Anterior abdominal wall

Abdomen anatomy

1. ANTERIOR ABDOMINAL WALL DR. TANYA RASHID ANATOMY DEPT

2. STRUCTURE MADE UP OF: Skin Superficial fascia Deep fascia Muscles Extraperitoneal fascia Parietal peritoneum

3. skin 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 linea alba. DERMATOME: The cutaneous nerve supply is derived from the anterior rami of the lower six thoracic and the first lumbar nerves. 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.

4. SUPERFICIAL FASCIA THE SUPERFICIAL FASCIA IS DIVIDED INTO: Superficial fatty layer (Camper’s fascia) Deep membranous layer ( S carpa’s fascia) The FATTY LAYER is continuous with the superficial fat over the rest of the body and may be extremely thick (8cm) or more in obese patients. 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. DEEP FASCIA It lies immediately deep to the membranous layer of superficial fascia

5. MUSCLES The muscles of anterior abdominal wall consists of three broad thin sheets. FROM EXTERIOR TO INTERIOR THEY ARE: External oblique Internal oblique Transversus abdominis On either side of the midline anteriorly is, in addition, a wide vertical muscle, the RECTUS ABDOMINUS . As the aponeuroses of the three sheets pass forward, they enclose the rectus abdominis to form the RECTUS SHEATH . The lower part of the rectus sheath might contain a small muscle called the PYRAMIDALIS.

6. a. External oblique ORIGIN: 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 A triangle shaped defect in the external oblique aponeurosis lies immediately above and medial to the pubic tubercle. This is known as the superficial inguinal ring. 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 .

7. 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.

8. EXTERNAL OBLIQUE MUSCLE FIBERS move downwards and medially. INTERNAL OBLIQUE MUSCLE FIBERS move upwards and medially.

9. C. TRANSVERSUS abdominus ORIGIN: T he 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.

10. D. RECTUS ABDOMINIS The rectus abdominis is a long strap muscle that extends along the whole length of the anterior abdominal wall. It is broaded above and lies close to the midline, being separated from its fellow by the linea alba. ORIGIN: pubic crest INSERTION: ribs (5 th , 6 th , 7 th ), xiphoid process.

11. The rectus abdominis muscle is divided into distinct segments by three transverse tendinous intersections : 1. one at the level of xiphoid process 2. one at the level of the umbilicus 3. one halfway between these two These insertions are strongly attached to the anterior wall of the rectus sheath.

12. E. PYRAMIDALIS The pyramidalis muscle is often absent. ORIGIN: anterior surface of the pubis INSERTION: linea alba It lies infront of the lower part of the rectus abdominis.

13. 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. 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.

14. FUNCTIONS OF MUSCLES OF ANTERIOR ABDOMINAL WALL OBLIQUE MUSCLE: laterally flex and route the trunk RECTUS ABDOMINIS: flexes the trunk and stabilizes the pelvis PYRAMIDALIS : keeps the linea alba taut during the process. 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. The muscles assist in the act of forces expiration that occurs during coughing and sneezing by pulling down the ribs and sternum. Their tone plays an important part in supporting and protecting the abdominal viscera.

15. By contracting simultaneously with the diaphragm, with the glottis of the larynx closed, they increase the intra abdominal pressure and help in: Micturation Defecation Vomiting Parturition

16. NERVE SUPPLY OF MUSCLES OF ANTERIOR ABDOMINAL WALL The oblique and transversus abdominis muscles are supplied by the lower six thoracic nerves and the iliohypogastric and ilioinguinal nerves (L1). The rectus muscle is supplied by the lower six thoracic nerves. The pyramidalis is supplied by the 12 th thoracic nerve.

17. FASCIA TRANSVERSALIS The fascia transversalis is a thin layer of fascia that lines the transversus abdominis muscle. EXTRAPERITONEAL FAT: The extraperitoneal fat is a thin layer of connective tissue that contains a variable amount of fat and lies between the fascia tranversalis and the parietal peritoneum. PARIETAL PERITONEUM: The walls of abdomen are lined with parietal peritoneum This is a thin serous membrane and is continuous below with the parietal peritoneum lining the pelvis.

18. BLOOD SUPPLY OF ANTERIOR ABDOMINAL WALL ARTERIAL SUPPLY: Superior Epigastric artery: branch of Internal Mammary artery. I nferior Epigastric artery: branch of External Iliac artery Two Posterior Intercostal art.: Desc . Thor. Aorta Four Lumbar arteries: Desc . Thor. Aorta Deep Circumflex iliac artery: branch of Ext. Iliac artery VEINS: Above the umbilicus mainly into the axillary vein via the lateral thoracic vein. Below the umbilicus into the femoral vein through the superficial epigastric and the great saphenous veins.

19. NERVE SUPPLY OF ANTERIOR ABDOMINAL WALL Anterior rami of Lower 6 thoracic nerves T7 – T11 intercostal nerves T12: S ubcostal nerve Anterior ramus of the 1 st lumbar nerve Ilioinguinal nerve Iliohypogastric nerve Pass forward between the internal oblique and transversus abdominis muscle.

20. LYMPH DRAINAGE OF ANTERIOR ABDOMINAL WALL SUPERFICIAL LYMPH VESSELS: Above umbilicus: anterior group of axillary nodes Below umbilicus: superficial inguinal lymph nodes DEEP YMPH VESSELS: Drain into the: I nternal thoracic, external iliac, posterior mediastinal and para aortic (lumbar) nodes.

21. MULTIPLE CHOICE QUESTIONS 1. SUPERIOR EPIGASTRIC ARTERY IS A BRANCH OF: A. Descending thoracic aorta B. Abdominal aorta C. Internal thoracic artery D. External iliac artery

22. 2. MUSCLE FIBERS OF THE EXTERNAL OBLIQUE MOVE IN WHICH DIRECTION: A. upwards and medially B. upwards and laterally C. downwards and laterally D. downwards and medially

23. 3. INSERTION OF RECTUS ABDOMINIS: A. linea alba B. pubic crest C. xyphoid process D. anterosuperior iliac spine

24. T hank y ou!