GI module Lecture: 9 د. عصام طارق Objectives: To list structures forming posterior abdominal wall. To follow aorta & its main branches. To describe IVC & its main tributaries. To list nerves of posterior abdominal wall.
Thoracolumbar fascia (TLF): It Encloses Very Medially, extends binds strong erector Q. it from splits & lumborum laterally spinae the into sacrum three to it in posterolateral gives lumbar to layers: the origin neck. region. to surface I.O. & of T.A. vertebrae. Mm. Psoas major Q. lumborum TLF Ant. layer Middle layer Post. layer Erector spinae
Posterior abdominal wall formed by In midline: Lumbar vertebrae & their intervertebral discs. Laterally: 4 2 1 12 th ribs & upper part of ilium. psoas, quadratus & iliacus Mm. 3 Aponeurosis of origin of transversus abdominis.
Psoas major Long muscle arises from Ant. surfaces of transverse processes Sides of vertebral bodies Intervertebral discs from T12-L5 It runs Ant. fascial covering of psoas thickened superiorly to form med. arcuate lig. It is a flexor of hip & lat. rotator of thigh.
Psoas minor Long small m. present in 60% Arises with upper most fibers of psoas major. It runs Inserted into fascial covering iliopsoas muscle Innervated by 1 st lumbar ventral ramus.
Iliacus It arises from floor of iliac fossa. Joins the tendon of psoas major. Leaves abdomen behind inguinal ligament. Inserted into lesser trochanter. Strong flexor of hip.
Quadratus lumborum flat, quadrilateral m., lies beside vertebral column It arises from: Iliolumbar It It is ascends a lateral ligament flexor of trunk Adjacent To be inserted part of into iliac crest Ant. Lower surface 2-4 lumbar of med. transverse half of 12 th rib. Upper processes lumbar transverse processes
Vessels of PAW Abdominal aorta It descends on vertebral col. from T12-L4. It lies on ant. longitudinal lig. & on Lt. lumbar veins Sup. it lies between crura of diaphragm Inf. between sympathetic trunks. Ant. it is crossed from above downward by : Pancreas Left Horizontal Root Peritoneum renal of the & vein part mesentery. splenic of duodenum. vein
Unpaired ventral branches: 1- Celiac trunk 2- Sup. Mesenteric a. Paired posterolateral branches: lumbar Aa. 1- Inferior phrenic 2- Renal arteries 3- Middle suprarenal a. 4- Rt. gonadal Vv. 3- Inf. Mesenteric a. 4- Median sacral a.
Inf. vena cava The widest vein in the body Begins by union of 2 CIV on front of L5 post. to Rt. common iliac a. It ascends to Rt. of median plane between ureter & aorta ant. To: Ascends Vertebral Rt. lumbar renal psoas sympathetic behind & column arteries. middle trunk liver suprarenal in the deep Aa. groove between Rt. & caudate lobes of liver
Inf. vena cava Inferior vena cava crossed anteriorly by: Portal SMV Head Tributaries: 3Liver Ileocolic rd part v. of in in root pancreas of lesser & duodenum of Rt. mesentery omentum colic & CBD Aa. & gonadal Vv. Common 3Renal Azygos Rt. Inf. Hepatic rd & Gonadal Suprarenal Phrenic 4 th veins lumbar iliac veins veins
Lymph Vv.& nodes of PAW These are scattered along Vv. on PAW& are represented by: 1-3- 2- External Lumbar Common nodes iliac nodes: scattered lie med. along & lat. corresponding aorta groups. & IVC. vessels. Efferent Vv. from lumbar nodes form Rt. & Lt. lumbar lymph trunk that drain to cisterna chyli.
Cisterna chyli: Long, white lymph sac measuring about 5cm. Lies on L1 &2 between aorta & azygos vein, hidden by Rt. crus of diaphragm. It ascends into the thorax, through the aortic hiatus It receives: Rt. & Lt lymph trunks. Intestinal lymph trunk. Lymph Vv. from lower intercostal L.N.
Nerves of PAW: I- Sympathetic trunk: Enters abdomen post. to medial arcuate lig. Descends in groove between psoas & vertebral bodies Ant. to the lumbar vessels. Enters pelvis post. to common iliac vessels.
Nerves of PAW: II- Subcostal nerves: It is ventral ramus of T12. Enters abdomen post. to lat. arcuate lig. Passes inferolaterally on ant. surface of Quadratus. At lat. border of Quadratus it pierces transversus m. to run in abd. wall between that muscle & I.O.
Nerves of PAW: III- Lumbar plexus: Formed in psoas from ant. rami of upper four lumbar nerves. Branches emerge from lateral borders of psoas. Branches emerge from medial borders of psoas. Branch emerges from ant. surface of psoas.
Summary: TLF binds erector spinae Mm. to posterolateral sides of vertebrae. TLF encloses Q. lumborum in the lumbar region. PAW formed by lumbar vertebrae, 12 th ribs, upper part of ilium & Mm. of PAW. Abdominal aorta & IVC represent the main Vv. Of PAW Sympathetic trunk, subcostal n. & lumbar plexus represent the main nerves of PAW