PELVIC FLOOR

PERINEAL BODY is essential for the integrity of the pelvic floor, particularly in females

Levator ani- 3 striated muscles: Puborectalis Pubococcygeous Iliococcygeous  

Puborectalis is innermost and merges with the external anal sphincter. Causes 120 deg angulation of anorectum due to the pull against the pubic bones. Shuts the lumen by apposing the post and the side walls of rectum

Puborectalis – from myotome S1-S4 Pubococcygeous and iliococcygeous help to close the urogenital diaphragm

EXTERNAL ANAL SPHINCTER: Superficial external sphincter Deep external sphincter – continuous with the puborectalis

The external anal sphincter and puborectalis muscles are innervated by the pudendal nerve.

INTERNAL ANAL SPHINCTER Circular layer of rectum becomes internal anal sphincter

Colon innervation: Intrinsic Auerbach plexus- segmentation and peristalsis Plexus of Meissner- secretions and sensation Extrinsic Parasympathetic increases and relaxes sphincters Sympathetic decreases motility and contracts sphincters

The muscular wall of the cecum and colon is innervated by: Vagus nerve- cranial nerve X in PNS Superior mesenteric plexus – SNS cord segment T9-L2 The rectum and anal canal innervation: Pelvic splanchnic nerves- parasympathetic S2-4 Hypogastric nerve- sympathetic T11-L2

Anal sphincters innervation: Internal anal sphincter- pelvic splanchnic nerves and hypogastric nerves External anal sphincter – pudendal nerve

Neural organization of anorectal sphincters: Somatic from S2,3,4 (pudendal nerve) to the external anal sphincter Sympathetic from L2,3,4 (superior hypogastric plexus/pelvic plexus) through hypogastric nerve to the internal anal sphincter Parasympathetic S2-4 (nervi erigentis or pelvic splanchnic nerves) to the internal anal sphincter

ADDITIONAL SLIDES FOR URINARY SYSTEM