The perivertebral space is one of the seven deep compartments of the head and neck.
The perivertebral space is a cylinder of soft tissue lying posterior to the retropharyngeal space and danger space surrounded by the prevertebral layer of the deep cervical fascia and extends from...
The ossiculum terminale appears as a secondary ossification centre of the dens between 3-6 years and normally fuses by 12 years. Failure of fusion results in a persistent ossiculum terminale (also called Bergmann's ossicle or ossiculum terminale of Bergmann) and is considered a normal anatomical...
Picture frame vertebral body is a radiologic appearance in which the cortex of the vertebral body is thickened. This sign is seen in a patient with Paget disease.
This is a result of disorganized new cortical bone formation after excessive osteoclastic activity causes the resorption of normal ...
A pine cone bladder or christmas tree bladder is a cystogram appearance in which the bladder is elongated and pointed with thickened trabeculated wall. It is typically seen in severe neurogenic bladder with increased sphincter tone (detrusor sphincter dyssynergia) due to suprasacral lesions (abo...
Pneumatic nerve root compression is a term given nerve root compression due to a presence of a juxtradiscal herniated gas locule. It is not a very common occurence 2. The gas locules in these instances typically arise herniation of intradiscal gas which occur as part of disc degenerative change....
Pneumorrhachis (PR) refers to a rare phenomenon characterized by the presence of air within the spinal canal (either intra- or extradural).
Patients can often be asymptomatic 3.
PR can result from a number of causes:
trauma (traumatic pneumorrhachi...
Polio-like paralysis refers to a paralytic state which is similar in clinical appearance to polio, but from which poliovirus is not isolated. Like polio, the main presenting symptoms is acute flaccid paralysis.
There are many causes, some of which are infective, e.g. coxsackie A9 and...
The polka-dot sign is the result of the replacement of the normal cancellous bone by thickened vertical trabeculae surrounded by fat marrow or vascular lacunae in vertebral intraosseous haemangiomas 2. It is the axial equivalent of the corduroy sign seen on sagittal and coronal images. On CT the...
Posterior ring apophysis fractures occur in the immature skeleton, most commonly in the lumbar spine.
Typically, adolescent males practicing sport activities.
muscle weakness related with root innervation
association with Scheuermann ...
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...
Posterior cord syndrome (also known as posterior spinal artery syndrome) is a rare syndrome associated with spinal cord injury. It is caused due to a lesion in the posterior column of spinal cord or occlusion of the posterior spinal artery.
The syndrome is clinically characterized by isolated l...
The posterior ligamentous complex acts to stabilise the vertebral column and is made up of the following structures:
facet joint capsule
In particular, it acts to hold the facet joints of the neighbouring vertebrae in fixed relat...
The posterior longitudinal ligament (PLL) arises from the back of the axis (C2) body and travels downward and posterior to the vertebral bodies (attached loosely) and intervertebral discs (firmly attaching to the posterior annulus), attaching to the back of the sacrum. It narrows as it travels d...
Posterior lumbar subcutaneous oedema is a very frequent finding on MRI of spine. A clinical correlation is almost always required to identify the significance of this.
overweight (raised BMI)
age (advancing age)
sex (more common in females)
posterior compartment degenerati...
The posterior spinal arteries are a pair of arteries that supply the respective ipsilateral grey and white posterior columns of the spinal cord.
The posterior spinal arteries arise from either the posterior inferior cerebellar or vertebral arteries (V3 or V4 segments) and runs t...
Pott disease, also known as tuberculous spondylitis, refers to vertebral body and intervertebral disc involvement with tuberculosis (TB). The spine is the most frequent location of musculoskeletal TB, and commonly related symptoms are back pain and lower limb weakness/paraplegia.
Powers ratio is a measurement of the relationship of the foramen magnum to the atlas, used in the diagnosis of atlanto-occipital dissociation injuries.
The ratio, AB/CD, is measured as the ratio of the distance in the median (midsagittal) plane between the:
basion (A) and the posterior spinola...
