VENTRAL CERVICAL MUSCLES 



267 



Origin. — The cariniform cartilage of the sternum. 

 Insertion. — The posterior border of the ramus of the mandible. 

 Action. — Acting together, to flex the head and neck; acting singlj^, to incline 

 the head and neck to the side of the muscle contracting. 



Structure. — The two muscles are fused at their origin, which is fleshy. Near 



Fig. 266. — Anteho- lateral View of Muscles and Skeleton of Horse. 

 a, Trapezius; c, bracbiocephaUcus; d, sterno-cephalicus ; /, long head, of triceps; /', lateral head of triceps; 

 ■(?, anterior superficial pectoral muscle; ff', posterior superficial pectoral; 7i.', anterior deep pectoral; v, cutaneus colli; 

 2, supraspinatus ; 2.9, omo-hyoideus; 30, sterno-thyro-hyoideus ; 31, jugular vein; 32, cephalic vein; 1, scapula; 

 i', cartilage of scapula; ,S, spine of scapula; ^, shaft of humerus; 4' lateral epicondyle; 5, lateral tuberosity of humerus; 

 6, deltoid tuberosity; 14, ventral border ("keel") of sternum; 1//, cariniform cartilage; I.R., first rib. (After Ellen- 

 berger-Baum, Anat. fur Kiinstler.) 



the middle of the neck they separate, and, becoming narrower and thinner, each 

 muscle passes under the parotid gland and terminates by a flat tendon. The latter 

 is connected by a thin aponeurosis with that of the brachiocephalicus. 



Relations. — Superficially, the cutaneous muscle; deeply, the sterno-thyro- 

 hyoideus and omo-hyoideus muscles. The dorsal edge of the muscle is related to 

 the jugular vein, which lies in the jugular furrow. The carotid artery, the vagus, 



