth weight, a...
Dacryocystitis is the inflammation of the nasolacrimal sac related to impairment in the lacrimal drainage system and superimposed infection.
Dacryocystitis has a bimodal distribution: neonates due to congenital abnormalities and, when acquired, usually affect individuals older th...
A convoluted cerebriform pattern is a term used to denote the appearance of a sinonasal inverted papilloma on MRI. The appearance is seen on both T2 and post contrast T1 images and appears as alternating roughly parallel lines of high and low signal intensity.
This sign has been reported as pre...
The middle cranial fossa is a butterfly-shaped depression of the skull base, which is narrow in the middle and wider laterally. It houses the temporal lobes of the cerebrum.
The middle cranial fossa can be divided into medial and lateral parts. In the medial part, the following s...
The anterior cranial fossa constitutes the floor of cranial vault which houses the frontal lobes of the brain.
Structures present in the midline of anterior cranial fossa from anterior to posterior are:
groove for superior sagittal sinus
groove for anterior meningeal vessels
Thyroid-associated orbitopathy (TAO) is the most common cause of proptosis in adults and is most frequently associated with Graves disease.
On imaging, it is characterised by enlargement of the extraocular muscles' bellies (frequently: inferior rectus > medial rectus > superior rectus) sparing...
The pterygopalatine fossa (PPF) is a small but complex space of the deep face in the shape of an inverted pyramid located between the maxillary bone anteriorly, the pterygoid process posteriorly and inferior to the orbital apex. It is quite important as it is a neurovascular crossroad of the nas...
The superior oblique muscle is one of the 6 extra-ocular muscles that control eye movements. It abducts, depresses and internally rotates the eye.
innervation: trochlear nerve (CN IV)
origin: lesser wing of sphenoid bone and is outside of Annulus of Zinn located supero-medially.
The levator palpebrae superioris muscle is a small muscle of the superior orbit that elevates and retracts the upper eyelid. It is not part of the extra-ocular muscles; it does not insert on the globe and therefore does not produce eye movements. It is mostly composed of skeletal muscle but ther...
Paranasal sinus mucoceles represent complete opacification of one or more paranasal sinuses by mucus, often associated with bony expansion due to obstruction of the nasal sinus drainage.
Clinical presentation depends on two factors:
location and direction of expansion
The ciliary ganglion is one of four parasympathetic ganglia of the head and neck. It receives parasympathetic fibres from the oculomotor nerve.
smallest of the ganglia (2mm in size)
located posterolaterally in the intraconal space of the orbit (towards the orbital apex) between ...
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,...
Optic nerve meningiomas are benign tumours arising from the arachnoid cap cells of the optic nerve sheath, and represent ~20% of all orbital meningiomas, the majority of which are direct extensions from intracranial meningiomas.
These tumours typically appear as masses within the optic nerve, ...
Sphenoid wing dysplasia is a characteristic but not pathognomonic feature of neurofibromatosis type 1 (NF1), it can also occur in isolated cases.
Sphenoid wing dysplasia is seen in 5-10% of cases of NF1 and is one of the diagnostic criteria of NF1 5,6.
Its exact aetiol...
The superior orbital fissure is the communication between the cavernous sinus and the apex of the orbit. It is straddled by the tendinous ring which is the common origin of the four rectus muscles (extraocular muscles).
medial: body of sphenoid
superior: lesser wing ...
Orbital venous varix (OVV) is an uncommon vascular malformation which is composed of enlarged single or multiple tubular venous channels with direct communication to the systemic venous system.
Orbital venous varices are divided into primary and secondary. Primary orbital varices ...
Foramen ovale is an oval shaped opening in the middle cranial fossa located at the posterior base of the greater wing of the sphenoid bone, lateral to the lingula. It transmits the mandibular division of the trigeminal nerve (CN Vc), accessory meningeal artery, emissary veins between the caverno...
The optic canal is a cylindrical canal running obliquely through the lesser wing of sphenoid bone near the base where it joins the body of sphenoid. It transmits the optic nerve and ophthalmic artery. The optic canal opens into the skull base at the optic foramen.
The lesser wing of the sphenoid bone, or orbito-sphenoid, is a sharp, pointed triangular plate arising laterally from the upper anterior portion of the sphenoid body.
