The iliolumbar ligament is a strong band of connective tissue which courses from the transverse process of L5 (in over 96% of cases) to the posterior iliac wing and iliac crest. It functions to maintain the alignment of L5 on the sacrum during various movements 1, 2.
It is an important landmark...
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...
Intercalary bones are common discal ossifications that are usually triangular in morphology, found in the anterior annular fibers of an intervertebral disc, and are thought to be degenerative in aetiology.
flexion or extension teardrop fracture
The intercristal line (also known as Jacobys’s Line or Tuffier’s Line) is a horizontal line drawn across the highest points of both the iliac crests in an anteroposterior (AP) lumbar radiography 1,2
Intercristal line most often intersects the body of the L4 or its inferior endplate in men and t...
The interspinous ligaments join the spinous processes along their adjacent borders. They are composed of relatively weak fibrous tissue that fuses with the stronger, supraspinous ligaments.
A interspinous processes spacer (also known as decompression spacer or interspinous posterior device) is a device implanted between interspinous processes to open narrowed exiting foraminal nerve channels to treat lumbar radiculopathy caused by spinal stenosis. It is used as an alternative to l...
The intertransverse ligaments consist of fibrous tissue joining transverse processes of adjacent vertebrae. In the cervical region, intertransverse ligaments are scattered fibres that are largely replaced by intertransverse muscles. In the thoracic region, these are fibrous cords blending with t...
Intervertebral discs are located between the vertebral bodies of C2/3 to L5/S1, totalling 23 in the conventional spine. Together they account for approximately 25% of the total height of the vertebral column. This decreases with age as disc height is lost.
The upper thoracic discs are the thinn...
Intervertebral disc calcification is seen with numerous conditions.
degenerative: relatively common and may occur in up to 6% in routine abdominal radiographs in adults
ochronosis: very dense central (nucleus pulposus) calcification associated with osteopaenia; begins ...
Vacuum phenomena involving the intervertebral discs is usually a result of accumulation of gas (principally nitrogen) within the crevices of the intervertebral discs or adjacent vertebrae.
It is a relatively common occurrence which can be observed in 1-3% of spinal radiographs and...
The intervertebral foramina allow passage of structures out of and into the vertebral canal.
Anterior- lower posterolateral aspect of a vertebral body and the intervertebral disc below
in the cervical region a portion of the vertebral body below, predominately the uncinate proce...
There are three intervertebral joints between each adjacent vertebra from the axis to the sacrum – one between the vertebral bodies and a pair between the facets of adjoining vertebral arches (zygapophysial joints, also called facet joints).
flexion: the anterior interv...
Intervertebral osteochondrosis represents the pathologic degenerative process involving the intervertebral disc and the respective vertebral body endplates (not necessarily symptomatic). It is believed to be different and a further stage of spondylosis deformans, which is a consequence of normal...
Intradural disc herniations (IDH) occur when disc material related to an intervertebral disc hernia penetrate the spinal dura and lies in an intradural extramedullary location.
IDH correspond to a rare presentation of a common pathology, comprising ~0.28% of all disc herniations 2...
Intradural extramedullary metastases are rare and only account for approximately 5% of spinal metastases.
Please refer on leptomeningeal metastases (brain) to a general discussion focused on the brain's subarachnoid space involvement.
The age at presentation depends on tumour typ...
Intradural extramedullary neoplasms are located outside the spinal cord but within the dural sheath.
The most common presenting symptoms include weakness, back pain and radicular pain.
Schwannomas are the most common intradural extramedullary spinal lesions (...
Intradural lipomas are a subset of spinal lipomas. They are typically intradural, subpial, juxtamedullary lesions 1 although they have occasionally been reported as entirely intramedullary lesions 2.
Mature fatty tissue within the spinal dura can be seen in a number of entities:
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...
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
direct extension from leptomeninges
Intramedullary spinal tumours are rare, representing 4-10% of all CNS tumours and less than 10% of all paediatric CNS neoplasms 5. They account for 20% of all intraspinal tumours in adults and 35% of all intraspinal tumours in children 8.
A long duration of symptoms prior to diagnosis is typica...
The inverted Napoleon hat sign is a radiologic sign seen on the frontal pelvic or lumbar radiograph at the level of the 5th lumbar vertebra and the sacrum.
It is seen when there is bilateral spondylolysis with marked anterolisthesis of L5 on S1 or marked exaggeration of the normal lordosis at t...
The inverted "V" sign, also known as the inverted rabbit ears sign, is a radiological sign described in subacute combined degeneration of the spinal cord.
It refers to the appearance of the spinal cord on axial MRI slices 1-3. On these slices in a patient with subacute combined degeneration of...
