Inguinal canal
Encyclopedia
The inguinal canal is a passage in the anterior (toward the front of the body) abdominal wall which in men conveys the spermatic cord
and in women the round ligament
. The inguinal canal is larger and more prominent in men.
. In both sexes the canal also transmits the ilioinguinal nerve
.
to the superficial inguinal ring
.
To help define the boundaries, the canal is often further approximated as a box with six sides. Not including the two rings, the remaining four sides are usually called the "anterior wall", "posterior wall", "roof", and "floor". These consist of the following:
One way to remember these structures is with the mnemonic "MALT", starting at the top and going counterclockwise:
The classic description of the contents of spermatic cord in the male are:
3 arteries: artery to vas deferens (or ductus deferens), testicular artery, cremasteric artery
3 fascial layers: external spermatic,internal spermatic,cremastic
3 other vessels: pampiniform plexus, vas deferens (ductus deferens), lymphatics
1 nerve: genital branch of the genitofemoral nerve (L1/2)
The ilioinguinal nerve passes through the superficial ring to descend into the scrotum, but does not formally run through the canal.
. The testis then descends through the abdominal wall into the scrotum, behind the processus vaginalis (which later obliterates). Thus lymphatic spread from a testicular tumour is to the para-aortic nodes first, and not the inguinal nodes.
. This can also cause infertility. This condition is far more common in men than in women, owing to the inguinal canal's small size in women.
A hernia that exits the abdominal cavity directly through the deep layers of the abdominal wall, thereby bypassing the inguinal canal, is known as a direct inguinal hernia
.
Spermatic cord
The spermatic cord is the name given to the cord-like structure in males formed by the ductus deferens and surrounding tissue that run from the abdomen down to each testicle.-Contents of spermatic cord:...
and in women the round ligament
Round ligament of uterus
The round ligament of the uterus originates at the uterine horns, in the parametrium. The round ligament leaves the pelvis via the deep inguinal ring, passes through the inguinal canal and continues on to the labia majora where its fibers spread and mix with the tissue of the mons...
. The inguinal canal is larger and more prominent in men.
Site
The inguinal canal is situated just above the medial half of the inguinal ligamentInguinal ligament
The inguinal ligament is a band running from the pubic tubercle to the anterior superior iliac spine. Its anatomy is very important for operating on hernia patients.-Anatomy:...
. In both sexes the canal also transmits the ilioinguinal nerve
Ilioinguinal nerve
The ilioinguinal nerve is a branch of the first lumbar nerve . It separates from the first lumbar nerve along with the larger iliohypogastric nerve....
.
Boundaries
A first-order approximation is to visualize the canal as a cylinder, stretching from the deep inguinal ringDeep inguinal ring
The deep inguinal ring is the entrance to the inguinal canal.-Location:...
to the superficial inguinal ring
Superficial inguinal ring
The superficial inguinal ring is an anatomical structure in the anterior wall of the human abdomen. It is a triangular opening that forms the exit of the inguinal canal, which houses the ilioinguinal nerve, the genital branch of the genitofemoral nerve, and the spermatic cord or the round ligament...
.
To help define the boundaries, the canal is often further approximated as a box with six sides. Not including the two rings, the remaining four sides are usually called the "anterior wall", "posterior wall", "roof", and "floor". These consist of the following:
| superior wall (roof): internal oblique transversus abdominis |
>- | (inguinal canal) | posterior wall: transversalis fascia Transversalis fascia The transversalis fascia is a thin aponeurotic membrane which lies between the inner surface of the Transversus abdominis and the extraperitoneal fascia.... conjoint tendon Conjoint tendon The conjoint tendon is a structure formed from the lower part transversus abdominis muscle as it inserts into the crest of the pubis and pectineal line immediately behind the superficial inguinal ring. It is usually conjoint with the tendon of the abdominal internal oblique muscle, but they may be... (medial third of canal only) deep inguinal ring Deep inguinal ring The deep inguinal ring is the entrance to the inguinal canal.-Location:... (lateral third of canal only) >- | |
inferior wall (floor): inguinal ligament Inguinal ligament The inguinal ligament is a band running from the pubic tubercle to the anterior superior iliac spine. Its anatomy is very important for operating on hernia patients.-Anatomy:... lacunar ligament Lacunar ligament The lacunar ligament is a ligament in the inguinal region that connects the inguinal ligament to the pectineal ligament near the point where they both insert on the pubic tubercle.-Anatomy:... (medial third of canal only) iliopubic tract (lateral third of canal only) |
One way to remember these structures is with the mnemonic "MALT", starting at the top and going counterclockwise:
- M - muscles
- A - aponeuroses (The A in MALT coincides with the position of the wall—anterior. This can be used to remember that the direction of the mnemonic is anticlockwise)
- L - ligaments
- T - transversalis/tendon
Contents
- in males : the spermatic cordSpermatic cordThe spermatic cord is the name given to the cord-like structure in males formed by the ductus deferens and surrounding tissue that run from the abdomen down to each testicle.-Contents of spermatic cord:...
and its coverings + the ilioinguinal nerveIlioinguinal nerveThe ilioinguinal nerve is a branch of the first lumbar nerve . It separates from the first lumbar nerve along with the larger iliohypogastric nerve....
. - in females : the round ligament of the uterus + the ilioinguinal nerveIlioinguinal nerveThe ilioinguinal nerve is a branch of the first lumbar nerve . It separates from the first lumbar nerve along with the larger iliohypogastric nerve....
.
The classic description of the contents of spermatic cord in the male are:
3 arteries: artery to vas deferens (or ductus deferens), testicular artery, cremasteric artery
3 fascial layers: external spermatic,internal spermatic,cremastic
3 other vessels: pampiniform plexus, vas deferens (ductus deferens), lymphatics
1 nerve: genital branch of the genitofemoral nerve (L1/2)
The ilioinguinal nerve passes through the superficial ring to descend into the scrotum, but does not formally run through the canal.
Development
During development gonads (ovaries or testes) descend from their starting point on the posterior abdominal wall (para-aortically) and near the kidneys down the abdomen and through the inguinal canal to reach the scrotumScrotum
In some male mammals the scrotum is a dual-chambered protuberance of skin and muscle containing the testicles and divided by a septum. It is an extension of the perineum, and is located between the penis and anus. In humans and some other mammals, the base of the scrotum becomes covered with curly...
. The testis then descends through the abdominal wall into the scrotum, behind the processus vaginalis (which later obliterates). Thus lymphatic spread from a testicular tumour is to the para-aortic nodes first, and not the inguinal nodes.
Disorders
Abdominal contents (potentially including intestine) can be abnormally displaced from the abdominal cavity. Where these contents exit through the inguinal canal the condition is known as an indirect inguinal herniaIndirect inguinal hernia
An indirect inguinal hernia is an inguinal hernia that results from the failure of embryonic closure of the deep inguinal ring after the testicle has passed through it. Like other inguinal hernias, it protrudes through the superficial inguinal ring...
. This can also cause infertility. This condition is far more common in men than in women, owing to the inguinal canal's small size in women.
A hernia that exits the abdominal cavity directly through the deep layers of the abdominal wall, thereby bypassing the inguinal canal, is known as a direct inguinal hernia
Direct inguinal hernia
The direct inguinal hernia, a type of inguinal hernia, enters through a weak point in the fascia of the abdominal wall, and its sac is noted to be medial to the inferior epigastric vessels...
.