The lesser wing features both superior and inferior surfaces:
the superior surface is flattened and is in conta...
Cavernous venous malformations of the orbit, also known as cavernous haemangiomas, are the most common vascular lesion of the orbit in adults.
It is important to note that according to newer nomenclature (ISSVA classification of vascular anomalies) these lesions are merely known as slow flow ve...
Tolosa-Hunt syndrome (THS) is an idiopathic inflammatory condition that involves the cavernous sinus and orbital apex, and is essentially a clinical diagnosis of exclusion.
Clinically it refers to the presence of a painful ophthalmoplegia secondary to surrounding cavernou...
The bony orbit refers to the bones that constitute the margins of the orbits, that is the roof, medial and lateral walls and floor. The orbital margin or rim refers to the anterior circular margin of the orbit. The orbital apex refers to the posterior confluence of the orbit, where the optic can...
The orbital septum is a thin sheet of fibrous tissue that originates from the orbital rim periosteum and blends with the tendon of the levator palpebrae superioris superiorly and inserts into the tarsal plate inferiorly.
The orbital septum separates the intra-orbital fat from eyelid fat and orb...
Cloverleaf skull, also known as kleeblattschädel, refers to a type of severe craniosynostosis which gives the skull a cloverleaf shape. It is very rare, with less than 130 case reports globally. It typically results from intrauterine premature closure of the sagittal, coronal and lambdoid suture...
Lymph node enlargement is often used synonymously with lymphadenopathy, which is not strictly correct.
Lymphadenopathy (or adenopathy) is, if anything, a broader term, referring to any pathology of lymph nodes, not necessarily resulting in increased size; this includes abnormal num...
The ultrasound "U" classification of thyroid nodules has been developed by the British Thyroid Association (BTA) as part of their 2014 guidelines on the management of thyroid cancer 1.
It allows for stratifying thyroid nodules as benign, suspicious or malignant based on ultrasound appearances t...
De Quervain thyroiditis, or subacute granulomatous thyroiditis, is a form of self-limited subacute thyroiditis usually preceded by an upper respiratory tract viral infection such as mumps, measles, coxsackie virus, adenovirus, and influenza viruses.
It usually affects middle age f...
The naso-orbital-ethmoid (NOE) region or interorbital region simply refers to the space between the orbits.
anterior: frontal process of the maxilla, nasal process of frontal bone, nasal bone
posterior: sphenoid sinus
lateral: medial orbital wall
Retinoblastoma staging can be via a number of systems with various end-points and multiple systems are often used concurrently.
Reese Ellsworth classification
The Reese Ellsworth classification is assessed with fundoscopy and aims at predicting the chance of preserving the eye with ex...
Internal auditory canal (IAC) diverticulum are small focal outpouching arising from the anterolateral wall of the IAC.
In one study, they were identified in 5% of petrous temporal bone CT-scan 1. In the same study, it was coexisting with otosclerosis in 1% of cases 1.
Successful treatment of thyroid cancer highly depends on accurate preoperative staging.
Ultrasound and ultrasound-guided FNA or core biopsy remain the investigation of choice for diagnosing primary thyroid malignancies. CT and MRI are inferior to ultrasound for characterising thyroid nodules, h...
Retropharyngeal abscess is a potentially life-threatening infection involving the retropharyngeal space which requires prompt diagnosis and aggressive therapy.
Retropharyngeal abscesses are most frequently encountered in children, with 75% of cases occurring before the age of 5 ye...
The Capps triad refers to the constellation of clinical and imaging findings in patients with spontaneous retropharyngeal haematomas, and consists of:
tracheal and oesophageal compression
anterior displacement of the trachea
subcutaneous bruising over the neck and anterior chest
History and ...
Warthin tumours, also known as lymphomatous papillary cystadenomas, are benign, sharply demarcated tumours of the salivary gland. They are of lymphoid origin and most commonly arise from parotid gland tail. They may be bilateral or multifocal in up to 20% of cases and are the most common neoplas...
Pleomorphic adenomas, also known as benign mixed tumours (BMT's), are the most common salivary gland tumours.
On imaging, they commonly present as well circumscribed rounded masses, most commonly located within the parotid gland, showing to be hypoechogenic on ultrasound and with bright T2 sign...
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...
