The abdominal wall

1. The abdominal wall

2. INGUINAL CANAL • Is an oblique passage through the lower part of the anterior abdominal wall and is present in both sexes. • It allows structures to pass to and from the testis to the abdomen in males. • In females it permits the passage of the round ligament of the uterus from the uterus to the labium majus. • In addition, it transmits the ilioinguinal nervein both sexes.

3. INGUINAL CANAL

4. INGUINAL CANAL • The canal is about (4 cm) long in the adult and extends from the deep inguinal ring downward and medially to the superficial inguinal ring. • It lies parallel to and immediately above the inguinal ligament. • In the newborn child, the deep ring lies almost directly posterior to the superficial ring so that the canal is considerably shorter at this age. • Later, as the result of growth, the deep ring moves laterally.

5. INGUINAL CANAL • The deep inguinal ring, an oval opening in the fascia transversalis, lies about (1.3 cm) above the inguinal ligament midway between the anterior superior iliac spine and the symphysis pubis. • Related to it medially are the inferior epigastric vessels, which pass upward from the external iliac vessels. • The margins of the ring give attachment to the internal spermatic fascia (or the internal covering of the round ligament of the uterus).

6. Walls of the lnguinal CanalAnterior wall of the canal • Is formed along its entire length by the aponeurosis of the external oblique muscle. • It is reinforced in its lateral third by the origin of the internal oblique from the inguinal ligament. • This wall is therefore strongest where it lies opposite the weakest part of the posterior wall, namely, the deep inguinal ring.

7. Walls of the lnguinal CanalPosterior wall of the canal • Is formed along its entire length by the fascia transversalis. • It is reinforced in its medial third by the conjoint tendon. • This wall is therefore strongest where it lies opposite the weakest part of the anterior wall, namely, the superficial inguinal ring.

8. Walls of the lnguinal CanalInferior wall of the canal (floor) • Is formed by the inguinal ligament and, at its medial end, the lacunar ligament.

9. Walls of the lnguinal CanalSuperior wall of the canal (roof) • Is formed by the arching lowest fibers of the internal oblique and transversusabdominis muscles.

10. Functions of the lnguinal Canal • In the male, the inguinal canal allows structures of the spermatic cordto pass to and from the testis to the abdomen. • (Normal spermatogenesis takes place only if the testis leaves the abdominal cavity to enter a cooler environment in the scrotum.) • In the female, the smaller canal permits the passage of the round ligamentof the uterus from the uterus to the labium majus. • In both sexes, the canal also transmits the ilioinguinal nerve.

12. Mechanics of the Inguinal Canal The presence of the inguinal canal in the lower part of the anterior abdominal wall in both sexes constitutes a potential weakness. It is interesting to consider how the design of this canal attempts to lessen this weakness.

13. Mechanics of the Inguinal Canal • Except in the newborn infant, the canal is an oblique passage with the weakest areas, namely, the superficial and deep rings, lying some distance apart. • The anterior wall of the canal is reinforced by the fibers of the internal oblique muscle immediately in front of the deep ring.

14. Mechanics of the Inguinal Canal • The posterior wall of the canal is reinforced by the strong conjoint tendon immediately behind the superficial ring. • On coughing and straining, as in micturition, defecation, and parturition, the arching lowest fibers of the internal oblique and transversus abdominis muscles contract, flattening out the arched roof so that it is lowered toward the floor. • The roof may actually compress the contents of the canal against the floor so that the canal is virtually closed.

15. Mechanics of the Inguinal Canal • When great straining efforts may be necessary, as in defecation and parturition, the person naturally tends to assume the squatting position: the hip joints are flexed, and the anterior surfaces of the thighs are brought up against the anterior abdominal wall. • By this means, the lower part of the anterior abdominal wall is protected by the thighs.

17. Spermatic Cord • The spermatic cord is a collection of structures that pass through the inguinal canal to and from the testis. • It is covered with three concentric layers of fascia derived from the layers of the anterior abdominal wall. • It begins at the deep inguinal ring lateral to the inferior epigastric artery and ends at the testis.

18. Coverings of the spermatic cord

19. Structures of the Spermatic Cord • The structures are as follows: • vas deferens, • testicular artery, • testicular veins (pampiniform plexus), • testicular lymph vessels, • autonomic nerves, • remains of processus vaginalis, • cremasteric artery, • artery of the vas deferens, • genital branch of the genitofemoral nerve.

20. Spermatic Cord Vas Deferens • The vas deferens is a cordlike structure that can be palpated between finger and thumb in the upper part of the scrotum. • It is a thick-walled muscular duct that transports spermatozoa from the epididymis to the urethra.

22. Spermatic CordTesticular Artery • A branch of the abdominal aorta(L2). • It is long and slender and descends on the posterior abdominal wall. • It traverses the inguinal canal and supplies the testis and the epididymis.

23. Spermatic CordTesticular Veins • An extensive venous plexus (pampiniform plexus), leaves the posterior border of the testis. • As the plexus ascends, it becomes reduced in size so that at about the level of the deep inguinal ring, a single testicular vein is formed. • This runs upon the posterior abdominal wall and drains into the left renal vein on the left side and into the inferior vena cava on the right side.

24. Spermatic Cord Lymph Vessels • The testicular lymph vessels ascend through the inguinal canal and pass up over the posterior abdominal wall to reach the lumbar (para-aortic) lymph nodes on the side of the aorta at the level of (L1). • This because the gonads had migrated from high up.

