PHYSIOLOGY, AND PATHOLOGY OF THE CHIMPANZEE. 389 



formed by the superiicialis volse and a branch of the ubiar artery; 

 (3) a digital arch (Dig.A) over the metacarpo-phalangeal joints 

 of the index and inedius is formed by a branch of the uhiar 

 artery with the continuation of the radial artery. The deep and 

 digital arches are connected by a thick vessel. 



The wrist joint is supplied by dorsal branches of the radial and 

 ulnar arteries, the anterior radial carpal artery, the anterior 

 interosseous artery, and the deep palmar arch. There is no 

 anastomosis round the elbow joint. 



The arrangements of the arteries in the pectoral extremity 

 favour a relatively slower circulation than in Man. The pro- 

 funda arteries break up into a much larger number of branches, 

 and the brachial artery terminates in a large number of vessels 

 which run distally in long, parallel trunks. Consequently the 

 frictional resistance resulting from more numerous branches, 

 combined with the relatively smaller and more uniform brachial 

 artery slow the circulation much more. The addition of a third, 

 or digital, arterial arch is an additional factor. As there are no 

 anastomoses round the joints and scapula, the connections must 

 be more numerous in the muscles, which will consequently play 

 an important part in maintaining the circulation. And finallj?^, 

 the vascular arrangements are such that the head, neck, and arm 

 get a relatively greater supply of blood than do the thorax, 

 abdomen, and legs. 



Arteries of the Pelvic Extremity. 



The femoral artery begins about the middle of Poupart's 

 ligament and courses downwards for an inch and a half. Then 

 it gives off the profunda and is continued as the superficial 

 femoral artery. The latter passes between the two parts of the 

 adductor magnus and becomes the popliteal artery. There is no 

 adductor canal. The common femoral artery gives off a trunk 

 which divides into an abdominal artery and the mesial circum- 

 flex artery; and the former, after giving a nutrient artery to 

 the ilium and the deep epigastric, is continued as the obturator 

 artery. From the common femoral artery the deep circumflex 

 iliac artery also arises. The profunda gives off the lateral 

 femoral circumflex artery, and the superficial femoral artery 

 gives off the saphenous artery, which goes down to the foot. 



The deep epigastric artery runs up in the sheath of the rectus, 

 but does not anastomose vpith a superficial epigastric branch of 

 the internal mammary artery. 



The obturator artery passes through the obturator foramen 

 after running down over the horizontal ramus and back of the 

 pubis. It supplies the symphysis pubis and muscles attached to 

 the bone around the foramen. 



The mesial femoral circimifex artery runs down over the head 

 of the femur under the adductor muscles, and supplies the 

 capsule of the hip joint, psoas, obturator internus, and adductor 



Proc. Zool. Soc— 1923, No XXYI. 26 



