2.10.5. Subclavius and the Scalene Muscles
As you can probably tell, subclavius is small in size and function (in relation to respiration). It does however provide a cushioning effect on the subclavian vessels and brachial plexus that run underneath it.
Origin: First costal cartilage.
Nerve supply: Subclavian nerve from brachial plexus (root of C5, C6).
Action: Depresses the clavicle and steadies it during movements of the shoulder.
Overview: Scalene Muscles
The three scalene muscles (anterior, middle and posterior) are typically examined while studying the anatomy of the neck, so I won't go into too much detail about them here. They originate from varying points on the cervical vertebrae and insert onto the first rib (anterior and middle) and the second rib (posterior). They are very much accessory muscles and function to lift up the first two ribs to increase the vertical diameter of the thoracic cage.