Structure passing through both greater and lesser sciatic foramen is
## **Core Concept**
The question tests knowledge of pelvic anatomy, specifically the structures passing through the greater and lesser sciatic foramina. These foramina are important passageways for nerves and vessels between the pelvic cavity and the gluteal region or perineum.
## **Why the Correct Answer is Right**
The correct answer, **Pudendal nerve**, is a branch of the sacral plexus (S2-S4). It passes through the greater sciatic foramen, below the piriformis muscle, and then re-enters the pelvic cavity through the lesser sciatic foramen, accompanying the internal pudendal vessels. This nerve provides sensory, motor, and sympathetic fibers to the external genitalia of both sexes and the skin around the anus.
## **Why Each Wrong Option is Incorrect**
- **Option A:** The **superior gluteal nerve** passes through the greater sciatic foramen above the piriformis muscle but does not pass through the lesser sciatic foramen.
- **Option B:** The **inferior gluteal nerve** passes through the greater sciatic foramen below the piriformis muscle but, like the superior gluteal nerve, does not pass through the lesser sciatic foramen.
- **Option D:** The **sciatic nerve** passes through the greater sciatic foramen, usually below the piriformis muscle, but it does not pass through the lesser sciatic foramen.
## **Clinical Pearl / High-Yield Fact**
The pudendal nerve can be blocked (pudendal nerve block) to provide analgesia during childbirth or for minor gynecological and urological procedures. This block is typically performed by inserting a needle through the vaginal wall or perineal skin to deposit local anesthetic near the nerve as it passes through the lesser sciatic foramen.
## **Correct Answer:** C. Pudendal nerve.