IXTEEOSSEOUS AETEEIES. iO^ 



an inch in length, which arises below the bicipital tuberosity of the 

 radius, beneath the flexor sublimis, and passes backwards to reach the 

 upper border of the interosseous ligament, where it divides into the 

 anterior and posterior interosseous arteries. 



The anterior interosseous descends upon the anterior surface of the 

 interosseous ligament, accompanied by the interosseous branch of the 

 median nerve and vena? comites, and overlapped by the contiguous 

 borders of the flexor profundus digitorum and flexor longus pullicis- 

 muscles. It continues its course directly downwards as for as the upper 

 border of the pronator quadratus muscle, then piei'ces the interosseous 

 ligament, and descends to the back of the carpus. 



The anterior interosseous artery gives off the following branches : — 



{(/} The artery of the median nerve, or the mcdinn ortcr)/, a long slender 

 branch, which accompanies the median nerve and sends offsets into its substance.. 

 This artery is sometimes much enlarged, and in that case it presents several pecu- 

 liarities to be hereafter noticed. 



{h) Miixcuhn' branches to the flexor profundus, flexor longus jwllicis, and pro- 

 nator quachatus muscles. 



{(■) The ntitrwiit arteries of the shafts of the radius and ulna, which diverging" 

 from one another, enter the obliqiio foramina in those bones to be distributed to 

 the meduUaiy membrane in their interior. 



(//) An anterior inoxrii/nfinrj branch, given off before the artery pierces the 

 interosseous membrane, and descending beneath the pronator quadratus muscle 

 to anastomose with the anterior carpal arteries. 



{/■) Terminal twigs inosculating with the posterior carpal arteries. 



The posterior interosseous artery passes backwards through the interval 

 left between the oblique ligament and the upper border of the interos- 

 seous ligament, and continuing its course downwards along the fore-arm, 

 between the superficial and deep layers of extensor nmscles, gives 

 branches to them, and reaches the carpus considerably diminished in 

 size. 



In addition to muscular branches, it gives off the following : — 

 (a) The jJo.'itcrior intcrof!.'<ciiiiK recurrent, which passes directly ujnvards, covered 

 by the anconeus, to reach the interval between the olecranon and external con- 

 dyle ; at which place it di'i'ides into several offsets which anastomose with the 

 superior profunda and the posterior ulnar recurrent. 



(Z*) Terminal branches, which anastomose with the posterior or terminal branch 

 of the anterior interosseous arterj', and with the carpal branches of the radial 

 and ulnar arteries. 



Muscular Branches of the ulnar artery arc distributed to the 

 muscles in the course of the vessel along the fore-arm : some of these- 

 perforate the interosseous ligament to reach the extensor muscles. 



The posterior ulnar carpal branch, of variable size, arises a little 

 above the pisiform bone, and winding back under the tendon of the 

 flexor carpi ulnaris, reaches the dorsal surface of the carpus beneath 

 the extensor tendons. 



Its branches are the following : — 



((?) A branch anastomoses with tlie posterior carpal artery derived from the 

 radial, so as to form t\\e j^ostcrior carpal arch, and from this arch are derived the 

 xecond and third doval infeJV.'<seoa,f arferiex. which descend on the spaces between 

 the third and fourth and the fourth and fifth metacarpal bones, and are reinforced 

 at the upper ends of those spaces by anastomoses with the posterior perforating; 

 branches of the deep palmar arch. 



{b) A brancli nms along the metacarpal bone of the little finger. Sometimes- 



