Scalenus medius muscle
Musculus scalenus medius
- Synonym: Middle scalene muscle
- Related terms: Scalenus medius; Middle scalene
Definition
Scalenus medius muscle | |
Origin | Transverse process of C2-C6 |
Insertion | First rib |
Blood supply | Ventral rami of C3 to C7 nerves |
Innervation | |
Action | Elevate 1st rib, rotate the neck to the opposite side |
The middle scalene muscle is the largest and longest of the three scalene muscles (anterior, middle, posterior) and forms the floor of the posterior triangle of the neck. It lies posterior to the anterior scalene.
Anatomical details
1. Origin
Posterior tubercles of the transverse processes of cervical vertebrae C2–C7
2. Insertion
Fibres descend to insert onto the upper surface of the first rib, posterior to the groove for the subclavian artery
Innervation
Ventral rami of the third to eighth cervical spinal nerves (C3 to C7).
Blood supply
All scalene muscles receive their arterial blood supply from the ascending cervical branch of the inferior thyroid artery. The posterior scalene receives an additional supply from the superficial cervical artery.
Relations
Aspect | Structures Related |
Anterior | Brachial plexus and subclavian artery (pass between anterior and middle scalenes) |
Posterior | Posterior scalene and levator scapulae muscles |
Medial | Anterior scalene muscle and longus colli |
Actions
Elevates the first rib during inspiration (accessory inspiratory muscle).
Laterally flexes the neck to the same side (acting unilaterally).
Stabilizes the cervical spine during neck movements.
References
Gray, H. (2016) Gray’s Anatomy: The Anatomical Basis of Clinical Practice. 41st edn. Edited by S. Standring. New York: Elsevier. Chapter 29: Neck, pp. 451.
