Posterior scalene

The posterior scalene (Latin: musculus scalenus posterior) is a muscle of the neck located in its lateral aspect. Therefore, it is also known as one of the lateral neck muscles. The posterior scalene is classified as the muscle of the scalene group. It is the smallest muscle of the group and is situated most profoundly.

Origin

The posterior scalene muscle originates from the posterior tubercles of the transverse processes of the 5th to 7th cervical vertebrae (C5 - C7).

Insertion

The posterior scalene inserts on the external surface of the second rib.

Action

By contracting on both sides, the anterior scalene muscle flexes the neck. By contracting on one side, it bends the neck laterally to the same side (ipsilateral). Also, unilateral contractions provide contralateral neck rotation and elevation of the second rib.

Innervation

The posterior scalene is innervated by the anterior rami of the 6th to 8th cervical spinal nerves (C6 - C8).

Blood supply

The posterior scalene muscle receives arterial blood supply from the ascending cervical branch of the inferior thyroid artery and the superficial cervical branch of the transverse cervical artery.