VENTRAL MUSCLES OF NECK 227 



on the loft side, the oesophagus. In its anterior ]:)art the musele blends with the 

 hyoid part of the sterno-thyro-hyoideus, the two covering the thyroid portion of the 

 latter muscle, the thyroid gland, and the ventral face of the larynx. 



Blood-supply. — Carotid and inferior cervical arteries. 



Nerve-supply. — Ventral branches of the cervical nerves. 



G. Scalenus (AI. scalenus primae costae). — This muscle is deeply situated on 

 the side of the posterior half of the neck. It is composed of two parts, between 

 which the roots of the brachial plexus of nerves emerge. 



Origin.— The anterior border and outer surface of the first rib. 



Insertion. — (1) The dorsal (smaller) portion is attached to the transverse 

 process of the seventh cervical vertebra; (2) the ventral portion is attached to the 

 transverse processes of the sixth, fifth, and fourth cervical vertebra?. 



Action. — The neck is flexed or inclined laterally, according as the muscles act 

 together or singly. If the neck be the fixed point, the muscle may have a respira- 

 tory action by pulling forward or fixing the first rib. 



Structure. — The dorsal portion is composed of three or four fleshy bundles.* 

 The ventral portion, which is much larger, is almost entirely fleshy, and not so 

 divided. 



Relations. — Superficially, the anterior deep pectoral, mastoido-humeralis, and 

 omo-hyoideus muscles, the phrenic nerve, and the other branches of the brachial 

 plexus; deeply, the vertebrae, the longus colli and intertransversales muscles, the 

 oesophagus (on the left side), the trachea (on the right side), the vertebral vessels, 

 the vagus, sympathetic, and recurrent nerves. The roots of the ]:>rachial plexus 

 form a flat anastomosis, which lies between the two portions of the muscle. The 

 brachial vessels cross the ventral edge close to the first rib. 



Blood-supply. — ^Carotid, vertebral, and inferior cervical arteries. 



Nerve-supply. — Ventral branches of the cervical nerves. 



7. Rectus capitis anterior major (M. longus capitis).- — This is the largest 

 of the three special flexors of the head, and lies along the ventro-lateral surface 

 of the anterior cervical vertebrae and the base of the cranium. 



Origin. — -The transverse processes of the fifth, fourth, and third cervical vej- 

 tebrae. 



Insertion. — The tubercles at the junction of the basilar process of the occipital 

 bone with the body of the sphenoid. 



Action. — -Acting together, to flex the head; acting singly, to incline it to the 

 same side also. 



Structure. — The origin of the muscle is l)y fleshy digitations. The belly in- 

 creases in size by the union of these digitations, reaching its maximum at the axis. 

 It then diminishes, passes toward the median plane, and terminates on a rounded 

 tendon. 



Relations. — -Superficially, the mastoido-humeralis, omo-hyoideus, and rectus 

 capitis anticus minor, the submaxillary gland, the carotid artery (which lies along 

 the lower border), the occipital and internal carotid arteries, and the tenth, eleventh, 

 and sympathetic nerves; deeply, the vertebrae, the longus colli, intertransversales, 

 and the small straight muscle. The terminal part of the muscle lies in contact 

 with its fellow above the pharynx and between the guttural pouches. 



Blood-supply. — Carotid, vertebral, and occipital arteries. 



Nerve-supply. — Ventral branches of the cervical nerves. 



8. Rectus capitis anterior minor (M. rectus capitis ventralis). — This is a small 

 muscle which lies under cover of the preceding one. 



Origin. — The ventral arch of the atlas. 



1 The upper part of this may be separated from the scalenus proper, and is then termed the 

 cervicalis ascendens or iho-costalis cervicis — a continuation in the neck of the transversahs cos- 

 tarum. 



