1. Dr. Mohamed Ahmad Taha Mousa Assistant Professor of Anatomy and Embryology

2. Objectives a. Discuss inguinal canal and its contents b. Discuss the rectus sheath and its contents c. Identify clinical applications (Abdominal incisions, extravasations of urine, abdominal and inguinal hernia)

3. Inguinal canal - It is oblique passage through the lower part of the anterior abdominal wall. - It is about 1.5 inch long in adult and extends from the deep inguinal ring to the superficial inguinal ring. Deep inguinal ring: It is oval opening in the fascia transversalis. - It lies about 0.5 inch above the midinguinal point. - The margins of the ring give attachment to the internal spermatic fascia. Superficial inguinal ring: It is triangular shaped opening in the aponeurosis of the external oblique muscle. - It lies above and medial to the pubic tubercle. - The margins of the ring called the crura and give attachment to the external spermatic fascia.

4. Walls of the Inguinal canal Anterior wall: - Medially: External oblique aponeurosis. - Laterally: External oblique and origin of the internal oblique from the inguinal ligament. - The lateral part is the strongest where it lies opposite the weakest part of the posterior wall (deep inguinal ring). Posterior wall: - Medially: Conjoint tendon and fascia transversalis. - Laterally: The fascia transversalis. - The medial part is the strongest where it lies opposite the weakest part of the anterior wall (superficial inguinal ring). Roof: Arching fibers of the internal oblique and transversus abdominis muscles. Floor: The inguinal ligament and at its medial end, the lacunar ligament. Deep inguinal ring Superficial inguinal ring External oblique Internal oblique Fascia transversalis Conjoint tendon Anterior wall Posterior wall Lateral Medial

5. Function of the Inguinal canal In male: - It is the passage for the spermatic cord from the testis to the abdomen - Ilioinguinal nerve. In the female: - It is the passage for the round ligament of the uterus from the uterus to the labium majora. - Ilioinguinal nerve.

6. Mechanics of the Inguinal Canal - It is the site of potential weakness in the anterior abdominal wall in both sexes. - The design of the inguinal canal decrease this weakness by: 1. The canal is an oblique passage: The weakest areas the superficial and deep inguinal rings lying a way from each others. 2. The anterior wall: It is reinforced by the fibers of the internal oblique muscle in front of the deep inguinal ring. 3. The posterior wall: It is reinforced by the strong conjoint tendon behind the superficial inguinal ring. Deep inguinal ring Superficial inguinal ring External oblique Internal oblique Fascia transversalis Conjoint tendon Anterior wall Posterior wall Lateral Medial

7. 4. On coughing and straining (in micturition, defecation and parturition): The arching fibers of the internal oblique and transversus abdominis muscles contracts leading to flattening of the roof. - The roof actually compress the contents of the canal against the floor so that the canal is virtually closed. 5. When great straining efforts may be necessary : The person naturally assume the squatting position so the lower part of the anterior abdominal wall is protected by the thighs.

8. Regions of the abdomen

9. Rectus sheath - It is the fibrous sheath that envelopes the rectus abdominis and pyramidalis muscle. - It is formed by the aponeurosis of the three lateral abdominal muscles. The rectus sheath is divided into 3 parts: 1. Above the costal margin: Anterior wall: It is formed by the aponeurosis of the external oblique muscle. Posterior wall: It is formed by the 5 th, 6 th and 7 th costal cartilages and the intercostal spaces. 2. Between the costal margin and the level of the anterior superior iliac spine: The aponeurosis of internal oblique splits into 2 lamellae. Anterior wall: It is formed by the aponeurosis of the external oblique and anterior lamellae of internal oblique.

10. Posterior wall: It is formed by the posterior lamellae of internal oblique and the transversus abdominis muscle. 3. Between the level of the anterior superior iliac spine and the pubis: Anterior wall: It is formed by the aponeurosis of all three muscles. Posterior wall: It is absent and the rectus abdominis muscle lies in contact with the fascia transversalis. - At the level of the anterior superior iliac spine the posterior wall form the arcuate line. - At this site the inferior epigastric vessels enter the rectus sheath and pass upward to anastomosis with the superior epigastric vessels.

11. a. Muscles: 1. Rectus abdominis muscle. 2. Pyramidalis muscle. b. Blood vessels: 1. Superior epigastric vessels. 2. Inferior epigastric vessels. c. Nerves: 1. Lower 5 intercostal nerves. 2. Subcostal nerve. Contents of the rectus sheath

12. Clinical application a. Surgical incisions: It should be made in parallel lines with the bundles of collagen fibers. - It heals as a narrow scar, whereas one that crosses the lines heals as wide scars. b. Extravasations of urine: Rupture of the penile urethra followed by extravasations of urine into the scrotum, perineum and penis and then up into the lower part of the anterior abdominal wall deep to the membranous layer of fascia. The passage of urine to the thigh is prevented by attachment of the membranous layer to the fascia lata of the thigh. c. Hematoma of the rectus sheath: It occurs on the right side below the umbilicus and causes abdominal pain. The source of bleeding is the inferior epigastric vein or artery. - It occurs during severe cough or blunt trauma.

13. d. Abdominal hernia: It is the protrusion of part of the abdominal contents through the anterior abdominal wall. Types of hernia: - Inguinal (indirect or direct) - Femoral - Umbilical - Epigastric - Incisional Indirect inguinal hernia: It is the most common congenital hernia. - The hernial sac enters the inguinal canal lateral to the inferior epigastric vessels down into the scrotum or labium majora. - It is about 20 times more common in males than in females. Direct inguinal hernia: The hernial sac bulges directly through the posterior wall of inguinal canal medial to the inferior epigastric vessels. Femoral hernia: It descends through the femoral canal within the femoral sheath..

14. Thank you