MCQ – 89026

Correct Answer � B Explanation

Answer B) Internal pudendal

Bright red blood in stool with a painful nodule at the rim of the anal opening suggests an external hemorrhoid.

Internal pudendal

• The internal pudendal artery gives rise to the inferior rectal artery, which supplies the part of the anal canal below the pectinate line, where external hemorrhoids develop. 

• An external hemorrhoid is often painful because the region below the pectinate line arises from ectoderm and is innervated by the inferior rectal nerve, which transmits somatic sensations such as pain. 

• Internal hemorrhoids, which arise above the pectinate line, are supplied by the superior rectal artery, a branch of the inferior mesenteric artery).

• Unlike external hemorrhoids, internal hemorrhoids are typically painless because the region of the anal canal above the pectinate line arises from endoderm and is innervated by the inferior hypogastric plexus, which carries visceral sensation only.

Deep circumflex iliac

• The deep circumflex iliac artery is a branch of the external iliac artery that supplies the iliacus, iliac fossa, and deep abdominal wall of the inguinal region.

•  This artery does not supply the anal canal.

Median sacral

• The median sacral artery is a branch of the abdominal aorta that supplies part of the lumbar vertebral column, the coccyx, and the sacrum. 

• This artery does not supply the anal canal.

Superior rectal

• The superior rectal artery supplies the anal canal above the pectinate line (where internal hemorrhoids develop). 

• In contrast to external hemorrhoids, internal hemorrhoids are typically painless.