The most common tumour of the spine is metastatic deposits. A number of both benign and malignant tumours may arise primarily from the spine.
giant cell tumour (GCT)
aneurysmal bone cyst (ABC)
eosinophilic granuloma (EG)
Pseudosubluxation of the cervical spine is the physiological anterior displacement of C2 on C3 in children. It is common in children <7 years, and less often present in older children. Less often it is seen at C3 on C4. It is more pronounced in flexion and is of clinical significance as it can b...
The quadratus lumborum muscle is an irregular quadrilateral muscle that forms part of the posterior abdominal wall.
location: dorsal abdominal wall
attachments: medial half of inferior margins of 12th ribs and upper four lumbar transverse processes
branches of the lumba...
Rachischisis (somtimes known as complete spina bifida) refers to a severe form of spina bifida where there is a cleft through the entire spine.
There is often a severe or complete defect involving the entire spine from the cervical region through to the sacrum.
Radiation induced MRI signal changes in bone are the earliest detectable changes in bone. They increase with increase in the radiation dose.
1st week: decreased marrow cellularity with oedema and haemorrhage
2nd week: increased marrow cellularity due to influx from unirradiated area...
The retrodural space of Okada is a wishbone-shaped potential space which links the facet joints to each other at a single level across the midline, and thus acts as a potential pathway for the spread of injected material (contrast, air, steroid, local anaesthetic) as well as infection.
The term retrolisthesis refers to posterior displacement (backward slip) of a vertebral body relative to one below. Causes include trauma, facet joint osteoarthritis or congenital anomalies (e.g. underdevelopment of the pedicles).
A retropulsed fragment is any vertebral fracture fragment that is displaced into the spinal canal, thereby potentially causing spinal cord injury.
They usually arise from the vertebral body with or without a portion of the pedicle, and are displaced posteriorly, hence the prefix 'retro'.
The Romanus lesion represents an early finding in inflammatory spondyloarthropathies, such as ankylosing spondylitis and enteropathic arthritis, and appears as irregularity and erosion involving the anterior and posterior edges of the vertebral endplates 1. Healing response to these inflammatory...
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...
The rubrospinal tract contains neurons that carry signals from the corticorubral tract. The tract is thought to excite flexor muscles and inhibit extensor muscles.
The magnocellular portion of the red nucleus gives rise to the rubrospinal tract. It decussates...
Rugger-jersey spine describes the prominent subendplate densities at multiple contiguous levels to produce an alternating sclerotic-lucent-sclerotic appearance. This simulates the transverse bands of a rugby jersey.
This term and pattern are distinctive for hyperparathyroidism.
Sacral agenesis (also considered as part of the caudal regression syndrome) is a rare and severe sacral developmental abnormality.
In normal pregnancy, the incidence is between 0.005 and 0.1%. However, in fetuses with diabetic mothers, the incidence rises to 0.2%. Of those with th...
Sacral dimples are a clinical and radiological feature that is associated with occult spinal dysraphism (e.g. tethered cord syndrome) but are more frequently a non-significant isolated finding.
Common in healthy children (~5%) 1.
Simple sacral dimples have the followin...
The sacral hiatus corresponds to the posterior caudal opening at the end of the sacral canal, which usually occurs at the fifth sacral vertebra (S5), at the posterior surface of the sacrum.
Commonly, the sacral hiatus corresponds to the non-formation of S5 spinous proce...
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.
They are usually seen in elderly female...
Sacrococcygeal teratoma (SCT) refers to a teratoma arising in the sacrococcygeal region. The coccyx is almost always involved 6.
It is the commonest congenital tumour in the fetus 11 and neonate 3. The incidence is estimated at ~1:35000-40000. There is recognised female predilecti...
The sacroiliac (SI) joint is a synovial and fibrous joint between ilium and the sacrum. It has little movement and its main function is to transfer weight between the axial and lower appendicular skeletons. The SI joint is a symmetrical joint (i.e. is paired) with an oblique coronal orientation ...
