The inferior hypogastric plexus includes efferent sympathetic fibers, afferent (sensory) fibers, and parasympathetic fibers arising from the pelvic splanchnic nerves (S2 to S4, nervi erigentes).
This paired plexus is the final common pathway of the pelvic visceral nervous system and is divided into three portions, representing distribution of innervation to the viscera: 1. Vesical plexus
Innervation: bladder and urethra  Course: along vesical vessels 2. Middle rectal plexus (hemorrhoidal)
Innervation: rectum  Course: along middle rectal vessels 3. Uterovaginal plexus (Frankenh¨auser ganglion)
Innervation: uterus, vagina, clitoris, vestibular bulbs
Course: along uterine vessels and through cardinal and uterosacral ligaments; sym pathetic and sensory fibers derive from T10, L1; parasympathetic fibers derive from
S2 to S4.
Afferent fibers from the pelvic viscera and blood vessels traverse the same pathways to provide sensory input to the central nervous system. They are involved in reﬂex arcs needed for bladder, bowel, and genital tract function. The afferent fibers reach the central nervous system to have their first synapse within the posterior spinal nerve ganglia.
Presacral neurectomy, in which a segment of the superior hypogastric plexus is divided and resected in order to interrupt sensory fibers from the uterus and cervix, is associated with relief of dysmenorrhea secondary to endometriosis in about 50% to 75% of cases in which it was used (18,19). Efferent fibers from the adnexa travel with the ovarian plexus; thus, pain originating from the ovary or tube is not relieved by resection of the presacral nerve. Because this plexus contains efferent sympathetic and parasympathetic nerve fibers intermixed with afferent fibers, disturbance in bowel or bladder function may result. An alternative surgical procedure is resection of a portion of the uterosacral ligaments; because they contain numerous nerve fibers with more specific innervation to the uterus, it is postulated that bladder and rectal function is less vulnerable to compromise (20).
An anesthetic block of the pudendal nerve is performed most often for pain relief with uncomplicated vaginal deliveries but may provide useful anesthesia for minor perineal surgical procedures. This nerve block may be accomplished transvaginally or through the perineum. A needle is inserted toward the ischial spine with the tip directed slightly posteriorly and through the sacrospinous ligament. As the anesthetic agent is injected, frequent aspiration is required to avoid injection into the pudendal vessels, which travel with the nerve.
The female urinary and genital tracts are closely related, anatomically and embryologically. Both are derived largely from primitive mesoderm and endoderm, and there is evidence that the embryologic urinary system has an important inductive inﬂuence on the developing genital system. About 10% of infants are born with some abnormality of the genitourinary system, and anomalies in one system are often mirrored by anomalies in another system (19).
Developmental defects may play a significant role in the differential diagnosis of certain clinical signs and symptoms and have special implications in pelvic surgery (21–26). Thus it is important for gynecologists to have a basic understanding of embryology.
Following is a presentation of the urinary system, internal reproductive organs, and external genitalia in order of their initial appearance, although much of this development occurs concurrently. The development of each of these three regions proceeds synchronously at an early embryologic age (Table 5.6).
Urinary System Kidneys, Renal Collecting System, Ureters