It measures approximately 42-45 cm in length, ~1 cm in diameter and 35 g in weight.
It is divided into cervical, thoracic and lumbar parts and terminates at the conus medullaris at approximately the T12/L1 vertebral body level.
The spinal cord is segmented by the nerve roots that emerge from it. There are 31 nerve roots in total:
- 8 cervical
- 12 thoracic
- 5 lumbar
- 5 sacral
- 1 coccygeal
A transverse section of the spinal cord shows a peripheral mass of white matter enclosing a central mass of grey matter with a small central canal filled with CSF 2. The central canal is lined by a single layer of ependymal cells. Surrounding this canal is the ‘H’ or butterfly shaped grey matter. The cord is incompletely divided into left and right halves by the posterior median sulcus and the anterior median fissure. The central limb of the ‘H’ connects the left and right halves of the grey matter, known as the grey commissure. Anterior to the grey matter, the white commissure connects both halves of the white matter.
The grey matter contains the cell bodies of neurons and glia, and is divided into anterior, dorsal and lateral horns 3:
- the anterior horn contains motor neurons for skeletal muscle
- the lateral horn contains autonomic neurons for pelvic and visceral organs
- the dorsal horns receive somatosensory information from the posterior roots of the spinal nerves
The grey matter is enlarged in the cervical and lumbosacral regions to provide fibres to the large nerve plexuses.
The white matter contains nerve fibres or tracts, and is divided into anterior, dorsal or lateral columns 3.
- the dorsal columns contain ascending fibres which are responsible for vibration, conscious proprioception, and fine (discriminative) touch sensations
- the lateral columns primarily contains the corticospinal tracts which are the principal motor pathway connecting the cerebral cortex to spinal motor neurons
- the anterior columns primarily contains the spinothalamic tracts which are responsible for pain, temperature, coarse (non-discriminative) touch, and pressure sensations
In general, neurons found posteriorly process and relay sensory information, neurons round laterally are preganglionic visceral motor neurons and somatic motor neurons are found anteriorly 4.
- spinal canal
- cervical spine
- thoracic spine
- lumbar spine
- vertebral body
- neural arch
- transitional vertebrae
- ossification centres
- intervertebral disc
- anterior longitudinal ligament
- posterior longitudinal ligament
- posterior ligamentous complex
- cervical spine ligaments
- iliolumbar ligament
- musculature of the vertebral column
- muscles of the neck
- muscles of the back
- gross anatomy
white matter tracts
- anterolateral columns
- lateral columns
- dorsal columns
- gray matter
- nerve root
- spinal meninges and spaces
- functional anatomy
- spinal cord blood supply