Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
ANTERIOR ABDOMINAL WALL Learning objectives At the end of the lecture the student should be able to: Know the details of anterior abdominal wall. Identify the layers of abdominal wall. Identify the fascia, muscles of wall. Abdominal wall Abdominal wall represents the boundaries of the abdominal cavity. Abdominal wall is split into: Posterior (back) Lateral (sides) Anterior (front). Borders of the Abdomen Superior: Costal cartilages 7-12. Xiphoid process: Level of 10th cartilage = L3 Inferior: Pubic bone and iliac crest: Level of L4. Umbilicus: Level of IV disc L3-4 Lines of the Anterior Abdominal Wall Linea alba: Located along the midline = connective tissue raphe. Linea semilunaris: Along each lateral border of rectus abdominis. Linea transversa: Tendinous bands of rectus abdominis Linea Alba Median raphe Extends from xiphoid to pubic symphysis. Lies between paired rectus abdominus muscles. Fusion of aponeuroses of transversus abdominus, internal oblique, and external oblique. Surface Features Linea semilunaris: o Along lateral margin of rectus abdominus. o Crosses costal margin near tip of 9th costal cartilage. Arcuate line: o Lower free edge of posterior lamina. o Lies midway between umbilicus and pubis. Layers of abdominal wall Layers of the abdominal wall are (from superficial to deep): Skin Fascia Camper's fascia - fatty superficial layer. Scarpa's fascia - deep fibrous layer. Muscle Three large flat sheets connecting rib cage to hip bone. Muscles posteriorly and laterally. Aponeurosis anteriorly and medially • Rectus abdominis • External oblique muscle • Internal oblique muscle • Transverse abdominal muscle Fascia transversalis Peritoneum Fascia Superficial: o o o o Camper’s fascia Continuous with fascia over thorax and thigh. Fatty layer. It is areolar in texture, and contains in its meshes a varying quantity of adipose tissue. In men, this superficial layer continues over the penis and, after losing its fat and fusing with the deeper layer of superficial fascia, continues into the scrotum where it forms a specialized fascial layer (the dartos fascia). In women, this superficial layer retains some fat and is a component of the labia majora. Fascia Deep Superficial: Scarpa’s fascia Membranous layer. It continues into the anterior part of the perineum where it is firmly attached to the ischiopubic rami and to the posterior margin of the perineal membrane. Here, it is referred to as the superficial perineal fascia (Colles' fascia). Deep: Thin layer covering abdominal muscles. Muscle Layers 5 muscles 3 horizontal External oblique. Internal oblique. Transversus abdominus. 2 vertical Rectus abdominus. Rectus sheath Rectus sheath: Encloses rectus abdominus. Formed by fusion of fascia of other three layers of abdominal muscles. Anterior and posterior laminae. (layers) Arcuate line is the lower free edge of the posterior lamina Lies midway between umbilicus and Rectus abdominis muscle Two parallel muscles Separated by a midline band of connective tissue called the linea alba Attachment Pubic crest, Pubic tubercle Pubic symphysis Costal cartilages of ribs V to VII; xiphoid process Anterior rami of lower seven thoracic spinal nerves (T7 to T12) Functions Compresses abdominal contents; Flexes vertebral column & tense abdominal wall. Pyramidalis Attachment Front of pubis and pubic symphysis Into linea alba. Anterior ramus of T12 Tenses the linea alba External oblique Most superficial of the three flat muscles Immediately deep to the superficial fascia. Large aponeurotic component covers the anterior part of the abdominal wall to the midline. Extensions of external oblique The lower border of the external oblique aponeurosis forms the inguinal ligament on each side. This thickened reinforced free edge of the external oblique aponeurosis passes between the anterior superior iliac spine laterally and the pubic tubercle medially. Lacunar ligament is a crescent-shaped extension of fibers at the medial end of the inguinal ligament that pass backward to attach to the pecten pubis on the superior ramus of the pubic bone. Additional fibers extend from the lacunar ligament along the pecten pubis of the pelvic brim to form the pectineal (Cooper's) ligament. Internal oblique muscle Deep to the external oblique muscle is the internal oblique muscle This muscle is smaller and thinner than the external oblique, with most of its muscle fibers passing in a superomedial direction. Its lateral muscular components end anteriorly as an aponeurosis that blends into the linea alba at the midline. Transversus abdominis Deep to the internal oblique muscle is the transversus abdominis muscle. So-named because of the direction of most of its muscle fibers. It ends in an anterior aponeurosis, which blends with the linea alba at the midline. Transversalis fascia Each of the three flat muscles is covered on its anterior and posterior surfaces by a layer of investing abdominal fascia. These layers are unremarkable except for the layer deep to the transversus abdominis muscle (the transversalis fascia), which is better developed. Deep to the transversalis fascia is a layer of connective tissue, the extraperitoneal fascia, which separates the transversalis fascia from the peritoneum Peritoneum Deep to the extraperitoneal fascia is the peritoneum. This thin serous membrane lines the walls of the abdominal cavity and, at various points, reflects onto the abdominal viscera, providing either a complete or a partial covering. Cutaneous Nerves The skin and muscles of the anterolateral abdominal wall are supplied by T7 to T12 and L1 spinal nerves. The intercostal nerves (T7 to T11) leave their intercostal spaces, passing deep to the costal cartilages, and continue onto the anterolateral abdominal wall between the internal oblique and transversus abdominis muscles. Cutaneous Nerves Ventral rami of T7 through T11:= thoracoabdominal nerves. T7 to dermatome over xiphoid process. T10 at level of umbilicus. Subcostal nerve Ventral ramus of L1: Gives rise to: iliohypogastric nerve. ilioinguinal nerve. Arterial supply Superior part of the wall Musculophrenic artery, a terminal branch of the internal thoracic artery. Inferior part of the wall Superficial epigastric artery Superficial circumflex iliac artery, both branches of the femoral artery Lateral part of the wall 10th and 11th intercostal arteries Subcostal artery Lymphatic Drainage Superficial lymphatics: Above the umbilicus: Drain into the axillary and sternal nodes. Below the umbilicus: Drain into the superficial inguinal nodes. Deep lymphatic drainage Follows the deep arteries back to parasternal nodes along the internal thoracic artery, lumbar nodes along the abdominal aorta external iliac nodes along the external iliac artery. Venous Drainage Superficial veins are paired with arteries. Above the umbilicus: Drain into the azygos venous system. Below the umbilicus: Drain into the femoral system (via great saphenous). Folds on Posterior Surface (of anterior wall) Median umbilical fold: Midline peritoneal fold on inner abdominal wall above bladder. Contains median umbilical ligament: Remnant of embryonic urachus. Medial umbilical fold: Paired peritoneal folds on either side of median fold. Contain medial umbilical ligaments: Remnants of umbilical arteries. Lateral umbilical fold: Paired peritoneal folds lateral to medial folds. Contain inferior epigastric vessels: From deep inguinal ring to arcuate line.