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Changes in the Lower Border of the Internal Oblique Muscle. Source: Pélissier E., Ngo P., (2007) [133].

The inferior fibrous arch of the internal oblique muscle is displaced with the fragile fascia in the wall of the inguinal canal. In 52% of cases, the lowest fibrous arch of the internal oblique muscle is composed of muscle fibers, and if this structure is still present, there will be gaps between the bands. A defect from above the spermatic cord may result in a defect in the mechanism of closure of the inguinal canal and result in a direct inguinal hernia. Similarly, such defects leading to Spigelian hernias may occur between the muscle bands, the hernia mass being located within the inguinal canal and then presenting as a direct hernia [9], [16], [133].


A. The lower border of the oblique muscle in the lower part completely covers the transverse fascia.

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B. The lower border of the internal oblique muscle is high and does not cover the transverse fascia.

C. Oblique muscle in muscle thickness defect

Figure 1.7. Changes in the lower border of the internal oblique muscle. Source: Pélissier E., Ngo P., (2007) [133].

1.2.2.9. Anatomical changes of the transverse abdominis muscle

According to Anson et al., when examining the transverse abdominis muscle, only 14% of cases found these muscle fibers in the lowest fiber arch covering the upper border of the tube.

In 67% of cases, the muscle only occupied the upper half of the inguinal region, and in no case did the muscle reach the lateral border of the rectus abdominis muscle. Similarly, in 71% of cases, the muscle fibers did not extend medially to the inferior epigastric vascular bundle [7], [9], [133].


Figure 1.8. Changes in the lower border of the transverse abdominis muscle. Source: Pélissier E., Ngo P., (2007) [133].

1.2.2.10. Inguinal nerve distribution

The motor and sensory nerve branches of the fascia and skin of the inguinal region originate mainly from the ilioinguinal and iliohypogastric nerves, which originate from the lumbar nerves (TL1, TL2) and the 12th thoracic nerve (N12). The spermatic cord and testicles are innervated by the sensory and sympathetic branches originating from the N10, N11, N12, and TL1 nerves.

- Iliohypogastric nerve, this nerve divides into two branches:

+ The iliac branch, separates after penetrating the transverse abdominal muscle, and goes to the buttocks.

+ The hypogastric branch goes forward and downward and distributes motor branches to the abdominal wall muscles along the way. This branch is easily violated when reconstructing the abdominal wall or when placing artificial mesh according to the Lichtenstein method.

- Ilioinguinal nerve: this nerve enters the inguinal region approximately 2 cm above and medial to the anterior superior iliac spine. This nerve can be easily injured when the external oblique fascia is split to expose the inguinal region.

- Genitofemoral nerve: this nerve originates from TL2 - TL3, runs from back to front in the preperitoneal cavity to reach the deep inguinal ring. Here, the genitofemoral nerve divides into two branches:

+ The genital branch penetrates the transverse fascia on the outside of the deep inguinal ring to enter the inguinal canal and goes with the spermatic cord to the superficial inguinal ring. Here, it gives a sensory branch to the skin of the scrotum and thigh and a motor branch to the cremaster muscle.

+ The femoral branch (usually has many branches) runs along the psoas muscle into the thigh and its terminal fibers penetrate the femoral fascia and reach the skin of the anterior superior thigh. The femoral branch can be violated during posterior hernia surgery or laparoscopic surgery [7], [9], [11], [14], [133].

Figure 1.9. Inguinal nerve distribution. Source: Skandalakis (2004) [110].

1.2.2.11. Distribution of blood vessels in the groin area

- Superficial blood vessels of the groin

+ The skin and subcutaneous layer of the inguinal region are supplied with blood from three arterial sources: the superficial circumflex iliac artery, the superficial epigastric artery, and the superficial external pudendal artery.

+ These three arteries all originate from the femoral artery and are small branches that can be cut and ligated without fear of causing ischemia.

+ The venous branches go with the artery and have the same name, they all drain into the femoral vein.

- Blood vessels of the deep layer of the groin

+ The external iliac artery runs along the medial border of the psoas muscle, below the iliopsoas band to enter the femoral sheath. It gives off branches that nourish the psoas muscle and two secondary branches: the inferior epigastric artery and the deep circumflex iliac artery.

+ Inferior epigastric artery: gives off two branches near its origin, the external spermatic artery and the pubic branch.