26. Spermatic CordAutonomic Nerves • Sympathetic fibers run with the testicular artery from the renal or aortic sympathetic plexuses. • Afferent sensory nerves accompany the efferent sympathetic fibers.

27. Spermatic CordOther Structures • Remnants of Processus Vaginalis. • Cremasteric artery (a branch of the inferior epigastric artery) supplies the cremasteric fascia. • Artery to the vas deferens (a branch of the inferior vesical artery). • The genital branch of the genitofemoral nerve, which supplies the cremaster muscle.

28. Coverings of the Spermatic Cord

29. Coverings of the Spermatic Cord • External spermatic fascia the external oblique aponeurosis • Cremasteric fascia the internal oblique muscle • Internal spermatic fascia the fascia transversalis

30. Development of the Inguinal Canal • A peritoneal diverticulum called the processus vaginalisis formed. • It passes through the layers of the lower part of the anterior abdominal wall. • It acquires a tubular covering from each layer.

31. Development of the Inguinal Canal • A band of mesenchyme, extending from the lower pole of the developing gonad through the inguinal canal to the labioscrotal swelling, has condensed to form the gubernaculum. • This band guides the descent of the developing gonad.

32. Development of the Inguinal Canal

33. Development of the Inguinal Canal • The testis descends through the pelvis and inguinal canal during the seventh and eighth months of fetal life. • The normal stimulus for the descent of the testis is testosterone, which is secreted by the fetal testes. • The testis follows the gubernaculum and descends behind the peritoneum on the posterior abdominal wall. • The testis then passes behind the processus vaginalis and pulls down its duct, blood vessels, nerves, and lymph vessels. • The testis takes up its final position in the developing scrotum by the end of the eighth month.

34. Development of the Inguinal Canal

35. Development of the Inguinal Canal

36. Development of the Inguinal Canal

37. Development of the Inguinal Canal • Because the testis and its accompanying vessels, ducts, and so on follow the course previously taken by the processus vaginalis, they acquire the same three coverings as they pass down the inguinal canal.

38. Development of the Inguinal Canal • Regarding females, the round ligament of the uterus is the part of the gubernaculum extending from uterus to the labium majus. • The inguinal canal in female transmits the round ligament of the uterus, lymph vessels and the ilioinguinal nerve.

39. VASECTOMY • Bilateral vasectomy is a simple operation performed to produce infertility. • Under local anesthesia, a small incision is made in the upper part of the scrotal wall, and the vas deferens is divided between ligatures. • Spermatozoa may be present in the first few post operative ejaculations, but that is simply an emptying process. • Now only the secretions of the seminal vesicles and prostate constitute the seminal fluid, which can be ejaculated as before.

40. Scrotum • The scrotum can be considered as an out- pouching of the lower part of the anterior abdominal wall. • It contains the testes, the epididymis, and the lower ends of the spermatic cords. • The wall of the scrotum has the following layers: • Skin, • Superficial fascia; • dartos muscle (fatty layer), • Colles fascia (membranous layer), • External spermatic fascia (external oblique), • Cremasteric fascia (internal oblique), • Internal spermatic fascia (fascia transversalis), • Tunica vaginalis.

42. Scrotum • The skin of the scrotum is thin, wrinkled, and pigmented and forms a single pouch. • The dartos muscle is innervated by sympathetic nerve fibers and is responsible for the wrinkling of the skin. • A slightly raised ridge in the midline indicates the line of fusion of the two lateral labioscrotal swellings. • Both layers of superficial fascia contribute to the median partition that crosses the scrotum and separates the testes from each other. • In the female, the swellings remain separate and form the labia majora.

44. Scrotum • The spermatic fasciae lie beneath the superficial fascia and are derived from the three layers of the anterior abdominal wall on each side.

45. Scrotum • The cremaster muscle can be made to contract by stroking the skin on the medial aspect of the thigh. This is called the cremasteric reflex. • The afferent fibers of this reflex arc travel in the femoral branch of the genitofemoral nerve (L1 and 2), and the efferent motor nerve fibers travel in the genital branch of the genitofemoral nerve. • The function of the cremaster muscle is to raise the testis and the scrotum upward for warmth and for protection against injury for testicular temperature and fertility.

46. Scrotum • The tunica vaginalis lies within the spermatic fasciae and covers the anterior, medial, and lateral surfaces of each testis. • It is the lower expanded part of the processus vaginalis; normally, just before birth, it becomes shut off from the upper part of the processus and the peritoneal cavity. • The tunica vaginalis is thus a closed sac, invaginated from behind by the testis.

47. Scrotum • Lymph drainage from the skin and fascia. including the tunica vaginalis, drains into the superficial inguinal lymph nodes.

48. Testis • The testis is a firm, mobile organ lying within the scrotum. • The left testis usually lies at a lower level than the right. • The upper pole of the gland is tilted slightly forward.

49. Testis • Each testis is surrounded by a tough fibrous capsule, the tunica albuginea. • Extending from the inner surface of the capsule is a series of fibrous septa that divide the interior of the organ into lobules.

50. Testis • Lying within each lobule are one to three coiled seminiferous tubules. • The tubules open into a network of channels called the rete testis. • Small efferent ductules connect the rete testis to the upper end of the epididymis.