A patient with external hemorrhoids develops pain while passing stools. Which
of the following nerve mediating this pain?
a) Pudendal nerve
b) Hypogastric nerve
c) Sympathetic plexus
d) Splanchnic visceral nerve
Correct Answer - A
External hemorrhoids are covered by the mucous membrane of the lower half of the anal
canal or the skin, and they are innervated by the inferior rectal nerves. Inferior rectal nerve
is a branch of pudendal nerve. Lower half of anal canal is sensitive to pain, temperature,
touch, and pressure.
The pectinate line indicates the level where the upper half of the anal canal joins the lower
half.
The mucous membrane of the upper half is sensitive to stretch and is innervated by
sensory fibers that ascend through the hypogastric plexuses.
The involuntary internal sphincter is supplied by sympathetic fibers from the inferior
hypogastric plexuses.
The voluntary external sphincter is supplied by the inferior rectal nerve, a branch of the
pudendal nerve and the perineal branch of the fourth sacral nerve