With the rise of preperitoneal repair and laparoscopic hernia repair in China in recent years, we must master the preperitoneal anatomy behind the groin area. This constitutes an anterior-posterior “three-dimensional anatomy”. This three-dimensional anatomy is necessary and helpful for our understanding of the hernia. In clinical practice, familiarity with the three-dimensional anatomy of the inguinal region is crucial to the completion of quality surgery. With this in mind, the anatomy of the inguinal region is summarized as “12345”.
The “1” refers to the 1 spermatic cord or the round ligament of the uterus (female).
”2″ refers to 2 ligaments, the inguinal ligament (followed by the iliopubic bundle) and the pubic comb ligament (Cooper’s ligament).
The “3” refers to 3 areas, namely the myopubic foramen (or inguinal box), the danger triangle and the pain triangle.
The “4” refers to 4 anatomical levels, from front to back, namely, the external oblique abdominal muscle and inguinal ligament, the internal oblique abdominal muscle and inferior arch, and the transverse abdominal fascia and peritoneum. This contains two other important gaps, the inguinal box and the preperitoneal space.
The “5” refers to the five inguinal nerves, namely the inferior iliac abdominal nerve, the inguinal iliac nerve, the genitofemoral nerve, the lateral femoral cutaneous nerve and the femoral nerve.
The “12345” concept does not cover all the anatomical elements of the inguinal region (which are of course intertwined), but only includes essentially the important factors that currently influence the outcome of the procedure. Therefore, it is hoped that it will be useful for the anatomical understanding of inguinal hernias for young physicians. Thus, it will help in the advancement of surgical standardization. It is also important to point out that the anatomy we see during surgery is “alive” and has more variation.
(1) Spermatic cord
The spermatic cord includes the vas deferens, the genitofemoral nerve, the trapezius plexus, the testicular artery, and the levator muscle fibers from the internal oblique muscle and the external fascia of the spermatic cord.
(2) Internal ring
The internal ring is an oval fissure in the transverse abdominal fascia. It is located lateral to the inferior abdominal wall artery, and the spermatic cord and the uterine round ligament pass through the internal ring out of the pelvis. A portion of the transversus abdominis fascia near the internal ring extends into the internal spermatic fascia. The internal spermatic fascia, testes, and spermatic cord (including the vas deferens, genitofemoral nerve, trapezius plexus, testicular artery, and levator muscle fibers originating from the internal oblique abdominal muscle and external spermatic fascia) pass through the internal ring.
(3) Inguinal ligament (inguinalligment, poupart ligment) and iliopubic tract (Thomsonligment)
The inguinal ligament is formed by the posterior-superior reflexion of the tendon membrane of the external oblique abdominal muscle between the anterior superior iliac spine and the pubic tuberosity, with some of its medial fibers reflexed posteriorly to form the lumbo-pubic ligament (aka trap ligament, Gimbernat ligament). The tendon membrane of the external oblique abdominal muscle is further divided into a medial pedicle above and a lateral pedicle below at the mouth of the external ring, while the lateral pedicle divides into some fibers (anteversion ligament), which are reflexed medially and superiorly, through the surface of the pubic tuberosity and posterior to the medial angle, attaching to the abdominal white line and participating in the composition of the anterior rectus abdominis sheath. The anteverse ligament and the nearby anterior rectus abdominis sheath are the important structures that hold our patch in place (and not on the periosteum of the pubic tuberosity!) .
The iliopubic fascia was described by Hesselbach in 1814 and described in detail by Thomson in 1836, so it is also known as Thomson’s ligament. The iliopubic bundle is a thickened portion of the transversus abdominis fascia that begins at the anterior superior iliac spine and ends at the superior pubic branch. It is usually more difficult to see in open anterior approach surgery and can be seen in open posterior approach repair or lumpectomy repair, especially more pronounced in direct hernias.
The relationship between the inguinal ligament and the iliopubic bundle is “just very close together”.
(4) Pectineal ligament (also known as Cooperligament)
The pubic comb ligament is anatomically controversial, but we can clinically understand it as a continuation of the ligament of the cavernous ligament (trap ligament) in the pubic comb. It is the main structure used for fixation of the patch, but care should be taken with the coronary vessels of death that travel over it during fixation.
