Articles

Articles are a collaborative effort to provide a single canonical page on all topics relevant to the practice of radiology. As such, articles are written and edited by countless contributing members over a period of time. A global group of dedicated editors oversee accuracy, consulting with expert advisers, and constantly reviewing additions.

441 results found
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Leptomeningeal metastases

Leptomeningeal metastases, also know as carcinomatous meningitis, refers to the spread of malignant cells through the CSF space. These cells can be originated both in primary CNS tumours (e.g. drop-metastases), as well as from distant tumours that have metastasised (haematogenous spread). This ...
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Sacral insufficiency fractures

Sacral insufficiency fractures are stress fractures, which are the result of normal stresses on abnormal bone, most frequently seen in the setting of osteoporosis. They fall under the broader group of pelvic insufficiency fractures. Clinical presentation They are usually seen in elderly female...
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Third condyle

The third condyle (also known as condylus tertius or median occipital condyle) is a rare anatomic variant of the occipital condyles. It is a small separate ossicle at the anteromedial margin of the occipital condyle formed by the failure of the embryonic proatlas (4th occipital sclerotome) to un...
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Intervertebral disc vacuum phenomena

The vacuum phenomena involving the intervertebral discs is a result of accumulation of gas (principally nitrogen) within the crevices of the intervertebral discs or adjacent vertebrae. Epidemiology It is a common occurrence which can be observed in 1-3% of spinal radiographs and may even reach...
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Vertebral pneumatocyst

Vertebral pneumatocysts refers to the presence of a gas-filled cavity within the vertebrae, more prevalent on the cervical spine. Intraosseous pneumatocysts are more common adjacent to the sacroiliac joint while it is rare in the vertebral column. Other causes of vertebral gas e.g. Kümmell disea...
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Kümmell disease

Kümmell disease is an eponymous name for avascular necrosis and collapse of a vertebral body. Pathology Kümmell disease represents delayed (usually two weeks) vertebral body collapse due to ischaemia and non-union of anterior vertebral body wedge fractures after major trauma. Risk factors Ri...
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Fluid sign (vertebral collapse)

The fluid sign is one of the radiological features of osteoporotic fractures, and can be helpful in distinguishing them from metastatic vertebral fractures, as it is seen more often in osteoporotic fractures and is rarely seen in metastatic fractures 1. It is not as helpful as identifying a para...
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Syrinx terminology

There are specific terms used when describing a syrinx or other cystic lesions within the spinal cord 1: hydromyelia: fluid accumulation/dilatation within the central canal, therefore, lined by ependyma syringomyelia: cavitary lesion within cord parenchyma, of any cause (there are many); locat...
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Roy-Camille classification of odontoid process fracture

The Roy-Camille classification of fractures of the odontoid process of C2 depends on the direction of the fracture line 1. The level of fracture line as described by the Anderson and D’Alonzo classification, is not predictive of the degree of instability or the risk of non-union. This classific...
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McAfee classification of thoracolumbar spinal fractures

McAfee classification of acute traumatic spinal injuries is based on the three column concept of the spine. CT is needed for accurate assessment. Classification wedge compression: isolated anterior column compression  stable burst: anterior and middle column compression but posterior column i...
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Occipital condyle fracture

Occipital condylar fractures result from high-energy blunt trauma and is a specific and localized type of basilar skull fracture. Epidemiology The exact incidence of these fractures is unknown but are reported to occur in 3-4% patients with moderate-severe traumatic brain injuries 3. Clinical...
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Spinal anatomy

Spinal anatomy encompasses the anatomy of all osseous and soft tissue structures of the spine and its immediate surroundings. However, the structures related to the spinal cord are covered in our neuroanatomy section. Overview The spine is located in the midline posteriorly, extending from the...
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Scheuermann disease

Scheuermann disease (also known as juvenile kyphosis, juvenile discogenic disease 11, or vertebral epiphysitis) is a common condition which results in kyphosis of the thoracic or thoracolumbar spine. The diagnosis is usually made on plain film. Epidemiology occurs in ~5% (range 0.4-8%) of the ...
Article

Spinal fractures

Spinal fractures are usually the result of significant trauma to a normally formed skeleton, or the result of trauma to a weakened spinal column. Examples include: Jefferson fracture: ring fracture of C1 hangman fracture: bilateral pedicle or pars fracture of C2 dens fracture flexion teardro...
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Bone within a bone appearance

