Which statement correctly describes the lymphatic drainage of the anal canal below the dentate line?

• A Drains to the inferior mesenteric nodes via the superior rectal chain
• B Drains only to the internal iliac nodes with no other pathway
• C Drains exclusively to the para-aortic nodes
• D Drains to the superficial inguinal nodes ✓

Explanation

Below the dentate line, the anal canal lymphatics drain mainly to the superficial inguinal nodes, which explains why lower anal canal and perianal malignancies can produce groin nodal metastases. Above the dentate line, drainage follows the superior rectal vessels to the inferior mesenteric chain and also communicates with the internal iliac nodes via the middle rectal vessels. The dual embryological origin of the anal canal creates this split in venous, nerve supply and lymphatic drainage.

Reference: Gray's Anatomy for Students, 4th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.