Iodophenylundecylic acid (brand name = Myodil (Glaxo)) is an oily organic iodinated contrast material which was used for myelography. It is no longer used. Residual contrast remains for years. Has been implicated in development of arachnoiditis, perhapse of the order of 1%.
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.
The cause for an ivory vertebra depends on the age o...
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.
A typical mechanis...
Klippel-Feil syndrome (KFS) is a complex heterogeneous entity that results in cervical vertebral fusion. Two or more non-segmented cervical vertebrae are usually sufficient for diagnosis.
There is a recognised female predilection 1. KFS has an incidence of 1:40,000-42,000 2.
Kümmell disease is an eponymous name for avascular necrosis and collapse of a vertebral body.
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.
Laminectomy refers to unilateral or bilateral surgical removal of the lamina of a vertebra body. It is performed to decompress the spinal canal in spinal canal stenosis. This is typically caused by degenerative changes.
The most common site of the procedure is the lumbar spine.
The lateral corticospinal tract is formed at the level of the of the medullary pyramids when the majority (90%) of descending corticospinal tract fibres decussate – the majority of the remaining non-decussating 10% of fibres form the much smaller anterior corticospinal tract, with only a few non...
A lateral hemivertebra is a form of hemivertebra which occurs when one of the two chondrification centre fails to develop. They can be single or multiple. and a usually associated this a resultant scoliosis.
Various subtypes have been descrbied
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...
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...
Lateral thoracic meningoceles are a type of spinal meningocoele.
As with any meningocele, it results from herniation of the meninges through a foramen or a defect in the vertebral column.
They are typically associated with neurofibromatosis type I but can rarely occur...
Leptomeningeal drop-metastases correspond to a CNS primary neoplasm spread inferiorly along the cerebrospinal spaces. It is usually presented as diffuse enhancing nodules along the spine and cauda equina.
Please refer on leptomeningeal metastases to a broad discussion on this entity.
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).
Levine and Edwards classification is used to classify hangman fractures of C2 (also known as traumatic spondylolisthesis of axis).
type I: fracture with <3 mm antero-posterior deviation
no angular deviation
type II: fracture with >3 mm antero-posterior deviation
Lhermitte sign or the barber chair phenomenon is an electrical shock sensation running down the spine and into the limb on neck flexion. It suggests compression of the upper cervical spinal cord and/or brainstem.
It is typically seen with multiple sclerosis but is also associated wit...
The ligamentum flavum is a paired ligament which runs between adjacent laminae of the vertebral bodies. It forms part of the posterior ligamentous complex of the vertebral column.
paired, yellowish, elastic ligament
forms part of the posterior border of the spinal canal
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...
Limbus vertebra is a well-corticated osseous density, usually of the anterosuperior vertebral body corner, that occurs secondary to herniation of the nucleus pulposus through the the vertebral body endplate beneath the ring apophysis (see ossification of the vertebrae). These are closely related...
Fatty filum terminale, also known as lipoma of the filum terminale or filar lipoma, is a relatively common finding on imaging of the lumbar spine, and in most cases is an incidental finding of no clinical concern. However, in some patients it may be associated with signs and symptoms of tethered...
Lipomyelocele is one of the most common closed spinal dysraphism. It is seen in thoracolumbar region and usually presents as a fatty subcutaneous mass.
It is twice as common as lipomyelomeningocele.
Affected individuals are usually asymptomatic at birth, but many (~ 50%)...
Locked facet joint is a type of facet joint dislocation that results from jumping of the inferior articular process over the superior articular process of the vertebra below and becomes locked in the position.
It can be unilateral or bilateral.
The tip ...
Longitudinally extensive spinal cord lesions (LESCL), also known as longitudinally extensive transverse myelitis (LETM), represent extensive involvement of the spinal cord, with abnormal T2 signal traversing at least three vertebral body segments in length.
They are typi...
Loss of intervertebral disc space can be due to a variety of causes:
degenerative disc disease of the spine: most common cause
dialysis related spondyloarthropathy
crystal deposition diseases
Several conditions may give vertebral endplate T1 low signal on MRI. They include:
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...
Lumbar disc disease is a very common entity with a high asymptomatic prevalence. Intervertebral disc abnormalities are found in 25% of individuals below the age of 60, and over 50% in those over the age of 60. It is therefore not enough to demonstrate a disc lesion in someone with non-specific b...
The lumbar enlargement of the spinal cord corresponds to the mild increase in cross sectional area of the cord from the T11 level to the conus medullaris. It is enlarged due to the present of spinal nerve anterior rami which contribute to the lumbar and sacral plexuses.
Lumbar interlaminar epidural injections are one of some possible spinal epidural injections. For an alternative approach for the same region, please refer to the article on lumbar transforaminal epidural injections.
Typically, epidural injections are performed in patients with rad...
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.
origin: ventral rami of T12 to L5
course: formed within the substance of the psoas ma...
