The spine or vertebral column has a complex anatomy that is important to understand in order to appreciate the numerous structures that could give rise to lower back, mid back or neck pain.  In this weeks blog we explore spinal anatomy and attempt to demystify the piece of our anatomy that accounts for approximately fifty per cent of all visits to physiotherapy clinics.

The spine is made up of 33 vertebrae.  Vertebrae are irregular shaped bones, which are connected to the vertebra above and below to make a column of vertebra – known as the vertebral column.   The vertebral column can be subdivided into its four distinct areas, with distinct curves – cervical spine, thoracic spine, lumbar spine and sacral spine.

Cervical Spine

The cervical spine (or neck) contains 7 vertebrae named C1, C2, C3, C4, C5 C6, and C7.  The cervical spine is curved concave posteriorly, meaning it curves inwards from the back.

Thoracic Spine

The thoracic spine (or trunk) contains 12 vertebrae named T1, T2, T3, T4, T5, T6, T7, T8, T9, T10, T11 and T12.  The thoracic spine is curved convex posteriorly, meaning it curves outwards at the back.

Lumbar Spine

The lumber spine (or lower back) contains 5 vertebrae named L1, L2, L3, L4 and L5.  The lumbar spine, like the cervical spine is curved concave posteriorly, meaning it curves inwards at the back. 

Sacral Spine

The sacral spine, including the coccygeal vertebrae, account for the remaining 9-10 vertebrae in the vertebral column.  There are 5 sacral vertebrae and 4-5 coccygeal vertebrae.  The sacral and coccygeal vertebrae are fused vertebra and unlike the cervical, thoracic or lumbar vertebra, don’t move independently of each other, rather they move as one unit.  The sacral and coccygeal vertebrae are convex posteriorly like the thoracic spine.

Intervertebral Discs

While the sacral and coccygeal vertebrae are fused and move as one unit, the vertebrae of the lumbar, thoracic and cervical spine articulate with each other and can move independently.  Between each of the independently articulating vertebrae is an intervertebral disc.  Intervertebral discs support the vertebral column, facilitate intervertebral movement and provide shock absorption to the spine.  Intervertebral discs are named after the vertebra above and below it.  For example, intervertebral disc lying between the 5th lumbar vertebra and the 1st sacral vertebra is simple called the L5/S1 disc.

Lying directly behind each intervertebral disc is the descending spinal canal containing the spinal cord.  At each vertebral level nerve roots exit the spinal canal and travel to various parts of your body and to the extremities of your limbs.  For this reason disc prolapses – a bulging out of a disc – can often affect nerves as they travel from the spinal cord giving rise to symptoms such as weakness in limbs, loss of sensation or pins and needles. 

Thankfully, disc bulges are relatively rare.  More common injuries associated with the spine are muscle and ligament strains and sprains, which settle a lot quicker.