Bone within a bone is a descriptive term applied to bones that appear to have another bone within them. There are numerous causes including: normal thoracic and lumbar vertebrae (neonates and infants) growth recovery lines (after infancy) cortical splitting and new periostitis sickle cell d...
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Bone within a bone appearance (mnemonic)

A useful mnemonic to remember the possible aetiologies of a bone within a bone appearance is: GHOST DRAGON Mnemonic G: growth arrest lines H: heavy metal, hypoparathryoid, hypothyroid O: osteopetrosis S: sickle cell anaemia, scurvy, syphilis T: thalassamia, tuberculosis D: disease of Caf...
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Boogard's angle

Boogard's angle is measured by drawing a line from basion to opisthion and another line along the plane of the clivus to the basion intersecting the first line - the angle between these two lines is measured . The normal angle is 126° +/- 6°. If the angle measures more than 136° it is indicativ...
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Vertebra plana

Vertebra plana (a.k.a. pancake / silver dollar / coin-on-edge vertebra) is the term given when a vertebral body has lost almost its entire height anteriorly and posteriorly, representing a very advanced compression fracture. Plural is vertebrae planae. It can occur in a variety of settings, incl...
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Coronal vertebral cleft

Coronal vertebral cleft refers to the presence of a radiolucent vertical defect on a lateral radiograph.   Epidemiology It is most often seen in premature male infants 1,3. As they can occur as part of normal variation (especially in the lower thoracic-upper lumbar spine of premature infants) ...
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Basion-dens interval

The basion-dens interval (BDI), as the name suggests, is the distance between the basion and the tip of the dens, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance from the most inferior portion of the basion to the closest point of the superior aspect of the ...
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Holocord presentation

Holocord presentation refers to a process which involves the spinal cord, from cervicomedullary junction to the tip of the conus. It does not relate to a specific condition nor does it distinguish between involvement by cystic expansion or solid tumour, or by a combination of both. It merely den...
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Empty thecal sac sign

The empty thecal sac sign or empty sac sign is when the thecal sac appears empty on MRI of the lumbar spine, best seen on T2-weighted images. If the empty thecal sac sign is present, a diagnosis of adhesive arachnoiditis can be made.​ Radiographic features MRI There is usually no gadolinium c...
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Traumatic spinal cord injury

Traumatic spinal cord injury can manifest as a wide variety of clinical syndromes resulting from damage to the spinal cord or its surrounding structures. It can result from minor injury if the spine is weakened from disease such as ankylosing spondylitis or if there is pre-existing spinal stenos...
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Haematomyelia

Haematomyelia refers to the presence of intramedullary haemorrhage or haematoma within the spinal cord. This is distinct from extramedullary haemorrhage, such as that seen in epidural haematomas. Although this can occur in the setting of trauma, the term is generally used to signify non-traumat...
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Atlas (C1)

The atlas is the first cervical vertebra, commonly called C1. It is an atypical cervical vertebra with unique features. It articulates with the dens of the axis and the occiput, respectively allowing rotation of the head, and flexion, extension and lateral flexion of the head.  Unlike the rest o...
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Dumbbell appearance of spinal tumours

The dumbbell appearance of spinal tumours refers to a tumour which has both a component within the canal and a component in the paravertebral space contiguous with each other via a thinner tumour component traversing the neural exit foramen. The appearance can be seen in: spinal nerve sheath t...
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Wedge fracture

Wedge fractures are hyperflexion injuries to the vertebral body resulting from axial loading. Most commonly affecting the anterior aspect, wedge fractures are considered a single-column (i.e. stable) fracture.  Less commonly wedge fractures refer to a subtype of tibial plateau fractures. This a...
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Jefferson fracture

Jefferson fracture is the eponymous name given to a burst fracture of C1. It was originally described as a four-part fracture with double fractures through the anterior and posterior arches, but three-part and two-part fractures have also been described. Pathology Mechanism A typical mechanis...
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Levine and Edwards classification

Levine and Edwards classification is used to classify hangman fractures of C2 (also known as traumatic spondylolisthesis of axis). Classification type I: fracture with <3 mm antero-posterior deviation no angular deviation type II: fracture with >3 mm antero-posterior deviation significant a...
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Thoracolumbar spinal fracture classification systems

There are several thoracolumbar spinal fracture classification systems: three column concept of thoracolumbar spinal fractures (Denis classification) Magerl classification McAfee classification thoracolumbar injury classification and severity score (TLICS)
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Magerl classification of thoracolumbar spinal fractures

