wall layer). As an operator, it is important to be aware of the level at which the operation is performed; TEP is performed mainly between the extraperitoneal fat and the peritoneum below the transversus abdominis fascia. Internal structures 1. external oblique abdominal muscle The external oblique abdominal muscle is in the inguinal region, no longer muscular, and is displaced into the external oblique abdominal tendon membrane. The extra-abdominal oblique tendon membrane is between the anterior superior iliac spine to the pubic tuberosity, reflexed and thickened to form the inguinal ligament. A small portion of the fibers of the medial portion of the inguinal ligament continue to reflex posteriorly downward and outward to form the trap ligament (also known as Gimbernat’s ligament), which attaches to the pubic comb with curved edges. The free inner edge of the trap ligament forms the inner border of the femoral ring. The trap ligament continues outward and attaches to the pubic sparing ligament (also known as Cooper’s ligament). Each of these ligaments is an important anatomic landmark in inguinal hernia repair. The fibers of the extra-abdominal oblique tendon membrane travel downward from the external superior and divide into two legs above the external pubic tuberosity, with a triangular cleft formed between the two legs, which is the external ring of the inguinal canal. In normal people, the mouth of the external ring can accommodate the tip of one index finger. In the deep surface of the tendon membrane of the external oblique muscle, there are two parallel inferior iliac abdominal nerve and iliac inguinal nerve walking on the surface of the internal oblique muscle. The internal oblique muscle and the transversus abdominis muscle, in the inguinal canal, both have muscle fibers that travel inward and downward, with the lower edge forming an arch that crosses the anterior and superior spermatic cord and ends at the pubic symphysis. Some textbooks and surgical atlases refer to the bowed inferior edge of the two muscles in this area as the joint tendon (or inguinal sickle). In fact, the inferior border of the arch of the internal oblique and transversus abdominis muscles is found to be mostly muscular during surgery and rarely forms a tendon membrane (only about 5%). Therefore, the term joint tendon is in most cases a misnomer. However, it should be noted that the inferior border of the arch of the internal oblique and transversus abdominis muscles (or joint tendon) is essential for repair of the posterior wall in classical repair (Bassini’s repair) and has a very important clinical significance. The transversalisfascia is a thin layer of connective tissue located posterior to the muscle layer of the abdominal wall, between the deep inner surface of the transversus abdominis muscle and the extraperitoneal fat layer. It is part of the abdominal wall fascia and is continuous with the renal fascia, iliac fascia and pelvic fascia. Above the midpoint of the inguinal ligament, there is an oval-shaped fissure in the transversus abdominis fascia, which is the internal inguinal ring. In men, the spermatic cord and in women, the uterine round ligament crosses the transversus abdominis fascia at the internal ring. It has been found that at the point where the spermatic cord passes through the mouth of the internal ring, the transversus abdominis fascia forms a sling that hangs down in folds around the spermatic cord, called the “monk`shood” (monk`shood). When the transverse abdominal muscle contraction, tension makes the inner ring like a sphincter, can be moderately wrapped around the tightening of the inner ring to play a protective role. In addition, during the development of the human body, the testis with the spermatic cord penetrates from the inner ring, and the transversus abdominis fascia wraps around it downward, becoming the inner spermatic cord fascia. The transverse abdominal fascia extends downward to cover the femoral artery and accompanies it to the femur, forming the anterior layer of the femoral sheath. 