172 ANATOMY IN A NUTSHELL. 



lower epiphysis, through appearing first, unites with the shaft before the upper 

 epiphysis. In birds, the head of the bone is large, and enters into the formation 

 of the knee-joint, while the lower end atrophies. The rule is this: Those ephy- 

 ses which are the last to form are first to join the bone. The fibula is an excep- 

 tion. Rule 1, page 19. 



LESSOX XLVI. 



Arteries 



The abdominal aorta (Plates LXXII-XC) divides into the right and left 

 common iliac arteries a little to the left side of the median line of the fourth 

 lumbar vertebra. This division is on a level with the highest points of the crest 

 of the ilii. Each of these common iliac arteries divides into an external and an 

 internal iliac branch at the lumbo-sacral joint. The branches of these com- 

 mon iliac arteries supply the peritoneum, ureter. Psoas magnus. 



The internal iliac branch (Plates LXXII-XCI) is about an inch and a half 

 long and divides into an anterior and posterior trunk at the upper margin of 

 the great sacro-sciatic foramen. The posterior trunk gives off the three fol- 

 lowing branches: (1) Ilio-hmibar, (2) lateral sacral, (3) gluteal. The ilio- 

 lumbar branch divides into an iliac branch for the Iliacus muscle and the ilium 

 and a lumbar branch for the Psoas magnus and Quadratus lumborum. The 

 branch to the Quadratus lumborum semis a spinal branch to the spinal cord 

 through the last intervertebral foramen. The lateral sacral branch divides 

 into a superior and inferior division. The superior one, after anastomosing 

 with the sacro-media, passes through the first or second anterior sacral foramen 

 to supply the canal, after which it passes through the corresponding posterior 

 foramen to the back. The inferior branch, after descending on the sacrum and 

 coccyx, anastomoses with the sacro-media and has a similar route as the super- 

 ior branch. 



The gluteal branch passes out of the pelvis through the great sacro-sciatic 

 foramen, above the Pyriformis muscle. While in the pelvis, it gives branches 

 to the ilium and adjacent muscles. Outside of the pelvis it divides into super- 

 ficial branch which passes undes the Gluteus maximus, and deep branch which 

 passes between the Gluteus medius and Gluteus minimus, and then divides into 

 an upper branch which runs along the upper border of the Gluteus minimus, 

 and a lower branch which runs downward. 



The anterior trunk (Plate- LXXII-XC) uives off the following branches: 

 (!) Superior vesical, (2) middle vesical, (3) inferior vesical. (4) middle hem- 

 orrhoidal. (.">) obturator. (Co internal pudic, (7) sciatic; and in the female (8) 

 uterine, ami (9) vaginal. The superior vesical branch is that portion of the 

 fetal hypogastric artery which is still used alter birth. It runs to the side of 

 the bladder and gives off the artery to the vas deferens, which artery runs with 

 tin- spermatic cord. In the fetus the external iliac artery is only about one- 

 half as large a- this hypogastric artery (umbilical). This artery in the fetus 

 runs to the bladder and from there along the abominal wall to pass through the 



