Organization of the antero-lateral abdominal wall G.LUFUKUJA
Anterolateral Abdominal Wall Although the abdominal wall is continuous, it is subdivided into the anterior wall, right and left lateral walls (flanks), and posterior wall for descriptive purposes. Layers of anterior abdominal wall Skin Subcutaneous (Superficial fascia): Fatty and membranous Deep fascia Muscles and their aponeurosis: Extra peritoneal tissue Peritoneum. G.LUFUKUJA
G.LUFUKUJA
Skin The skin attaches loosely to the subcutaneous tissue, except at the umbilicus, where it adheres firmly. Shows ‘creases' which represent the lines of orientation of collagen fibres in the dermis- Langer's lines. These lines are surgically important – incisions along them heal better leaving a thin scar; while those across them leave big scars. In pregnant women, obese people and those with abdominal distention from whatever cause, there are dark elongate lines called striae gravidara. The skin is very sensitive to touch, and quickly when touched, the muscles contract. G.LUFUKUJA
Fascia of the Anterolateral Abdominal Wall Consists of two layers; Superficial fatty layer (Camper's fascia) containing variable amounts of fat, more in females and in the lower abdomen. Deep membranous layer (Scarpa's fascia). (+) Contains fibrous tissue and very little fat. (+) Fuses with fascia lata below inguinal ligament) (+) Continuous with the superficial perineal fascia (Colle's fascia) and with that investing the scrotum and penis. Note: Deep fascia is Unremarkable G.LUFUKUJA
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Applied anatomy G.LUFUKUJA
There are 4 main muscles to note: External oblique; Internal oblique; Transversus abdominis; Rectus abdominis G.LUFUKUJA
Compresses and supports abdominal viscera Transverse abdominal Internal surfaces of 7 and 12th costal cartilages, thoracolumbar fascia, iliac crest, and lateral third of inguinal ligament Linea alba with aponeurosis of internal oblique, pubic crest, and pecten pubis via conjoint tendon Thoracoabdominal nerves (anterior rami of inferior 6 thoracic nerves) and first lumbar nerves Compresses and supports abdominal viscera Internal oblique Thoracolumbar fascia, anterior two-thirds of iliac crest, and lateral half of inguinal ligament Inferior borders of 10 and 12th ribs, linea alba, and pecten pubis via conjoint tendon Compress and support abdominal viscera, flex and rotate trunk External oblique External surfaces of 5 and 12th ribs Linea and alba, pubic tubercle, and anterior half of iliac crest Thoracoabdominal nerves (inferior 5 [T7 and T11] thoracic nerves) and subcostal nerve G.LUFUKUJA
The Rectus Sheath G.LUFUKUJA
Rectus sheath G.LUFUKUJA
Location Fibrous compartment for rectus abdominis muscle in the paramedian abdominal wall. Formation Formed of the aponeurosis of abdominal muscles. It has a posterior layer and anterior layer. Proximal 1/3rd The anterior layer joins the aponeurosis of the external oblique to form the anterior wall of the rectus sheath. The posterior layer joins with the aponeurosis of the transversus abdominis to form the posterior wall of the rectus sheath. G.LUFUKUJA
Location… Middle 1/3 rd Aponeurosis of internal oblique joins external oblique aponeurosis to form anterior wall. Posterior wall is formed by aponeurosis of transversus abdominis muscle Distal 1/3 rd Mid way between umbilicus and pubic crest all three aponeurosis form the anterior layer The posterior layer is formed only by fascia transversalis G.LUFUKUJA
Location… The anterior and posterior layers fuse in the midline to form the linear alba, a fibrous intersection extending from the xiphoid process to the pubic symphysis. The inferior ¼ of the rectus sheath is deficient posteriorly. The limit of the posterior wall is marked by the arcuate line The lateral margin of rectus sheath is called linea semilunaris G.LUFUKUJA
Contents of Rectus Sheath Rectus abdominis muscle Inferior and superior epigastric vessels Terminal parts of the lower five intercostal nerves, and the Subcostal nerve. Fibro fatty connective tissue Occasionally lymph node(s) G.LUFUKUJA