4, iliopubic fascia The iliopubic fascia (iliopubictract) was discovered and named by the British scholar Alexander Thomson, so it is also known as Thomosn’s ligament. For a long time since the term never appeared in our Chinese textbooks of surgery, it may be related to the fact that doctors in earlier times did not do hernia repair by posterior approach. As a result, our physicians and anatomical professionals have little knowledge of this structure. In recent years, especially with the introduction of laparoscopic techniques into the field of hernia surgery, this structure has been seen during TEP surgery when separating the anterior peritoneal space, which has led to a renewed awareness of the iliopubic bundle. The iliopubic fasciculus is a thickened portion of the transversus abdominis fascia that runs parallel to the inguinal ligament on its deep surface. The iliopubic bundle originates medially directly above the pubic body, posterior to the union of the pubic tubercle ligament with the pubic bone, and externally extends in a fan-like pattern to intertwine with the transversus abdominis fascia and the iliac fascia, which is not directly connected to the iliac spine throughout. The width of the iliopsoas bundle averages 4.6 mm at the junction with the femoral artery and 5.3 mm adjacent to the anterior superior iliac spine. measurements have been made and the thickness of the iliopsoas bundle is approximately twice that of the transverse abdominal fascia. Therefore, it is not significant. The iliopubic fasciculus has several implications in hernia surgery, and both Shouldice repair and Nyhus repair specifically use the iliopubic fasciculus to repair the posterior wall of the inguinal canal. the establishment of the anterior peritoneal space in TEP surgery, the iliopubic fasciculus is one of the markers of the separation process. The Bogros space is part of the abdominal wall and peritoneal space, with the iliac fascia on the outside, the transverse abdominal fascia in front and the mural peritoneum in the back. The access to this gap is generally from the posterior aspect of the rectus abdominis muscle below the umbilicus, separating outward and downward. From this gap the abdominal wall is easily separated from the peritoneum. This gap was proposed by Bogros, a French anatomist and surgeon, in 1832 to find a way to ligate the vessels of the lower extremities, and was later found to be associated with the spread of pelvic abscesses in women. Nowadays, for hernia surgery, Bogros’ hiatus is significant because it is the passage or the space to be separated for posterior approach repairs (Stoppa, Nyhus repairs) and laparoscopic repairs (TEP and TAPP), as well as the space to place patches. The Retzus gap, also known as the retropubic gap or the anterior bladder gap, is easily accessible behind the rectus abdominis muscle and down to the retropubic gap, which is used to create the operative space for TEP surgery. The skin of the anterior lower abdominal wall from the level of the umbilicus to the level of the pubic symphysis and part of the skin of the external genitalia is innervated by the trunk branches of the 10th thoracic nerve (umbilical level) to the 12th thoracic nerve (subcostal nerve) and the 1st lumbar nerve. The thoracic nerve has anterior and lateral cutaneous branches. The trunk branches of the 1st lumbar nerve are involved in the composition of the inferior iliac abdominal and iliac inguinal nerves. The inferior iliac abdominal nerve has a branch that emerges from the external abdominal oblique muscle directly above the iliac crest and innervates the skin of the upper lateral gluteal region. More important in hernia repair is the anterior branch of the inferior ilioinguinal nerve, which emerges from the external ring of the inguinal canal just above the tendon membrane of the external oblique abdominal muscle and innervates the skin of the suprapubic region downward. The iliac inguinal nerve innervates part of the internal oblique abdominal muscle, does not penetrate the muscle, passes through the external ring of the inguinal canal, accompanies the spermatic cord inferiorly, and innervates the skin of the lower limb distal to the inguinal ligament, the root of the penis, and the anterior superior scrotum. In females, the nerve dives out of the external ring and innervates the mons pubis and labia majora. The genital and femoral branches of the genitofemoral nerve unite or divide into two branches that emerge from the anterior aspect of the psoas major muscle. The genital branch exits the pelvis through the internal ring of the inguinal canal and travels with the spermatic cord to innervate the sole dominant muscle of the testicularis raphe nerve, or the genitofemoral nerve crosses the spermatic cord and innervates most of the anterolateral region of the scrotum when it penetrates lateral to the external ring of the inguinal canal. The femoral branch of the genitofemoral nerve originates from the 1st to 2nd lumbar nerves, passes through or under the inguinal ligament, crosses lateral to the saphenous foramen, and innervates the skin of the femoral sheath region after traveling a short distance in the femoral sheath.