Musculus serratus posterior inferior

The serratus posterior inferior muscle is a thin, quadrilateral muscle of the posterior thorax. It extends from the vertebrae to the ribs and aids in deep inspiration.

Summary

Gross anatomy

The serratus posterior inferior muscle forms from a thin, broad aponeurosis which is attached to the spinous processes of T11 to L2 vertebrae, and the intervening supraspinous ligament. It passes superolaterally and inserts onto the inferior border, just lateral to the angles of the 9 to 12ribs . It is separated from the serratus posterior superior muscle by a wide interval.

Innervation

The serratus posterior inferior muscle receives motor supply from the ventral rami of the 9 to 12 thoracic spinal nerves (intercostal nerves) .

Action

This muscle depresses the inferior ribs which aids in expiration.