The innervation of the pelvic structures has an important role in the surgical knowledge, especially when the surgeon is dealing with radical surgery for cancer and with extensive surgical procedures for deep infiltrating endometriosis.
Reprinted with kind permission from TheTrocar.com
Publication Date: 06/02/2003 Update Date: 06/02/2003
The innervation of the pelvic structures has an important role in the surgical knowledge, especially when the surgeon is dealing with radical surgery for cancer and with extensive surgical procedures for deep infiltrating endometriosis. The classical anatomical description of the nerves of the pelvis are somehow difficult to understand and insufficient for the surgeon because of the tri-dimensional distribution of these nerves in the posterior part of the pelvis. Another main problem during open surgery is the difficulty in seeing the nerves, while the magnification of the laparoscope allows better visualization of the fibers.
The nerves for the pelvic organs can be sensitive, sympathetic or parasympathetic. The sympathetic fibers and the sensitive part can be found in the inferior hypogastric nerve, while the parasympathetic part is linked to the pelvic splanchnic nerves originating from the sacral plexus.
The superior hypogastric nerves form the superior hypogastric plexus at the level of the sacral promontory.
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The inferior hypogastric nerves originate in the same level.
The nerves cross the uterosacral ligament from the medial aspect to the lateral part converging with the ureter, so that the surgeon can isolate a fibrous part of the uterosacral ligament which lies medial and a nervous one which lies lateral. The nerves lie in the lateral part of the uterosacral ligament at about two centimeters from their origin from the uterus. The inferior hypogastric nerves carry the sensitive fibers and the sympathetic fibers responsible for the relaxation of the bladder detrusor muscle and for the contraction of the urethral sphincter.
The pelvic splanchnic nerves run from the S2-S4 roots of the sacral plexus and join in the inferior hypogastric plexus with the inferior hypogastric nerves at the level of the lateral part of the uterosacral ligaments, anteriorly and laterally to the rectum.
Some of the splanchnic nerves are distributed to the rectum forming a net originating from the uterosacral ligaments.
The inferior hypogastric plexus form a “triangularly shaped plexus, placed in a sagittal plane”, of about 4 cm in length, 3 cm in width, 0.5 cm in thickness, which is called inferior hypogastric plexus or Frankenhauser's ganglion.
The inferior hypogastric plexus runs lateral to the vagina going to the base of the bladder.
The uterosacral ligaments are related to the upper part of the plexus. The pelvic splanchnic nerves carry the parasympathetic fibers which are responsible for the voiding function of the detrusor of the bladder. Most of the fibers, but not all, of the inferior hypogastric plexus run in the pars nervosa of the parametrium which is limited in the upper part by the medial rectal artery and in the lower part by the levator ani muscle. Some of the nerves are placed in the anterior parametrium in the upper part showing a straight course to the bladder. The lower nerves are responsible for the contraction of the bladder after radical hysterectomy, if this part of the parametrium has been conserved. These nerves spread out to the bladder with a different course of those of the upper part, going to the bladder almost vertically in the most distal part of the anterior parametrium.
We believe that a thorough knowledge of the distribution of the nerves to the pelvic organs is necessary for the pelvic surgeon, mostly when dealing with radical surgery. Many unexpected side effects of our surgery, such as rectal constipation and voiding dysfunctions may be better understood and foreseen when the course of the pelvic nerves is known. However, training is necessary to dissect the fibers although the vision through the laparoscope helps in this training.
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