Structure of the Human Spine

The vertebral (spinal) column surrounds and protects the spinal cord (central energy channel, aka Sushumna nadi). Axis around which yoga poses revolve

The vertebral column consists of 24 individual bones and two sections of naturally fused vertebrae (33 vertebrae):

– Cervical: 7 vertebrae (C1-C7)
– Thoracic: 12 vertebrae (T1-T12)
– Lumbar: 5 vertebrae (L1-L5)
– Sacral: 5 vertebrae fused together
– Coccyx: 4 vertebrae fused together

Typical vertebra – structure and components:
– body
– vertebral arch
– Vertebral foramen is defined by those two components. Successive vertebral foramina form the spinal canal.

Only the top two have vertebrae have their unique names as they have their unique functions:

C1 – Atlas bone – supports weight of the entire head – connecting skull and spine – ring-like structure – no body
C2 – Axis bone – fits perfectly into the atlas bone thanks to tooth-like dens, allows the head to rotate.

The vertebral unit comprises of two adjacent vertebral bodies and intervertebral disc. The intervertebral disc is made of nucleus pulposus and annulus fibrosis. Movement between the vertebrae is possible in several planes (including small amounts of rotation, flexion and extension). The combination of motion across multiple vertebral units culminates in spinal movement.

Movements of the spine:
– forward
– backward
– lateral (side to side)
– rotation (twist)
– axial extension
– axial compression

Spianal curves:
We determine the spinal curves by viewing them from the side. Kyphosis is a convex curve and lordosis is a concave curve.

Four normal curves in the spine:

Primary (concave):
– thoracic kyphosis
– sacral kyphosis

Secondary (convex)
– cervical lordosis
– lumbar lordosis

Important ligaments:

– Anterior longitudinal – connects to vertibral bodies and intervertbral discs. Stabilisation during extension
– Posterior longitudinal – stabilisation during flexion
– Ligamentum Flavum – helps to straighten the column after it has been flexed.

Joints and range of motion:

Zygapophyseal joints are the only synovial joints in the spine. Segmental differences in orientation of Zygapophyseal joints which result in different range of motion. For example in cervical region orientation of articulations is more oblique – greater range of motion, thoracic – anterior-posterior direction, this limits the range of motion to some degree additionally superimposed ribs will further restrict the range of motion and lumbar – more lateral orientation of the articulations restricts the most the range of motion.

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