human anatomy Human anatomy (gr. ἀνατομία, "dissection", from ἀνά, "up", and τέμνειν, "cut") is primarily the scientific study of the morphology of the human body. Anatomy is subdivided into gross anatomy and microscopic anatomy. Gross ...

, the spinal canal, vertebral canal or spinal cavity is an elongated

body cavity A body cavity is any space or compartment, or potential space, in an animal body. Cavities accommodate organs and other structures; cavities as potential spaces contain fluid. The two largest human body cavities are the ventral body cavity, a ...

enclosed within the dorsal bony arches of the

vertebral column The spinal column, also known as the vertebral column, spine or backbone, is the core part of the axial skeleton in vertebrates. The vertebral column is the defining and eponymous characteristic of the vertebrate. The spinal column is a segmente ...

, which contains the

spinal cord The spinal cord is a long, thin, tubular structure made up of nervous tissue that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

, spinal roots and

dorsal root ganglia A dorsal root ganglion (or spinal ganglion; also known as a posterior root ganglion) is a cluster of neurons (a ganglion) in a dorsal root of a spinal nerve. The cell bodies of sensory neurons known as first-order neurons are located in the dors ...

. It is a process of the dorsal body cavity formed by alignment of the vertebral foramina. Under the vertebral arches, the spinal canal is also covered anteriorly by the posterior longitudinal ligament and posteriorly by the ligamentum flavum. The

potential space In anatomy, a potential space is a space between two adjacent structures that are normally pressed together (directly apposed). Many anatomic spaces are potential spaces, which means that they are potential rather than realized (with their realiz ...

between these ligaments and the dura mater covering the spinal cord is known as 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 ...

Spinal nerve A spinal nerve is a mixed nerve, which carries Motor neuron, motor, Sensory neuron, sensory, and Autonomic nervous system, autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each s ...

s exit the spinal canal via the intervertebral foramina under the corresponding vertebral pedicles. In humans, the spinal cord gets outgrown by the vertebral column during development into adulthood, and the lower section of the spinal canal is occupied by the filum terminale and a bundle of spinal nerves known as the cauda equina instead of the actual spinal cord, which finishes at the L1/L2 level.

Structure

The vertebral canal is enclosed anteriorly by the vertebral bodies, intervertebral discs, and the posterior longitudinal ligament; it is enclosed posteriorly by the vertebral laminae and the ligamenta flava; laterally, it is incompletely enclosed by the pedicles with the interval between two adjacent pedicles on either side creating an

intervertebral foramen The intervertebral foramen (also neural foramen) (often abbreviated as IV foramen or IVF) is an opening between (the intervertebral notches of) two pedicles (one above and one below) of adjacent vertebra in the articulated spine. Each interve ...

(allowing the passage of the

spinal nerves A spinal nerve is a mixed nerve, which carries motor, sensory, and autonomic signals between the spinal cord and the body. In the human body there are 31 pairs of spinal nerves, one on each side of the vertebral column. These are grouped into ...

and radicular blood vessels). The vertebral canal progressively narrows inferiorly. It is wider in the cervical region to accommodate the cervical enlargement of the spinal cord.

The outermost layer of the

meninges In anatomy, the meninges (; meninx ; ) are the three membranes that envelop the brain and spinal cord. In mammals, the meninges are the dura mater, the arachnoid mater, and the pia mater. Cerebrospinal fluid is located in the subarachnoid spac ...

, the dura mater, 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 cr ...

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 that extends from the medulla oblongata in the lower brainstem to the lumbar region of the vertebral column (backbone) of vertebrate animals. The center of the spinal c ...

. A subdural space 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 Extracellular fluid#Transcellular fluid, transcellular body fluid found within the meninges, meningeal tissue that surrounds the vertebrate brain and spinal cord, and in the ventricular system, ven ...

and contains the vessels that supply the

, namely the anterior spinal artery and the paired posterior spinal arteries, accompanied by corresponding spinal veins. The anterior and posterior spinal arteries form

anastomoses An anastomosis (, : 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, leaf veins, or streams. Such a connection may be ...

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

contains loose fatty tissue, and a network of large, thin-walled blood vessels called the internal vertebral venous plexuses.

Clinical significance

Spinal stenosis 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 result in cervical myelopathy if the narrowed canal impinges on the spinal cord itself. 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.

References

External links

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

Structure

Contents

Clinical significance

History

References

External links