A handy mnemonic to recall the roots of the lumbar plexus is:
2 from 1, 2 from 2, 2 from 3
2 nerves from 1 root: ilioinguinal (L1), iliohypogastric (L1)
2 nerves from 2 roots: genitofemoral (L1/L2), lateral femoral cutaneous (L2/L3)
2 nerves from 3 roots: obturator (L2/L3/L4), femo...
Lumbar (or 13th) ribs are a rare anatomical variant and represent transitional vertebrae at the thoracolumbar junction with a prevalence of ~1% 1. It presents as an additional rib coming off T13 or L1 (depending on numbering classification) and may be unilateral or bilateral. Lumbar ribs are mos...
The lumbar spine consists of five adjacent vertebrae of the mid-lower vertebral column. They participate in the lumbar lordosis, a natural curve in the spine, that is convex anteriorly.
Articulations of the facet (zygapophyseal) joints permit flexion/extension and abduction movements. Rotation...
The lumbar spine AP view images the lumbar spine which consists of five vertebrae. It is utilised in many imaging contexts including trauma, postoperatively, and for chronic conditions.
the patient is erect or supine, depending on clinical history
ideally, spinal imaging sho...
Lumbosacral transitional vertebrae (LSTV) are a relatively common variant and can be seen in ~25% (range 15-35%) of the general population 1-3. Non-recognition of this variant and/or poor description in the report can lead to operations or procedures performed at the wrong level.
Depending on ...
Lymphoma of the spinal cord is an uncommon manifestation of lymphoma. Although lymphoma more commonly involves the vertebral body (vertebral body tumours) or epidural compartment, intramedullary lymphoma may rarely occur.
Apparent intramedullary spinal cord lymphoma may often, in fact, repres...
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.
A: compression injuries
A1: impaction fractures
A1.1: endplate impaction
A1.2: wedge impaction
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.
The Matterhorn sign is a descriptive sign for a calcified disc herniation that impales the dural sac and sometimes the cord, typically located in the thoracic spine.
History and etymology
The Matterhorn sign is named after one of the most iconic mountains in the Alps: the Matterhorn.
McAfee classification of acute traumatic spinal injuries is based on the three column concept of the spine. CT is needed for accurate assessment.
wedge compression: isolated anterior column compression
stable burst: anterior and middle column compression but posterior column i...
McRae line is a radiographic line drawn on a lateral skull radiograph or midsagittal section of CT or MRI, joining the basion and opisthion.
Normal position of the tip of dens is 5mm below this line. If the tip of the dens migrates above this line it indicates the presence of basilar invaginati...
Meningeal melanocytomas are rare benign primary melanocytic tumours of the CNS that are derived from leptomeningeal melanocytes. They can occur anywhere along the neuraxis but are most commonly found in the spinal canal near the foramen magnum, as well as the posterior fossa, Meckel’s cave, or a...
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...
Meningocele manqué (from French, literally "missed meningocele") is a rare condition characterized by focal dorsal tethering of the spinal cord. The term is used to designate a meningocele which failed to develop and became atretic.
It has been reported in neonates, but median age...
Modic type endplate changes represent a classification for vertebral body end-plate MRI signal, first described in 1988 1. It is widely recognised by radiologists and clinicians and is a useful shorthand for reporting MRIs of the spine.
Recently Modic type I has received renewed attention due t...
Modic type I endplate change is the most controversial and important of the three types described (see Modic endplate change). It is seen on MRI of the spine and represents the presence of low T1 and high T2 signal within the bone marrow of a vertebral body adjacent to a disk. Type 1 change can...
The modified Memphis criteria are a set of screening criteria for blunt cerebrovascular injury (BCVI) in trauma. The presence of one or more of these criteria makes necessary a complementary CTA or DSA study to exclude a BCVI.
The screening protocol criteria for BCVI are:
base of skull fractur...
Movements of the spine are possible due to intervertebral discs, and with the fulcrum of movement occurring primarily around the nucleus pulposus. Specialized motion occurs at the atlanto-occipital and atlantoaxial joints, which do not contain a disc.
The spine (vertebral column) forms the cent...
Disc degeneration can be graded on MRI T2 spin-echo weighted images using a grading system proposed by Pfirrmann 1. This classification is not used on routine spine reports, being more important for research purposes.
grade I: disc is homogeneous with bright hyperintense white signal intensity ...
Musculoskeletal hydatid infections are a very rare form of Echinococcosis/hydatidosis.
For a general discussion see hydatid disease.
Patients usually present with slow growing swelling with or without pain.
They can present almost anywhere, but most common loc...
Myelitis, is a collective term simply referring to any inflammation of the spinal cord. It is a form of myelopathy.
The two major sub types include:
ideopathic transverse myelitis
secondary transverse myelitis: viral, syphillis 2, ...
