660 



THE ARTERIES. 



2. The inferior thyroid, the origia of wliich, and some branches, we find in the ascending 

 branch {ascending cervical) of the inferior cervical artery in the Horse. 



3. The internal mammary artery divides into two branches 

 at the xiphoid cartilage of tlie sternum. 



4. The superior intercostal artery, the analogue of which we 

 see in Solipeds, in the subcostal branch of the dorsal. 



5. The supra- scapular artery, present in all animals and dis- 

 posed in the same manner. 



6. The transverse cervical (transversa colli), represented by 

 the extra-thoracic branches of the dorsal artery. 



The Axillary Artery, or extra-thoracic portion of the 

 subclavian trunk, extends to the external border of tlie pectoral 

 muscle, where it is continued by tlie humeral artery. The 

 axillary gives off: th^ thoracica acromialis, resembling the de- 

 scending branch of the interior cervical artery of large quad- 

 rupeds; the external mammary ; subscapular; -dnd posterior a.i\d 

 anterior circumflex, branches of the preceding in Solipeds. 



Humeral (Brachial) Artery. — Tliis artery extends from 

 the external border of the pectoral muscle to the bend of the 

 elbow : here it divides into two terminal branches — the ulnar 

 and radial. 



In its course it gives off several muscular braichcs, and an 

 external and internal collateral of the elbow (coUateralis ulnaris 

 superior and inferior). In the lower third of the arm, the 

 brachial artery is comprifod between the brachialis anticus and 

 inner border of the biceps ; so that, during flexion, and especially 

 active and forced flexion, of the forearm on the arm, in vigorous 

 subjec's, the circulation is arrested in the vessels of the hand. 



The radial artery oi Man is represented in the Horse by the 

 posterior radial artery. It is directed downward and a little 

 inward, supposing the hand to be in a state of [)ronation ; it 

 crosses the carpus in front of the trapezium and scaphoides, at 

 the bottom of tlie anatomical snuff-box, and beneath the flexor 

 tendons of the phalanges forms the deep palmar arch, finally 

 anastomosing with a brancli of the ulnar at the hypothenar 

 eminence. Along its course it furnishes muscular branches : 

 the carpea anterior ; radio-palmar, which passes outwards, and 

 unites with a branch of the ulnar artery to form the superficial 

 palmar artery ; the dursalis pollicis ; the carpea posterior, which 

 concurs in the formation of the dorsal arch of the carpus, that 

 gives origin to the dorsal interosseous branches. 



Tiie ulnar artery, formed, in Solipeds, by the anterior radial, 

 passes downward atid outward ; it is at first covered by the 

 great pronator muscles, great and small palmar, and superficial 

 flexor ; lower, it is only protected by the antibrachial aponeurosis 

 and the skin. On the anterior face of the carpus, it passes 

 within the pisiform bone, and auiistomoses with the radio-palmar 

 artery ; whence results the superficial palmar arch. It gives 

 rise to two recurrent arteries that ascend to receive the collateral 

 vessels of tlie elbow, then to a trunk seen in animals, and which 

 divides into the anterior and posterior interossecB. 



The three arches in the vicinity of the carpus, the constitu- 

 tion of which has been already given, are distributed in the 

 following manner : — 



The superficial palmar arch is situated at the surface of the 

 flexor tendons ; from its convexity it emits four or five meta- 

 carpal branches : the first reafhes the external border of tho 

 little finger as the external collateral of that organ ; the other 

 four are lodged in the interosseous spaces, and when they reach 

 the roots of the finders they bifurcate and form the external 

 or internal collateral arteries of the five fingers. The deep 

 palmar arch furnishes: articular branches to the wrist, the 



ABTKRIES OF THE HUMAN 

 FOREARM. 



1, Lower part of biceps ; 2, 

 inner condyle of humerus ; 

 3, deep portion of pronator 

 radii tei-es; 4, supinator 

 longus ; 5, flexor longus 

 pollicis; 6, pronator quad- 

 ratus ; 7, flexor profundus 

 digitorum ; 8, flexor carpi 

 ulnaris; 9, annular liga- 

 ment ; 10, brachial artery ; 

 11, anastomotica longus 

 magna, inosculating above 

 with the inferior profunda, 

 and below with the anterior 

 ulnar recurrent ; 12, radial 

 artery; 13, radial recurrent, 

 inosculating with the supe- 

 rior profunda ; 14, super- 

 ficialis vola; ; 15, ulnar ar- 

 tery ; 16, superficial palmar 

 arch, giving off digital 

 branches to three fingers 

 and a half; 17, magna 

 pollicis and radialis in<licis ; 

 18, posterior ulnar recur- 

 rent; 19, anterior inter- 

 osseous; 20, posterior inter- 

 osseoas. 



