Vertebral column (Spine)

Overview

  • The vertebral column consists of 33 vertebrae.
    • 7 cervical
    • 12 thoracic
    • 5 lumbar
    • 5 sacral (fused)
    • 3–5 coccygeal (fused)
  • Functions of the vertebral column
    • Protects the spinal cord
    • Supports the weight of the head and trunk
    • Aids in respiration
      • Pump handle movement: superior and anterior movement of the sternum
      • Bucket handle movement: elevation of the lateral portion of the ribs
    • Supports the upright position for bipedalism

Anatomy

Vertebrae

Consist of a vertebral body and a vertebral arch, which together form the vertebral foramen

  • Vertebral body : Cylindric bone, responsible for weight bearing
    • Between two vertebral bodies lies the intervertebral disc (cartilaginous joint)
    • Thoracic vertebral bodies contain costal facets → articulate with ribs of the corresponding vertebra and the vertebra below
  • Vertebral arch : Consists of two pedicles (laterally) and two laminae (posteriorly) with several processes
    • Vertebral pedicles
      • Lateral part of the vertebral arch, between the body and transverse processes
      • Connects the lamina to the vertebral body
    • Vertebral laminae
      • Posterior part of the vertebral arch, between transverse processes and spinous process
      • Attachment site of the ligamentum flavum
    • Each arch consists of the following 7 vertebral processes:
      • One spinous process: posterior bony projection
        • Bifid in cervical vertebrae (except for C7)
        • Rigid in thoracic vertebrae
        • Oblong in lumbar vertebrae
      • Two transverse processes: lateral bony projections
      • Four articular processes (two superior, two inferior): articulate with articular processes from adjacent vertebral bodies
    • Intervertebral foramina
      • Between pedicles of two adjacent vertebrae
      • Passage for spinal nerves and their respective vessels
        • C1–C7 nerves exit superior to pedicles of vertebrae C1–C7
        • C8 nerves exit inferior to C7 pedicles
  • Vertebral foramen
    • Formed by a vertebral arch and a vertebral body
    • All vertebral foramina together form the vertebral canal, which contains
      • The spinal cord
      • Meninges
      • Nerve roots
      • Vessels

Intervertebral disc

Regions of the vertebral column

Atlanto-axial subluxation is associated with rheumatoid arthritis, Down syndrome, and osteogenesis imperfecta (among other conditions)!

  • Thoracic spine
    • 12 vertebrae
    • Has costal facets
      • Superior costal facet:
        • In the body of the vertebra
        • Articulates with the head of the corresponding rib
      • Inferior costal facet: articulates with the rib inferior to the vertebral level
    • Transverse processes of thoracic vertebrae articulate with the tubercles of the ribs
  • Lumbar spine
    • 5 vertebrae
    • Largest vertebral bodies
    • The 5th lumbar vertebra articulates with the sacral promontory
    • Has accessory and mamillary bodies
  • Sacrum
    • 5 fused vertebrae
    • 4 pairs of foramina: The passage for sacral nerves.
    • Articulates with the 5th lumbar vertebra and the pelvis
    • Characteristic structures
      • Medial sacral crest
      • Sacral horn (cornu)
      • Sacral hiatus
  • Coccyx

Curvatures of the vertebral column

  • Primary curvatures (kyphosis, formed during fetal development)
    • Thoracic
    • Sacral
  • Secondary curvatures (lordosis, formed after birth)
    • Cervical (from lifting of the head)
    • Lumbar (from adopting the upright position and walking)

Ligaments

Anatomy Function
Anterior longitudinal ligament
  • Supports the annulus fibrosus anteriorly
  • Limits hyperextension of the vertebral column
Posterior longitudinal ligament
  • Limits hyperflexion of the vertebral column
Ligamenta flava
  • They run between the laminae of adjacent vertebrae
  • Form the posterior wall of the spinal canal
Nuchal ligament
  • Runs from the external occipital protuberance to C7
  • Attached to the posterior tubercles of the atlas and spinous processes of cervical vertebrae
  • Triangular shape
  • Limits hyperflexion of the vertebral column
Supraspinous ligament
  • Runs from C7 to the sacrum
  • Attached to the tips of the spinous processes
  • Limits hyperflexion of the vertebral column
Interspinous ligaments
  • They run between spinous processes of adjacent vertebrae
Intertransverse ligaments
  • They run between transverse processes
  • Limit lateral hyperflexion of the vertebral column

Vessels

Arterial system

The vertebral column is supplied by branches of the aorta and vertebral, subclavian, and internal iliac arteries.

  • Cervical: Vertebral artery and subclavian branches
  • Thoracic: Segmental branches from the aorta
    • Divided into lateral and dorsal branches
  • Lumbar: Segmental branches from the aorta
    • Divided into lateral and dorsal branches
  • Sacral: Branches of the internal iliac artery
    • Iliolumbar, lateral, and sacral arteries
    • Middle sacral artery

Venous system

Formed by valveless venous plexuses

  • Vertebral vein
  • Internal vertebral venous plexus
    • Found within the epidural space (between the dura mater and the vertebral canal)
    • Connects with veins from the spinal cord, vertebral veins, basilar plexus, occipital and sigmoid dural sinuses
    • Communicates with pelvic, azygos, and caval veins via Batson venous plexus → thought to be the route of metastasis
    • Drains into intervertebral veins and basivertebral veins (within vertebral bodies)
  • External vertebral venous plexus
    • Anterior branches lie anterior to the vertebral column.
    • Posterior branches lie on vertebral arches.
    • Communicates with the internal vertebral venous plexus
    • Connects with the vertebral, posterior intercostal, lumbar, and lateral sacral veins

Embryology

The vertebral column is derived from the somites of the paraxial mesoderm; , beginning in the 4th week of embryonic development.

Clinical significance

last updated 11/26/2018
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