The spinal canal (or vertebral canal or spinal cavity) is the canal that contains the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

within the

vertebral column The vertebral column, also known as the backbone or spine, is part of the axial skeleton. The vertebral column is the defining characteristic of a vertebrate in which the notochord (a flexible rod of uniform composition) found in all chordata, ...

. The spinal canal is formed by the

vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...

through which the spinal cord passes. It is a process of the

dorsal body cavity The dorsal body cavity is located along the dorsal (posterior) surface of the human body, where it is subdivided into the cranial cavity housing the brain and the spinal cavity housing the spinal cord. The two cavities are continuous with one ano ...

. This canal is enclosed within the

foramen In anatomy and osteology, a foramen (;Entry "foramen"
in

of the vertebrae. In the intervertebral spaces, the canal is protected by the

ligamentum flavum The ligamenta flava (singular, ''ligamentum flavum'', Latin for ''yellow ligament'') are a series of ligaments that connect the ventral parts of the laminae of adjacent vertebrae. They help to preserve upright posture, preventing hyperflexion, a ...

posteriorly and the

posterior longitudinal ligament The posterior longitudinal ligament is a ligament connecting the posterior surfaces of the vertebral bodies of all of the vertebrae. It weakly prevents hyperflexion of the vertebral column. It also prevents posterior spinal disc herniation, althou ...

anteriorly.

Structure

The outermost layer of the meninges, the

dura mater In neuroanatomy, dura mater is a thick membrane made of dense irregular connective tissue that surrounds the brain and spinal cord. It is the outermost of the three layers of membrane called the meninges that protect the central nervous system. ...

, is closely associated with the

arachnoid mater The arachnoid mater (or simply arachnoid) is one of the three meninges, the protective membranes that cover the brain and spinal cord. It is so named because of its resemblance to a spider web. The arachnoid mater is a derivative of the neural c ...

which in turn is loosely connected to the innermost layer, the

pia mater Pia mater ( or ),Entry "pia mater"
in
epidural space In anatomy, the epidural space is the potential space between the dura mater and vertebrae (spine). The anatomy term "epidural space" has its origin in the Ancient Greek language; , "on, upon" + dura mater also known as "epidural cavity", "e ...

and the subarachnoid space. The

pia mater Pia mater ( or ),Entry "pia mater"
in
spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue, which extends from the medulla oblongata in the brainstem to the lumbar region of the vertebral column (backbone). The backbone encloses the central canal of the spi ...

. A

subdural space The subdural space (or subdural cavity) is a potential space that can be opened by the separation of the arachnoid mater from the dura mater as the result of trauma, pathologic process, or the absence of cerebrospinal fluid as seen in a cadaver. ...

is generally only present due to trauma and/or pathological situations. The subarachnoid space is filled with

cerebrospinal fluid Cerebrospinal fluid (CSF) is a clear, colorless body fluid found within the tissue that surrounds the brain and spinal cord of all vertebrates. CSF is produced by specialised ependymal cells in the choroid plexus of the ventricles of the bra ...

and contains the vessels that supply the

, namely the

anterior spinal artery In human anatomy, the anterior spinal artery is the artery that supplies the anterior portion of the spinal cord. It arises from branches of the vertebral arteries and courses along the anterior aspect of the spinal cord. It is reinforced by sever ...

and the paired

posterior spinal arteries The posterior spinal artery (dorsal spinal arteries) arises from the vertebral artery in 25% of humans or the posterior inferior cerebellar artery in 75% of humans, adjacent to the medulla oblongata. It supplies the grey and white posterior columns ...

, accompanied by corresponding

spinal veins The spinal veins (veins of the medulla spinalis or veins of the spinal cord) are situated in the pia mater and form a minute, tortuous, venous plexus. They emerge chiefly from the median fissures of the medulla spinalis and are largest in the lum ...

. The anterior and posterior spinal arteries form

anastomoses An anastomosis (, plural anastomoses) is a connection or opening between two things (especially cavities or passages) that are normally diverging or branching, such as between blood vessels, leaf veins, or streams. Such a connection may be normal ...

known as the vasocorona of the spinal cord and these supply nutrients to the canal. The

epidural space In anatomy, the epidural space is the potential space between the dura mater and vertebrae (spine). The anatomy term "epidural space" has its origin in the Ancient Greek language; , "on, upon" + dura mater also known as "epidural cavity", "e ...

contains loose fatty tissue, and a network of large, thin-walled blood vessels called the

internal vertebral venous plexuses The internal vertebral venous plexuses (intraspinal veins) lie within the vertebral canal in the epidural space, and receive tributaries from the bones and from the spinal cord. They form a closer network than the external plexuses, and, running m ...

. The spinal canal is wider in the cervical spine region to provide space for the

cervical enlargement The cervical enlargement corresponds with the attachments of the large nerves which supply the upper limbs. Located just above the brachial plexus, it extends from about the fifth cervical to the first thoracic vertebra, its maximum circumferen ...

of the spinal cord.

Clinical significance

Spinal stenosis Spinal stenosis is an abnormal narrowing of the spinal canal or neural foramen that results in pressure on the spinal cord or nerve roots. Symptoms may include pain, numbness, or weakness in the arms or legs. Symptoms are typically gradual i ...

is a narrowing of the canal which can occur in any region of the spine and can be caused by a number of factors. It may be caused by

cervical myelopathy Myelopathy describes any neurologic deficit related to the spinal cord. The most common form of myelopathy in humans, '' cervical spondylotic myelopathy (CSM)'', also called ''degenerative cervical myelopathy'', results from narrowing of the spina ...

. Spinal canal

endoscopy An endoscopy is a procedure used in medicine to look inside the body. The endoscopy procedure uses an endoscope to examine the interior of a hollow organ or cavity of the body. Unlike many other medical imaging techniques, endoscopes are insert ...

can be used to investigate the epidural space, and is an important spinal diagnostic technique.

History

The spinal canal was first described by

Jean Fernel Jean François Fernel ( Latinized as Ioannes Fernelius; 1497 – 26 April 1558) was a French physician who introduced the term "physiology" to describe the study of the body's function. He was the first person to describe the spinal canal. The l ...

References

External links

Diagram at wisc.edu
{{Authority control Bones of the thorax Bones of the vertebral column