There are 31 pairs of spinal roots from the spinal cord:

• Eight cervical
• Twelve thoracic
• Five lumbar
• Five sacral and
• One coccygeal.

The spinal cord is supplied by two posterior and one anterior spinal arteries which do not form a direct anastomosis.

The anterior spinal artery supplies the anterior two-thirds of the spinal cord and medulla. Disruption of the anterior spinal artery supply is characterised by ischaemia or infarction of motor tracts (corticospinal) and loss of pain and temperature sensation below the level of the lesion.

The posterior spinal arteries supply the posterior columns (posterior third of the spinal cord). Infarction of the posterior columns results in the loss of proprioceptive, vibration and two-point discrimination.

The spinal cord normally ends at the level of L1 or L2 in an adult and L3 in a newborn.