Scalenus posterior muscle
Musculus scalenus posterior
- Latin synonym: Musculus scalenus dorsalis
- Synonym: Posterior scalene muscle
- Related terms: Scalenus posterior; Posterior scalene
Definition
Scalenus posterior muscle | |
Origin | Transverse processes of C4 - C6 |
Insertion | 2nd rib |
Blood supply | Ascending cervical artery, superficial cervical artery |
Innervation | C6, C7, C8 |
Actions | Elevate 2nd rib, tilt the neck to the same side |
The scalenus posterior (posterior scalene) muscle is the smallest and most posterior of the three scalene muscles in the lateral neck. It forms part of the muscular floor of the posterior triangle and assists in elevation of the second rib during inspiration.
Anatomical details
1. Origin
Posterior tubercles of the transverse processes of cervical vertebrae C4–C6.
2. Insertion
The fibres descend to insert into the upper surface of the 2nd rib (positioned posterior to the scalenus medius muscle).
Innervation
Ventral rami of cervical spinal nerves C5–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
Anteriorly: Scalenus medius muscle.
Posteriorly: Levator scapulae
Actions
Bilateral contraction: Elevates the second rib during forced inspiration.
Unilateral contraction: Laterally flexes the neck to the same side (ipsilateral flexion).
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. 451-452.
