Origin: Sacrum, Erector spinae Aponeurosis, PSIS, and Iliac crest , mamillary processes
Insertion: Spinous process
Nerve: Posterior branches
Action: Stabilizes vertebrae in local movements of vertebral column
The multifidus muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. The multifidus is a very thin muscle.
Deep in the spine, it spans three joint segments, and works to stabilize the joints at each segmental level.
The stiffness and stability makes each vertebra work more effectively, and reduces the degeneration of the joint structures.
These fasciculi arise:
Each fasciculus, passing obliquely upward and medialward, is inserted into the whole length of the spinous process of one of the vertebræ above.
These fasciculi vary in length: the most superficial, the longest, pass from one vertebra to the third or fourth above; those next in order run from one vertebra to the second or third above; while the deepest connect two contiguous vertebrae.
The multifidus lies deep relative to the Spinal Erectors, Transverse Abdominus, Abdominal internal oblique muscle and Abdominal external oblique muscle.