PELVIC FLOOR

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

Levator ani- 3 striated muscles:PuborectalisPubococcygeous 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 sphincterDeep external sphincter – continuous

with the puborectalis

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

INTERNAL ANAL SPHINCTERCircular layer of rectum becomes

internal anal sphincter

Colon innervation:Intrinsic1. Auerbach plexus- segmentation and peristalsis2. Plexus of Meissner- secretions and sensationExtrinsic3. Parasympathetic increases and relaxes sphincters4. Sympathetic decreases motility and contracts

sphincters

The muscular wall of the cecum and colon is innervated by:

Vagus nerve- cranial nerve X in PNSSuperior mesenteric plexus – SNS cord segment

T9-L2

The rectum and anal canal innervation:Pelvic splanchnic nerves- parasympathetic S2-4Hypogastric nerve- sympathetic T11-L2

Anal sphincters innervation:Internal anal sphincter- pelvic splanchnic

nerves and hypogastric nervesExternal anal sphincter – pudendal nerve

Neural organization of anorectal sphincters:Somatic from S2,3,4 (pudendal nerve)to the external anal sphincterSympathetic 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