(5) The inguinal box and the myopectineal foramen (MyopectinealOrifice)
A closed anatomical gap in the inguinal canal under the external oblique abdominal muscle is usually called the “inguinal box”. The average results of foreign measurements are 12 cm from the anterior superior iliac spine to the pubic symphysis, 5 cm from the internal ring to the pubic symphysis, and 5 cm from the insertion of the tendon membrane of the external oblique abdominal muscle in the anterior sheath of the rectus abdominis to the concave end of the inclined edge of the inguinal ligament. It is for this reason that it is possible to design a definitive patch that is suitable for all primary hernias. In the Lichtenstein procedure, Amid recommends a patch size of 8 x 15 cm (originally 5 x 10 cm). This size has been inconsistently reported in the literature. This size is smaller in our country than in Europe and the United States, but at least a 6 x 11 cm size patch is required.
The myopubic foramen was proposed by the French physician Fruchaud in 1957. The human body has a weak area in the inguinal region, the inner boundary of which is the outer edge of the rectus abdominis muscle, the outer boundary of which is the iliopsoas muscle, the upper boundary of which is the transversus abdominis muscle and the internal oblique abdominal muscle, and the lower boundary of which is the bony edge of the pelvis, and this area is called the myopubic foramen. There is no musculo-pubic foramen and only the transversus abdominis fascia resists the intra-abdominal pressure, and inguinal hernia occurs when the transversus abdominis fascia is weak.
The concept of myopubic foramen has provided a reliable theoretical and anatomical basis for preperitoneal repair of hernias.
Figure 2-1 Schematic diagram of the myopectineal orifice (MPO) in the inguinal region
It was proposed by Spaw in 1991. It refers to the area between the vas deferens and the spermatic vessels, through which the external iliac arteries and veins pass. It is worth pointing out that the angle of this triangular plane is variable and varies from person to person and should be taken into account when performing a vena cava hernia surgery.
(6) Pain triangle
The pain triangle is located on the lateral side of the spermatic vessels and below the iliopubic bundle. It is crossed by branches of the lumbar plexus nerve (genital and femoral branches of the genitofemoral nerve, femoral nerve, and lateral femoral cutaneous nerve). It is the lateral femoral cutaneous nerve and the femoral branch of the genitofemoral nerve that are more likely to be injured. So no stapled patches can be placed in that area!
(7) Reacquaintance with the transversalis fascia (abdominal fascia)
The anatomy of the transversalis fascia is so bizarre that we are familiar with it but at the same time know very little about it. It is currently thought to be a fascia with extensive continuity that surrounds the peritoneum: the transversalis fascia is thickened in the inguinal region, abuts the joint tendon, the transversus abdominis tendon membrane, and the deep surface of the inguinal ligament with which it forms a stronger posterior wall of the inguinal canal, covering the cleft between the transversus abdominis tendon membrane arch and inguinal ligament.
The transversus abdominis fascia surrounds the spermatic cord in a funnel shape at the inner ring, forming the internal spermatic fascia. In case of dysplasia or degenerative deformation, the peritoneum protrudes outward from the funnel opening and is an important factor in inguinal hernia.
Some literature describes the transverse abdominal fascia as divided into two layers, which I believe is inappropriate. In fact, it is confused with the division of the anterior peritoneal space into two layers. During surgery, especially during TEP, we find that the anterior peritoneal space is divided into two posterior layers: the anterior layer (superficial layer): the deep surface immediately adjacent to the transversus abdominis muscle and its tendon membrane, rich in fat, through which the inferior abdominal wall arteries pass, also called the subperitoneal fascia. All operations are performed in the posterior part of this layer. Posterior layer (deep layer): consists of irregularly thickened fibrous tissue, easily separated from the peritoneum, also known as the preperitoneal fascia, which requires some intraoperative separation. The level where we operate should be placed between the superficial layer and the peritoneum, and this is where we put the preperitoneal patch.
