Quick Facts
Origin: Posterior tubercles of transverse processes of C4-C6 vertebrae.
Insertion: External surface of second rib.
Action: Laterally flexes neck; elevates second rib.
Innervation: Anterior rami of fourth to sixth cervical nerves (C4-C6).
Arterial Supply: Ascending cervical artery.
Related parts of the anatomy
Origin
The scalenus posterior muscle arises from the posterior tubercles of the transverse processes of the fourth to sixth cervical vertebrae (C4-C6).
Insertion
The scalenus posterior muscle inserts into the external surface of the second rib, behind the tuberosity for serratus anterior muscle.
Key Features & Anatomical Relations
The scalenus posterior muscle has a considerable amount of variation in its attachments and, thus, its segmental innervation may also vary accordingly.
Actions
The scalenus posterior muscle is involved in multiple actions:
- during unilateral contraction, it laterally flexes the neck to the same side at the cervical vertebral joints;
- it elevates the second rib and can act as an accessory muscle of inspiration (Standring, 2016).
References
Standring, S. (2016) Gray's Anatomy: The Anatomical Basis of Clinical Practice. Gray's Anatomy Series 41st edn.: Elsevier Limited.
