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Anatomy and function of the ilioinguinal nerve.
Hey everyone! This is Nicole from Kenhub, and in this tutorial, we will be discussing the ilioinguinal nerve.
So, the ilioinguinal nerve which is shown here in green arises from the ventral ramus of L1 which is the first lumbar spinal nerve of the lumbar plexus and the ilioinguinal nerve arises with the iliohypogastric nerve as a single trunk from the L1 nerve root. Now, this short common trunk enters the abdomen posterior to the medial arcuate ligament and runs parallel and superior to the iliac crest as it traverses along the anterior surface of the quadratus lumborum muscle. And at the lateral edge of the psoas major muscle, the iliohypogastric and ilioinguinal nerves divide as we can see in this image. And we can't see the psoas major muscle here but we can imagine the muscles coming down on either side just here.
Now, after separating from the iliohypogastric nerve, the ilioinguinal nerve obliquely traverses the quadratus lumborum muscle as well as the iliacus muscle of the iliac crest. It then pierces the transversus abdominis and the internal oblique muscles to enter the inguinal canal. The ilioinguinal nerve then travels through the inguinal canal and exits at the superficial inguinal ring alongside the spermatic cord in males or the round ligament in females. And the superficial inguinal ring is just about here.
And, of course, the ilioinguinal nerve has both motor and sensory functions. Motor innervation is provided to the transversus abdominis muscle and the internal oblique muscle by the ilioinguinal nerve as it passes through both muscles on its way to the inguinal canal.
The ilioinguinal nerve also provides sensory innervation to the skin of the superomedial thigh and the groin region and in males this includes cutaneous innervation of the anterior third of the scrotum and the root of the penis while in females, this includes the cutaneous innervation of the anterior third of the labia majora and the root of the clitoris.
So let's have a brief chat about the clinical significance of the ilioinguinal nerve. So as we can sort of tell from its location, the ilioinguinal nerve can be damaged either through surgery or as a result of trauma to the abdominal wall. And this kind of damage may result in the weakening of the transversus abdominis and internal oblique muscles which in turn can lead to the development of an inguinal hernia.
Now, the surgical repair of an inguinal hernia may sometimes cause a condition known as nerve entrapment and both injury or entrapment of the ilioinguinal nerve can lead to post herniorrhaphy pain syndrome or inguinodynia which is chronic pain in the groin region lasting more than three months. And if this occurs, this condition can be treated with an ilioinguinal nerve block.
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