DISSECTING MANUAL. 



SYMPATHETIC SYSTEM. 



The sacral part of the cord lies on the sacrum, internal to 

 the foramina ; it is continuous with the lumbar cord above and 

 ends below, over the coccyx, in a plexiform (parietal branches) 

 union with the opposite cord, the two parts often being con- 

 nected by a ganglion (ganglion impar) ; it usually presents four 

 ganglia. It receives no white rami communicantes, but gray 

 ones pass from it to the sacral and coccygeal nerves. Visceral 

 branches from its upper part join the pelvic plexus. [711] 



The hypogastric plexus is formed by the hypogastric nerves 

 (from the aortic plexus) , and lies on the bifurcation of the aorta 

 and the sacral promontory; it descends on either side of the 

 rectum and ends in the pelvic plexuses. The pelvic plexuses 

 lie on each side of the rectum and accompany the internal iliac 

 arteries, giving off subordinate plexuses along the branches; 

 each gets fibres from the upper sacral part of the cord, and 

 visceral branches from the sacral nerves. [714] 



ARTERIES. 



Internal Iliac. Beginning at the lumbo-sacral joint, this de- 

 scends on the pelvic wall and divides, usually at the upper bor- 

 der of the great sciatic notch, into two divisions, anterior and 

 posterior. [848] 



Branches of Posterior Division. Ilio-lumbar, to the iliac 

 fossa, sending a branch (lumbar) upward under the Psoas, and 

 another (spinal) to the spine. Lateral sacral; superior and infe- 

 rior, descending on the front of the sacrum and coccyx. Glu- 

 teal; a continuation of the division, which gives off muscular, 

 neural (to the sacral plexus), and nutrient (to the hip-bone) 

 branches in the pelvis. It then runs through the great sacro- 

 sciatic foramen above the Pyriformis and divides under the 

 Gluteus maximus into two branches, superficial and deep ; the 

 former at once breaks up. The deep branch divides into two 

 branches, upper and lower, which run forward between the 



[288] 