Extra peritoneal fascia Transparent ‘membrane' which lines the inside of the abdominal wall. Its parts are named according to what it lines e.g. (+) diaphragmatic fascia; (+) iliac fascia; (+) psoas fascia. (+) fascia transversalis ( part covering the muscle transversus abdominis ). G.LUFUKUJA
Blood supply to the anterior abdominal wall Arteries Inferior epigastric : External iliac Superficial circumflex iliac : Femoral arterty Deep circumflex iliac : femoral artery Superior epigastric : internal thoracic Lower intercostal : Abdominal Aorta Subcostal arteries : Abdominal aorta G.LUFUKUJA
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Veins The veins correspond to the arteries, but: Inferior epigastric vein anastomoses with lateral thoracic vein. Superficial epigastric vein anastomoses with lateral thoracic vein. These two unite the veins of the upper and lower halves of the body (of the azygous system). G.LUFUKUJA
Lymphatic Drainage Superior to the umbilical level: Axillary nodes Parasternal nodes Inferior to the umbilical level: Superficial Inguinal lymph nodes Deep inguinal nodes External iliac nodes Lumbar nodes G.LUFUKUJA
Innervation The skin and muscles of the anterolateral abdominal wall are supplied mainly by the following nerves Thoracoabdominal nerves: the distal, the anterior rami of the inferior six thoracic spinal nerves; Lateral (thoracic) cutaneous branches: of the thoracic spinal nerves T7 and T9 or T10. Subcostal nerve: the large anterior ramus of spinal nerve T12. Iliohypogastric and ilioinguinal nerves: terminal branches of the anterior ramus of spinal nerve L1. G.LUFUKUJA
The internal surface of anterior abdominal wall Inferior to the umbilicus, there are 5 folds: The median umbilical fold is due to median umbilical ligament, the remnant of the urachus, which develops from the allantois. It attaches to the urinary bladder. 2 medial umbilical folds formed by medial umbilical ligaments – the obliterated umbilical arteries. 2 lateral umbilical folds – formed by the inferior epigastric vessels G.LUFUKUJA
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INGUINAL REGION G.LUFUKUJA
The inguinal canal Canal represents path taken by testis out of the abdomen. Boundaries Floor: Inguinal ligament and lacunar ligament Roof: Arching fibres of internal oblique and transversus abdominis. Antero lateral:Aponeurosis of external oblique Posterior: Fascia transversalis laterally and conjoint tendon medially (of transversus and internal oblique abdominal muscles) G.LUFUKUJA
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Applied anatomy Direct hernia Less common type more likely in older men (over 40). Protrudes anteriorly through the posterior wall of inguinal canal Medial to inferior epigastric artery. passes through inferior part of inguinal triangle. Does not pass through the deep inguinal ring, but pass through superficial ring. Usually results from weakening of the Conjoint tendon G.LUFUKUJA
G.LUFUKUJA
Indirect hernia More common type, makes 75% of all. more common in male children, Takes the path taken by testis through inguinal canal Leaves lateral to inferior epigastric artery. Passes outside inguinal triangle. Passes through the deep inguinal ring and superficial ring to enter the scrotum More likely in patent processus vaginalis G.LUFUKUJA
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Review Questions Describe the muscles, blood supply, lymphatic drainage and sensory innervation of the anterior abdominal wall Discuss the formation and contents of the inguinal canal. Add notes on the distinction between direct and indirect inguinal hernias. List six structures that must be safeguarded during hernial repair Describe the formation and contents of the rectus sheath G.LUFUKUJA
Review Questions Outline the general organization of the superficial fascia of the anterior abdominal wall, and the perineum. Add clinical notes on the implication of this organization Describe in detail the pattern and clinical significance of the blood supply of the anterior abdominal wall. State the advantages and disadvantages of the various incisions in the anterior abdominal wall. G.LUFUKUJA
G.LUFUKUJA