The sacrum is the penultimate segment of the vertebral column and also forms the posterior part of the bony pelvis. It transmits the total body weight between the lower appendicular skeleton and the axial skeleton.
The sacrum is an irregularly-shaped bone, roughly an inverted tri...
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...
Sandwich vertebral body is a radiologic appearance in which the endplates are densely sclerotic, giving the appearance of a sandwich.
This term and pattern are distinctive for osteopetrosis.
the sandwich vertebrae appearance resembles Rugger-jersey spine but can be diff...
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.
occurs in ~5% (range 0.4-8%) of the ...
Schmorl nodes, also referred as intravertebral disc herniations, refer to protrusions of the cartilage of the intervertebral disc through the vertebral body endplate and into the adjacent vertebra. The protrusions may contact the marrow of the vertebra, leading to inflammation.
Scoliosis is defined as an abnormal lateral curvature of the spine. It is quite common in young individuals and is often idiopathic and asymptomatic. In some cases, however, it is the result of underlying structural or neurological abnormalities.
By definition, a scoliosis is any lateral spina...
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
Sesamoid ossicles of the nuchal ligament are a relatively common anatomical variant that are usually asymptomatic and most commonly occur at the C5/6 or C6/7 vertebral levels.
They occur in ~7.5% of the population, with a male predominance of 3:1 1.
The shiny corner sign is a spinal finding in ankylosing spondylitis, representing reactive sclerosis secondary to inflammatory erosions at the superior and inferior endplates (corners on lateral radiograph) of the vertebral bodies which are known as Romanus lesions. Eventually, the vertebral bod...
Solitary bone plasmacytomas (SBP) may involve any bone, but they have a predisposition for the red marrow-containing axial skeleton:
spinal disease is observed in ~50% (range 34-72%) of cases
the thoracic vertebrae are most commonly involved, followed by lumbar, sacral, and cervical vertebrae
Spina bifida is a type of neural tube defect/spinal dysraphism which can occur to varying degrees of severity. It is often considered the most common congenital CNS malformation.
The estimated incidence is at 1:1000-2000 live births 2.
A constellation of fe...
Spina bifida occulta is the mildest form of spina bifida and is a type of neural tube defect that affects the spinal cord.
Spinda bifida occulta is the commonest form of spina bifida, and is estimated to affect between 10-20% of the population in most western countries.
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.
The spine is located in the midline posteriorly, extending from the...
Spinal arachnoid cysts are relatively uncommon and may be either intradural (type III meningeal cyst) or extradural (type IA meningeal cyst).
This article specifically focuses on spinal arachnoid cysts. For a general discussion of arachnoid cysts, refer to the main article: arachnoid cyst.
Spinal arteriovenous malformations (AVMs) are characterised by arteriovenous shunting with a true nidus. They represent ~25% of spinal vascular malformations.
Different types of spinal AVM (see below) have differing age of presentation, but overall 80% present between the age 20 ...
Spinal astrocytomas are the second most common spinal cord tumour overall, representing 40% of intramedullary tumours 3. They account for 60% of paediatric intramedullary tumours, making them the most common spinal cord tumour in children 6.
This article specifically relates to spinal astrocyto...
The spinal cord is the part of the central nervous system that is found within the vertebral canal of the vertebral column.
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...
The spinal cord blood supply is formed by many different vessels with an extensive collateral supply and drainage.
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...
Spinal cord cavernous malformations, also known as spinal cavernomas, are vascular malformations that occur within the spinal cord.
This article specifically relates to spinal cord cavernomas. For a discussion of cerebral cavernomas and a general discussion of the pathology refer to the main ar...
Spinal cord compression is a surgical emergency, usually requiring prompt surgical decompression to prevent permanent neurological impairment.
There are numerous causes of cord compression. These can be divided according to the location of the compressing mass:
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.
