The inguinal canal is a tubular connection between the abdominal cavity and the external pubic region. In men, the spermatic cord passes through here; in women, only a retaining ligament of the uterus and fatty tissue pass through. If parts of the intestine emerge through the inguinal canal, it is called an inguinal hernia.
What is the inguinal canal?
The inguinal canal (canalis inguinalis) is four to six centimeters long. It runs tubularly from the abdominal cavity through the abdominal wall at an angle to the front. In both men and women, the genitofemoral nerve and the ilioinguinal nerve pass through the inguinal canal, two nerves that innervate parts of the thigh, abdominal muscles, and external genitalia. In addition, the lymphatic vessels of the inguinal lymph node pass through the inguinal canal.
Anatomy and structure
The roof of the inguinal canal is formed by the internal oblique abdominal muscle (Musculus obliquus internus abdominis) and the transverse abdominal muscle (Musculus transversus abdominis). The floor of the inguinal canal consists of the fibers of the inguinal ligament (ligamentum reflexum). This extends from the anterior superior iliac spine to the pubic bone and forms a boundary of the abdominal wall. Part of the external oblique abdominal muscle, the musculus obliquus externus abdominis, is both a lower and anterior boundary of the inguinal canal, creating a connective tissue groove that runs obliquely toward the center. The posterior wall of the inguinal canal is formed by the internal abdominal wall fascia, the fascia transversalis, a connective tissue sheath covering the inner side of the abdominal wall. The inguinal canal begins at the inguinal fossa profundus, a shallow pit on the inside of the abdominal wall, and ends at the side of the pubic bone (Os pubis) at the bony tubercle pubicum. The inguinal canal has an internal and an external opening. The internal opening, also called the internal inguinal ring or annulus inguinalis profundus, is located above the inguinal ligament. It is identifiable by a retraction of the processus vaginalis from the inside. In the male, it extends toward the testis as fascia spermatica interna, a thin fascia enveloping the spermatic cord. The external inguinal ring, annulus inguinalis superficialis, is a slit-shaped opening located in the tendon plate of the obliquus externus abdominis muscle, i.e. the external oblique abdominal muscle. The external opening of the inguinal canal is covered by the superficial abdominal fascia, which in males wraps around the spermatic cord just like the fascia spermatica interna. Here, however, it is referred to as the fascia spermatica externa.
Function and tasks
In the male fetus, the testes move from the abdominal cavity, where they originally develop, through the inguinal canal into the scrotum. In the process, the testis protrudes all layers of the abdominal wall with it. This protrusion envelops the testis and is also called the vaginal process or processus vaginalis. The layers of the abdominal wall that are also protruded then form the spermatic cord (funiculus spermaticus) in the inguinal canal. Blood vessels such as the testicular artery, the testicular vein, the ductus deferentis artery and the ductus deferentis vein run in the spermatic cord. In addition, various nerves such as the testicular plexus and the ductus deferentis plexus as well as the ramus genitalis run through the funiculus spermaticus. In women, the uterine ligament, the ligamentum teres uteri, runs through the inguinal canal to the labia. It is accompanied by a supplying artery, the arteria ligamenti teretis uteri. The uterine ligament serves to secure the uterus and is additionally supported by fatty tissue in the inguinal canal. The processus vaginalis, which is still present in the male, normally regresses in the female. If it does not, this is called a female hydrocele or a Nuck cyst. This anomaly is very rare and is most likely to occur in premature infants.
Diseases
When intestines leak from a weak point in the inguinal canal, it is called a hernia, an inguinal hernia or, in technical terms, a hernia. The inguinal hernia is one of the most common hernias, along with the femoral and umbilical hernias. Men are affected significantly more often than women. Depending on the location of the hernia, a distinction is made between direct and indirect inguinal hernias. The direct inguinal hernia passes through the posterior wall of the inguinal canal. The hernial orifice is located in the immediate vicinity of the medial inguinal fossa in the so-called Hesselbach triangle.The Hesselbach triangle is a part of the abdominal wall that is free of muscle and therefore predisposed to an inguinal hernia. The indirect inguinal hernia, in contrast to the direct inguinal hernia, can also be congenital. The hernial orifice is always located in the inner inguinal ring. In this case, the inguinal hernia can extend into the scrotum and cause massive swelling. In adulthood, an inguinal hernia may be caused by either abdominal wall weakness or an excessively wide inguinal canal. An increase in pressure in the abdomen, for example, due to chronic coughing, pressing when going to the toilet or heavy physical exertion can also cause an inguinal hernia. Symptoms of inguinal hernia are usually painless swelling in the groin area. The swelling can usually be pushed away when lying down. If sudden severe pain occurs in combination with a swelling that cannot be pushed away, the cause may be an incarcerated inguinal hernia. This leads to circulatory disturbances of the trapped viscera parts with the danger of death. A life-threatening intestinal obstruction can also be the result. An inguinal hernia is usually treated surgically. The operation can be performed with an open or a minimally invasive procedure. Also of clinical importance is the uterine ligament which runs through the inguinal canal. Tumor cells can travel through the connecting inguinal canal from the uterus to the labia via the uterine ligament, where they can metastasize.