Carotidynia, also known as Fay syndrome, is a rare syndrome characterised by neck pain in the region of the carotid bifurcation.
There is confusion in the literature as to what this term actually refers to, with some authors suggesting that the term should be reserved for a pain syndrome with n...
The parietal and occipital bones in particular are common regions for accessory sutures because of their multiple ossification centres.
The occipital bone has complex development, ossifying from six centres. The foramen magnum is surrounded by four ossification centres. On each side are the exo...
The tentorial nerve is the first branch of the ophthalmic division of the trigeminal nerve (CN Va) which is the dominate dural nerve supplying most of the supratentorial dura. It specifically supplies the falx, calvarial dura and superior surface of the tentorium.
The infratemporal fossa is a complex space that lies posterolateral to the maxillary sinus and many important nerves and vessels traverse it.
The infratemporal fossa is the space between the skull base, lateral pharyngeal wall and the ramus of mandible.
The deep cervical fascia consists of 3 separate but related fascial layers that encircle structures in the neck and allow anatomic compartmentalisation. These layers cannot be visualized directly by cross sectional imaging. All 3 layers meet to form the carotid sheath. From superficial to deep, ...
The black turbinate sign refers to an area of non-enhancing mucosa on MRI in a patient with angioinvasive fungal sinus infection / rhinocerebral mucormycosis.
Mucormycosis is caused by fungi that include Mucor, Rhizopus, and Absidia species. It is seen in diabetic and immunocompromised patient...
The orbit is a feature of the face and contains the globe and it's supporting structures, as well as many nerves and vessels.
In the adult, the orbit has a volume of approximately 30 mL, of which the globe occupies 6.5 mL. It has a roof, floor, medial and lateral wall. The orbit ...
The petrous part of the temporal bone (or more simply petrous temporal bone, PTB) forms the part of skull base between the sphenoid and occipital bones.
The petrous temporal bone has a pyramidal shape with an apex and a base as well as three surfaces and angles:
The trigeminal nerve is the fifth cranial nerve and its primary role is relaying sensory information from the face and head, although it does provide motor control to the muscles of mastication. It is both large and complicated and has multiple brainstem nuclei (sensory and motor) as well as man...
The temporal fossa is located in the temporal region and communicates inferiorly with infratemporal fossa deep to the zygomatic arch.
The temporal fossa is bounded by a few anatomical landmarks, anteriorly the frontal process of the zygomatic bone, superiorly and posteriorly the...
The frontal bone is a skull bone that contributes to the cranial vault. It contributes to form part of the anterior cranial fossa.
The frontal bone has two portions:
vertical portion (squama): has external/internal surfaces
horizontal portion (orbital): has superior/inferior su...
The lateral pterygoid muscle, also known as pterygoideus externus or external pterygoid muscle, is one of the muscles of mastication.
The lateral pterygoid is a short, thick muscle, somewhat conical in form, which extends almost horizontally, posteriorly and laterally between th...
The squamous part of the temporal bone (or squamous temporalis/squamous temporal bone) is a very thin bone and forms the anterosuperior aspect of the temporal bone.
The squamous temporal bone's outer convex surface provides attachment to the temporalis muscle and forms a boundary...
The pterion is the H-shaped formation of sutures on the side of the calvarium representing the junction of four skull bones:
the greater wing of the sphenoid bone
squamous portion of the temporal bone
It is located at the the anterior end of the squamous suture, w...
The pterygoid processes or pterygoid plates are paired posteroinferior projections of the sphenoid bone.
Each pterygoid process projects inferiorly from the junction of the body and greater wing of the sphenoid bone and bifurcates into a medial pterygoid plate and a lateral ptery...
The body of the sphenoid bone is the midline cubical portion of the sphenoid bone, hollowed by the sphenoid air sinuses.
The body has superior, inferior, anterior, posterior, and lateral surfaces.
The superior surface features:
ethmoidal spine: prominent spine that articulates...
The middle meningeal artery branches off the first part of the maxillary artery. It passes vertically through the roots of the auriculotemporal nerve and enters the middle cranial fossa via the foramen spinosum. Here it gives off two branches - superior tympanic branch and ganglionic branch - be...
The foramen rotundum is located in the middle cranial fossa, inferomedial to the superior orbital fissure at the base of greater wing of the sphenoid bone. Its medial border is formed by lateral wall of sphenoid sinus. It runs downwards and laterally in an oblique path and joins the middle crani...
