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;