This is a summary article; read...
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...
Spinal dermoid cysts are uni or multilocular cystic tumours lined by squamous epithelium containing skin appendages (hair follicles, sweat glands, sebaceous glands) 6. They are congenital in origin.
Forty percent are intramedullary, and 60% are extramedullary 6.
This article specifically relat...
Spinal dural arteriovenous fistulas (SDAVF) are the most common type of spinal vascular malformation, accounting for ~70% of all such lesions.
This article specifically relates to spinal dural arteriovenous fistulas. For a discussion of intracranial dural arteriovenous fistulas refer to the mai...
The spinal dura mater is the outermost layer of the meninges that surround the spinal cord.
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 ...
Spinal dysraphism is a broad term given to a group of anomalies where there are malformations in the dorsum of the embryo. Neural tube defects come under this group as well.
There is often abnormal fusion of the midline embryonic neural, vertebral and mesenchymal structures.
Spinal ependymomas are the most common spinal cord tumour overall, seen both in adult and paediatric population.
This article specifically relates to spinal cord ependymomas. For a discussion of intracranial ependymomas and for a general discussion of the pathology refer to the main article: e...
Spinal epidermoid cysts are cystic tumours lined by squamous epithelium. Unlike dermoid cysts, they do not contain skin appendages (hair follicles, sweat glands, sebaceous glands) 10.
They are usually extramedullary but rarely can be intramedullary 1. They may be congenital or acquired.
Spinal epidural abscess represents infection of the epidural space, located between the spinal dura mater and the vertebral periosteum. It can present with rapidly deteriorating neurological function due to compression. Imaging is best performed with MRI and emergency surgery is often required. ...
Spinal epidural haematomas (spinal EDH) are a rare spinal pathology can result in serious morbidity with delayed or non-treatment. They are typically considered a surgical emergency.
The patient's symptoms and signs will depend on the location of the EDH, and degree of s...
Epidural spinal injections are one of the more frequently performed spinal interventional procedures.Three approaches to the epidural space exist:
transforaminal epidural injection
interlaminar epidural injection
cervical interlaminar epidural injection
lumbar interlaminar epidural injection...
The differential diagnosis for a spinal epidural mass includes:
herniated nucleus pulposus
epidural arteriovenous malformation
The spinal epidural (extradural) space is distinctly separate from and not continuous with the cranial epidural space. Its exact definition and description are contentious 3.
The spinal epidural space is located between the spinal dura mater and the vertebral column and extends ...
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
Spinal gangliogliomas are rare, comprising 1.1% of all spinal cord neoplasms 2. They are more frequent in children, representing 15% of intramedullary neoplasms in the paediatric age group 4.
This article specifically relates to spinal gangliogliomas. For a discussion on intracranial gangliogli...
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 ...
Spinal hydatid disease is an uncommon manifestion of hydatid disease, caused by the larval stage of Echinococcus granulosus, or less commonly E. alveolaris or E. multilocularis, and describes a spectrum of disease involving the spinal cord, the spine, or both.
Hydatid disease is e...
The spinal instability neoplastic score (SINS) helps to assess tumour related instability of the vertebral column. It has been shown to useful in guiding the mobilisation or operative management of patients with neoplastic spinal disease.
Studies have reported good inter-observer agreement amon...
Back pain is a common condition that is often difficult to treat. Lumbar degenerative facet joints, lumbar disc disease and sacroiliac joint pain account for nearly 70% of cases of lower back pain.
Unfortunately, as the incidence of degenerative changes in the spine is so high (e.g. disc abnorm...
Spinal meningeal cysts are diverticulae of the arachnoid or dura mater or of the nerve root sheath. They are uncommon, usually asymptomatic and typically found incidentally at MRI (that has been performed for another reason).
They cysts are usually asymptomatic, but if th...
The spinal meninges are contained within the spinal canal and encase the spinal cord, spinal nerve roots and the cauda equina.
