Congenital muscular torticollis Congenital muscular torticollis is thought to result from injury to the sternocleidomastoid muscle during birth trauma, resulting in fibrosis and unilateral shortening of the sternocleidomastoid muscle. Congenital muscular torticollis is thus etiologically and phenotypically distinct from spasmodic torticollis. UMLS:C0079352 Torticollis, congenital HP:0005988 SNOMEDCT_US:268240006 A congenital form of torticollis resulting from shortening of the sternocleidomastoid muscle and leading to a limited range of motion in both rotation and lateral bending. Abnormal morphology of the musculature of the neck