The Magerl classification of thoracolumbar spinal fractures is based on the three column concept by Denis, and the McAfee classification. It relies exclusively on CT findings. Classification A: compression injuries A1: impaction fractures A1.1: endplate impaction A1.2: wedge impaction A1.3...
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Thoracolumbar injury classification and severity score (TLICS)

The thoracolumbar injury classification and severity score (TLICS) has been developed by the Spine Trauma Group to overcome some of the perceived difficulties regarding the use of other thoracolumbar spinal fracture classification systems for determining treatment 1. Classification Classificat...
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Cervical spine fracture classification systems

There are several cervical spine fracture classification systems: ​Anderson and D'Alonzo classification (odontoid fracture) Roy-Camille classification (odontoid fracture) Levine and Edwards classification (for traumatic injuries to axis) Allen and Ferguson classification (subaxial spine inju...
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Allen and Ferguson classification of subaxial cervical spine injuries

Allen and Ferguson classification is used for research purposes to classify subaxial spine injuries. It is based ofn the mechanism of injury and position of the neck during injury. This classification was proposed by Allen and Ferguson in 19823 and at the time of writing (July 2016) remains the ...
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Anderson and D'Alonzo classification of odontoid process fracture

The Anderson and D'Alonzo classification is the most commonly used classification of fractures of the odontoid process of C2. Classification type I rare fracture of the upper part of the odontoid peg above the level of the transverse band of the cruciform ligament usually considered stable...
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Odontoid fracture

Odontoid process fracture, also known as the peg or dens fracture, occurs where there is a fracture through the odontoid process of C2. Pathology The mechanism of injury is variable, and can occur both during flexion or extension with or without compression 5. Classification There are two cl...
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Cervical spine fractures

Cervical spine fractures can occur secondary to exaggerated flexion or extension, or because of direct trauma or axial loading. Pathology The cervical spine is susceptible to injury because it is highly mobile with relatively small vertebral bodies and supports the head which is both heavy and...
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Disc herniation

Disc herniation refers to the displacement of intervertebral disc material beyond the normal confines of the disc but involving less than 25% of the circumference (to distinguish it from a disc bulge. A herniation may contain nucleus pulposus, vertebral endplate cartilage, apophyseal bone/osteop...
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Ventral cord herniation

Ventral cord herniation, also known by a variety of other terms such as spontaneous thoracic cord herniation or idiopathic spinal cord herniation, is a rare cause of focal myelopathy due to herniation of the thoracic cord through a dural defect.  Post surgical cord herniation can occur at any l...
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Spinal cord stimulator

A spinal cord stimulator is a surgically placed device to aid with symptom relief in individuals with chronic neurological pain resulting from, for example, post failed spinal surgery, brachial plexopathy, post laminectomy syndrome etc.) It uses low voltage electrical current delivered by elect...
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Diffuse T1 bone marrow signal loss

Diffuse T1 vertebral bone marrow signal loss has a number of causes. T1-weighted imaging without fat suppression is one of the most important sequences for distinguishing between normal and abnormal bone marrow. Given the homogeneity, this appearance can often be difficult to spot as abnormal.  ...
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Basilar invagination

Basilar invagination, also called basilar impression, is a congenital or acquired craniocervical junction abnormality where the tip of the odontoid process projects above the foramen magnum.  Terminology The terms basilar invagination and basilar impression are often used interchangeably becau...
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Intramedullary spinal metastasis

Intramedullary spinal metastases are rare, occurring in ~1% of autopsied cancer patients, and are less common than leptomeningeal metastases. Intramedullary lesions may result from: growth along the Virchow-Robin spaces haematogenous dissemination direct extension from leptomeninges Epidemi...
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Anterior spinothalamic tract

The anterior spinothalamic tract, also known as the ventral spinothalamic fasciculus, is an ascending pathway located anteriorly within the spinal cord, primarily responsible for transmitting coarse touch and pressure.  The lateral spinothalamic tract (discussed separately), in contrast, primar...
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Column of Goll

The column of Goll, also known as the gracile fasciculus or fasciculus gracilis, represents the medial portion of the dorsal columns and carries input from below and including T7 1. Function The gracile fasciculus is responsible for transmitting vibration, conscious proprioception, and fine (d...
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Lateral spinothalamic tract

The lateral spinothalamic tract, also known as the lateral spinothalamic fasciculus, is an ascending pathway located anterolaterally within the peripheral white matter of the spinal cord. It is primarily responsible for transmitting pain and temperature as well as coarse touch.  The anterior sp...
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Basion-axial interval

