THE VASCULAR SYSTEM 215 



to the femur excludes the possibility of any homology with the 

 femoral artery such as Osawa's description seems to suggest. 



(ii) The A. obturatoria (a.ob.) or A. pelvica (Osawa) is a small 

 vessel arising from the external iliac at about the same level as the 

 gluteal, or occasionally from a common stem with this vessel. It 

 passes ventralwards over the dorsal surface of the pubo-ischium and 

 supplies the origin of the M. pubo-ischio-femoralis internus, and, 

 after passing through the obturator foramen, the origins of the 

 muscles arising from the ventral face of the pubo-ischium, e.g. the 

 MM. pubo-ischio-femoralis externus, pubo-ischio-tibialis, &c. 



The external iliac then turns rather more ventrally and passes 

 round the pelvis in company with the pelvic vein, crossing lateral to 

 this vessel in the inguinal region. At the anterior border of the limb 

 it gives off(iii) a small branch which enters the thigh between the 

 MM. pubo-ischio-femoralis internus and extensor ilio-tibialis, and 

 there divides into a branch supplying these muscles — particularly the 

 former — and a cutaneous branch passing out to the skin — the A. 

 cutanea femoralis lateralis. Although it is only small and compara- 

 tively insignificant the position and distribution of this vessel would 

 suggest that it is to be regarded as the A. femoralis. The greater 

 portion of the region characteristic of this artery is supplied by a 

 circumflex and recurrent vessel from the A. ischiadica (q.v.). 



(iv) The remaining portion of the external iliac is the posterior 

 epigastric artery (a.e.p.), which, like its anterior counterpart, runs 

 along the lateral body-wall at the level of the ventral border of the 

 oblique muscles, just outside the peritoneum. It gives off segment- 

 ally RR. abdominales to the muscles of the body-wall, and finally 

 anastomoses with the posterior extremity of the anterior epigastric 

 artery so as to form a complete arterial loop along the side of the 

 trunk (cf. p. 211). 



{})) The A. vesicalis (a.ves.) passes ventro-mesialwards to the 

 neck of the bladder, and care must be taken on stretching open the 

 pelvis — after having split the pubic symphysis — to avoid rupturing 

 the artery. On reaching the bladder it breaks up into a tuft of five 

 or six small arteries, of which the majority supply the bladder, but 

 one or two twigs spread over the ventral side of the rectum, while 

 one branch passes back towards the cloaca and supplies the cloacal 

 gland. This last branch sometimes fuses with the mesial cloacal artery. 



(c) The A. pudenda (a. pud.) turns postero-ventrally and divides 

 into two main branches, although other accessory twigs may occur. 

 Of these one is a muscular branch and is distributed to the M. 



