626 TEE ARTERIES. 



detaching on its course a series of collateral ramuscules, which are expended in the 

 muscles and integuments of the tail. 



There has been described a superior lateral artery, a branch of the preceding, 

 and which passes between the erector coccygis and the superior face of the 

 coccygeal vertebrae ; but this artery never exists : the superior coccygeal muscle 

 receives its blood by branches analogous to the spinal branches of the intercostal, 

 lumbar, and sacral arteries, and which emanate from the lateral coccygeal artery 

 at each of the vertebral bodies. 



3. Middle Coccygeal Artery. — The origin of this vessel is liable to 

 numerous variations. Ordinarily, it is detached from the right lateral sacral 

 arteiy, in common with the lateral coccygeal of the same side. At other times, 

 it escapes from the lateral at 5 or 6 inches from its origin. In a specimen now 

 before us, it arises nearly from the middle of the lateral sacral artery. And it 

 may also proceed from either the left sacral or the corresponding lateral coccygeal 

 artery. 



Whatever may be its point of emergence, this vessel is placed beneath the 

 inferior face of the coccygeal vertebrae, between the two compressores coccygis, 

 crosses the suspensory ligament of the rectum, and extends to the extremity of 

 the coccyx, distributing ramuscules to right and left, and even downwards. 



4. Ilio-lumbar or Ilio-muscular Artery (Figs. 368, 14 ; 370, 8). 



Immediately after clearing the inferior face of the lateral angle of the sacrum — 

 and even often before — the internal iliac artery gives off from its external side, 

 and at a right angle, the ilio-lumbar artery, which passes directly outwards, 

 behind the sacro-iliac articulation, between the iliacus muscle and the bony 

 surface covered by it, and emits divisions that proceed to the above-named 

 articulation, as well as to the muscles of the suhlumbar region. Near the angle 

 of the haunch, it terminates in several branches, which bend upwards on the 

 external border of the ilium, to penetrate the principal gluteal muscle, or the 

 tensor vaginae femoris. 



5. Gluteal Artery (Figs. 368, 13 ; 370, 7). 



This, the most voluminous of the branches emanating from the internal iliac, 

 arises opposite the preceding, and from ^^ of an inch to 1| inches behind the 

 lateral sacral. It is immediately reflected on the internal border of the ilium, 

 and emerges from the pelvis by the great sacro-sciatic foramen, along with the 

 anterior gluteal nerves, dividing into several branches which ramify in the texture 

 of the great and small gluteal muscles. 



6. Obturator Artery (Figs. 368, 19 ; 370, 10). 



This vessel, the origin of which has been already indicated, directs its couree 

 backward and downward, accompanied by a satellite vein and nerve, passes 

 between the peritoneum and ilium in following the inferior border of the pyri- 

 formis muscle, and finally insinuates itself beneath that muscle to make its exit 

 from the pelvis by creeping through the obturator foramen, after furnishing a 

 constant vesical twig. Placed between the external obturator muscle and the 

 inferior face of the ischium, it separates into several branches, the majority of 

 which descend into the internal crural and ischio-tibial muscles, anastomosing 

 with the ultimate divisions of the ischiatic and deep femoral arteries. Among 

 these branches there are two or three which go to the roots of the penis, and 



