570 THE AETEE1ES. 



arch, in contradistinction to the subcarpal or deep palmar arch, the source 

 of the interosseons arteries of the metacarpus. This ramification furnishes 

 one or more muscular twigs that usually anastomose with the other branches 

 of the posterior radial artery ; and an inferior division, 1 which descends in 

 the carpal arch, within the pisiform bone, to the superior extremity of the 

 metacarpus, where it inosculates with the radio-palmar artery, after detach- 

 ing several carpal ramuscules, the principal of which turns round the inferior 

 border of the pisiform bone. 



2. On its course, numerous and fine synovial tendinous and cutaneous 

 divisions. 



3. A trunk springing from the terminal extremity of the vessel, between 

 the two digital arteries, sometimes even from one of these, which is placed 

 at the posterior face of the principal metacarpal bone, within the two 

 branches of the suspensory ligament, and, passing upwards, soon divides into 

 two branches ; these anastomose by inosculation with the posterior inter- 

 osseous arteries of the metacarpus, after giving off on each side two other 

 ramuscules which wind round the borders of the middle metacarpal bone, 

 receiving the dorsal interosseous arteries, and ramify in front of the fetlock, 

 on the anterior face of the cannon bone, and in the texture of the capsular 

 ligament of the metacarpo-phalangeal articulation (Fig. 283, 10). 



Terminal branches. These are, as we said, the digital arteries, whose dis- 

 position almost exactly repeats that of these vessels in the posterior limb, 

 and which have been described at page 551. 



DIFFERENTIAL CHARACTERS IN THE AXILLARY ARTERIES OF OTHER THAN SOLIPED ANIMALS. 



1. Axillary Arteries of Ruminants. 



These vessels comport themselves in their origin, course, and relations, as in Solipeds. 

 The special characters they present in their distribution are as follows : 



1. Dorsal artery. This arises from a trunk common to it and the vertebral artery, 

 and usually leaves the thorax by passing above the first costo-vertebral articulation. Its 

 subcostal branch proceeds directly from the above-named trunk. 



2. Superior cervical artery. This is absent, and is replaced by a branch of the dorsal 

 artery, but particularly by the superior muscular divisions of the vertebral artery. 



3. Vertebral artery. Extremely voluminous, and terminates in the muscles of the 

 neck, after passing through the foramen of the axis ; it is remarkable for the considerable 

 size of its spinal branches. 



4. Inferior cervical, internal and external thoracic arteries. 'These do not present 

 anything worthy of special consideration, except that the last is very voluminous in the 

 Ox and very slender in the Sheep, and supplies the satellite arterial branch of the 

 cephalic vein, which, in Solipeds, arises from the inferior cervical artery. 



5. Superscapular artery. This vessel appears to us to be absent in the Sheep, and 

 its place supplied by the divisions of the inferior cervical artery. 



6. Subscapular artery. The scapulo-humeral branch gives oft the majority of the 

 branches destined to the posterior brachial muscles. 



7. Humeral artery. The muscular arteries are of small size, particularly the deep 

 humeral, which is largely replaced by the scapulo-humeral branch. 



8. Anterior radial artery. This comports itself similarly to that of the Horse, and 

 is liable to as frequent anomalies. 



9. Posterior radial artery. This artery follows the same course as in Solipeds ; only 

 instead of furnishing the radio-palmar artery near the carpus, at the point where it 

 becomes the collateral artery of the cannon, it gives off that vessel much higher, and near 

 the upper third or middle of the fore-arm. Its interosseous branch, lodged in the deep 

 channel on the outside of the bones of this region, where the radius and ulna join, is 

 separated into two branches near the inferior extremity of that groove. The anterior of 

 these ramifies on the dorsal face of the carpus, and anastomoses with the divisions of the 



Analogous to the radio-ulnar artery of Man. 



