The inferior hypogastric plexus, also referred to as the pelvic plexus, is a major autonomic nerve network situated in the pelvic region. It lies on the lateral aspects of the rectum and the bladder, extending from the sacral promontory to the level of the pelvic floor. The plexus comprises both sympathetic and parasympathetic fibers, which combine to regulate the functions of pelvic viscera.
Anatomical components
- Sympathetic contributions – Derived primarily from the lumbar splanchnic nerves (L1–L2) and the sacral sympathetic trunks. These fibers travel through the superior hypogastric plexus before descending into the inferior hypogastric plexus.
- Parasympathetic contributions – Originating from the pelvic splanchnic nerves (S2–S4), which join the plexus directly.
- Visceral branches – The plexus gives rise to several named nerves that supply specific pelvic organs:
- Uterovaginal plexus (in females) – innervation of the uterus, cervix, and upper vagina.
- Vesical plexus – innervation of the urinary bladder and ureters.
- Rectal plexus – innervation of the rectum and anal canal.
- Prostatic plexus (in males) – innervation of the prostate, seminal vesicles, and distal urethra.
Physiological functions
- Sympathetic fibers – Mediate vasoconstriction of pelvic blood vessels, regulate urethral sphincter tone, and contribute to ejaculation in males.
- Parasympathetic fibers – Facilitate detrusor muscle contraction for bladder emptying, promote vasodilation, and support sexual arousal mechanisms.
Clinical relevance
- Surgical considerations – The plexus is at risk during pelvic surgeries such as radical hysterectomy, prostatectomy, and low anterior resection of the rectum. Injury can result in postoperative urinary or sexual dysfunction.
- Pelvic pain syndromes – Chronic pelvic pain may involve irritation or entrapment of the inferior hypogastric plexus; nerve blocks are sometimes employed for diagnostic or therapeutic purposes.
- Neurogenic bladder – Dysfunction of the plexus' autonomic fibers can contribute to neurogenic bladder disorders, influencing both storage and voiding phases.
Histological features
The plexus consists of a dense array of myelinated and unmyelinated nerve fibers embedded within a connective tissue matrix. It is surrounded by small blood vessels and lymphatics, which provide metabolic support.
Terminology
The term “inferior hypogastric plexus” reflects its location relative to the “superior hypogastric plexus,” which lies higher in the abdomen near the aortic bifurcation. “Hypogastric” derives from Greek roots meaning “below the stomach,” denoting the pelvic position of the structure.
