434 LUMBAR AND SACRAL GANGLIA. 



The Spermatic plexus is formed principally by the renal plexus. 

 The Inferior mesenteric plexus receives filaments from the aortic 

 plexus. 



LUMBAR GANGLIA. 



The Lumbar ganglia are four in number on each side, of the 

 peculiar pearly gray colour, fusiform, and situated upon the ante- 

 rior part of the bodies of the lumbar vertebrae. 



The superior and inferior branches of the lumbar ganglia are 

 branches of communication with the ganglion above and below, as 

 in the dorsal region. 



The external branches, two or three in number, communicate 

 with the lumbar nerves. 



The internal branches consist of two sets ; of which the upper 

 pass inwards in front of the abdominal aorta, and form around that 

 trunk a plexiform interlacement, which constitutes the aortic plexus ; 

 the Iqwer branches cross the common iliac arteries, and unite over 

 the promontory of the sacrum, to form the hypogastric plexus. 



The Aortic plexus is formed by branches from the lumbar ganglia, 

 and receives filaments from the solar and superior mesenteric' 

 plexuses. It sends filaments to the inferior mesenteric plexus, and 

 terminates in the hypogastric plexus. 



The Hypogastric plexus is formed by the termination of the aortic 

 plexus, and by the union of branches from the lower lumbar gan- 

 glia. It is situated over the promontory of the sacrum, between the 

 two common iliac arteries, and bifurcates inferiorly into two lateral 

 portions, which communicate with branches from the fourth and 

 fifth sacral nerves. It distributes branches to all the viscera of the 

 pelvis, and to the branches of the internal iliac artery. 



SACRAL GANGLIA. 



The Sacral ganglia are four or five in number on each side. They 

 are situated upon the sacrum, close to the anterior sacral foramina, 

 and resemble the lumbar ganglia in form and mode of connexion, 

 although they are much smaller in size. 



The superior and inferior branches communicate with the gan- 

 glia above and below. 



The external branches communicate with the sacral and coccygeal 

 nerves. 



The internal branches communicate very freely with the lateral 

 divisions of the hypogastric plexus, and are distributed to the pelvic 

 viscera. The last sacral ganglia of the opposite sides give off 

 branches which join a small ganglion, situated on the first bone of the 

 coccyx, called the ganglion impar, or azygos. This ganglion resem- 

 bles in its position and function the ganglion of Ribes, serving to 

 connect the inferior extremity of the sympathetic system, as does 

 the former ganglion its upper extremity. It gives off a few small 

 branches to the coccyx and rectum. 



