What is the origin of the inferior rectal artery?

Inferior Rectal Artery Origin

The inferior rectal artery originates from the internal pudendal artery as it courses through the ischioanal (ischiorectal) fossa. 1

Anatomical Origin and Course

• The inferior rectal artery is a branch of the internal pudendal artery, which itself arises from the anterior division of the internal iliac artery 2
• The internal pudendal artery gives off the inferior rectal artery while traversing the ischioanal fossa, before continuing forward to supply the perineum 1
• The internal iliac artery originates from the common iliac artery at the level of the sacroiliac joint and descends to divide into anterior and posterior divisions 2

Branching Patterns and Variations

• The inferior rectal artery demonstrates significant anatomical variation in its branching pattern 1
• In 43% of cases, a single inferior rectal artery is present on each side 1
• In 31% of cases, two inferior rectal arteries arise on one side 1
• In 4% of cases, three arteries are present on one side 1
• In 22% of cases, two or more arteries are present bilaterally 1

Clinical Relevance

• The inferior rectal artery supplies the anal canal and perianal tissues, with lymphatic drainage from this region going to the inguinal, femoral, and external iliac nodes 3
• Understanding this vascular anatomy is critical during anorectal surgical procedures to avoid inadvertent vascular injury 2
• The variable branching pattern necessitates careful surgical dissection in the ischioanal fossa to identify and preserve these vessels 1

Important Distinction from Middle Rectal Artery

• The middle rectal artery, when present (only in 50-56.7% of cases), originates most commonly from the internal pudendal artery (40%), inferior gluteal artery (26.7%), or directly from the internal iliac artery (16.8%) 4, 5
• The middle rectal artery is a separate vessel that supplies the rectum proper, not the anal canal 4, 6