They are composed of three layers (outer to inner)
dura mater (also known as theca or pachymeninx)
Collectively the arachno...
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...
Spinal metastases is a vague term which can be variably taken to refer to metastatic disease to any of the following:
vertebral metastases (94%)
may have epidural extension
intradural extramedullary metastases (5%)
intramedually metastases (1%)
Each of these are discussed separately. Below...
Spinal muscular atrophy (SMA) is a type of congenital neuromuscular disease affecting anterior horn cells of the brainstem and spinal cord.
This disorder affects 1 in 6000-10000 infants 1.
The condition typically affects infants and young children, presenti...
Spinal myxopapillary ependymomas are a variant type of spinal ependymoma that occur almost exclusively in the conus medullaris and filum terminale. They represent 13% of all spinal ependymomas, and are by far the most common tumours of the conus medullaris and filum terminale.
Spinal nerve sheath tumours are the most common intradural extramedullary mass.
They include, in order of decreasing frequency:
spinal schwannoma (30% of all intradural extramedullary lesions 6 and 65% of intradural extramedullary nerve sheath tumours 7)
Spinal neurofibromas are benign peripheral nerve sheath tumours, usually of the localized subtype.
This article specifically relates to spinal neurofibromas. For a general discussion of neurofibromas, including their epidemiology and pathology, refer to neurofibroma. For a discussion of the gen...
Spinal paragangliomas are tumours of neuroendocrine origin that rarely involve the central nervous system, usually the filum terminale and cauda equina). They are indolent and considered WHO grade I lesions 5.
Paragangliomas overall are most commonly located within the adrenal gland (pheochrom...
Although rare, pilocytic astrocytomas are the most common spinal cord tumours in the paediatric population.
This article specifically relates to spinal pilocytic astrocytomas. For a discussion on intracranial pilocytic astrocytomas refer to pilocytic astrocytoma. For a general discussion on spi...
Spinal primitive neuroectodermal tumours (PNETs) are rare. Most cases are secondary to metastatic spread through the subarachnoid space from a primary intracranial tumour although rare cases of primary spinal PNETs have been reported.
This article specifically relates to spinal PNETs. For a dis...
Spinal schwannomas are schwannomas arising from nerves within the spinal canal. They are the most common intradural extramedullary spinal tumours, representing 30% of such lesions. They are most frequently seen in the cervical and lumbar regions, far more frequently than in the thoracic spine.
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...
Synovial cysts of the spine are cystic formations connected to the facet joint and containing synovial fluid lined by a cuboid or pseudostratified columnar epithelium. They may be result in lumbar radiculopathy in a significant number of cases.
They may be asymptomatic an...
Spinal vascular malformations (SVM) are rare but knowledge of them is important as if undiagnosed and untreated they can lead to serious complications.
There are two main types of SVMs 1,2:
spinal arteriovenous fistula (AVF): 70% of SVMs
pial: small, large, or giant
dural AVF (DA...
The spinocerebellar tracts are afferent neurons that convey proprioceptive data from the spinal cord to the cerebellum. There are anterior and posterior spinocerebellar tracts, the latter also referred to as Flechsig's tract. Both the anterior and posterior spinocerebellar tracts lie in the peri...
The spinothalamic tracts are ascending pathways primarily concerned with sensory function. They are responsible for transmitting pain, temperature, coarse (non-discriminative) touch and pressure sensations 1.
The spinothalamic tract is divided into lateral and anterior tracts, which are discuss...
The splenius capitis is a strap-like muscles that, along with the splenius cervicis, comprise the superficial layer of intrinsic back muscles.
origin: ligamentum nuchae, and the tips of the spinous processes and associated supraspinous ligaments of C7 and the upper t...
The splenius cervicis is part of the superficial layer of the intrinsic back muscles. It is one of the two muscles in this group, the other being the splenius capitis.
origin: spinous processes of T3-T6
insertion: transverse processes of C1-C3
innervation: dorsalrami of the lower cer...