origin: posterior tubercles of the transverse process of 2nd to 7th cervical vertebrae;
insertion: superior surface of the 1st rib behind subclavian groove;
action: acting unilaterally, flexes and rotates cervical vertebrae; raises first rib; when acting bilaterally, flexes the neck;
nerve supply: posterior branches of anterior primary rami of C3, C4; lateral muscular branches C3, C4;
synergists: sternocleidmastoid, Scalenus Anterior & Scalenus Posterior, Longus Capitis, longus coli, suprahyoid, infrahyoid and the platysma