About 33 bones in five regions, from the neck to the tailbone, enclosing the spinal cord in a bony canal
Vertebral column — 7 cervical, 12 thoracic, 5 lumbar, 5 sacral (fused) and 4 coccygeal (fused).
Anatomy · Bones
Vertebral column
About 33 vertebrae in five regions
Axial skeleton · back
The vertebral column, also called the spine, spinal column or backbone, is the flexible stack of about 33 vertebrae that supports the head, neck and trunk and encloses the spinal cord. It is divided into cervical, thoracic, lumbar, sacral and coccygeal regions, and shows four curves. Intervertebral discs of fibrocartilage separate and cushion the movable vertebrae.
How to spot them
- ▸A curved stack of bones running from skull to pelvis, in five regions: 7 cervical, 12 thoracic, 5 lumbar, 5 fused sacral and 4 fused coccygeal
- ▸Each typical vertebra has a weight-bearing body in front and an arch behind that encloses the spinal cord
- ▸Adjacent bodies are separated by fibrocartilage discs; in the adult there are four curves
- ▸The bodies get progressively larger from the neck to the lower back, where they carry most weight
What to know
Its two primary curves, thoracic and sacrococcygeal, are retained from the C-shape of the foetus, while two secondary curves develop after birth
Vertebral column — the secondary curves are cervical (holding up the head) and lumbar (standing).
A sideways curvature with twisting of this whole structure is called scoliosis; the four normal front-to-back curves are named for its regions
Vertebral column — scoliosis, kyphosis and lordosis are disorders of its curvature.
The number of movable bones in it is usually 24, and there are 23 discs between them
Vertebral column — 24 movable vertebrae; the sacrum and coccyx are fused.
Its bony canal is formed by the alignment of the holes in the arches of successive vertebrae, so the spinal cord is protected inside it
Vertebral column — the vertebral (spinal) canal.
Long ligaments run down its front and back surfaces, uniting the bodies and resisting hyperextension and hyperflexion
Vertebral column — the anterior and posterior longitudinal ligaments.
Key ideas
- Four functions: protecting the spinal cord, supporting the weight of the body above the pelvis, forming the central axis of the body, and allowing movement and posture.
- Vertebrae in the lower part of the column have larger bodies than those above, to support the increasing weight.
Quick-fire facts
- •About 33 vertebrae originally develop: 7 cervical, 12 thoracic, 5 lumbar, 5 sacral and 4 coccygeal
- •Of these, 24 are separate movable vertebrae; the sacral and coccygeal vertebrae fuse
- •Two primary curves (thoracic and sacrococcygeal) and two secondary (cervical and lumbar)
- •Almost all mammals have seven cervical vertebrae, regardless of body size
- •Adjacent vertebral bodies are joined by intervertebral discs of fibrocartilage
- •The disc has an outer anulus fibrosus and an inner gel-like nucleus pulposus
- •Kyphosis is an excessive backward curve of the thoracic spine; lordosis an excessive forward curve of the lumbar region; scoliosis a lateral curve with twisting
- •The sacral and coccygeal fusions do not begin until about age 20 and are not complete until middle age
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Sources
- TeachMeAnatomy — The Vertebral Column
- OpenStax — Anatomy and Physiology 2e, 7.3 The Vertebral Column