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Structure

Vertebral column

Not medically reviewed · Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The vertebral column is the flexible axial skeleton that supports the trunk, protects the spinal cord and spinal nerves, and provides attachment for the muscles of the back and ribs. It is made of vertebrae separated by intervertebral discs.

Terminologia Anatomica (Latin): Columna vertebralis · Open in the 3D atlas

Location

Extends from the skull base to the coccyx in the posterior midline of the trunk, enclosing the vertebral canal.

Structure

Usually 33 vertebrae: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral and 3 to 5 coccygeal (variable). Primary curvatures are thoracic and sacral (kyphoses); secondary curvatures are cervical and lumbar (lordoses). A typical vertebra has a body, arch, pedicles, laminae, spinous and transverse processes and articular facets. C1 (atlas) and C2 (axis, with the dens) are atypical. Discs have a nucleus pulposus and annulus fibrosus; ligaments include the anterior and posterior longitudinal and the ligamentum flavum.

Blood supply

At group level: segmental arteries (vertebral and ascending cervical in the neck, posterior intercostal, subcostal and lumbar arteries) give spinal branches that supply the vertebral bodies and arches; veins form the internal and external vertebral venous plexuses (Batson plexus), which have no valves.

Innervation

At group level the periosteum, annulus fibrosus (outer part), facet joints and ligaments are supplied by the meningeal (sinuvertebral) branch of the spinal nerve and by the dorsal rami; the nucleus pulposus is not innervated. Spinal nerves exit through the intervertebral foramina.

Function

It supports body weight, permits flexion, extension, lateral flexion and rotation (range differs by region: cervical most mobile, thoracic limited by ribs), absorbs load through its curvatures and discs, and protects the spinal cord.

Clinical correlations

Disc herniation most often affects L4-L5 and L5-S1 and typically compresses the nerve root that exits one level below in the lumbar region (for example L4-L5 posterolateral herniation compresses L5). Other conditions: cervical spondylosis, spinal stenosis, scoliosis, excessive kyphosis, osteoporotic compression fractures, and cervical fractures with cord injury (for example dens fracture). Lumbar puncture uses the L3-L4 or L4-L5 interspace.

Common exam points

  • Counts: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused), 3-5 coccygeal (variable).
  • Primary curves (kyphoses): thoracic and sacral; secondary curves (lordoses): cervical and lumbar.
  • Atlas has no body; axis has the dens; atlanto-axial joint permits head rotation.
  • Lumbar disc herniation: usually L4-L5 or L5-S1; posterolateral herniation compresses the root below.
  • Intervertebral foramina transmit spinal nerves; Batson venous plexus is valveless (metastasis route).

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Netter FH. Atlas of Human Anatomy. Elsevier — Tier 3 (textbook)

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