Reproduction: neural control of ejaculation: practice question

A Physiology 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

Physiology · Reproduction: neural control of ejaculation

Sample item

After retroperitoneal lymph node dissection for a testicular tumour, a man has normal erections and orgasm but ejaculates no semen. Which pathway was most likely damaged?

AGenitofemoral nerve, which mediates the cremasteric reflexBSympathetic fibres from T10 to L2 through the hypogastric plexus, which mediate emissionCParasympathetic pelvic splanchnic nerves (S2 to S4), which mediate erectionDPudendal nerve (S2 to S4), which mediates rhythmic expulsion by the bulbospongiosus

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

The answer and the reasoning

B. Sympathetic fibres from T10 to L2 through the hypogastric plexus, which mediate emission

Emission, the movement of sperm and secretions into the prostatic urethra, depends on sympathetic outflow from T10 to L2 through the hypogastric plexus, which also closes the bladder neck. Expulsion is somatic through the pudendal nerve, and erection is parasympathetic. Damage to the sympathetic chain during the operation causes dry ejaculation with preserved erection.

Option by option

A. Genitofemoral nerve, which mediates the cremasteric reflex
The genitofemoral nerve has no role in ejaculation.
B. Sympathetic fibres from T10 to L2 through the hypogastric plexus, which mediate emission (correct)
Interruption of the sympathetic outflow abolishes emission and leaves erection and orgasm intact.
C. Parasympathetic pelvic splanchnic nerves (S2 to S4), which mediate erection
Pelvic splanchnic damage would impair erection, which is preserved here.
D. Pudendal nerve (S2 to S4), which mediates rhythmic expulsion by the bulbospongiosus
Pudendal nerve injury impairs expulsion and the orgasmic contractions, and emission would still occur.

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 Physiology question

What is the answer to this Physiology question?

The best answer is B, Sympathetic fibres from T10 to L2 through the hypogastric plexus, which mediate emission. Emission, the movement of sperm and secretions into the prostatic urethra, depends on sympathetic outflow from T10 to L2 through the hypogastric plexus, which also closes the bladder neck.

Why is "Genitofemoral nerve, which mediates the cremasteric reflex" not the answer?

The genitofemoral nerve has no role in ejaculation.

Why is "Parasympathetic pelvic splanchnic nerves (S2 to S4), which mediate er…" not the answer?

Pelvic splanchnic damage would impair erection, which is preserved here.

Why is "Pudendal nerve (S2 to S4), which mediates rhythmic expulsion by the b…" not the answer?

Pudendal nerve injury impairs expulsion and the orgasmic contractions, and emission would still occur.

What concept does this question test?

It tests Reproduction: neural control of ejaculation in Physiology. Expulsion is somatic through the pudendal nerve, and erection is parasympathetic. Damage to the sympathetic chain during the operation causes dry ejaculation with preserved erection.

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 Reproduction: neural control of ejaculation?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.