Interspinales muscles are short, insignificant paired muscles situated either side of the interspinous ligament, attaching to the apices of adjacent spinous processes.  They are best developed in the cervical and lumbar regions where they consist of 6 pairs (C2/C3 to C7/T1) and four pairs (L1/L2 to L4/L5): in the thoracic region they occur between T1/T2, T2/T3 and T11/T12.

Nerve Supply
They are supplied by dorsal rami of adjacent spinal nerves.

Action
They extend the cervical and lumbar spine, but are more significant in stabilizing the vertebral column during movement.