Anterior Abdominal Wall, Part 1 PDF

Anterior Abdominal Wall “Part Dr. Emad 1”MD. I Shaqoura M.Sc. Lecturer of Anatomy & Histology Faculty of Medicine, IUG Outlines Introduction. Layers of the anterior abdominal wall:  Skin.  Fascia.  Muscles.  Peritoneum. Nerves & vessels of...

Anterior Abdominal Wall “Part Dr. Emad 1”MD. I Shaqoura M.Sc. Lecturer of Anatomy & Histology Faculty of Medicine, IUG Outlines Introduction. Layers of the anterior abdominal wall:  Skin.  Fascia.  Muscles.  Peritoneum. Nerves & vessels of the anterior abdominal wall. Introduction The abdomen is the region of trunk that lies between the diaphragm above and the 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  Anterior Abdominal Wall Superficial Fascia Superficial fatty layer (fascia of Camper) Superficial Fascia Deep membranous layer (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  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  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.  Anterior Abdominal Wall Muscles Muscles of ant. abd. wall external internal transversus oblique oblique abdominis In addition to the rectus abdominis in the midline & a small muscle called pyramidalis *3 broad anterolateral + 2 Mid line flat Muscles *continuation of the thorax muscles (external/internal intercostal and innermost ms) *NV plan is present b/w IO and TA *TIRE *functions  Anterior Abdominal Wall External Oblique Muscle Is a broad, thin, muscular sheet. (Pocket muscle) Arises from the outer surfaces of the lower 8 ribs. Inserted by a broad aponeurosis into the:  xiphoid process,  linea alba,  pubic crest,  pubic tubercle,   Anterior Abdominal Wall External Oblique Muscle  The superficial inguinal ring is a V shaped defect in the external oblique aponeurosis lies immediately above and medial to the pubic tubercle.  Anterior Abdominal Wall External Oblique Muscle 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 “Poupart ligament”. From the medial end of the ligament, the lacunar ligament (Gimbernat) extends backward and  Anterior Abdominal Wall External Oblique Muscle The sharp, free crescentic edge of the lacunar ligament forms the medial margin of the femoral ring. On reaching the pectineal line, the lacunar ligament becomes continuous with a thickening of the periosteum called the  Anterior Abdominal Wall External Oblique Muscle It transmits the spermatic cord (or round ligament of the uterus) which carries the external spermatic fascia (or the external covering of the round ligament of  Anterior Abdominal Wall External Oblique Muscle  To the inferior rounded border of the inguinal ligament is attached the deep fascia of the thigh, “the fascia lata”.  Anterior Abdominal Wall Internal Oblique Muscle A broad, thin, muscular sheet that lies deep to the external oblique; most of its fibers run at right angles to those of the external oblique (upward and forward). It arises from:  lumbar fascia,  the anterior 2/3 of the iliac crest,  the lateral 2/3 of the  Anterior Abdominal Wall Internal Oblique Muscle The muscle is inserted into:  the lower border of the lower 3 ribs,  the xiphoid process,  the linea alba,  the symphysis  Anterior Abdominal Wall Internal Oblique Muscle It has a lower free border that arches over the spermatic cord (or round ligament of the uterus) and then descends behind it to be attached to the pubic crest and the pectineal  Anterior Abdominal Wall Internal Oblique Muscle Near their insertion, the lowest tendinous fibers are joined by similar fibers from the transversus abdominis to form the conjoint tendon. The conjoint tendon is attached  Anterior Abdominal Wall Internal Oblique Muscle The spermatic cord carries with it some of the muscle fibers that are called the cremaster muscle. The cremasteric fascia = the cremaster muscle + its fascia. Is supplied by the genital branch of the genitofemoral  Anterior Abdominal Wall Transversus Abdominis Muscle A thin sheet of muscle that lies deep to the internal oblique, and its fibers run horizontally forward. (corset muscle) Laterally is fibers and meadially is apponeurosis It arises from:  the deep surface of the lower 6 costal cartilages (interdigitating with the diaphragm),  the lumbar fascia,  the anterior 2/3 of the iliac crest,  Anterior Abdominal Wall Transversus Abdominis Muscle It is inserted into the:  xiphoid process,  the linea alba,  the smphysis pubis.  Anterior Abdominal Wall Transversus Abdominis Muscle The lowest tendinous fibers join similar fibers from the internal oblique to form the conjoint tendon, which is fixed to the pubic crest and the N.B. The posterior border of the external oblique muscle is free, whereas the posterior borders of the internal oblique and transversus muscles are attached to the lumbar vertebrae by the lumbar fascia.  Anterior Abdominal Wall Rectus Abdominis Muscle 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  Anterior Abdominal Wall Rectus Abdominis Muscle It arises by two heads, from the front of the symphysis pubis and from the pubic crest. It is inserted into the 5th, 6th, and 7th costal cartilages and the xiphoid process.  Anterior Abdominal Wall Rectus Abdominis Muscle When it contracts, its lateral margin forms a cowed ridge that can be palpated and often seen and is termed the linea semilunaris. This extends from the tip of the 9th costal cartilage to the pubic  Anterior Abdominal Wall Rectus Abdominis Muscle The rectus abdominis muscle is divided into distinct segments by three transverse tendinous intersections:8 packs - at the xiphoid process,  Anterior Abdominal Wall Pyramidalis Muscle The pyramidalis muscle is often absent, it arises by its base from the anterior surface of the pubis and is inserted into the linea alba. It lies in front of the lower part of the rectus abdominis.  References Clinical anatomy by regions, 9th edition, Richard S. Snell, MD, PhD. Gray’s anatomy for students, 3 rd edition. Moore clinically oriented anatomy, 7th edition. Netter’s clinical anatomy, 3rd edition.