572 TSE AUTERIES. 



■with its homologne; it is directed backward and downward on the bulb of the heel, 

 where it forms aranastomotio arch with the lateral digital artery ; from the convexity 

 of this arch which is turned downwards, there escape a large number ot reticulating 

 ramuscules, destined for the keratogenous membrane and the plantar cushion. 



c The latm-al digital arteries are distinguished into internal and external, ihe lirst 

 has its origin at the bend formed by the collateral of the cannon, when that vessel is 

 inflected on the posterior face of the perfuratus tendon to become the median digital 

 arterv most frequently in common with the branch whose divisions joia the metacai-pal 

 interosseous arteries. The second commences a little further off, after having received a 

 branch from either this communicating artery, or from the external interosseous palmar ; 

 it is not rare to see it entirely formed by one of these bjanches, or by the two together 

 Whatever may be their point of origin, the lateral digital arteries descend on the ex- 

 centric side of the digits, without the flexor tendons, and terminate in anastomosing 

 by inosculation witli the artery of the plantar cushion. Among the collateral branches 

 emanating from these arteries, there ouglit to be distinguished that which goes to the 

 ergot, and the transverse branch thrown across between each, as well as tlie niediau 

 digital artery.' 



2. Axillary Arteries of the Pig. 



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

 aorta. The right artery, or hrachio-cephalia trunk, first arises ; the left comes immediately 



a. The hracMo-eephalio trunk is directed forwards, under the inferior face of the trachea, 

 and leaves the thorax to reach the inner face of the anterior limb, as in other animals. 



It furnishes successively : — 



1. At the first rib, and below, the two carotid arteries, rising singly from nearly the 

 same point. 



2. Directly opposite to these vessels, a trunk remarkable for the complication 

 attending its mode of distribution ; it is directed upwards and backwards, on the side 

 of the trachea and longus coUi, crosses the interval between the second and third ribs, 

 and elevates itself into 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, whose mode of termination is exactly the same as in the 

 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 thorax, the subcostal or superior intercostal artery, placed across the superior 

 extremities of the third, fourth, apd fifth ribs. 



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

 cervical artery, divided into several ascending blanches ; and the two thoracic arteries, 

 which offer nothing particular for description. 



4. Without the thorax, on the internal face of the scapnlo-hnmeral 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 Euminants; the second courses upwards in 

 the space between the subscapular muscle and the teres major, and soon divides into 

 two temiinal branches, one of which continues tlie primitive track of the vessel, while 

 the other passes beneath the subscapular muscle to carry its ramifications into the 

 antero-external muscles of the shoulder, furnishing m its course : 1, The great dorsal 

 artery, throwing a part of its ramifications into the olecranian muscles: 2, A volu- 

 minous branch which provides the greater number of the divisions given off, in the 

 Horse, by the deep humeral and prehumeral arteries ; 3, Two articular branches, one 

 of which closely represents the superscapular artery. 



b. The left brachial trunk only differs from the right in the disposition of the 

 superior cervical, djirs'd, and vertebral arteries, which have distinct origins; the two 

 last are very close to each other, and the first furnishes the suhcostal braTich. 



3. Axillary Arteries of Camivora. 



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

 furnish successively, apart from the carotids, special branches of the brachio-cephalic 

 trunk : — 



1. A voluminous trunk, the common origin of the dorsal, superior cervical, and siib- 



' In several instance^, we have seen the lateral digital arteries stop at this transverse 

 anastomosis, which then received them entirely. 