The basion-axial interval (BAI), as the name suggests, is the horizontal distance between the basion and the posterior cortex of the axis, used in the diagnosis of atlanto-occipital dissociation injuries. It is the distance (in mm) between the basion and the superior extension of the posterior ...
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Magnetic resonance neurography

Magnetic resonance neurography (MRN) is a relatively new non-invasive imaging technique for dedicated assessment of peripheral spinal nerves. It is used to assess peripheral nerve entrapments and impingements as well as localization and grading of nerve injuries and lesions. Dedicated high-res...
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Cauda equina syndrome

Cauda equina syndrome refers to a collection of symptoms and signs that result from severe compression of the descending lumbar and sacral nerve roots. It is considered a diagnostic and surgical emergency.  Epidemiology Cauda equina syndrome is rare with prevalence estimated at approximately 1...
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Tarlov cyst

Tarlov cysts, also called perineural cysts, are CSF filled dilatations of the nerve root sheath at the dorsal root ganglion (posterior nerve root sheath). These are type II spinal meningeal cysts that are, by definition, extradural but contain neural tissue. Epidemiology They occur in ~5% of t...
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Sagittal balance (C7 plumb line)

Sagittal balance forms part of the plain radiographic assessment of spinal deformity including kyphotic or lordotic deformities and scoliosis. There are numerous ways of assessing this, using various bony landmarks and angles to evaluate whether or not a normal distribution of weight and stresse...
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Spinal meningioma

Meningiomas arising from the coverings of the spinal cord represent a minority of all meningiomas (approximately 12% 5) but are the second most common intradural extramedullary spinal tumour representing 25% of all such tumours 2. Despite usually being small, due to the confines of the spinal ca...
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Dagger sign (spine)

The dagger sign is a radiographic feature seen in ankylosing spondylitis as a single central radiodense line on frontal radiographs related to ossification of the supraspinous and interspinous ligaments.
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Curtain sign

The curtain sign (or draped curtain sign) in neuroimaging refers to the appearance of a vertebral body mass that extends to the anterior epidural space. The posterior longitudinal ligament is strongly attached to the posterior vertebral body cortex in the midline and is more loosely attached la...
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Lumbar plexus

The lumbar plexus is a complex neural network formed by the lower thoracic and lumbar ventral nerve roots (T12 to L5) which supplies motor and sensory innervation to the lower limb and pelvic girdle. Summary origin: ventral rami of T12 to L5 course: formed within the substance of the psoas ma...
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Vertebral vascular foramen

Vertebral vascular foramina are normal findings seen on cross-sectional imaging and should not be mistaken for a fracture, especially in the setting of trauma. They transmit: basivertebral veins (forms Hahn's canal): foramen is seen on the posterior surface of the vertebral body in the midline...
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Ependymoma vs astrocytoma of the spinal cord

A number of factors are useful when differentiating between spinal cord ependymoma and spinal cord astrocytoma.  Ependymoma child or adult more central in location bone remodelling is common low T1 signal well-defined enhancement syrinx is more common haemorrhage is more common Astrocyt...
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Fluoroscopy guided lumbar puncture

Fluoroscopy-guided lumbar puncture (LP) is a minimally invasive, image-guided diagnostic and therapeutic procedure that involves the removal of a small volume of cerebrospinal fluid (CSF) from, or an injection of medication or other substance (e.g. radiotracer, chemotherapy agents) into the lumb...
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Spinal cord compression (summary)

  Spinal cord compression is a surgical emergency and if unrecognised or untreated, can result in irreversible neurological damage and disability. If the spinal roots below the conus medullaris are involved, it is termed cauda equina syndrome. Reference article This is a summary article; read...
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Atlanto-occipital assimilation

Atlanto-occipital assimilation is the fusion of the atlas (C1) to the occiput and is one of the transitional vertebrae.  Epidemiology Atlanto-occipital assimilation occurs in approximately 0.5% (range 0.25-1%) of the population 2-4.  Clinical presentation Atlanto-occipital is typically asymp...
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Insufficiency fracture

Insufficiency fractures are a type of stress fracture, which are the result of normal stresses on abnormal bone. They should not be confused with fatigue fractures which are due to abnormal stresses on normal bone, or with pathological fractures, the result of diseased, weakened bone due to foca...
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Corduroy sign (vertebral haemangioma)

