138 THE POSTERIOR AORTA. 



given ofF between the two mesenteries (Fig \S ./. Plate 

 IV. E) ; and are very considerable trunks. Arising at 

 right angles from the aorta, they at once reach their appro- 

 priate kidneys; giving off in their passage branches to supply 

 the renal capsules. The spermatics {Fig 13 . g, g) follow 

 next in order ; parting from the main trunk, about midway 

 between the origin of the renals and the division of the 

 aorta. These are peculiar for being the longest arteries, in 

 proportion to their diameters, in the body ; and also for 

 travelling a greater distance in a straight line ; as well as for 

 giving off no branches ; the generality of arteries being 

 much convoluted, and sending off numerous twigs. These 

 vessels, in the male, pass down the abdominal rings, to join 

 the spermatic chords ; and in the female, go to the ovaries 

 and Fallopian tubes. The lumbar arteries (Fig 13 . i) are 

 usually five or six pairs ; which arise from the superior 

 part of the aorta ; being distributed to the spinal canal 

 and lumbar muscles. 



The iliac arteries. — When the aorta has arrived to about 

 the fifth lumbar vertebra, it first gives off the two external 

 ihacs ; and in about three quarters of an inch more, the 

 trunk divides finally into two larger divisions.— The internal 

 iliacs are so called from their pelvic situation and distribu- 

 tion {Fig 14 . i). The first to notice is the artery of the 

 bulb {Fig 14 . j) ; sometimes given off before the iliac divi- 

 sion, but always near it. It bends itself within the pelvis, 

 furnishing the prostatic gland in the male ; and vagina in 

 the female ; after which it proceeds to the bulb of the penis ; 

 or to the vagina. The gluteal {Fig 14 . 7i) is also a branch 

 from the internal iliacs ; and going through the sacro-sciatic 

 notch, supplies the gluteal, and some of the neighbouring 

 muscles. The lateral sacral {Fig 14 . o), likewise originating 

 from the same trunk ; sends off the peroneal {Fig 14 . p) ; 

 which supplies a gluteal branch ; the flexors of the thigh ; 

 and the anal muscles with part of their blood. The middle 

 sacral {Fig 14 . ^) is like the lateral, given off by the internal 

 iliac ; and both commonly travel to the end of the tail ; the 

 middle however being the smaller within the pelvis. The 

 obturator {Fig 14 . Z) often follows next ; the main trunk 

 of which traversing the pelvis, ultimately passes through 

 the obturator foramen to the muscles of the haunch ; before 