+ The pubic branch is a small branch, originating near the origin of the inferior epigastric artery, going down in front of the pubic iliac band, running across the pectinate ligament downward to connect with the obturator artery.

+ Deep circumflex iliac artery: also originates from the external iliac artery but soon penetrates the transverse fascia so it is not located in the preperitoneal space. Unlike the inferior epigastric artery, this artery is not exposed during inguinal hernia surgery, so it is never violated during inguinal hernia surgery [9], [14], [133].

1.3. PHYSIOLOGICAL CHARACTERISTICS OF THE INGUINAL TUBE

The inguinal region is a naturally weak area of ​​the abdominal wall, the most common location for hernias. Therefore, inguinal-femoral hernia is a common surgical pathology in clinical practice. The basic knowledge required for surgery and techniques is still controversial and discussed. Therefore, this is a very complex issue. Physiologically in normal people, there are two mechanisms of action to preserve the inguinal canal and prevent internal organs from

Hernia through the deep inguinal ring. According to Nyhus Lioyd M, in normal people there are two mechanisms that operate to keep the inguinal canal intact to prevent abdominal organs from going down the deep inguinal ring.

1.3.1. First mechanism - sphincter

Acting as a sphincter of the transverse abdominis and internal oblique, the deep inguinal ring is attached to the transverse abdominis, and the transverse fascia is attached to the deep inguinal ring by the interfollicular ligament. Contraction of the transverse abdominis pulls the interfollicular ligament upward and outward, while the internal oblique pulls the superior and lateral borders of the deep inguinal ring downward and inward, narrowing the deep inguinal ring. This provides support below the internal oblique. Any surgery that fixes the transverse fascia or deep inguinal ring to more superficially fixed structures such as the inguinal ligament will destroy the sphincter action of the transverse abdominis.

1.3.2. Second mechanism - shutter

The transverse abdominal muscle arch acts like a curtain hanging down to cover the posterior wall of the inguinal canal. Normally, this muscle structure is curved like a bow. At rest, this arch is stretched and convex. When the internal oblique muscle and the transverse abdominal muscle contract, the transverse abdominal muscle arch straightens and runs down to the inguinal ligament and the iliopsoas band to cover the posterior wall of the inguinal canal. This action covers the spermatic cord and strengthens the posterior wall of the inguinal canal.

According to Berliner, there are three factors that play a role in the prevention of deep inguinal hernias and all are related to the posterior wall of the inguinal canal. When the abdominal pressure increases, it acts as a sphincter to narrow the deep inguinal ring at the same time the spermatic cord from the deep inguinal ring moves up and lies under the internal oblique muscle. Finally, when contracting, the internal oblique muscle and the transverse abdominal muscle come into contact with the inguinal ligament to create a protection for the deep inguinal ring and the posterior wall of the inguinal canal [9], [11], [16], [50].

1.3.3. The role of the transverse fascia

Modern authors such as Anson, Morgan, Mc Vay, Harkins, Lytle… agree on the important role of the transverse fascia, which is the deepest and strongest component to resist the increase in abdominal pressure. Author Forgue believes that:

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During exertion, the transverse fascia and supporting structures including the interfoveal ligament, the ligament of Henle, and the iliopubic band are all stretched by muscle contraction and create a solid barrier against abdominal pressure [9], [11].

1.3.4. Specific defense mechanisms for deep inguinal ring

When doing strenuous movements, the transverse fascia will stretch like a plane, at this time the deep inguinal ring always creates a dangerous hole. Through the research of Ogilvie, Lytle, and Bradon, it is shown that there are separate protective mechanisms for the deep inguinal ring.

- The levator scrotum muscle: in the resting state, the levator scrotum muscle supports the testicle, its tone exerts a steady tension on the spermatic cord, but when performing strenuous movements, the muscle will actively contract to pull the testicle up, out and back by turning the origin of the spermatic cord into the abdomen. Thus, when the origin of the spermatic cord turns into the deep inguinal ring, it will certainly form a stopper against abdominal pressure.

- Mechanism of closing the deep inguinal ring: Lytle described the inner edge of the deep inguinal ring, the transverse fascia converges as a U-shaped band, the spermatic cord is supported right at the depression of the inguinal ring. The two branches of the U extend upward and outward to form a hook facing the back of the transverse abdominal muscle. This U-shaped fold is called the sling of the transverse fascia, which has the function of contracting during coughing or exertion. When the pillars of the inguinal ring contract together, the entire sling is pulled upward and outward, resulting in angulation below the origin of the spermatic cord. Thus, increasing the distance of the spermatic cord created by the levator scrotum muscle, each time the abdominal pressure increases, the transverse fascia will stretch to the maximum and it is also thanks to this abdominal pressure that the inclination of the inguinal canal is increased due to the correlation with the direction of the abdominal pressure, at the same time the upper edge of the deep inguinal ring is pressed closer together, tightening around the spermatic cord and reducing the horizontal size of the deep inguinal ring [9], [11].