The corduroy sign refers to vertically-oriented, thickened trabeculae seen in intraosseous haemangiomas of the spine. It is the sagittal/coronal equivalent of the polka-dot sign seen on axial imaging.  It is caused by the replacement of the normal cancellous bone by thickened vertical trabecula...
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Bullet-shaped vertebra

Bullet-shaped vertebra refers to the anterior beaking of the vertebral body. It is seen in the following conditions: mucopolysaccharidosis (Morquio disease, Hurler disease) achondroplasia congenital hypothyroidism  See also weapons and munitions inspired signs
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Spinal subarachnoid space

The spinal subarachnoid space is the space between the arachnoid mater and pia mater in the spine and is continuous with the intracranial subarachnoid space.  It communicates with the intracranial subarachnoid space via the foramen magnum and ends at the level of the S2 vertebra.  It is a relat...
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Lumbar cistern

The lumbar cistern refers to the subarachnoid space in the lower lumbar spinal canal. The cistern is an enlargement of the subarachnoid space in the dural sac, distal to the conus medullar is. It contains cerebrospinal fluid and the nerve roots of the cauda equina. As the conus (usually) termin...
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Spinal cord blood supply

The spinal cord blood supply is formed by many different vessels with an extensive collateral supply and drainage. Arterial supply The spinal cord is supplied by three longitudinal arteries: single anterior spinal artery: supplies the anterior two-thirds of the spinal cord paired posterior s...
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Spinal dura mater

The spinal dura mater is the outermost layer of the meninges that surround the spinal cord. Gross Anatomy The spinal dura mater is a fibrous, non-adherent, tough layer surrounding the spinal cord.  It is separated from the wall of the vertebral canal by the epidural space. This space contains ...
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WHO classification of CNS tumours

The WHO classification of CNS tumours is the most widely accepted system for classifying CNS tumours and was based on the histological characteristics of the tumour. Although the most recent version of the 'blue book' is the 4th edition from 2007, an update has been released in 2016 3, which sho...
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Vertebral artery

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. Summary origin: branches off the 1st part of t...
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Bamboo spine

Bamboo spine is a radiographic feature seen in ankylosing spondylitis that occurs as a result of vertebral body fusion by marginal syndesmophytes. It is often accompanied by fusion of the posterior vertebral elements as well.  A bamboo spine typically involves the thoracolumbar and/or lumbosacr...
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Baastrup syndrome

Baastrup syndrome (also referred to as kissing spines) results from adjacent spinous processes in the lumbar spine rubbing against each other and resulting in hypertrophy and sclerosis with focal midline pain and tenderness relieved by flexion and aggravated by extension.  Epidemiology It tend...
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Scottie dog sign (spine)

The Scottie dog sign refers to the normal appearance of the lumbar spine when seen on oblique radiographic projection. On oblique views, the posterior elements of the vertebra form the figure of a Scottie dog with: the transverse process being the nose the pedicle forming the eye the inferior...
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Andersson lesion

Andersson lesions refer to an inflammatory involvement of the intervertebral discs by spondyloarthritis. Epidemiology Rheumatic spondylodiscitis is a non-infectious condition that has been shown to occur in about 8% of patients with ankylosing spondylitis, as detected at radiography. Patholog...
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Intradural spinal mass lesions (an approach)

Intradural spinal mass lesions are relatively uncommon, compared to intracranial or extradural masses, and can be challenging to diagnose. Additionally, the need for a pre-operative/non-operative diagnosis is in many ways greater as biopsy of lesions within the cord has the potential of devastat...
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Spinal haemangioblastoma

Spinal haemangioblastomas are the third most common intramedullary spinal neoplasm, representing 2-6% of all intramedullary tumours 1,4,7. This article specifically relates to spinal hemangioblastomas. For a discussion on intracranial hemangioblastomas and a general discussion of the pathology ...
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Spinal muscular atrophy

Spinal muscular atrophy (SMA) is a type of congenital neuromuscular disease affecting anterior horn cells of the brainstem and spinal cord. Epidemiology This disorder affects 1 in 6000-10000 infants 1. Clinical presentation The condition typically affects infants and young children, presenti...
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Meningocele

Meningoceles are protrusions of the meninges through a defect or weak point in the skull or spine, usually involving the soft tissues beneath the surface of the skin. They are typically categorized into congenital, iatrogenic (e.g. following a craniotomy, sinus surgery, or as a laminectomy compl...
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Lateral meningocele syndrome

The lateral meningocele syndrome is an extremely rare hereditary connective tissue disorder characterized by multiple lateral lumbar meningoceles, distinctive facial features, joint hypermobility, hypotonia, skeletal abnormalities, congenital cardiovascular malformations, urogenital anomalies an...
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Lateral thoracic meningocele

