The ilioinguinal nerve is a branch of the first
lumbar nerve (L1). It separates from the first lumbar nerve along with the larger
iliohypogastric nerve. It emerges from the lateral border of the
psoas major
The psoas major ( or ; from ) 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 iliopsoas. In other animals, this muscle is e ...
just inferior to the
iliohypogastric, and passes obliquely across the
quadratus lumborum and
iliacus. The ilioinguinal nerve then perforates the
transversus abdominis near the anterior part of the
iliac crest
The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superolateral margin of the greater pelvis.
Structure
The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the posterio ...
, and communicates with the
iliohypogastric nerve 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
The spermatic cord is the cord-like structure in males formed by the vas deferens (''ductus deferens'') and surrounding tissue that runs from the deep inguinal ring down to each testicle. Its serosal covering, the tunica vaginalis, is an exten ...
(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. It originates at the junction of the uterus and uterine tube. It passes through the inguinal canal to insert at the labium majus.
The two round ligame ...
(in females) through the
superficial inguinal ring. Its fibres are then distributed to the skin of the upper and medial part of the
thigh
In 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 tissu ...
, and to the following locations in the male and female:
* In the male ("
anterior scrotal nerve"): to the skin over the root of the
penis
A penis (; : penises or penes) is a sex organ through which male and hermaphrodite animals expel semen during copulation (zoology), copulation, and through which male placental mammals and marsupials also Urination, urinate.
The term ''pen ...
and upper part of the
scrotum
In most terrestrial mammals, the scrotum (: scrotums or scrota; possibly from Latin ''scortum'', meaning "hide" or "skin") or scrotal sac is a part of the external male genitalia located at the base of the penis. It consists of a sac of skin ...
.
* In the female ("
anterior labial nerve"): 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 s ...
and
labia majora
In primates, and specifically in humans, the labia majora (: labium majus), also known as the outer lips or outer labia, are two prominent Anatomical terms of location, longitudinal skin folds that extend downward and backward from the mons pubis ...
.
The ilioinguinal nerve does not pass through the
deep inguinal ring
The inguinal canal is a passage in the anterior abdominal wall on each side of the body (one on each side of the midline), which in males, convey the spermatic cords and in females, the round ligament of the uterus. The inguinal canals are large ...
, and thus only travels through part of the
inguinal canal
The inguinal canal is a passage in the anterior abdominal wall on each side of the body (one on each side of the midline), which in males, convey the spermatic cords and in females, the round ligament of the uterus. The inguinal canals are lar ...
. It mediates the
cremasteric reflex
The cremasteric reflex is a superficial (i.e., close to the skin's surface) reflex observed in human males.
This reflex is elicited by lightly stroking or poking the superior and medial (inner) part of the thighâregardless of the direction of ...
.
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
Nerve block or regional nerve blockade is any deliberate interruption of signals traveling along a nerve, often for the purpose of pain relief. #Local anesthetic nerve block, Local anesthetic nerve block (sometimes referred to as simply "nerve b ...
.
The indications for nerve block include
anaesthesia
Anesthesia (American English) or anaesthesia (British English) is a state of controlled, temporary loss of sensation or awareness that is induced for medical or veterinary purposes. It may include some or all of analgesia (relief from or prev ...
for procedures involving the abdominal region such as
inguinal herniorrhaphy or pain relief for procedures such as a
caesarean section
Caesarean section, also known as C-section, cesarean, or caesarean delivery, is the Surgery, surgical procedure by which one or more babies are Childbirth, delivered through an incision in the mother's abdomen. It is often performed because va ...
.
Ropivacaine
Ropivacaine (International Nonproprietary Name, 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 mark ...
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. Anterior and posterior views.
File:Gray826and831.svg, Cutaneous nerves of the right lower extremity. Anterior 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