The deep temporal nerves are a pair of motor branches of the anterior division of the mandibular division of the trigeminal nerve. It should not be confused with the temporal branch of the facial nerve.
The two deep temporal nerves divide off the anterior division and course abov...
The sphenosquamosal suture is a vertical cranial suture between the sphenoid and temporal bones bilaterally. It is formed by the articulation between the posterior border of the greater wing of the sphenoid bone and the anterior border of the squamous part of the temporal bone 1.
The sphenofrontal suture is a cranial suture where the frontal bone meets the sphenoid bone bilaterally. From an anterior perspective of the skull, this suture appears in the roof of the bony orbits. From a lateral perspective, it appears as the meeting of the inferoposterior edges of the fronta...
The sphenopetrosal suture is the cranial suture connecting the greater wing of sphenoid with the petrous part of temporal bone in the middle cranial fossa. This fissure forms part of the posterior wall of the foramen lacerum.
The vertebral arteries (VA) are paired arteries, each arising from the respective subclavian artery and ascending in the neck to supply the posterior fossa and occipital lobes, as well as provide segmental vertebral and spinal column blood supply.
origin: branches off the 1st part of t...
The orbital spaces are important when considering different pathologies:
subdivided into anterior and posterior segments by the lens
optic nerve-sheath complex
central retinal artery and vein
surrounding sheath of meninges as an extension of the cerebr...
Cervical lymph node staging is important in a variety of tumours, especially squamous cell carcinoma of the head and neck.
TNM nodal staging
Nodal staging is the same for squamous cell carcinomas of most regions of the upper aerodigestive tract of the head and neck, including those of the of t...
The ballet sign refers to the paralysis of voluntary movements of the eyeball with preservation of the automatic movements. Sometimes this sign is present with exophthalmic goitre and hysteria.
The Coca-Cola bottle sign refers to the appearance of the muscles of the orbit in thyroid eye disease. The belly of the muscle enlarges with sparing of the tendinous insertion, giving the appearance of the traditional Coca-Cola bottle.
The enlargement of the muscles follows the I'M SLOW format...
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...
The uvea (also called the uveal layer or vascular tunic) is the middle three layers that make up the eye. It is the pigmented layer and its main function is of nutrition and gas exchange. It sits between the retina (innermost layer) and sclera.
It is traditionally split up into three anatomica...
Cervical lymph node groups describe the anatomic position of the nodes. It differs from cervical lymph node levels, covering all lymph nodes not just those relevant to head and neck surgery.
Groups described in the literature include but are not limited to:
A perilymphatic fistula (PLF) (also known as a labyrinthine fistula) is a pathologic communication between the fluid-filled space of the inner ear and the air-filled space of the middle ear, most commonly occurring at either the round or oval window.
The primary manifestations of perilymphatic...
The Delphian (prelaryngeal/precricoid) node is one of the cervical lymph node groups that comprise level VI cervical lymph nodes and is not routinely excised in radical neck dissections.
It is located between the cricothyroid muscles, above the thyroid isthmus, lying directly ant...
Lymph nodes in the neck have been divided into seven levels, generally for the purpose of squamous cell carcinoma staging. This system is not inclusive of several important groups, however, such as the supraclavicular, parotid, retropharyngeal space, and occipital nodes.
A useful mnemonic for remembering the differentials for pituitary region masses is:
S: sarcoid, sellar tumour (pituitary adenoma)
T: teratoma or tuberculosis (and other granulomatous diseases)
C: craniopharyngioma, cleft cyst (Rathke), ...
A mnemonic to remember the order in which extraocular muscles are involved in thyroid-associated orbitopathy (TAO) is:
I: inferior rectus
M: medial rectus
S: superior rectus
L: lateral rectus
There is some debate about this however. Some claim superior rectu...
A simple mnemonic to recall a list of commonly calcifying metastases is:
B: breast cancer
T: papillary thyroid cancer
O: ovarian cancer (especially mucinous)
M: mucinous adenocarcinoma (especially colorectal carcinoma)
Pott puffy tumour refers to a non-neoplastic complication of acute sinusitis characterised by a primarily subgaleal collection, also subperiosteal abscess and osteomyelitis. It is usually related to the frontal sinus but sometimes also related with the mastoid. Forehead swelling is seen, which i...
