A 32-year-old woman was admitted to the hospital with a complaint of pain over her umbilicus. Radiographic examination revealed acute appendicitis. The appendix was removed successfully in an emergency appendectomy. One week postoperatively the patient complained of paresthesia of the skin over the pubic region and the anterior portion of her perineum. Which of the following nerves was most likely injured during the appendectomy?

**Core Concept**
The question tests the student's knowledge of the innervation of the abdominal wall and its relationship to surgical procedures such as appendectomy. The underlying principle is the anatomy of the nerves supplying the abdominal wall, particularly the ilioinguinal and iliohypogastric nerves.

**Why the Correct Answer is Right**
The patient's symptoms of paresthesia over the pubic region and the anterior portion of her perineum suggest involvement of the nerves that supply these areas. The ilioinguinal nerve, which arises from the L1 spinal nerve, provides sensory innervation to the skin of the pubic region and the medial aspect of the thigh. The iliohypogastric nerve, which also arises from the L1 spinal nerve, provides sensory innervation to the skin of the lower abdomen and the upper portion of the pubic region. Given the location of the patient's symptoms, it is likely that the ilioinguinal nerve was injured during the appendectomy.

**Why Each Wrong Option is Incorrect**
**Option A:** The genitofemoral nerve is not primarily responsible for the symptoms described, as it provides motor innervation to the cremaster muscle and sensory innervation to the medial aspect of the thigh and the skin of the labia majora.
**Option B:** The obturator nerve is not directly involved in the innervation of the skin over the pubic region and the anterior portion of the perineum.
**Option C:** The femoral nerve is primarily responsible for the innervation of the anterior thigh and is not directly involved in the symptoms described.
**Option D:** The lateral femoral cutaneous nerve is primarily responsible for the innervation of the skin of the lateral thigh and is not directly involved in the symptoms described.

**Clinical Pearl / High-Yield Fact**
The ilioinguinal and iliohypogastric nerves are at risk during abdominal and pelvic surgeries, including appendectomy. These nerves can be injured during surgical dissection, leading to sensory deficits in the affected areas.

**Correct Answer:** C. The ilioinguinal nerve.

✓ Correct Answer: B. Ilioinguinal