Deep Intrinsic Muscles: Origin, Insertion, Nerve Supply & Action

Deep intrinsic muscles are located under the erector spinae. They are a group of short muscles, associated with transverse and spinous processes of the vertebral column.

Three major muscles in this group are-

• Semispinalis
• Multifidus
• Rotators

Semispinalis

The semispinalis is the most superficial muscles in this group. Much like the intermediate muscles, The semispinalis can be divided by its superior attachments into thoracic, cervicis and capitis.

Function: Contralaterally rotates and extends the head and vertebral column.

Multifidus

The multifidus is located under the semispinalis muscle. Multifidus is best developed in the lumbar area.

Function: Stabilizes the vertebral column.

Rotatores

The rotators are the most prominent muscle in the thoracic region.