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Lect 1, Anterior abdominal wall


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  • there's no deep fascia in the anterior abdominal wall to permit the extension .eg:- during pregnancy , and the seconed layer of fascia here is tansversalis fascia
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Lect 1, Anterior abdominal wall

  1. 1. Structure of the Anterior Abdominal Wall Dr . Mohaned abu lehea
  2. 2. • The anterior abdominal wall is made up of : 1. Skin 2. Superficial fascia 3. Deep fascia 4. Muscles 5. Extraperitoneal fascia 6. Parietal peritoneum
  3. 3. 1. Skin • The skin is loosely attached to the underlying structures except at the umbilicus, where it is tethered to the scar tissue. • The umbilicus is a scar representing the site of attachment of the umbilical cord in the fetus; it is situated in the linea alba
  4. 4. Nerve Supply to Skin • The cutaneous nerve supply to the anterior abdominal wall is derived from the anterior rami of the lower six thoracic and the first lumbar nerves.
  5. 5. • The dermatome of T7 is located over the xiphoid process. • The dermatome of T10 includes the umbilicus. • That of L1 lies just above the inguinal ligament and the symphysis pubis.
  6. 6. Blood Supply of Skin • The skin near the midline is supplied by branches of the superior and the inferior epigastric arteries. • The skin of the flanks is supplied by branches of the 1. Intercostal arteries 2. Lumbar arteries 3. Deep circumflex iliac arteries
  7. 7. • Veins • The venous drainage passes above mainly into the axillary vein via the lateral thoracic vein & • Below into the femoral vein via the superficial epigastric and the great saphenous veins
  8. 8. 2. Superficial Fascia • The superficial fascia is divided into: 1. Superficial fatty layer (fascia of Camper) 2. Deep membranous layer (Scarpa's fascia)
  9. 9. • The fatty layer is continuous with the superficial fat over the rest of the body and may be extremely thick [8 cm] or more in obese patients.
  10. 10. • The membranous layer is thin and fades out laterally and above, where it becomes continuous with the superficial fascia of the back and the thorax, respectively.
  11. 11. 3. Deep Fascia • It lies immediately deep to the membranous layer of superficial fascia.
  12. 12. 4. Muscles • The muscles of the anterior abdominal wall consist of three broad thin sheets. • From exterior to interior they are the 1. External oblique 2. Internal oblique 3. Transversus abdominis
  13. 13. • On either side of the midline anteriorly is, in addition, a wide vertical muscle, the rectus abdominis.
  14. 14. • As the aponeuroses of the three sheets pass forward, they enclose the rectus abdominis to form the rectus sheath.
  15. 15. • The lower part of the rectus sheath might contain a small muscle called the pyramidalis.
  16. 16. A. External Oblique • Origen : the outer surfaces of the lower eight ribs and fans out to be • Insertion : the xiphoid process, the linea alba, the pubic crest, the pubic tubercle, and the anterior half of the iliac crest • Most of the fibers are inserted by means of a broad aponeurosis.
  17. 17. • A triangular-shaped defect in the external oblique aponeurosis lies immediately above and medial to the pubic tubercle. • This is known as the superficial inguinal ring
  18. 18. • The spermatic cord passes through this opening and carries the external spermatic fascia (or the external covering of the round ligament of the uterus) from the margins of the ring.
  19. 19. • Between the anterior superior iliac spine and the pubic tubercle, the lower border of the aponeurosis is folded backward on itself, forming the inguinal ligament.
  20. 20. B. Internal Oblique • Origin : lumbar fascia, the anterior two thirds of the iliac crest, and the lateral two thirds of the inguinal ligament. • Insertion : the lower borders of the lower three ribs and their costal cartilages, the xiphoid process, the linea alba, and the symphysis pubis.
  21. 21. C. Transversus • Origin : the deep surface of the lower six costal cartilages, the lumbar fascia, the anterior two thirds of the iliac crest, and the lateral third of the inguinal ligament. • Insertion : the xiphoid process, the linea alba, and the symphysis pubis.
  22. 22. D. Rectus Abdominis • The rectus abdominis is a long strap muscle that extends along the whole length of the anterior abdominal wall. • It is broader above and lies close to the midline, being separated from its fellow by the linea alba.
  23. 23. • The rectus abdominis muscle is divided into distinct segments by three transverse tendinous intersections: 1. One at the level of the xiphoid process, 2. One at the level of the umbilicus 3. One halfway between these two
  24. 24. • These intersections are strongly attached to the anterior wall of the rectus sheath.
  25. 25. E. Pyramidalis • The pyramidalis muscle is often absent. • Origin : anterior surface of the pubis and is • Insertion : linea alba • It lies in front of the lower part of the rectus abdominis.
  26. 26. Rectus Sheath
  27. 27. Rectus Sheath • The rectus sheath is a long fibrous sheath that encloses the rectus abdominis muscle and pyramidalis muscle (if present). • It is formed mainly by the aponeuroses of the three lateral abdominal muscles.
  28. 28. • Between the costal margin and 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.
  29. 29. Function of the Anterior Abdominal Wall Muscles
  30. 30. • The oblique muscles laterally flex and rotate the trunk. • The rectus abdominis flexes the trunk and stabilizes the pelvis, and • The pyramidalis keeps the linea alba taut during the process.
  31. 31. • The muscles of the anterior and lateral abdominal walls assist the diaphragm during inspiration by relaxing as the diaphragm descends so that the abdominal viscera can be accommodated.
  32. 32. • The muscles assist in the act of forced expiration that occurs during coughing and sneezing by pulling down the ribs and sternum.
  33. 33. • Their tone plays an important part in supporting and protecting the abdominal viscera.
  34. 34. • By contracting simultaneously with the diaphragm, with the glottis of the larynx closed, they increase the intra-abdominal pressure and help in 1. 2. 3. 4. Micturition, Defecation, Vomiting Parturition
  35. 35. Nerve Supply of Anterior Abdominal Wall Muscles • The oblique and transversus abdominis muscles are supplied by the lower six thoracic nerves and the iliohypogastric and ilioinguinal nerves (L1).
  36. 36. • The rectus muscle is supplied by the lower six thoracic nerves.
  37. 37. • The pyramidalis is supplied by the 12th thoracic nerve.
  38. 38. Fascia Transversalis • The fascia transversalis is a thin layer of fascia that lines the transversus abdominis muscle.
  39. 39. 5. Extraperitoneal Fat • The extraperitoneal fat is a thin layer of connective tissue that contains a variable amount of fat and lies between the fascia transversalis and the parietal peritoneum.
  40. 40. 6. Parietal Peritoneum • The walls of the abdomen are lined with parietal peritoneum . • This is a thin serous membrane and is continuous below with the parietal peritoneum lining the pelvis.
  41. 41. Thanks