The inferior oblique muscle is one of six extra-ocular muscles that control eye movements.
innervation: inferior branch of the oculomotor nerve (CN III)
origin: orbital surface of the maxilla
insertion: globe (posterior, inferolateral surface)
primary function: one of two ocular ext...
The medial rectus muscle is one of the 6 extra-ocular muscles that control eye movements.
innervation: inferior branch of the oculomotor nerve (CN III)
origin: Annulus of Zinn (tendinous ring)
insertion: globe (anterior, medial surface)
primary function: one of three ocular adductor...
The lateral rectus muscle is one of the 6 extra-ocular muscles that control eye movements. It is responsible for abduction and is the only muscle that is innervated by the abducens nerve (CN VI). It should normally measure 2.9 ± 0.6mm.
innervation: abducens nerve (CN VI)
The inferior rectus muscles is one of the 6 extra-ocular muscles that control eye movements.
innervation: inferior branch of the oculomotor nerve (CN III)
origin: Annulus of Zinn (tendinous ring)
insertion: globe (anterior, inferior surface)
primary function: one of two ocular depre...
Superior rectus muscle is one of the 6 extra-ocular muscles that control eye movements.
innervation: superior branch of the oculomotor nerve (CN III)
origin: Annulus of Zinn (tendinous ring)
insertion: globe (anterior, superior surface)
primary function: one of two ocular elevators
The extra-ocular muscles are the six muscles that insert onto the eye and hence control eye movements:
superior rectus: elevation
superior oblique: intorsion
medial rectus: adduction
lateral rectus: abduction
inferior oblique: extorsion
inferior rectus: depression
The intraconal orbital compartment or intraconal space is the conical space within the orbit and musculofascial cone, the base of which is anterior and is formed by the posterior half of the globe. The sides are formed by the extraocular muscles and their surrounding fascia which pass posteriorl...
The extraconal orbital compartment or extraconal space is the space within the orbit outside the musculofascial cone. The base of which is anterior and is formed by the orbital septum that surrounds the equator of the globe. The external sides are formed by the bones of the orbit and their perio...
Phthisis bulbi, also known as end-stage eye, is an atrophic scarred and disorganised globe that may result from a variety of severe ocular insults.
The globe is reduced in size (usually < 20 mm) with a thickened/folded posterior sclera. Dystrophic calcification is common, and osseou...
Leukocoria (also spelled as leucocoria or leukokoria) refers to an abnormal white reflection from the retina of the eye. Despite its colour, the reflection is related to the familiar red-eye effect. Usually, when a light is shone through the iris, the retina appears red to the observer. In leuko...
Ectopia lentis refers to subluxation or dislocation of the lens of the eye secondary to dysfunction or disruption of zonular fibres.
systemic and syndromic disorders
typically upwards and out
most common spontaneous cause 2
homocystinuria - ty...
Malignant uveal melanomas, also referred as choroidal melanomas, are the most common primary tumour of the adult eye 3.
Malignant melanoma of the uvea is the most common primary intraocular malignancy and is predominantly seen in Caucasians 5. The incidence of these tumours incre...
Cataract is an opacification or thickening of the lens within the globe and is the leading cause of blindness in the world 2.
Visual deterioration occurs with increasing degrees of severity. The diagnosis is made clinically.
Common causes include:
The increased globe size or macrophthalmia may have many differentials:
buphthalmos (congenital glaucoma)
macrophthalmus in neurofibromatosis type 1 (NF1)
connective tissue disorders: Marfan syndrome, Ehlers-Danlos syndrome
Eye movements are a complex set of movements of the globe that are performed by the extra-ocular muscles that are grouped by the muscles that perform particular movements:
ocular internal rotators
ocular external rotators
Calcification of the globe has many causes, varying from the benign to malignant. When calcification is seen of the posterior half of the globe, it could relate to any of the layers (scleral, choroidal or retinal), as it is not possible to separate them out on CT.
drusen: 1% population...
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...
The mastoid part of the temporal bone is its posterior component.
The mastoid part is normally pneumatised by the mastoid air cells and is perforated by the mastoid foramen. The roof of the mastoid antrum, which separates the mastoid from the cranial cavity, is called the tegment...