STERNO-CLEIDO-MASTOID

n. Stu5rii'"o-klid"o-ma2st'- oid. For deriv., see STERNUM, CLEIDION, and MASTOID. Lat., sternocleidomastoideus. Fr., sterno-cleido-mas to'idien. Ger., Kopfneigemuskel,Kopfnickermuskel,Brustschlii elbeinzitzenfortsatzmuskel. A muscle arising from the anterior surface of the mauubrium and the upper side of the inner third of the clavicle, and inserted into the external surface of the mastoid proce of the temporal bone and the superior curved line on the occipital bone. The two s.-c.-m's acting together bend the head forward or elevate the upper portion of the thorax. When one of them acts separately, it flexes and rotates the head. This has been described by some anatomists as two muscles, viz., the sternomastoideus and cleidomastoideus. [L.] STERNOCOSTAL IS [Coues] (Lat.), n. m. Sturn(ste2rn)-o- (os)-ko2st-al(a3l)'i2s. From sternum (q. v.), and costa, a rib. Fr., sterno-costal. See TRIANGULAR IS stern i. [s. 538]