1.3.5. Protection of the dangerous inner angle of the inguinal region

In the lower medial part of the pelvis, the inguinal region forms a very wide open medial angle. This angle is not protected by the closing mechanism of the internal oblique muscle or the associated tendon. Therefore, the dangerous medial angle is protected by the layers

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Arranged from back to front: inferior epigastric vascular bundle, ligament of Henle, medial part of the pubic iliac band, lacunae ligament. In cases where surgical intervention has been performed due to dissection causing damage and deformation of the supporting components of the internal angle, in patients with recurrent surgery: direct hernia or femoral hernia is more common [16], [50].

1.4. CAUSES OF INGUINAL HERNIA

Inguinal hernia has many causes. However, most authors accept that there are two main causes: congenital and acquired.

1.4.1. Congenital causes

The cause of indirect inguinal hernia in children is mainly due to the existence of the peritoneal canal after birth [38]. Obstruction of the peritoneal canal was described by Cloquet and later named after him as Cloquet's ligament.

In the late 18th century, John Hunter's research confirmed that in cases of inguinal hernia, the hernia sac is nothing more than a peritoneal canal.

In 1817, Cloquet observed that the peritoneal canal was not always closed immediately after birth. In a group of adult men, 15 - 30% still had a peritoneal canal but did not show clinical signs of inguinal hernia until death.

In 1906, Russel, a pediatric surgeon in Australia, proposed the "Saccular theory" of the hernia sac that formed during the opening and dissection of the hernia sac. He affirmed that the sac was simply a peritoneal diverticulum.

Recently, people have also proposed the cause of inguinal hernia in patients with peritoneal dialysis in chronic renal failure. The mere existence of the peritoneal canal does not necessarily lead to indirect inguinal hernia. When indirect inguinal hernia occurs, there is often a predisposing factor such as frequent increased intraperitoneal pressure [9], [11].

1.4.2. Causes

Nowadays, with the advancement in many fields of science, it is shown that inguinal hernia is not simply a congenital defect like the existence of a peritoneal canal.

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There are many other causes of indirect inguinal hernia or direct inguinal hernia.

1.4.2.1. Exertion related to inguinal hernia

Studies have shown that heavy work, physical exertion, surrounding environment and occupation are related to inguinal hernia. However, recent studies in Europe have shown that although the above factors do cause inguinal hernia, they are not as significant as congenital defects [9], [11].

1.4.2.2. Abdominal diseases leading to inguinal hernia

It has been mentioned that ascites due to liver cancer, cirrhosis or heart disease is related to hernia, the mechanism as presented above in patients with peritoneal dialysis, the pressure of the amount of fluid in the peritoneal cavity has dilated the anterior wall outside the peritoneal cavity and the abdominal organs will enter these cavities [9], [11].

1.4.2.3. Inguinal hernia in patients after appendectomy

In 1911, author Hoguet was the first to describe the association in patients with inguinal hernia after appendectomy. Authors Condon, Elshof, Thomas found the association after appendectomy with right-sided inguinal hernia. Similarly, other researchers also agree with this thesis [9], [56], [114], [116].

1.4.2.4. Inguinal hernia in polycystic kidney disease patients

Polycystic kidney disease is an autosomal dominant genetic disease, occurring in about 1/1000 newborns, due to defective epithelial cell function, the cause of abdominal wall hernia, inguinal hernia combined with renal failure or hematuria. Author Morris - Stiff with 38 patients with polycystic kidney disease with abdominal wall hernia including: 25 inguinal hernia, 7 periumbilical hernia, 5 incisional hernia [94], [115].

1.4.2.5. Inguinal hernia in patients after abdominal and inguinal trauma and in patients with pelvic fracture

In closed abdominal trauma leading to hernia is very rare. However, with abdominal trauma in the groin and pelvic injuries can occur. Diagnosis of hernia due to trauma, initially only detects symptoms such as: local soft tissue damage, bruising, hematoma... and only after a while

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