658 THE ARTERIES. 



2. Axillary Arteries of the Pig. 



Both spring separately from the arch of the aorta : consequently, there is no anterior aorta. 

 Tlie right axillary artery, or hrachio cephalic trunk, first arises ; the left comes immediately 

 after. 



0. The right axillary artery is directed forwards, under the inferior face of the trachea, and 

 leBTes the thorax to reach the inuer face of the anterior limb, as in other animals. 



It furnishes successively : — 



1. At the first rib, an I below, the two carotid arteries, rising singly from nearly the same 

 point. 



2. Directly opposite to these vessels, a trunk remarkable for the complexity of its dis- 

 tribution ; it is directed upwards and backwards, on the hide of tlie trachea and longus colli, 

 crosses the interval between the second and third ribs, and rises to the deep cervical muscles 

 to terminate in the vicinity of the nape of the neck. It evidently represents the deep or 

 superior cervical artery. Near its origin it gives off the vertebral artery, the termination of 

 wliich is exactly the same as in tlie Horse. Beyond this, it detaches the dorsal artery, which 

 ascends into the muscles of the withers, after passing into the first intercostal space. Lastly, 

 it supplies, before leaving the thurax, the subcostal or superior intercostal artery, placed across 

 the superior extremities of the third, fourth, and fifth ribs. 



8. Always within, but a little more forward than the first rib, a voluminous inferior cervical 

 artery, divided into several ascending branches ; and tlie two thoracic arteries, which offer 

 nothing particular for description. 



4. Oiitside the thorax, on the internal face of the scapulo-humeral articulation, the humeral 

 or subscapular arteries. The first, less voluminous than the other, presents, from its origin to 

 the distribution of its branches in the foot, a disposition essentially resembling that observed 

 in this vessel in Euminauts ; the second courses upwards in the space between the sub- 

 scapularis and the teres major, and sorm divides into two terminal branches, one of which 

 conilnues the course of tlie vessel, while the other passes beneath the subscapularis muscle to 

 carry its ramifications into the antero-external muscles of the shoulder, furnishing in its 

 course: (1) The great dorsal artery, throwing a part of its ramifications into the olecranian 

 muscles. (2) A voluminous branch tliat provides the greater number of the divisions given off, 

 in the Horse, by the deep humeral and prehumeral arteries. (.S) Two articular brandies, one 

 of which clo.sely represents the supra-scapular artery. 



h. The left axillary artery only differs from the right in the disposition of the superior 

 cervical, dorsal, and vertebral arteries, which iiave distinct origins ; the two last are very close 

 to each other, and the first furnishes the subcostal branch. 



3. Axillary Arteries of Carnivora. 



These arise separately from the convexity of the arch of the aorta, as in the Pig, and 

 furnish successively, besides the carotids, .'special branches of the axillary artery trunk : — 



1 . A voluminous trunk, the common origin of the dorsal, superior cervical, and subcostal or 

 superior intercostal arteries. The first passes between the two anterior ribs ; tlie second in 

 front of the first ; the third across the internal face of the first, second, and third ribs, near 

 their cartilages, where it emits ascending and descending intercostal branches. 



2. The vertebral artery, anastomosing, as in Solipeds, with a retrograde branch from the 

 occipital artery ; it supplements, in very great part, the superior cervical, the volume of which 

 is diminutive; it is only distributed to the superior part of the neck. 



3. The inferior cervical artery, giving off the pectoral branches. 



4. The internal th: racic artery, remarkable for its large volume, and for a superficial 

 division cliiefly destined to the mammae, which joins an analogous branch from the external 

 pudic artery. 



5. An external thoracic branch, the origin of which more resembles that of the supra- 

 scapular artery, which appears to be absent. 



G. The subscapular artery. — After furnishing this vessel, the axillary is continued by the 

 humeral artery, which we will now examine in detail. 



Humeral Artery. — Placed at first immediately behind the biceps muscle, this vessel 

 descends beneath the pronator teres, and divides at the superior extremity of the radius into 

 two terminal branches — the ulnar and radial arteries. 



It detaches on its course collateral branches, analogous to those which have been described 

 for Solipeds, and among which is a thin vessel— a vestige of the anterior radial artery, that 

 passes beneath the terminal extremity of the biceps to supply the muscles covering, anteriorly, 

 the articulation of the elbow. 



