Learning objectives:

  • Describe the extent and enlist the structures forming various walls of inguinal canal in correlation with muscles and fasciae of anterior abdominal wall.
  • Locate the superficial & deep inguinal rings on the surface of given subject/manikin
  • Analyze the functions & mechanics of inguinal canal Enlist the structures passing through the inguinal canal in males and females
  • Define hernia. Name different parts of a hernial sac.  
  • Differentiate between direct & indirect inguinal hernia with regards to their relation with age, predisposing factor, frequency, coverings on exit from abdominal cavity, course, & exit from anterior abdominal wall



ORIGIN: Pubic symphysis and pubic crest

INSERTION: Xiphoid process and 5th–7th costal cartilages

ACTION: Flexes trunk lumbar vertebrae and compresses abdominal viscera


The rectus sheath is the strong, incomplete fibrous compartment of the rectus abdominis and pyramidalis muscles. The sheath has two walls, anterior and posterior.


Along with muscles, It also contains the anterior rami of the lower six thoracic nerves and the superior and inferior epigastric vessels and lymph vessels.

LINEA SEMILUNARIS: When the muscle contracts, its lateral margin forms a curved palpatable ridge. Extending from 9th costal cartilage to pubic tubercle

TENDINOUS INTERSECTIONS: rectus is divided into distinct segments by three transverse tendinous intersections. One at xiphoid, one at umbilicus, one halfway between them


Above the costal margin, the anterior wall is formed by the aponeurosis of the external oblique.

The posterior wall is formed by the thoracic wall i.e.  the fifth, sixth, and seventh costal cartilages and the intercostal spaces.


Between the costal margin and the arcuate line (at about the level of the anterior superior iliac spine), the aponeurosis of the internal oblique splits to enclose the rectus muscle.

The external oblique aponeurosis is directed in front of the muscle, and the transversus aponeurosis is directed behind the muscle.


Between the level of the arcuate line (at about the anterior superior iliac spine) and the pubis, the aponeuroses of all three muscles form the anterior wall.

The posterior wall is absent, and the rectus muscle lies in contact with the transversalis fascia.

ARCUATE LINE: where the aponeuroses forming the posterior wall pass in front of the rectus at the level of the ASIS, the posterior wall has a free, curved lower border called the arcuate line. At this site, the inferior epigastric vessels enter.

LINEA ALBA: The rectus sheath is separated from its fellow on the opposite side by a fibrous band called the linea alba. This extends from the xiphoid process down to the symphysis pubis and is formed by the fusion of the aponeuroses of the lateral muscles of the two sides.


The inguinal region, or groin, extends between the ASIS and pubic tubercle.

It is important anatomically because it is the region where structures exit and enter the abdominal cavity and clinically because the pathways of exit and entrance are potential sites of herniation.


The inguinal ligament is a dense band constituting the inferior most part of the external oblique aponeurosis.


The inherent weakness in the anterior abdominal wall in the groin is caused by changes that occur during the development of the gonads.

Inguinal Canal

  • The inguinal canal is a slit-like passage that extends in a downward and medial direction, just above and parallel to the lower half of the inguinal ligament.
  • It begins at the deep inguinal ring and continues for approximately 4 cm, ending at the superficial inguinal ring

Deep inguinal ring

The deep (internal) inguinal ring is the beginning of the inguinal canal and is at a point midway between the ASIS and the pubic symphysis

It is an oval opening in the transversalis fascia

It is present just above the inguinal ligament and inferior epigastric vessels lie medial to it.

The margins of the ring give attachment to the internal spermatic fascia

Superficial inguinal ring

Superficial inguinal ring is a triangular-shaped defect in the aponeurosis of the external oblique muscle.

It lies immediately above and medial to the pubic tubercle.

The margins of the ring, give attachment to the external spermatic fascia.


Anterior wall: Formed by the external oblique aponeurosis and reinforced laterally by the origin of the internal oblique from the inguinal ligament.

This wall is strongest where it lies opposite the weakest part of the posterior wall, namely, the deep inguinal ring.

Posterior wall: Formed by the conjoint tendon medially and the transversalis fascia laterally.

This wall is strongest where it lies opposite the weakest part of the anterior wall, namely, the superficial inguinal ring.

Superior wall (roof): Formed by the arching lowest fibers of the internal oblique and transversus abdominis muscles.

Inferior wall (floor): Formed by the upturned lower edge of the inguinal ligament and, at its medial end, the lacunar ligament


  • the canal is an oblique passage
  • reinforce the anterior wall
  • reinforces the posterior wall
  • arching lowest fibers of the internal oblique and transversus abdominis muscles contract
  • squatting position


Inguinal triangle is located withing the inferomedial aspect of the abdominal wall. Its boundaries are:

Medial: lateral border of rectus abdominus

Lateral: inferior epigastric artery

Inferior: inguinal ligament


The iliopubic tract is the thickened inferior margin of the transversalis fascia, which appears as a fibrous band running parallel and posterior (deep) to the inguinal ligament


The inguinal ligament and iliopubic tract span an area of innate weakness in the body wall in the inguinal region or groin called the myopectineal orifice


Abdominal Herniae

A hernia is the protrusion of part of the abdominal contents beyond the normal confines of the abdominal wall

It consists of three parts: the sac, the contents of the sac, and the coverings of the sac.

The hernial sac is a pouch (diverticulum) of peritoneum and has a neck and a body


  • Inguinal (indirect or direct)
  • Femoral
  • Umbilical (congenital or acquired)
  • Epigastric
  • Separation of the recti abdominis
  • Incisional
  • Hernia of the linea semilunaris (spigelian hernia)
  • Lumbar (Petit’s triangle hernia)
  • Internal

Indirect Inguinal Hernia

1.It is the remains of the processus vaginalis and therefore is congenital in origin.

2.It is more common than a direct inguinal hernia.

3.It is much more common (20times) in males than females.

4.It is more common on the right side.

5.It is most common in children and young adults.

6.The hernial sac enters the inguinal canal through the deep inguinal ring and lateral to the inferior epigastric vessels.

7.The neck of the sac is narrow.

8.The hernial sac may extend down into the scrotum or labium majus, inside the spermatic cord.

9.The hernial sac may extend through the superficial inguinal ring above and medial to the pubic tubercle. (Femoral hernia is located below and lateral to the pubic tubercle.)

Direct Inguinal Hernia

1.It Is caused because of weak abdominal muscles

2.Less common than indirect (15%)

3.More common in males

4.Doesn’t have a specific side. Mostly bilateral

5.More common in older men

6.The hernial sac bulges forward through the posterior wall of the inguinal canal medial to the inferior epigastric vessels.

7.The neck of the hernial sac is wide.

8.Hernial sac exits through the superficial ring, lateral to the cord and bulges on the skin of abdomen.



Femoral Hernia

1.It is a protrusion of abdominal parietal peritoneum down through the femoral canal to form the hernial sac. It forms a swelling on the upperpart of thigh

2.It is more common in women than in men.

3.The neck of the hernial sac lies below and lateral to the pubic tubercle.

4.The neck of the hernial sac lies at the femoral ring

5.The neck of the sac is narrow

Hernias can be

  • Reducible
  • Irreducible
  • Strangulated

Umbilical Herniae:

  • Congenital umbilical hernia
  • Acquired infantile umbilical hernia
  • Paraumbilical hernia

Other hernias:

Epigastric hernia

Separation of the Recti Abdominis

  • Incisional Hernia
  • Spigelian Hernia
  • Lumbar Hernia
  • Internal Hernia

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