The ilioinguinal nerve is a branch of the first

lumbar nerve The lumbar nerves are the five pairs of spinal nerves emerging from the lumbar vertebrae. They are divided into posterior and anterior divisions. Structure The lumbar nerves are five spinal nerves which arise from either side of the spinal cord b ...

(L1). It separates from the first lumbar nerve along with the larger

iliohypogastric nerve The iliohypogastric nerve is a nerve that originates from the lumbar plexus that supplies sensation to skin over the lateral gluteal and hypogastric regions and motor to the internal oblique muscles and transverse abdominal muscles. Structure ...

. It emerges from the lateral border of the

psoas major The psoas major ( or ; from grc, ψόᾱ, psóā, muscles of the loins) is a long fusiform muscle located in the lateral lumbar region between the vertebral column and the brim of the lesser pelvis. It joins the iliacus muscle to form the iliop ...

just inferior to the

iliohypogastric The iliohypogastric nerve is a nerve that originates from the lumbar plexus that supplies sensation to skin over the lateral gluteal and hypogastric regions and motor to the internal oblique muscles and transverse abdominal muscles. Structure ...

, and passes obliquely across the

quadratus lumborum The quadratus lumborum muscle, informally called the ''QL'', is a paired muscle of the left and right posterior abdominal wall. It is the deepest abdominal muscle, and commonly referred to as a back muscle. Each is irregular and quadrilateral in sh ...

and iliacus. The ilioinguinal nerve then perforates the

transversus abdominis The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) th ...

near the anterior part of the iliac crest, and communicates with the

between the transversus and the internal oblique muscle. It then pierces the internal oblique muscle, distributing filaments to it, and then accompanies the spermatic cord (in males) or the

round ligament of uterus The round ligament of the uterus is a ligament that connects the uterus to the labia majora. Structure The round ligament of the uterus originates at the uterine horns, in the parametrium. The round ligament exits the pelvis via the deep inguinal ...

(in females) through the

superficial inguinal ring The inguinal canals are the two passages in the anterior abdominal wall of humans and animals which in males convey the spermatic cords and in females the round ligament of the uterus. The inguinal canals are larger and more prominent in males. Th ...

. Its fibres are then distributed to the skin of the upper and medial part of the

thigh In human anatomy, the thigh is the area between the hip (pelvis) and the knee. Anatomically, it is part of the lower limb. The single bone in the thigh is called the femur. This bone is very thick and strong (due to the high proportion of bone ...

, and to the following locations in the male and female: * In the male ("

anterior scrotal nerve The anterior scrotal nerves are branches of the ilioinguinal nerve. The nerves innervates the scrotum in males. The equivalent nerves in the female are the anterior labial nerves. See also * Posterior scrotal nerves The posterior scrotal branches ...

"): to the skin over the root of the

penis A penis (plural ''penises'' or ''penes'' () is the primary sexual organ that male animals use to inseminate females (or hermaphrodites) during copulation. Such organs occur in many animals, both vertebrate and invertebrate, but males do n ...

and upper part of the

scrotum The scrotum or scrotal sac is an anatomical male reproductive structure located at the base of the penis that consists of a suspended dual-chambered sac of skin and smooth muscle. It is present in most terrestrial male mammals. The scrotum cont ...

. * In the female ("

anterior labial nerve The anterior labial nerves are branches of the ilioinguinal nerve. The nerves innervate the mons pubis and labium majus in females. The equivalent nerves in the male are the anterior scrotal nerves. See also * Posterior labial nerves The posteri ...

"): to the skin covering the

mons pubis In human anatomy, and in mammals in general, the ''mons pubis'' or pubic mound (also known simply as the mons, and known specifically in females as the ''mons Venus'' or ''mons veneris'') is a rounded mass of fatty tissue found over the pubic symp ...

and

labia majora The labia majora (singular: ''labium majus'') are two prominent longitudinal cutaneous folds that extend downward and backward from the mons pubis to the perineum. Together with the labia minora they form the labia of the vulva. The labia majo ...

. The ilioinguinal nerve does not pass through the deep inguinal ring, and thus only travels through part of the inguinal canal. It mediates the cremasteric reflex.

Variations

The size of this nerve is in inverse proportion to that of the iliohypogastric. Occasionally it is very small, and ends by joining the iliohypogastric; in such cases, a branch from the iliohypogastric takes the place of the ilioinguinal, or the latter nerve may be altogether absent.

Ilioinguinal nerve block

The ilioinguinal nerve is clinically important when considering an ilioinguinal or iliohypogastric nerve block. The indications for nerve block include anaesthesia for procedures involving the abdominal region such as inguinal herniorrhaphy or pain relief for procedures such as a c-section.

Ropivacaine Ropivacaine (rINN) is a local anaesthetic drug belonging to the amino amide group. The name ropivacaine refers to both the racemate and the marketed ''S''-enantiomer. Ropivacaine hydrochloride is commonly marketed by AstraZeneca under the brand na ...

is an example of the anaesthetic which may be used for the block.

Additional images

File:Gray824.png, Deep and superficial dissection of the lumbar plexus. File:Gray825and830.PNG, Cutaneous nerves of the right lower extremity. Front and posterior views. File:Gray826and831.PNG, Cutaneous nerves of the right lower extremity. Front and posterior views.

References

External links

* * - "Posterior abdominal wall, dissection, anterior view" * - "Anterior Abdominal Wall: The Iliohypogastric and IlioInguinal Nerves" * - "Posterior Abdominal Wall: Nerves of the Lumbar Plexus" * * () {{Authority control Nerves of the lower limb and lower torso