Front of abdomen, showing surface markings for arteries and inguinal canal. (Inguinal canal is tube at lower left.)
The inguinal canals are the two passages in the anterior abdominal wall which in males convey the spermatic cords and in females the round ligament of uterus. The inguinal canals are larger and more prominent in males. There is one inguinal canal on each side of the midline.
The inguinal canals are situated just above the medial half of the inguinal ligament. In both sexes the canals transmit the ilioinguinal nerves. The canals are approximately 3.75 to 4 cm long., angled anteroinferiorly and medially.
A first-order approximation is to visualize each canal as a cylinder.
To help define the boundaries, these canals are often further approximated as boxes with six sides. Not including the two rings, the remaining four sides are usually called the "anterior wall", "inferior wall ("floor")", "superior wall ("roof")", and "posterior wall". These consist of the following:
|superior wall (roof):|
Medial crus of aponeurosis of external oblique
Musculoaponeurotic arches of internal oblique and transverse abdominal
aponeurosis of external oblique
fleshy part of internal oblique (lateral third of canal only)
superficial inguinal ring (medial third of canal only)
|(inguinal canal)||posterior wall:|
conjoint tendon (Inguinal falx,reflected part of inguinal ligament, medial third of canal only)
deep inguinal ring (lateral third of canal only)
|inferior wall (floor):
lacunar ligament (medial third of canal only)
iliopubic tract (lateral third of canal only)
During development each gonad (ovary or testicle) descend from their starting point on the posterior abdominal wall (para-aortically) from the labioscrotal swellings near the kidneys, down the abdomen, and through the inguinal canals to reach the scrotum. Each testicle 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.
The structures which pass through the canals differ between males and females:
- in males: the spermatic cord and its coverings + the ilioinguinal nerve.
- in females: the round ligament of the uterus + the ilioinguinal nerve.
The classic description of the contents of the spermatic cords in the male are:
Abdominal contents (potentially including intestine) can be abnormally displaced from the abdominal cavity. Where these contents exit through the inguinal canal, having passed through the deep inguinal ring, the condition is known as an indirect or oblique inguinal hernia. This can also cause infertility. This condition is far more common in males than in females, owing to the inguinal canal's small size in females.
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.
In males with strong presentation of the cremasteric reflex, the testes can--during supine sexual activity or manual manipulation--partially or fully retract into the inguinal canal for a short period of time. In juveniles and adults with inguinal injury, retraction can be prolonged and potentially lead to overheating-related infertility.
|Wikimedia Commons has media related to Inguinal canal.|
- "Gross Anatomy Image". Retrieved 2007-11-20.
- Adam Mitchell; Drake, Richard; Gray, Henry David; Wayne Vogl (2005). Gray's anatomy for students. Elsevier/Churchill Livingstone. p. 260. ISBN 0-443-06612-4.
- Dalley, Arthur F.; Moore, Keith L. (2006). Clinically oriented anatomy. Hagerstown, MD: Lippincott Williams & Wilkins. p. 217. ISBN 0-7817-3639-0.
- Arthur F., II Dalley; Anne M. R. Agur. Grant's Atlas of Anatomy. Hagerstown, MD: Lippincott Williams & Wilkins. p. 102. ISBN 0-7817-4255-2.
- "Anatomy Tables - Inguinal Region". Retrieved 2007-11-20.
- Mayo Clinic Staff. "Retractile testicle". Mayo Clinic. Mayo Foundation for Medical Education and Research. Retrieved 10 February 2018.