256 THE MUSCLES. 



slender muscle in two portions ; digastric ; situated in front of the trachea ; con- 

 founded at their inferior extremity and united to those of the opposite side, so as 

 to form a single fasciculus which is attached to the cariniform cartilage of the 

 stevnnm—Jixed insertion ; isolated from each other above the tendon which makes 

 thera digastric, and terminating by their superior extremity — movable insertion : 

 the first, on tlie inferior surface of the body of the hyoid bone in common with 

 the subscapulo-hyoideus ; the second, on the posterior border of the thyroid 

 cartilage. 



Relations. — Covered by the sterno-niaxillaris and the panniculus muscle, they 

 cover the anterior face of the trachea. 



Action. — Depressors of the hyoid bone aiid larynx. 



5. Subscapulo-hyoideus (Figs. 159, 11 ; 174, 5). 



Synonyms. — Hyoideus — Bourgelat. (^Subscapulo-hyoideus — Percivall.) 



Form — Structure — Situation — Direction. — This muscle forms a thin and wide 

 band, almost entirely fleshy, ol)lique forwards and upwards, extending from the 

 scapulo-humeral angle to the submaxillary space, and applied to the side of the 

 trachea, which it slightly crosses. 



Attachments. — It derives its fixed insertion from the inner surface of the 

 subscapularis, by an aponeurosis w^hich is detached from that covering the latter 

 muscle. Its movable insertion is into the body of the hyoid bone, in becoming 

 confounded with the sterno-thyro-hyoideus, and in being intimately united to the 

 muscles of the opposite side. 



Relations. — Outwardly, with the subscapularis, supra-spinatus, small pectoral, 

 mastoido-humeralis — which closely adheres to it, the jugular vein, the sterno- 

 maxillaris, and the panniculus. Inwardly, with the scalenus, the large anterior 

 straight muscle of the head, the main trunk of the carotid artery and the nerves 

 accompanying it, the trachea, thyroid gland, and the inferior face of the larynx. 

 The jugular vein is entirely separated from the carotid artery by this muscle in 

 the upper half of the neck. 



Action. — It is a depressor of the hyoid bone and its appendages. 



6. Great Anterior Straight Muscle of the Head (Rectus Capitis 

 Anticus Major) (Figs. 161 and 162, 10 ; 163, 13). 



Synonyms. — Long flexor of the head — Bourgelat. Trachelo-subocci pita lis — Girard. (Rectus 

 capitis unticus major — Percivall. TracJielo-occipitalis — Leyh.) 



Form — Structure — Situation — Direction. — A long, flat muscle, fasciculated in 

 its posterior half, terminated in a tendinous cone at its anterior extremity, and 

 passing along the fii-st cervical vertebrae in front. 



Attachments. — Behind, to the transverse processes of the third, fourth, and 

 fifth cervical vertebrae by as many fleshy digitations, the most inferior of which 

 are the ]onge&t—^ftxed insertion. In front, into the imprints on the body of the 

 sphenoid bone and the basilar process, by its terminal tendon — movable visertion. 



Relations. — Outwardly, with the mastoido-humeralis, the subscapulo-hyoideus, 

 and the small anterior straight muscle. Inwardly, with the longus colli and 

 the muscle of the opposite side. In front, with the common carotid, the nerves 

 accompanying this arteiy, and the guttural pouch, which lines it near its movable 

 insertion. Behind, with the great oblique muscle of the head and the occipitc 

 atloid articulation. 



