From the Guidelines
The ilioinguinal nerve courses laterally to the boundaries of the pelvic lymph node dissection, specifically delineated by the iliac bifurcation proximally, the ilioinguinal nerve laterally, and the obturator nerve medially, as described in the context of penile cancer management 1.
Anatomical Course
The ilioinguinal nerve arises from the first lumbar nerve (L1) and emerges from the lateral border of the psoas major muscle. It then courses obliquely across the quadratus lumborum muscle and passes through the transversus abdominis muscle near the anterior superior iliac spine.
- The nerve continues between the internal oblique and external oblique muscles, running parallel but inferior to the iliohypogastric nerve.
- As it approaches the inguinal canal, the ilioinguinal nerve enters the canal through its posterior wall and travels along its length.
- Within the inguinal canal, it accompanies the spermatic cord in males or the round ligament in females.
- The nerve ultimately exits through the superficial inguinal ring to provide sensory innervation to the skin of the upper and medial thigh, the root of the penis and anterior scrotum in males, or the mons pubis and labia majora in females.
Clinical Importance
Understanding the course of the ilioinguinal nerve is crucial for surgeons performing inguinal hernia repairs or pelvic lymph node dissections, as the nerve may be at risk of injury during dissection, potentially leading to chronic pain or sensory deficits in its distribution area, highlighting the need for precise anatomical knowledge to minimize morbidity and improve patient outcomes 1.
From the Research
Course of the Ilioinguinal Nerve
- The ilioinguinal nerve originates from the L1 spinal nerve, with variations in its origin and branching patterns reported in several studies 2, 3.
- The nerve courses anteriorly to the psoas major muscle and descends to the inguinal region, where it provides sensory innervation to the medial thigh, groin, and genitalia 2, 3.
- Anatomical variations of the ilioinguinal nerve, including its absence, have been reported, with a range of 0% to 35% absence in cadaveric studies 2.
- The ilioinguinal nerve may be damaged during spinal anesthesia and surgical procedures in the lower abdominal region, highlighting the importance of understanding its regional anatomy and variations 2, 3.
- Knowledge of the ilioinguinal nerve's course and variations is essential for the improvement of peripheral nerve blocks and the prevention of iatrogenic nerve injuries during abdominal surgeries 2, 3, 4.
Branching Patterns and Exits
- The ilioinguinal nerve may have different branching patterns and exits in relation to the psoas major muscle, with some studies reporting the presence of double nerves 3.
- The nerve's retroperitoneal course and its relation to anatomical landmarks, such as the iliac vessels, may also vary 3.
- Understanding these variations is crucial for the safe and effective performance of peripheral nerve blocks and other surgical procedures 2, 3, 4.
Clinical Implications
- The ilioinguinal nerve's course and variations have significant implications for postoperative pain management, particularly in inguinal hernia repair 5, 6, 4.
- Ilioinguinal nerve blocks, performed using either anatomical landmark or ultrasound-guided techniques, can provide effective analgesia and reduce opioid-induced side effects 6, 4.
- However, the success of these blocks depends on a thorough understanding of the nerve's anatomy and variations, highlighting the need for careful patient selection and technique 6, 4.