OBTURATOR INTERNAL PTJDIC. 433 



The internal branch curves inwards along the inner margin of the obturator 

 foramen, distributing branches to the Obturator muscles, Pectineus, Adductors, 

 and Gracilis, and anastomoses with the external branch, and with the internal 

 circumflex artery. 



The external branch curves round the outer margin of the foramen, to the space 

 between the Gemellus inferior and Quadratus femoris, where it anastomoses with 

 the sciatic artery. It supplies the Obturator muscles, anastomoses, as it passes 

 backwards, with the internal circumflex, and sends a branch to the hip-joint 

 through the cotyloid notch, which ramifies on the round ligament as far as the 

 head of the femur. 



Peculiarities. In two out of every three cases the obturator arises from the internal iliae. In 

 one case in three and a half cases, from the epigastric ; and in about one in seventy-two cases by 

 two roots from both vessels. It arises in about the same proportion from the external iliac 

 artery. The origin of the obturator from the epigastric is not commonly found on both sides of 

 the same body. 



When the obturator artery arises at the front of the pelvis from the epigastric, it descends 

 almost vertically downwards to the upper part of the obturator foramen. The artery in this 

 course usually descends in contact with the external iliac vein, and lies on the outer side of the 

 femoral ring (fig. 228) ; in such cases it would not be endangered in the operation for femoral 

 hernia. Occasionally, however, it curves inwards along the free margin of Gimbernat's ligament 

 (fig. 229), and under'such circumstances would almost completely encircle the neck of a hcrnial 

 sac (supposing a hernia to exist in such a case), and would be in great danger of being wounded 

 if an operation was performed. 



Variations in Origin and Course of Obturator Artery. 

 Fig. 228. Fig. 229. 



The INTERNAL PUDIC is the smaller of the two terminal branches of the anterior 

 trunk of the internal iliac, and supplies the external organs of generation. It passes 

 downwards and outwards to the lower border of the great sacro-sciatic foramen, 

 and emerges from the pelvis between the Pyriformis and Coccygeus muscles ; it 

 then crosses the spine of the ischium, and re-enters the pelvis through the lesser 

 sacro-sciatic foramen. The artery now crosses the Obturator internus muscle, to 

 the ramus of the ischium, being covered by the obturator fascia, and situated 

 about an inch and a half from the margin of the tuberosity ; it then ascends for- 

 wards and upwards along the ramus of the ischium, pierces the posterior layer of 

 the deep perineal fascia, and runs forwards along the inner margin of the ramus 

 of the pubes ; finally, it perforates the anterior layer of the deep perineal fascia, 

 and divides into its two terminal branches, the dorsal artery of the penis and the 

 artery of the corpus cavernosum. 



Relations. In the first part of its course, within the pelvis, it lies in front of the 

 Pyriformis muscle and sacral plexus of nerves, and on the outer side of the rectum 

 (on the left side). As it crosses the spine of the ischium, it is covered by the 

 Glutens maximus, and great sacro-sciatic ligament; and when it enters the pelvis, 

 it lies on the outer side of the ischio-rectal fossa, upon the surface of the Obtura- 

 tor internus muscle, contained in a fibrous canal formed by the obturator fascia 

 and the falciform process of the great sacro-sciatic ligament. It is accompanied 

 by the pudic veins, and the internal pudic nerve. 



Peculiarities. The internal pudic is sometimes smaller than usual, or fails to give off one 01 

 two of its usual branches; in such cases, the deficiency is supplied by branches derived from an 

 additional vessel, the accessory pudic, which generally arises from the pudic artery before its exit 



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