WINDSOR UNIVERSITY SCHOOL OF MEDICINE DEPARTMENT OF ANATOMY ABDOMEN Dr. SREEKANTH THOTA

Structure of the Posterior Abdominal Wall The posterior abdominal wall is formed in the midline by the five lumbar vertebrae and their intervertebral discs and laterally by the 12th ribs, the upper part of the bony pelvis.

Posterior abdominal wall Muscles of the posterior abdominal wall Arteries of the posterior abdominal wall Veins of the posterior abdominal wall Nerves of the posterior abdominal wall

Muscles of the posterior abdominal wall 1. Psoas major and minor 2. Quadratus lumborum 3. Iliacus

Psoas major Origin : Lateral surface of bodies of TXII and LI to LV vertebrae Insertion: Lesser trochanter of the femur N. supply: Lumbar plexus Action : Flexes thigh on trunk

Iliacus Origin : Iliac fossa Insertion: With psoas into lesser trochanter of femur N. supply: Femoral nerve Action : Flexes thigh on trunk

Psoas minor Origin : Lateral surface of bodies of TXII and LI vertebrae Insertion: Pectineal line of the pelvic brim N. supply: Lumbar plexus Action : Weak flexion of lumbar vertebral column

Quadratus lumborum Origin : Transverse process of LV vertebra, iliolumbar ligament, and iliac crest Insertion: 12th rib N. supply: Lumbar plexus Action :Depress and stabilize rib XII and some lateral bending of trunk

Arteries of the posterior abdominal wall Abdominal Aorta The abdominal aorta is approximately 13 cm in length. It begins at the aortic hiatus in the diaphragm at the level of the T12 vertebra and ends at the level of the L4 vertebra by dividing into the right and left common iliac arteries. On its right side lie the inferior vena cava, the cisterna chyli, and the beginning of the azygos vein. On its left side lies the left sympathetic trunk.

Branches The branches of the abdominal aorta may be described as arising and coursing in three vascular planes. 1. Anterior midline: Unpaired visceral 2. Lateral: Paired visceral 3. Posterolateral: Paired parietal

Anterior midline: Unpaired visceral 1. Celiac: L1 2. Superior mesenteric:L1 3. Inferior mesenteric: L3

Lateral: Paired visceral 1.Suprarenal :L1 2. Renal: L1 3.Gonadal (testicular or ovarian) :L2

Posterolateral: Paired parietal 1. Subcostal 2.Inferior phrenic 3. Lumbar :L1 to L4

Three terminal branches The two common iliac arteries and the median sacral artery.

Veins of the posterior abdominal wall The IVC begins anterior to the L5 vertebra by the union of the common iliac veins. Pierces the diaphragm at T8. Drains into the Rt atrium

Inferior vena cava and its tributaries The veins of the posterior abdominal wall are tributaries of the IVC, except for the left testicular or ovarian vein, which enters the left renal vein instead of entering the IVC.

Nerves of the posterior abdominal wall Lumbar plexus: Formed in the psoas muscle from the anterior rami of the upper four lumbar nerves. The branches of the plexus emerge from the lateral and medial borders of the muscle and from its anterior surface.

Lumbar plexus

Branches 1-Iliohypogastric & ilioinguinal (L1)---emerge from the lateral border of psoas major 2-Genitofemoral (L1,L2) ------on the anterior surface of the psoas major 3-Lateral cut. N.of the thigh( L2,L3)---lateral border of psoas major in front of iliacus m 4-Obturator(L2,L3 and L4) ------medial border of Ps. Mj 5-Femoral(L2,L3 and L4)-------- lateral border of Ps. Mj

Lymphatics on the posterior abdominal wall: The common iliac lymph nodes receive lymph from the external and internal iliac lymph nodes. Common iliac lymph nodes passes to the right and left lumbar lymph nodes. Preaortic lymph nodes ---celiac and superior and inferior mesenteric nodes Right and left lumbar (caval and aortic) lymph nodes-------- kidneys, ureters, testes or ovaries, uterus, and uterine tubes. Chyle cistern------ Thoracic duct--- Left venous angle

Lymphatic system