THE LATERAL SACRAL ARTERIES 



607 



and then between the psoas muscles and the vertebral column. On reaching the 

 superior aperture of the pelvis it divides into two branches, an iliac and a lumbar 

 (fig. 489). 



The iliac branch [ramus ihacus] passes laterally beneath the psoas and the femoral (anterior 

 crural) nerve and, perforating the iliacus, ramifies in the iliac fossa between that muscle and the 

 bone. It supphes a nutrient artery to the bone, and then breaks up into several branches which 

 radiate from the parent trunk, upward toward the sacro-ihac synchondrosis, laterally toward 

 the crest of the ihum, downward toward the anterior superior spine, and medially toward the 

 pelvic cavity. The first anastomoses with the last lumbar; the second with the external circum- 

 flex and gluteal; the third with the deep circumflex ihac from the external ihac; the fourth with 

 the ihac branch of the obturator. The lumbar branch [ramus lumbalis] ascends beneath the 

 psoas, and, supplying that muscle and the quadratus lumborum, anastomoses with the last lum- 

 bar artery. It sends a spinal branch (ramus spinalis) into the vertebral canal through the inter- 

 vertebral foramen between the last lumbar vertebra and the sacrum; this branch anastomoses 

 with the other spinal arteries. The iiio-lumbar artery is serially homologous with the lumbar 

 arteries. Hence the similarity in its course and distribution. 



2. THE LATERAL SACRAL ARTERIES 



The lateral sacral artery [a. sacralis lateralis], commonly arises as two vessels 

 from the posterior division of the hypogastric. The superior artery, when two 



Fig. 490.- 



-The Gluteal Arteries. (After Toldt, "Atlas of Human Anatomy," Rebman, 

 London and New York.) 



Glutsus medius muscle 



Inferior branch 



Superior branch — 

 Superior gluteal artery — 



Piriformis muscle— 

 Inferior gluteal artery 



Internal pudendal artery 



A. comitans nervi 



ischiadici 

 Obturator fascia 



Inferior haemor- 



rhoidal artery 



Sacro -tuberous 



ligament 



Perineal artery 



Medial circumflex 

 femoral artery 

 (deep branch) 



\ ^ Gluteeus minimus muscle 



Obturator internus muscle 



Biceps femoris muscle 

 (long bead) 



Quadratus femoris 

 muscle 



Attachment of the ilio- 

 psoas muscle to the 

 trochanter minor 



Adductor minimus muscle 



First perforating artery 

 Adductor magnus muscle 



Second perforating artery 



are present, runs downward and medially to the first anterior sacral foramen, 

 through which it passes; and, after supplying the spinal membranes and anas- 

 tomosing with the other spinal arteries, passes through the first posterior sacral 