Lateral thoracic meningoceles are a type of spinal meningocoele. Pathology As with any meningocele, it results from herniation of the meninges through a foramen or a defect in the vertebral column.  Associations They are typically associated with neurofibromatosis type I but can rarely occur...
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Diffuse idiopathic skeletal hyperostosis

Diffuse idiopathic skeletal hyperostosis (DISH), also referred to as Forestier disease, is a common condition characterised by bony proliferation at sites of tendinous and ligamentous insertion of the spine affecting elderly individuals. On imaging, it is typically characterised by the flowing ...
Article

Spondylodiscitis

Spondylodiscitis is characterised by infection involving the intervertebral disc and adjacent vertebrae. Epidemiology Spondylodiscitis has a bimodal age distribution, which many authors consider essentially as separate entities: paediatric older population ~50 years Clinical presentation T...
Article

Ivory vertebra sign

The ivory vertebra sign refers to diffuse and homogeneous increase in opacity of a vertebral body that otherwise retains its size and contours, and with no change in the opacity and size of adjacent intervertebral discs. Pathology Aetiology The cause for an ivory vertebra depends on the age o...
Article

Abscess

Abscesses are focal confined collections of suppurative inflammatory material and can be thought of as having three components 1: a central core consisting of necrotic inflammatory cells and local tissue peripheral halo of viable neutrophils surrounded by a 'capsule' with dilated blood vessel...
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Spinal cord

The spinal cord is the part of the central nervous system that is found within the vertebral canal of the vertebral column.  Gross anatomy It measures approximately 42-45 cm in length, ~1 cm in diameter and 35 g in weight.  It is divided into cervical, thoracic and lumbar parts and terminates...
Article

Atlanto-occipital articulation

The atlanto-occipital articulation is comprised of a pair of condyloid synovial joints that connect the occiput (C0) to the first cervical vertebra (atlas/C1). Gross anatomy Articulations Each joint is comprised of two concave articular surfaces on the superior aspect of the lateral mass of a...
Article

Cruciate ligament of the atlas

The cruciate ligament of the atlas (also known as the cruciform ligament) is an important ligamentous complex that holds the posterior dens of C2 in articulation at the median atlantoaxial joint. It lies behind a large synovial bursa (surrounded by loose fibrous capsule) and consists of two band...
Article

Paracondylar process

Paracondylar process is a rare anatomical variant of the occipital bone, where a bony exostosis extends caudally from the paracondylar region (lateral to the native occipital condyles), typically articulating with the superior surface of a transverse process of the atlas. This may be unilateral ...
Article

Ligamentum nuchae

The ligamentum nuchae is a large median ligament composed of tendons and fascia located between the posterior muscles of the neck. It covers the spines of C1 to C6 vertebrae. It is a superior and posterior extension of the supraspinous ligament. It rises from the spinous process of C7 to the ini...
Article

Os odontoideum

Os odontoideum is an anatomic variant of the odontoid process of C2 and needs to be differentiated from persistent ossiculum terminale and from a type 2 odontoid fracture. It can be associated with atlantoaxial instability.  Although it was originally thought to be a congenital lesion due to a ...
Article

Axis (C2)

The axis is the second cervical vertebra, commonly called C2. It is an atypical cervical vertebra with unique features and important relations that make it easily recognisable. Its most prominent feature is the odontoid process, which is embryologically the body of the atlas (C1) 1,2. It plays a...
Article

Anterior longitudinal ligament

The anterior longitudinal ligament (ALL) arises from the anteroinferior basilar portion of occipital bone, traverses the entire length of the spine, and ends on the anteriosuperior portion of the sacrum. The ALL runs along the anterior surface of the vertebral bodies (firmly united to the perio...
Article

Posterior atlanto-occipital membrane

The posterior atlanto-occipital membrane attaches the upper border of the posterior arch of the atlas (C1) to the outer margin of the foramen magnum. It is continuous with the posterior atlantoaxial membrane and ligamentum nuchae and lies immediately posterior to the dura. Posteriorly lie the su...
Article

Anterior atlanto-occipital membrane

The anterior atlanto-occipital membrane is a thin membrane that joins the upper border of the anterior arch of the atlas (C1) to the anterior inferior surface of the foramen magnum. It is a continuation of the anterior longitudinal ligament above the C1 level. It is immediately posterior to the ...

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