LUMBAR AXD SACRAL PORTIOXS OF GAXGLLATED CORD 833 



LUMBAR PORTION OF THE GANGLIATED CORD 



TIk' lumbar part of the gangliated cord consists of a chain of ganglia, usually 

 four in number, which are placed in front of the bodies of the vertel)ri;e, close to 

 the anterior border of the psoas muscle. On the right side the cord is covered by 

 the vena cava, and on the left side it is behind and external to the aorta. Above, 

 it is continuous with the thoracic part of the cord. Below, it is continued into the 

 sacral i)art of the cord by passing behind the common iliac vessels. The rami 

 communicantes are longer in tliis part of the gangliated cord than in any other 

 region of the Ijody. Usually two rami pass from each ganglion backwards through 

 the tibrous arches from which the psoas takes origin, and join the lumbar ners'es in 

 a somewhat variable manner. Frequently there is only one ramus communicans 

 and sometimes the number of rami is increased. The rami communicantes are 

 attoiiipaiiied by the lumbar arteries. 



Branches. ^-Some of the branches join the aortic plexus; others pass in front 

 of the common iliac arteries to form the hypogastric plexus, and some terminate in 

 the vertebra? and ligaments. 



The lumbar j)ortion of the sympathetic cord contains a number of fibres already 

 described (p. 881) which have descended to it from the dorsal region, but it also 

 obtains others by the white rami from the lumbar ners'es; amongst the latter are 

 additional vaso-constrictor fibres for the renal blood-vessels, secretor}- fibres for the 

 glands of the hind limb, constrictor fibres for the blood-vessels of the lower 

 extremity, ])ilo-motor fibres, motor fibres for the circular, and inhibitory fibres for 

 tile longitudinal nuiscle of the rectum, motor fibres for the uterus, vas deferens and 

 round ligament, motor fibres for the circular and inhibitory fibres for the longi- 

 tudinal fibres of the IJadder, and vaso-motor fibres for the penis. 



The motor filjres for the bladder and uterus leave the lumbar sympathetic cord 

 by the rami efferentes and pass by the aortic plexus to the inferior mesenteric 

 ganglion. The motor fibres to the vas deferens and spermatic cord enter the genito- 

 crural nerve. Of the vaso-motor fibres of the penis some of the constrictor fibres 

 ]»ass down to the sacral portion of the sympathetic cord where they ramify round 

 the cells of the sacral ganglia, the impulses they carry being transmitted by the 

 grey rami of the sacral ganglia to the pudic ner%-e. Others travel by the inferior 

 mesenteric ganglion, and the latter are accompanied by the vaso-dilator fibres of 

 the penis. 



SACRAL PORTION OF THE GANGLIATED CORD 



Tlie sacral part of the gangliated cord consists of a chain of four small 

 ganglia, which is placed in front of the sacrum internal to the anterior sacral fora- 

 mina. From the lowest of these ganglia, branches proceed on each side and 

 converge to a median ganglion (ganglion impar) which is situated in front of the 

 last i>iece of the sacrum or the first piece of the coccyx. The sacral ganglia are 

 connected in a somewhat irregular manner to the sacral nerves by short grey 

 rami communicantes. 



Branches. — From the upper sacral ganglia branches are given off which join 

 the i»elvie i>lexuses. Others pass across the sacrum to join corresponding branches 

 from the cord of the opposite side. From the ganglion impar twigs pass down- 

 wards to enter the coccygeal body. 



There are no white rami from the sacral ner\'es to the sacral sympathetic ganglia, 

 therefore all the medullated fibres contained in the sacral sympathetic cord have 

 descended to it from the dorsal and lumbar regions. They include some vaso- 

 constrictor and secretory fibres for the hind limb, pilo-motor fibres for the posterior 

 part of the body, including, in the cat, the tail, and some vaso-constrictor fibres of 

 the penis. 



The white rami of the sacral nerves are represented by their visceral branches, 

 the so-called pelvic splanchnics. These contain motor fiV)res to the longitudinal 

 muscle of the bladder, motor fibres for the longitudinal and inhibitory fibres for 

 the circular muscle of the rectum, motor fibres for the utt^us, secretory fibres for 

 the prostate gland, and vaso-dilator fibres for the penis. 

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