With this in mind, in order to unify the understanding and the terminology of open preperitoneal hernia repair and lumpectomy preperitoneal repair, it is beneficial to describe the procedure. I propose to divide the transverse abdominal fascia into “three layers”, 1. the hyaline fascial layer, which is actually translucent. It is the densest and plays a major strengthening role. It is thickened in the inguinal region and even locally reinforced by the iliopubic fascia, the intercondylar ligament, the pseudohernia sac of direct hernia, etc.; 2. The preperitoneal fat layer (formerly the superficial layer of the transverse abdominal fascia), which is very unevenly distributed and is absent at the umbilical ligament, but most abundant in the anterior, medial and lateral traps of the iliac vessels. It contains a rich capillary network. The inferior arterioles of the abdominal wall travel through them. In the pathogenesis of inguinal hernia, it is often present in the form of “lipoma”.3. The thinnest layer of the reticular fibrous layer (formerly the deep transverse abdominal fascia, called by some authors the anterior umbilical bladder fascia) is fibrous connective tissue, almost devoid of blood vessels, loosely bound to the peritoneum and evident after lumpectomy inflation. It is the ideal pre-peritoneal layer for manipulation.
Of course, there are many scholars who divide the transverse abdominal fascia into two layers and believe that the second preperitoneal fat layer described earlier cannot be a layer of its own because it is too soft and discontinuous in texture. However, I believe that it is better to emphasize the preperitoneal fat layer in view of its importance in positioning during surgery.
(8) Inferior iliac abdominal nerve (iliohypogastric nerve)
The inferior iliohypogastric nerve crosses the internal oblique muscle approximately 2.5 cm anterior to the anterior superior iliac spine, travels inward and downward to the deep surface of the external oblique muscle, then crosses the tendon membrane of the external oblique muscle approximately 2.5 cm above the external ring and leaves the inguinal canal.
(9) Iliogastric nerve (ilioinguinal nerve)
The ilioinguinal nerve is thinner than the inferior ilioinguinal nerve, below and almost parallel to it, and travels in the groin with the spermatic cord, then exits the external ring and distributes to the scrotum or labia majora.
(10) Genitofemoral nerve
The genitofemoral nerve arises from the lumbar plexus (L1-2 nerve) and divides into femoral and genital branches before entering the internal ring of the inguinal canal. The femoral branch enters the femoral sheath and innervates sensation in the skin of the proximal anterior thigh; injury can cause sensory hypersensitivity in the femoral triangle. The genital branch: crosses the inguinal canal and penetrates the posterior lateral aspect of the spermatic cord, distributing over the levator ani and the scrotal meatus, providing innervation of the levator ani, scrotum and medial thigh sensation. Injury can cause ejaculation disorders and painful ejaculatory sensations.
(11) Lateral femoral cutaneous nerve (lateral femoral cutaneousnerve)
The lateral femoral cutaneous nerve comes from the lumbar plexus (L2-3 nerve) and passes under the iliopubic fasciculus in front of the iliacus muscle, providing innervation of the skin sensation on the lateral thigh.
(12) Femoral nerve (femoralnerve)
The femoral nerve is the largest branch of the lumbar plexus and mainly innervates the skin and extensor muscles of the anterior thigh. It is located in a relatively deep plane and is usually less susceptible to injury. However, be careful of injuries to its smallest branches!
(13) Retzius interval, Bogros interval and interval splitting ligament (intervalligament)
The Retzius interval was introduced by the Swedish anatomist Retzius and refers to the pubococcygeal space. It is located in the midline, with the rectus abdominis, transversus abdominis fascia and pubic bone in front and the bladder behind. This gap extends from the umbilical level up to the pelvic floor muscle and externally to the inferior abdominal wall artery and is mainly composed of loose connective tissue and fat and is essentially avascular.
The Bogros space can be considered as a lateral continuation of the Retzius space, which is located lateral to the inferior abdominal wall artery, with one such space on each side of the lower abdomen. This gap was first proposed by Bogros and later introduced into the LIHR by Nyhus. This gap contains some important vessels and nerves and must be operated with care.
It is worth mentioning that between the Retzius interval and the Bogros interval, there is a separation in a significant number of patients, which is particularly evident in TEP surgery, and is manifested by a thin layer of tougher ligaments, which I call “interstitial segmentation ligaments” (not the interconcave ligaments, which are anterior to the inferior arteries of the abdominal wall, and the The iliopubic bundle is one level). It must be cut with scissors to allow the two gaps to pass through.