The following are impoant in maintenance of normal fecal continence except -
Anorectal angulation
Rectal innervation
Internal sphincter
Haustral valve
Ans. is 'd' i.e., Haustral valve Normal fecal continence requires - adequate rectal wall compliance to accommodate the fecal bolus. appropriate neurogenic control of the pelvic floor and sphincter mechanism, and - functional internal and external sphincter muscles At rest the puborectalis muscle creates a 'sling' around the distal rectum, forming a relatively acute angle (Anorectal angle). Anorectal angle distributes intraabdominal forces onto the pelvic floor and play an impoant role in the continence mechanism. At the time of defecation, this angle straightens, allowing the downward force to be applied along the axis of the rectum and anal canal. The internal & external sphincters are tonically active at rest. - the internal sphincter is responsible for most of the resting, involuntary sphincter force - the external sphincter is responsible for voluntary sphincter force. Both the internal and external sphincters are innervated by pudendal nerve. Finally, the hemorrhoidal cushions may contribute to continence by mechanically blocking the anal canal. Thus impaired continence may result from : - poor rectal compliance - injury to internal and/or external sphincter or puborectalis, or - nerve damage or neuropathy