Pelvis: anorectal anatomy: practice question

A Anatomy question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

Try it

Anatomy · Pelvis: anorectal anatomy

Sample item

A patient has carcinoma of the lower anal canal below the pectinate line. To which lymph nodes will it first drain?

ASuperficial inguinal nodesBPara-aortic nodesCInferior mesenteric nodesDInternal iliac nodes

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

A. Superficial inguinal nodes

Below the pectinate line the anal canal is somatic: it drains by the inferior rectal vessels to the superficial inguinal nodes. Above the line it drains to the internal iliac and inferior mesenteric nodes.

Option by option

A. Superficial inguinal nodes (correct)
Correct. Lymph from the skin-lined lower canal follows the perineal skin to the inguinal nodes.
B. Para-aortic nodes
Para-aortic nodes are a later, secondary station.
C. Inferior mesenteric nodes
Inferior mesenteric nodes drain the upper rectum.
D. Internal iliac nodes
Internal iliac nodes drain the part above the pectinate line.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is A, Superficial inguinal nodes. Below the pectinate line the anal canal is somatic: it drains by the inferior rectal vessels to the superficial inguinal nodes.

Why is "Para-aortic nodes" not the answer?

Para-aortic nodes are a later, secondary station.

Why is "Inferior mesenteric nodes" not the answer?

Inferior mesenteric nodes drain the upper rectum.

Why is "Internal iliac nodes" not the answer?

Internal iliac nodes drain the part above the pectinate line.

What concept does this question test?

It tests Pelvis: anorectal anatomy in Anatomy. Above the line it drains to the internal iliac and inferior mesenteric nodes.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Pelvis: anorectal anatomy?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.