Spinal canal

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Spinal canal
Scheme body cavities-en.svg
Spinal cavity shown as part of dorsal body cavity.
Gray82.png
A typical thoracic vertebra viewed from above. (Spinal canal is not labeled, but the foramen in the center would make up part of it.)
Details
Identifiers
Latin c. vertebralis
MeSH D013115
TA98 A02.2.00.009
TA2 1009
FMA 9680
Anatomical terminology

In human anatomy, the spinal canal, vertebral canal or spinal cavity is an elongated body cavity enclosed within the dorsal bony arches of the vertebral column, which contains the spinal cord, spinal roots and dorsal root ganglia. 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 between these ligaments and the dura mater covering the spinal cord is known as the epidural space. Spinal nerves exit the spinal canal via the intervertebral foramina under the corresponding vertebral pedicles.

Contents

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 (allowing the passage of the spinal nerves and radicular blood vessels). [1]

The vertebral canal progressively narrows inferiorly. [1] It is wider in the cervical region to accommodate the cervical enlargement of the spinal cord. [2] [3]

Contents

The outermost layer of the meninges, the dura mater, is closely associated with the arachnoid mater which in turn is loosely connected to the innermost layer, the pia mater. The meninges divide the spinal canal into the epidural space and the subarachnoid space. The pia mater is closely attached to the spinal cord. A subdural space is generally only present due to trauma and/or pathological situations. The subarachnoid space is filled with cerebrospinal fluid and contains the vessels that supply the spinal cord, namely the anterior spinal artery and the paired posterior spinal arteries, accompanied by corresponding spinal veins. The anterior and posterior spinal arteries form anastomoses known as the vasocorona of the spinal cord and these supply nutrients to the canal. The epidural space contains loose fatty tissue, and a network of large, thin-walled blood vessels called the internal vertebral venous plexuses.[ citation needed ]

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 [4] if the narrowed canal impinges on the spinal cord itself.

Spinal canal endoscopy can be used to investigate the epidural space, and is an important spinal diagnostic technique. [5] [6]

History

The spinal canal was first described by Jean Fernel.[ citation needed ]

Related Research Articles

Articles related to anatomy include:

<span class="mw-page-title-main">Spinal nerve</span> Nerve that carries signals between the spinal cord and the body

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 the corresponding cervical, thoracic, lumbar, sacral and coccygeal regions of the spine. There are eight pairs of cervical nerves, twelve pairs of thoracic nerves, five pairs of lumbar nerves, five pairs of sacral nerves, and one pair of coccygeal nerves. The spinal nerves are part of the peripheral nervous system.

<span class="mw-page-title-main">Dura mater</span> Outermost layer of the protective tissues around the central nervous system (meninges)

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. The other two meningeal layers are the arachnoid mater and the pia mater. It envelops the arachnoid mater, which is responsible for keeping in the cerebrospinal fluid. It is derived primarily from the neural crest cell population, with postnatal contributions of the paraxial mesoderm.

<span class="mw-page-title-main">Epidural space</span> Space between the dura mater and vertebrae

In anatomy, the epidural space is the potential space between the dura mater and vertebrae (spine).

<span class="mw-page-title-main">Spondylosis</span> Degeneration of the vertebral column

Spondylosis is the degeneration of the vertebral column from any cause. In the more narrow sense it refers to spinal osteoarthritis, the age-related degeneration of the spinal column, which is the most common cause of spondylosis. The degenerative process in osteoarthritis chiefly affects the vertebral bodies, the neural foramina and the facet joints. If severe, it may cause pressure on the spinal cord or nerve roots with subsequent sensory or motor disturbances, such as pain, paresthesia, imbalance, and muscle weakness in the limbs.

<span class="mw-page-title-main">Neuromere</span>

Neuromeres are distinct groups of neural crest cells, forming segments in the neural tube of the early embryonic development of the brain. There are three classes of neuromeres in the central nervous system – prosomeres, mesomeres and rhombomeres that will develop the forebrain, midbrain, and hindbrain respectively.

<span class="mw-page-title-main">Cervical vertebrae</span> Vertebrae of the neck

In tetrapods, cervical vertebrae are the vertebrae of the neck, immediately below the skull. Truncal vertebrae lie caudal of cervical vertebrae. In sauropsid species, the cervical vertebrae bear cervical ribs. In lizards and saurischian dinosaurs, the cervical ribs are large; in birds, they are small and completely fused to the vertebrae. The vertebral transverse processes of mammals are homologous to the cervical ribs of other amniotes. Most mammals have seven cervical vertebrae, with the only three known exceptions being the manatee with six, the two-toed sloth with five or six, and the three-toed sloth with nine.

<span class="mw-page-title-main">Filum terminale</span> Fibrous tissue supporting the spinal cord

The filum terminale is a delicate strand of fibrous tissue, about 20 cm in length, extending inferior-ward from the apex of the conus medullaris to attach onto the coccyx. The filum terminale acts to anchor the spinal cord and spinal meninges inferiorly.

<span class="mw-page-title-main">Anterior longitudinal ligament</span> Ligament running down the front of the vertebral column

The anterior longitudinal ligament is a ligament that extends across the anterior/ventral aspect of the vertebral bodies and intervertebral discs the spine.

<span class="mw-page-title-main">Ligamenta flava</span> Ligaments connecting the laminae of adjacent vertebrae

The ligamenta flava are a series of ligaments that connect the ventral parts of the laminae of adjacent vertebrae. They help to preserve upright posture, preventing hyperflexion, and ensuring that the vertebral column straightens after flexion. Hypertrophy can cause spinal stenosis.

