436 ARTERIES. 



sciatic nerve for a short distance ; it then penetrates it, and runs in its substance 

 to the lower part of the thigh. 



The muscular branches supply the muscles on the back part of the hip, anas- 

 tomosing with the gluteal, internal and external circumflex, and superior per- 

 forating arteries. 



Some articular branches are distributed to the capsule of the hip-joint. 



The GLUTEAL ARTERY is the largest branch of the internal iliac, and appears to 

 "he the continuation of the posterior division of that vessel. It is a short thick 

 trunk, which passes out of the pelvis above the upper border of the Pyriformis 

 muscle, and immediately divides into a superficial and deep branch. Within the 

 pelvis, it gives off' a few muscular branches to the Iliac us, Pyriformis, and Obtu- 

 rator internus, and just previous to quitting that cavity a nutritious artery, which 

 enters the ilium. 



The superficial branch passes beneath the Gluteus maximus, and divides into 

 numerous branches, some of which supply this muscle, whilst others perforate its 

 tendinous origin, and supply the integument covering the posterior surface of the 

 sacrum, anastomosing with the posterior branches of the sacral arteries. 



_ The deep branch runs between the Gluteus medius and Gluteus minimus, and sub- 

 divides into two. Of these, the superior division, continuing the original course of 

 the vessel, passes along the upper border of the Gluteus minimus to the anterior 

 superior spine of the ilium, anastomosing with the circumflex iliac and ascending 

 branches of the external circumflex artery. The inferior division crosses the 

 Gluteus minimus obliquely to the trochanter major, distributing branches to the 

 Glutei muscles, and inosculates with the external circumflex artery. Some 

 branches pierce the Gluteus minimus to supply the hip-joint. 



The llio-lumbar Artery ascends beneath the Psoas muscle and external iliac 

 vessels, to the upper part of the iliac fossa, where it divides into a lumbar and an 

 iliac branch. 



The lumbar branch supplies the Psoas and Quadratus lumborum muscles, anas- 

 tomosing with the last lumbar artery, and sends a small spinal branch through 

 the intervertebral foramen, between the last lumbar vertebra and the sacrum, into 

 the spinal canal, to supply the spinal cord and its membranes. 



The iliac branch descends to supply the Iliacus internus, some offsets running 

 between the muscle and the bone, one of which enters an oblique canal to supply 

 the diploe, whilst others run along the crest of the ilium, distributing branches to 

 the Gluteal and abdominal muscles, and anastomosing in their course with the 

 gluteal, circumflex iliac, external circumflex, and epigastric arteries. 



The Lateral Sacral Arteries are usually two in number on each side, superior 

 and inferior. 



The superior, which is of large size, passes inwards, and, after anastomosing with 

 branches from the middle sacral, enters the first or second sacral foramen, is dis- 

 tributed to the contents of the sacral canal, and, escaping by the corresponding 

 posterior sacral foramen, supplies the skin and muscles on the dorsum of the sacrum. 



The inferior branch passes obliquely across the front of the Pyriformis muscle 

 and sacral nerves to the inner side of the anterior sacral foramina, descends on 

 the front of the sacrum, and anastomoses over the coccyx with the sacra media 

 and opposite lateral sacral arteries. In its course, it gives off branches, which 

 enter the anterior sacral foramina ; these, after supplying the bones and membranes 

 of the interior of the spinal canal, escape by the posterior sacral foramina, and are 

 distributed to the muscles and skin on the dorsal surface of the sacrum. 



EXTERNAL ILIAC ARTERY. 



The External Iliac Artery is the chief vessel which supplies the lower limb. It 

 is larger in the adult than the internal iliac, and passes obliquely downwards and 

 outwards along the inner border of the Psoas muscle, from the bifurcation of the 

 common iliac to the femoral arch, where it enters the thigh, and becomes the 



