scalenus medius (anatomy)
Last reviewed 01/2018
Scalenus medius is one of the muscles in the floor of the posterior triangle of the neck. It is covered by deep cervical fascia. Its origin is the posterior tubercles of the transverse processes of vertebrae C2 to C7. It inserts into the superior aspect of the neck of the first rib.
The action of scalenus medius is as an accessory muscle of inspiration by elevation of the first rib. Also, it flexes and rotates the cervical part of the vertebral column to the contralateral side. It is innervated by the anterior primary rami of C3 to C8.
The brachial plexus and third part of the subclavian artery emerge between scalenus medius and scalenus anterior.