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Rectum and Anal Canal

GASTROINTESTINAL PHYSIOLOGY

Sigmoid colon

Rectosigmoid junction Superior rectal valvt* Middle rectal valve

. Interior i

^Peritoneal

Rectal fascia —- l.ongitudinal muscle Circular muscle Levator ani muscle Rec tal column tMorgagni)

Rectal sinus

Submucous space and internal hemorrhoidal plexus Pectinate (dentatet linę (anatomie anorectal linei Deep external sphincler Internal sphincter Anal valvo

--Anal erypt

Superficial extemal sphincter Perianal gland Perianal space

Subcutaneous external sphincter

sweat glands

in perianal skin

Podeń f Anoderm

External hemorrhoidal ploxus m perianal space Intersphincteric linę (white linę of Hilton; intermuscular groove)

Figurę 7.21 Structure of the Rectum and Anal Canal

The terminal end ot the large intestine is the rectum and anal canal \ormally, the anal canal is closed due to the tonie contraction of the iternal (smooth muscle) and external tskeletal muscle) anal spltino •ers. Whcn the rectum is distenrlerl by fecal matenal, the internal sphincter rclaxes but defccation docs not occur umil tfu* voluntar> extemal sphincter is relaxed and the muscles of the distal colon and rectum contract.

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