The lymphatics from the uterine corpus are distributed to two groups of nodes. One set of vessels drains into the internal iliac nodes. The other set, after joining lymphatics from the ovarian region, terminates in the paraaortic lymph nodes. Lymphatics from the cervix terminate mainly in the internal iliac nodes, which are situated near the bifurcation of the common iliac vessels.
As a brief review, the peripheral nevous system is divided into a somatic division, which innervates skeletal muscle, and an autonomic division, which innervates smooth muscle, cardiac muscle, and glands. Pelvic visceral innervation is predominantly autonomic, which is further divided into sympathetic and parasympathetic components.
Sympathetic innervation to pelvic viscera begins with the superior hypogastric plexus, also termed the presacral nerve (Fig. 2-13). Beginning below the aortic bifurcation and extending downward retroperitoneally, this plexus is formed by sympathetic fibers arising from spinal levels TID through L2• At the level of the sacral promontory, this superior hypogastric plexus divides into a right and a left hypogastric nerve, which run downward along the pelvis sidewalls (Ripperda, 20i1i5).
Fibers to vestibular bulbs
FIGURE 2-13 Pelvic innervation. (Reproduced with permission from Corton MM: Anatomy. In Hofman BL, Schorge JO, Bradshaw KD, et al (eds):
Williams Gynecology, 3rd ed. New York, McGraw-Hili Education, 2016.)
In contrast, parasympathetic innervation to the pelvic viscera derives from neurons at spinal levels 52 through 54' heir axons exit as part of the anterior rami of the spinal nerves for those levels. These combine on each side to form the pelvic splanchnic nerves, also termed nervi erigentes.
Blending of the two hypogastric nerves (sympathetic) and the two pelvic splanchnic nerves (parasympathetic) gives rise to the inferior hypogastric plexus, also termed the pelvic plexus. his retroperitoneal plaque of nerves lies at the 54 and 55 level (Spackman, 2007). From here, fibers of this plexus accompany internal iliac artery branches to their respective pelvic viscera. Thus, the inferior hypogastric plexus divides into three plexuses. he vesical plexus innervates the bladder, and the middle rectal plexus travels to the rectum. he uterovaginal plexus, also termed F rankenhauser plexus, reaches the proximal fallopian tubes, uterus, and upper vagina. Extensions of the inferior hypogastric plexus also reach the perineum along the vagina and urethra to innervate the clitoris and vestibular bulbs (Montoya, 2011). Of these, the uterovaginal plexus is composed of variably sized ganglia, but particularly of a large ganglionic plate that is situated on either side of the cervix, proximate to the uterosacral and cardinal ligaments (Ramanah, 2012).
For the uterus, most of its aferent sensory fibers ascend through the inferior hypogastric plexus and enter the spinal cord via T 10 through T 12 and L] spinal nerves. These transmit the painful stimuli of contractions to the central nervous system. For the cervix and upper part of the birth canal, sensory nerves pass through the pelvic splanchnic nerves to the second, third, and fourth sacral nerves. Last, those from the lower portion of the birth canal pass primarily through the pudendal nerve. Anesthetic blocks used during delivery target these levels of innervation.