Myelomeningocoele, also known as spina bifida cystica, is a complex congenital spinal anomaly that results in spinal cord malformation (myelodysplasia).
It is one of the commonest congenital CNS anomalies and thought to occur in approximately 1:500 of live births 5. There may be ...
The naked facet sign (also known as the hamburger sign or reverse hamburger bun sign) refers to the CT appearance of an uncovered vertebral articular facet when the facet joint is dislocated, most often in cases of locked facet.
This CT sign is characteristic of a flexion-distraction injury an...
The differential diagnosis for masses of the cauda equina region is often considered separately to the remainder of the spinal cord. It is often difficult to determine whether masses in this region are intramedullary or intradural-extramedullary.
Most common tumours
Neoplasms of the spinal canal encompass a range of tumours which arise from or involve the spinal cord, theca and nerves.
These can be divided according to the tissue/structure of origin. Tumours of vertebral bodies are discussed separately: see vertebral body tumours.
Spinal cord ...
The neurenteric canal or canal of Kovalevsky is the transient communication of the amnion through notochordal canal to the yolk sac during notochordal formation at day 16-17.
Abnormalities during this stage produce the neurenteric cyst spectrum.
Neurenteric cysts are a rare type of foregut duplication cyst, accounting for ~1% of all spinal cord tumours. They are usually classified as spinal or intracranial, and are associated with vertebral or CNS abnormalities respectively.
Neurenteric cysts result from incomplete resorpti...
Neurogenic bladder is a term applied to a dysfunctional urinary bladder that results from an injury to the central or peripheral nerves that control and regulate urination. Injury to the brain, brainstem, spinal cord or peripheral nerves from various causes including infection, trauma, malignanc...
This page lists examples of normal imaging of the spine, divided by region and modality.
example 1: AP, lat, obliques only
example 2: PEG view
example 3: flexion and extension views only
example 4: paediatric - 12 years old
example 5: including Swimmer's view
The nucleus pulposus is the central part of each intervertebral disc.
It is located within the annulus fibrosus and between the vertebral body endplates. It is composed of a thin lattice of collagen fibres (type II) which traverse though hydrophilic glycosaminoglycans.
A nude nerve root is perhaps not as exciting as the name would suggest. It refers to an uncommon anatomical variant where nerve roots simply exit the theca without investing dural sleeves 1. These have been associated, at least in case reports, with spontaneous craniospinal hypotension 1.
Occipital condylar fractures result from high-energy blunt trauma and is a specific and localized type of basilar skull fracture.
The exact incidence of these fractures is unknown but are reported to occur in 3-4% patients with moderate-severe traumatic brain injuries 3.
Occipital vertebrae is a very rare anatomical variant and results from incomplete or aberrant fusion of occipital bone ossification centres. There is a broad spectrum of occipital vertebrae variations and the four most common include:
third condyle (condylus tertius)
Occult intrasacral meningocoele is a rare congenital lesion characterised by the presence of a cyst within the sacral thecal sac. It is an extradural sacral arachnoid cyst- Nabor's type Ib meningeal cyst. It is not a true meningocoele, since meninges are not involved.
It is associated with spin...
Ochronosis, or alkaptonuria, is a rare multisystem autosomal recessive metabolic disorder.
On imaging, the most particular presentation is on the spine, with osteoporotic bones and dense disc calcifications.
The term ochronosis usually refers to the bluish black discoloration of ...
Odontoid process fracture, also known as the peg or dens fracture, occurs where there is a fracture through the odontoid process of C2.
The mechanism of injury is variable, and can occur both during flexion or extension with or without compression 5.
There are two cl...
Olisthesis, also known as the etymologically less correct listhesis, means slipping or sliding.
It can be:
Oppenheimer ossicles are accessory ossicles associated with the facet joints found in ~4% (range 1-7%) 1 of lumbar spines.
Oppenheimer ossicles are thought to arise as a result of non-union of a secondary ossification centre of the articular process. They predominantly occur as a single, unila...
Opticospinal multiple sclerosis (OSMS) is a demyelinating disease and has been considered a variant of multiple sclerosis (MS) encountered in Asian populations, who are generally rarely affected by normal multiple sclerosis. It has similar clinical and imaging features to neuromyelitis optica (N...
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 ...
Ossification of the vertebral column is complex but an overview of primary and secondary ossification centres is given below:
Primary ossification centres
The C3-L5 vertebrae typically have three primary ossification centres that start appearing at 9 weeks in utero and finish primary ossificat...
Ossification of the ligamentum flavum (OLF) is a phenomenon where there is formation of ossific-calcific components in the ligamentum flavum. It is recognised causes of myelopathy (especially in the thoracic and to a lesser degree the cervical region).
The condition as a whole is ...