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.
Abdominal Quadrants • Formed by two intersecting lines: Intersect at umbilicus. • Quadrants: Upper left. Upper right. Lower left. Lower right.
Abdominal Regions • Divided into 9 regions by two pairs of planes: Vertical Planes: Left and right lateral planes = midclavicular planes Horizontal Planes: Transpyloric plane: Midway between jugular notch and pubic symphysis (between xiphoid and umbilicus). Intertubercular plane: Through tubercles of iliac crests.
Abdominal Regions • Right and left hypochondriac: Contain liver • Epigastric: Contains: liver, stomach, pancreas • Right and left lateral (lumbar): Right contains ascending colon. Left contains descending colon.
Abdominal Regions • Umbilical: Contains small intestine and transverse colon. • Right and left inguinal: Right contains ileocecal junction and appendix. Left contains sigmoid colon. • Hypogastric: Contains small intestine, urinary bladder (full), pregnant uterus.
Cutaneous Nerves • Derived from ventral rami of T7 through L1. • Pass inferiorly and medially in plane between transverse and internal oblique muscles. • Motor innervation: To abdominal muscles. • Cutaneous innervation: Lateral cutaneous branches. Anterior cutaneous branches: Penetrate rectus sheath.
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.
Fascia • Superficial: Camper’s fascia Continuous with fascia over thorax and thigh. Fatty layer.
Fascia • Deep Superficial: Scarpa’s fascia Membranous layer. Continues into perineum as: Superficial perineal fascia = Colle’s fascia. • Deep: Thin layer covering abdominal muscles.
Arterial Supply Above Umbilicus • Posterior intercostal arteries 10-11. • Subcostal artery. • Lumbar arteries 1-4. • Musculophrenic arteries. • Superior epigastric arteries. • Inferior epigastric arteries.
Arterial Supply Below Umbilicus • Superficial epigastric arteries. • Superficial circumflex iliac arteries. • Superficial external pudendal arteries.
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).
Lymphatic Drainage • Above the umbilicus: Drain into the axillary and sternal nodes. • Below the umbilicus: Drain into the superficial inguinal nodes.
Anterior Abdominal Wall Arteries • Superior epigastric: Terminal branch of internal thoracic. Descends in rectus sheath posterior to muscle. Anastomoses with inferior epigastric.
Anterior Abdominal Wall Arteries • Inferior epigastric: Arises from external iliac artery. Enters rectus sheath at arcuate line. Branches: Cremasteric artery. Pubic branch.
Anterior Abdominal Wall Arteries • Deep circumflex iliac artery: Branch of external iliac. • Superficial epigastric artery: Arises from femoral artery. • Superficial circumflex iliac artery: Arises from femoral artery. • Superficial external pudendal artery: Arises from femoral artery.
Anterior Abdominal Wall Veins • External iliac vein: Receives from epigastric and deep circumflex iliac veins. • Femoral vein: Receives superficial circumflex iliac vein, Superficial epigastric vein, Superficial external pudendal vein. Superior epigastric vein: Drains to brachiocephalic vein.
Muscle Layers • General Characteristics: Three large flat sheets connecting rib cage to hip bone. Muscular posteriorly and laterally. Aponeurotic anteriorly and medially.
Muscle Layers • Include: External oblique. Internal oblique. Transversus abdominus. Rectus abdominus.
Muscle Layers: Innervations • Lower intercostal spinal nerve. • Subcostal spinal nerve. • First lumbar spinal nerve.
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: Along lateral margin of rectus abdominus. Crosses costal margin near tip of 9th costal cartilage. • Arcuate line: Lower free edge of posterior lamina. Lies midway between umbilicus and pubis.
Inguinal Ligament • Inguinal ligament: Thickened lower border of external oblique aponeurosis. From anterior superior iliac spine to pubic tubercle.
Muscle Layers • 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 pubis.
Inguinal Region • Inguinal Canal: Oblique passage through lower abdominal wall. Site of potential weakness. Transmits: Spermatic cord in males. Round ligament of uterus in females. Extends between superficial and deep inguinal rings.
Inguinal Region • Inguinal Canal: Superficial inguinal ring: Triangular defect in the aponeurosis of the external oblique muscle layer. Superficial opening of the inguinal canal. Lies above and lateral to pubic tubercle. Larger in males: Transmits spermatic cord in males. Transmits round ligament of uterus in females.
Inguinal Region • Inguinal Canal: Deep inguinal ring: Opening of the evagination of the transversalis fascia. Lies above inguinal ligament midway between anterior iliac spine and pubic tubercle.
Inguinal Region • Inguinal Canal: Male: spermatic cord: Vas deferens. Ilioinguinal nerve. Genital branch of genitofemoral nerve. Testicular arteries and veins. Pampiniform plexus Lymph vessels. Cremaster muscle.
Inguinal Region • Inguinal Canal: Female: Round ligament. Ilioinguinal nerve. Lymph vessels.
Inguinal Region • Hernias: Direct inguinal: Occurs in older men (rarely women). Due to weakness in abdominal wall behind or lateral to superficial inguinal ring. Passes directly through abdominal wall to superficial inguinal ring. Does not extend into scrotum. Has sac formed by peritoneum.
Inguinal Region • Hernias: Indirect inguinal: Traverses deep and superficial inguinal rings and inguinal canal. Lies within coverings of spermatic cord. May descend into scrotum. More common than a direct inguinal hernia. More common in boys and young men. May be congenital.
Inguinal Region • Hernias: Femoral: Occurs within femoral canal. More common in females. Umbilical: Occurs at site where umbilical cord penetrates between muscles and fascia of anterior abdominal wall.
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.
Folds on Posterior Surface (of anterior wall) • Lateral umbilical fold: Paired peritoneal folds lateral to medial folds. Contain inferior epigastric vessels: From deep inguinal ring to arcuate line.
Folds on Posterior Surface (of anterior wall) • Falciform ligament: Double layer of peritoneum. Attaches liver to anterior abdominal wall and to inferior surface of diaphragm. Contains ligamentum teres hepatis (round ligament of liver): Remnant of left umbilical vein.