<span class="mw-page-title-main">Intervertebral foramen</span> Foramen between spinal vertebrae

The intervertebral foramen is an opening between two pedicles of adjacent vertebra in the articulated spine. Each intervertebral foramen gives passage to a spinal nerve and spinal blood vessels, and lodges a posterior (dorsal) root ganglion. Cervical, thoracic, and lumbar vertebrae all have intervertebral foramina.

<span class="mw-page-title-main">Posterior longitudinal ligament</span> Ligament connecting vertebral bodies of all of the vertebrae

The posterior longitudinal ligament is a ligament connecting the posterior surfaces of the vertebral bodies of all of the vertebrae of humans. It weakly prevents hyperflexion of the vertebral column. It also prevents posterior spinal disc herniation, although problems with the ligament can cause it.

<span class="mw-page-title-main">Posterior spinal artery</span>

The posterior spinal artery 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 is usually double, and spans the length of the spinal cord. It supplies the grey and white posterior columns of the spinal cord.

<span class="mw-page-title-main">Internal vertebral venous plexuses</span>

The internal vertebral venous plexuses lie within the vertebral canal in the epidural space, embedded within epidural fat. They receive tributaries from bones, red bone marrow, and spinal cord. They are arranged into four interconnected, vertically oriented vessels - two situated anteriorly, and two posteriorly:

<span class="mw-page-title-main">Posterior atlantooccipital membrane</span> Membrane at the base of the skull

The posterior atlantooccipital membrane is a broad but thin membrane extending between the to the posterior margin of the foramen magnum above, and posterior arch of atlas below. It forms the floor of the suboccipital triangle.

<span class="mw-page-title-main">Segmental medullary artery</span>

Segmental medullary arteries are arteries of varying size in the thoracolumbar region that arise from segmental arteries of this region and pass through intervertebral foramina to supply the spinal cord. They may join the anterior spinal artery.

<span class="mw-page-title-main">Outline of human anatomy</span> Overview of and topical guide to human anatomy

The following outline is provided as an overview of and topical guide to human anatomy:

<span class="mw-page-title-main">Spinal cord</span> Part of the vertebral column in animals

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 cord is hollow and contains a structure called the central canal, which contains cerebrospinal fluid. The spinal cord is also covered by meninges and enclosed by the neural arches. Together, the brain and spinal cord make up the central nervous system.

<span class="mw-page-title-main">Vertebral column</span> Bony structure found in vertebrates

The vertebral column, also known as the spinal column, spine or backbone, is the core part of the axial skeleton in vertebrate animals. The vertebral column is the defining and eponymous characteristic of the vertebrate endoskeleton, where the notochord found in all chordates has been replaced by a segmented series of mineralized irregular bones called vertebrae, separated by fibrocartilaginous intervertebral discs. The dorsal portion of the vertebral column houses the spinal canal, an elongated cavity formed by alignment of the vertebral neural arches that encloses and protects the spinal cord, with spinal nerves exiting via the intervertebral foramina to innervate each body segments.

<span class="mw-page-title-main">Vertebra</span> Bone in the vertebral column

Each vertebra is an irregular bone with a complex structure composed of bone and some hyaline cartilage, that make up the vertebral column or spine, of vertebrates. The proportions of the vertebrae differ according to their spinal segment and the particular species.

References

  1. 1 2 Sinnatamby, Chummy S. (2011). Last's Anatomy (12th ed.). p. 425. ISBN   978-0-7295-3752-0.
  2. Kim, Hak-Jin (2010-01-01), Kim, Daniel H.; Kim, Yong-Chul; Kim, Kyung-Hoon (eds.), "Chapter 3 - Radiologic Anatomy of the Spine", Minimally Invasive Percutaneous Spinal Techniques, New York: W.B. Saunders, pp. 46–57, doi:10.1016/b978-0-7020-2913-4.00003-3, ISBN   978-0-7020-2913-4 , retrieved 2020-11-03
  3. Haran, Crishan. "Spinal canal | Radiology Reference Article | Radiopaedia.org". Radiopaedia.
  4. Lewit, Karel; Ellis, Richard M (2010-01-01), Lewit, Karel; Ellis, Richard M (eds.), "Chapter 3 - Functional anatomy and radiology of the spinal column", Manipulative Therapy, Edinburgh: Churchill Livingstone, pp. 39–85, doi:10.1016/b978-0-7020-3056-7.00003-6, ISBN   978-0-7020-3056-7 , retrieved 2020-11-03
  5. Datta, Sukdeb (2009-01-01), Smith, HOWARD S. (ed.), "Chapter 87 - EPIDURAL ADHESIOLYSIS", Current Therapy in Pain, Philadelphia: W.B. Saunders, pp. 629–639, doi:10.1016/b978-1-4160-4836-7.00087-0, ISBN   978-1-4160-4836-7 , retrieved 2020-11-03
  6. Saberski, Lloyd R. (2007-01-01), Waldman, Steven D.; Bloch, Joseph I. (eds.), "chapter 15 - Spinal Canal Endoscopy", Pain Management, Philadelphia: W.B. Saunders, pp. 167–178, doi:10.1016/b978-0-7216-0334-6.50019-4, ISBN   978-0-7216-0334-6 , retrieved 2020-11-03