Anterior Abdominal Wall, Part 1 PDF

Introduction The abdomen is the region of trunk that lies between the diaphragm above and the inlet of pelvis below. Functions of the Abdomen Functions of the Abdomen  Structure of the Abdominal Walls The diaphragm separates the abdomen from the chest supe...

Introduction The abdomen is the region of trunk that lies between the diaphragm above and the inlet of pelvis below. Functions of the Abdomen Functions of the Abdomen  Structure of the Abdominal Walls The diaphragm separates the abdomen from the chest superiorly. Inferiorly: the abdomen is continuous with the pelvis. Anteriorly: the anterior abdominal wall. Posteriorly: the abdominal wall is made by the lumbar vertebrae, 12th ribs, muscles, and upper part of bony pelvis. Note: these walls are lined by fascia and parietal peritoneum. Structure of the Anterior Abdominal Wall Anterior Abdominal Wall Skin Superficial Fascia Deep Fascia Muscles Extra- Peritoneal Fascia Parietal Peritoneum  Anterior Abdominal Wall Skin The skin is loosely attached to the underlying structures except at the umbilicus, where it is tethered to the scar tissue. The natural lines of cleavage in the skin are constant and run downward and forward almost horizontally around the trunk.  Surgical Incisions If possible, all surgical incisions should be made in the lines of cleavage where the bundles of collagen fibers in the dermis run in parallel rows. An incision along a cleavage line will heal as a narrow scar, whereas one that crosses the lines will heal as wide or heaped-up scars.  Anterior Abdominal Wall Superficial Fascia Superficial Fascia Superficial fatty layer Deep membranous layer (fascia of Camper) (Scarpa’s fascia).  Anterior Abdominal Wall Superficial Fascia The fatty layer is continuous with the superficial fat over the rest of the body and may be extremely thick (3 in.) or more in obese subjects.  Anterior Abdominal Wall Superficial Fascia 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.  Anterior Abdominal Wall Superficial Fascia Inferiorly, the membranous layer passes onto the front of the thigh, where it fuses with the deep fascia one fingerbreadth below the inguinal ligament.  Anterior Abdominal Wall Superficial Fascia In the midline inferiorly, the membranous layer of fascia is not attached to the pubis but forms a tubular sheath for the penis (or clitoris).  Anterior Abdominal Wall Superficial Fascia Below in the perineum, it enters the wall of the scrotum (or labia majora). From there it passes to be attached on each side to the margins of the pubic arch; it is here referred to as Colles’ fascia.  Anterior Abdominal Wall Superficial Fascia Posteriorly, it fuses with the perineal body and the posterior margin of the perineal membrane.  Anterior Abdominal Wall Superficial Fascia In the scrotum, the fatty layer of the superficial fascia is represented as a thin layer of smooth muscle, the dartos muscle. The membranous layer of the superficial fascia persists as a separate layer.  General Appearance of the Abdominal Wall The normal abdominal wall is soft and pliable and undergoes inward and outward excursion with respiration. The contour is subject to considerable variation and depends on the tone of its muscles and the amount of fat in the subcutaneous tissue. Well-developed muscles or an abundance of fat can prove to be a severe obstacle to the palpation of the abdominal viscera. Membranous Layer of Superficial Fascia and the Extravasation of Urine The membranous layer of the superficial fascia is important clinically because beneath it is a potential closed space that does not open into the thigh but is continuous with the superficial perineal pouch via the penis and scrotum. Rupture of the penile urethra may be followed by extravasation 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. Membranous Layer of Superficial Fascia and the Extravasation of Urine The urine is excluded from the thigh because of the attachment of Scarpa’s fascia to the fascia Iata. Membranous Layer of Superficial Fascia and Abdominal Wounds When closing abdominal wounds it is usual for a surgeon to put in a continuous suture uniting the divided membranous layer of superficial fascia. This strengthens the healing wound, prevents stretching of the skin scar, and makes for a more cosmetically acceptable result.  Anterior Abdominal Wall Deep Fascia The deep fascia in the anterior abdominal wall is merely a thin layer of connective tissue covering the muscles; it lies immediately deep to the membranous layer of superficial fascia.