424 ANGIOLOGY. 



originate two anterior and two posterior interosseous pal mars. 

 The anterior ones pass round the heads of the small metacarpal 

 bones, and along -the grooves between them and the large bone, 

 anastomosing with the spiral above, and a branch of the large 

 metacarpal artery below. The posterior interossei descend on 

 either side of the suspensory ligament, inosculating near the 

 distal end of the metacarpus with branches from the large meta- 

 carpal artery. One of them gives off the nutrient artery of the 

 great metacarpal bone. 



LARGE METACARPAL ARTERY. 



(Fio. 162. 7.) 



This is the continuation of the posterior radial artery. It 

 runs beneath the posterior annular ligament in company with the 

 flexor tendons, afterwards descending to their inner side, along 

 with the internal metacarpal nerve and vein. Above the fetlock 

 it passes between the tendons and suspensory ligament, dividing 

 into the external and internal digital arteries. At its bifurca- 

 tion it gives off a recurrent branch, which divides and ascends, 

 one branch on the inner, another on the outer lateral aspect of 

 the suspensory ligament, anastomosing with the posterior inter- 

 ossei. From the sesamoidean arch, thus formed by union of all 

 the posterior arteries of the region, the digital arteries may be 

 said to arise, and likewise small transverse branches, which 

 encircle the fetlock joint. The metacarpal artery gives off 

 branchlets to the tendons and ligaments during its course. 



The circulation of the digit is the same as in the pelvic limb. 



CEPHALIC AND CAROTID ARTERIES. 



(Fie. 161. //'/") 



The right brachial artery, besides supplying branches corre- 

 sponding to those of the left, gives off the common carotid or 

 cephalic artery, which is detached at an acute angle, and directed 

 forwards under the trachea and above the anterior vena cava. 

 On reaching the anterior opening of the thorax, it bifurcates, 

 forming the Left and Right carotids, which pass up the side of 

 the neck, diverging as they ascend, at first below, afterwards on 

 the sides of the trachea, to which they are attached by areolar 

 tissue. At the middle of the neck, they reach the posterior 



