origin: anterior tubercles of the transverse process of the 2nd to 6th cervical vertebrae;
insertion: scalene tubercles on anterior superior surface of the 1st rib;
action:
- acting unilaterally, flexes and rotates cervicals and raises first rib;
- when acting bilaterally, flexes the neck;
nerve supply: anterior branches, C5, C6, C7, C8;
synergists: sternocleidmastoid, scalenus medius and scalenus posterior longus capitis, longus coli, suprahyoid, infrahyoid and the platysma