**Core Concept**
The lesser sciatic foramen is a passage in the pelvis through which various nerves, vessels, and other structures traverse from the gluteal region to the perineal area. Understanding the contents of this foramen is crucial for diagnosing and treating various pelvic and perineal pathologies.

**Why the Correct Answer is Right**
The internal pudendal vessels, which supply the external genitalia and perineal skin, actually pass through the greater sciatic foramen, not the lesser sciatic foramen. This is because the greater sciatic foramen is a larger opening that allows for the passage of larger structures, whereas the lesser sciatic foramen is a smaller opening that primarily transmits smaller nerves and vessels.

**Why Each Wrong Option is Incorrect**
**Option A:** The pudendal nerve, which is responsible for innervating the external genitalia and perineal muscles, does pass through the lesser sciatic foramen. It is a key structure that transmits sensory and motor information from the perineum to the spinal cord.

**Option C:** The nerve to obturator internus, which innervates the obturator internus muscle, passes through the lesser sciatic foramen. This nerve is responsible for controlling the movement of the hip joint and maintaining pelvic stability.

**Option D:** The inferior gluteal vessels, which supply the gluteus maximus muscle, do pass through the lesser sciatic foramen. These vessels are essential for maintaining blood flow to the gluteal region and supporting muscle function.

**Clinical Pearl / High-Yield Fact**
Remember that the contents of the lesser sciatic foramen include the pudendal nerve, nerve to obturator internus, and inferior gluteal vessels, but not the internal pudendal vessels. This knowledge is crucial for diagnosing and treating various pelvic and perineal pathologies, such as pudendal nerve entrapment or gluteal muscle injuries.

✓ Correct Answer: B. Internal pudendal vessels