In mammals, the inguinal canal ( Canalis inguinalis ) is an anatomical structure in the groin area of the abdominal wall . Parts of the anterior abdominal wall (see structure below) collide in such a way that an elongated canal is formed which, starting from the abdominal cavity , runs diagonally forward through the abdominal wall. The term inguinal canal is more or less identical to the term inguinal space ( Spatium inguinale ).
First, the extensive surface has the anterior abdominal wall from the xiphoid process and to the side of the rib cage ( Arcus costal ) to the pelvic bone , a major improvement in the understanding of the inguinal canal and typical layer structure. Under the skin and subcutaneous fatty tissue there are various structures, some of which are connective tissue, superficial fasciae or muscles and their fasciae. Then in the depths, i.e. from the skin downwards, there is an extraperitoneal fascia and the parietal peritoneum .
From the navel down on the anterior wall, the otherwise typical single-layer, superficial fascia merges into a two-layer structure, the panniculus adiposus abdominis . It is formed from a superficial, fat-rich layer ( camper fascia ) and a corresponding, deeper, membranous layer ( Scarpa fascia ). The five abdominal muscles consist of:
- three oblique muscles, also lateral abdominal wall muscles: Musculus obliquus externus abdominis , Musculus obliquus internus abdominis and Musculus transversus abdominis
- two straight muscles, also anterior abdominal wall muscles: the rectus abdominis muscle and the ultimately inconstant pyramidalis muscle .
The naming of the groups can also be done differently: the lateral and front muscles are called the lateral and middle muscles of the superficial abdominal muscles. a) External muscle Each of the three oblique abdominal muscles has its own thin fascia on its front and back surface. The inside of the transversus abdominis muscle is the strong transversalis fascia . This lines the abdominal cavity and goes headward (cranial) into the diaphragmatic fascia and backward (dorsal) into the thoracolumbar fascia . Towards the pelvis (caudal) it is attached to the iliac crest and merges into the endopelvic fascia . The anterior abdominal muscles are covered by the superficial abdominal fascia , which then divides into two sheets in the lower abdomen:
- a superficial camper fascia , which continues in the direction of the dam and the genital organs as the fascia perinei superficialis ,
- a deeper Scarpa fascia , which continues as a coarse structure in men as Colles fascia in the direction of the genital organs as the Fascia spermatica externa and the funiculus spermaticus and is thus connected to the inguinal canal.
The inguinal canal has an internal and external boundary:
- the outer inguinal ring ( annulus inguinalis superficialis )
- the inner inguinal ring ( annulus inguinalis profundus )
The outer inguinal ring is a slit-shaped opening in the tendon plate of the outer oblique abdominal muscle ( Musculus obliquus externus abdominis ). The inner inguinal ring lies above (superior) the inguinal ligament ( arcus inguinalis , also ligamentum inguinale ) and on the outside (lateral) of the arteria epigastrica inferior ; the transversalis fascia is turned inside.
The inguinal canal is limited as follows:
- ventrally: aponeurosis of the externus abdominis oblique muscle
- dorsal: Fascia transversalis abdominis
- cranial: Musculus transversus abdominis and parts of the musculus obliquus internus abdominis
- caudal: inguinal ligament
Organs that pass through the inguinal canal
Regardless of gender, the genital branch of the genitofemoral nerve , the ilioinguinal nerve and the lymph vessels of the superficial inguinal lymph nodes ( Nll. Inguinales superficiales ) pass through the inguinal canal. In most mammals, the external pubic artery ( arteria pudenda externa ) also runs through the inguinal canal, in humans this runs over the thigh triangle into the genital area.
During the fetal development of the developed in the abdominal cavity testis migrates at most male mammals through the inguinal canal into the scrotum ( scrotum ), the so-called. Descent of the testis (testis descent). The testicle everts the peritoneum (peritoneum) and the inner body fascia ( fascia transversalis ) through the inguinal canal. This bulge is called the processus vaginalis ("vaginal skin extension"), this envelops the testicles. The layers of the abdominal wall continue as a result of the protrusion of the vaginal process. These layers unite in the inguinal canal itself to form the spermatic cord ( funiculus spermaticus ), which in its interior leads the testicular artery and vein, the spermatic duct , and nerves . Fibers from the internal oblique and transverse abdominal muscles accompany the testicles on its way and form the cremaster muscle , which is also located in the inguinal canal .
In female mammals, the ligamentum teres uteri ( round uterine ligament to fix the uterus) runs through the inguinal canal and in women it reaches the great labia ( labia majora ). The vaginal process in women (Nuck's canal) mostly recedes in the course of development, but it can persist in whole or in part (female hydrocele, Nuck's cyst). A vaginal process occurs regularly in a few adult female mammals, e.g. B. with the bitch . But it only contains fat .
- Inguinal hernia ( hernia inguinalis )
- Keith Lean Moore, Arthur F. Dalley: Clinically Oriented Anatomy. Lippincott Williams & Wilkins, Philadelphia 2006, ISBN 978-0-7817-3639-8 , p. 217.