Touro College Anatomy Lab - Abdomen PDF

Touro College Anatomy LAB Lesson ABDOMEN ABDOMINAL CAVITY Houses two hollow tubular structures: gastro-intestinal and uro-genital, the latter found predominantly in the pelvis. It extends from the diaphragm to the floor of the pelvis and is divided into the abdomen proper and the pelvis by the follo...

Touro College Anatomy LAB Lesson ABDOMEN ABDOMINAL CAVITY Houses two hollow tubular structures: gastro-intestinal and uro-genital, the latter found predominantly in the pelvis. It extends from the diaphragm to the floor of the pelvis and is divided into the abdomen proper and the pelvis by the following landmarks Superior boundary abdomen: diaphragm Inferior boundary abdomen: plane connecting two superior edges ileum Pelvis goes from edges of ileum to floor of pelvis (pelvic diaphragm) – next lesson 4 Quadrants: R upper, L upper, R lower, L lower Layers of abdominal wall (external to internal): Skin, Fascia, Muscle, Serous membrane § Campa’s fascia (superficial fascia): contiguous with superficial fascia of thigh § Scarpa’s fascia (deep membranous fascia): over lower portion anterior abdominal wall and fuses with the fascia lata at the inguinal ligament Flat Muscles External and Internal abdominal obliques Transverse Abdominis These muscles converge anteriorly in the connective tissue (CT) aponeurosis on and around the rectus abdominis forming the rectus sheeth. The muscles on each side of the abdomen converge in midline to form Linea Alba…… important surgical structure as incisions made here avoid injuring blood vessels and nerves. 1 Deepest layer of abdominal wall = deep fascia of Transversus Abdominis = Transversalis Fascia which lines the inside of the abdominal wall § In both sexes, holes exist in the lower quadrant of the anterior abdominal where either the spermatic cord or the round ligament of the uterus pass. They are known as the inguinal canals because they pass through ALL layers of the abdominal wall forming short canals § The inguinal canal passes through the lower abdominal wall from the deep ring in the transversalis fascia to the superficial ring in the aponeurosis of the external oblique o In the male each layer of the anterior abdominal wall contributes a concentric layer of spermatic cord surrounding the ductus deferens and testicular vessels as these structures traverse the inguinal canal Posterior Abdominal wall: made of supporting musculature that maintain posture, flex the hips and keep them stable while walking Psoas (from inside lumbar vertebrae to the femur) Quadratus lumborum (extends from hips to lower ribs) posterior portions of transverse abdominis NERVOUS INNERVATION Ventral Rami T6-T12 and L1 spinal nerves supply sensory and motor fibers to the abdominal wall & skin Autonomics: Lower thoracic and upper lumbar sympathetic splanchnic nerves and vagal and pelvic splanchnic parasympathetic nerves BLOOD SUPPLY OF ABDOMINAL WALL MIMICS THAT OF THE THORACIC WALL Arterial Blood Supply ANTERIOR Abdominal wall: Terminal end Internal thoracic, the superior epigastric Ascending inferior epigastric off external iliac in pelvis Similar to the thoracic wall POSTERIOR Abdominal wall: Lumbar arteries off descending aorta Venous Supply Also similar to the thoracic wall- Posterior veins off azygos system and epigastric veins 2 ABDOMINAL CONTENTS GI organs: esophagus, stomach, small intestine, large intestine, rectum, anal canal and associated organs…….the Liver, Gall bladder, Pancreas NOT GI Organs: Spleen, Kidney, Ureters and Urinary Bladder Other structures that communicate with the contents of the abdomen and pass through the diaphragm: aorta, vagus nerves, sympathetic trunks, inferior vena cava and azygos vein (the esophagus is also a communicating organ) Alimentary canal is a long tube – about 25ft in length Esophagus extends from pharynx to stomach (thru cardiac orifice diaphragm)~ (9-9.5inches) Stomach located in LUQ and empties into duodenum through the pyloric sphincter Composed of: Cardiac, fundus, body, pyloric antrum and pylorus Lined with longitudinal folds called rugae PYLORIC STENOSIS 1. AKA Infantile Hypertrophic Pyloric Stenosis (IHPS) 2. Most common cause of intestinal obstruction in infancy (“projectile vomiting”) 3. IHPS occurs secondary to hypertrophy and hyperplasia of the muscular layers of the pylorus, causing a functional gastric outlet obstruction. 4. 2-4/1000 live births 5. Male: female = 4:1 3 Duodenum is 1st and shortest part small intestine …..~ 9.5 in (12cm or 12 finger breaths) in length ….. receives digestive enzymes from Pancreas and Bile from the Gall Bladder Composed of 4 sections After the 1st section, the duodenum becomes retroperitoneal First part of duodenum is most common site of duodenal ulcers The Ligament of Treitz is at the duodenojejuno junction Jejunum (2/5ths) and ileum (3/5ths) are remaining longer sections of small intestines …. Most Absorption nutrients occurs here Ileum empties into large intestine at iliocecal junction Cecum: 1st part large intestine (colon) = “blind pouch” … appendix found here Remainder large intestine “frames out” small intestine 1. Ascending colon (R side abdomen) 2. Transverse colon (crosses across upper abdomen) … note the Hepatic flexure in RUQ and Splenic flexure in LUQ 3. Descending colon (L side abdomen) continues to become the sigmoid colon which continues with the rectum and anal canal in the pelvis View of large intestine (colon)( Left) and stomach and duodenum (Right) after ingestion/administration of contrast material (UGI vs. Barium enema) LIVER : located in RUQ just inferior to the diaphragm Venous hepatic portal system brings venous blood from the entire digestive system to the liver …. This venous blood caries vital nutrients and occasionally TOXINS Surrounded by Gleason’s capsule Porta Hepatis of liver : “the doorway to the liver” The inferior portion (doorway) of the liver contains three important structures: the hepatic artery, the portal vein and the hepatic bile ducts 4 Also found on the Inferior surface of liver is the Gallbladder, ligamentum teres (round ligament), Falciform ligament and IVC Ligamentum teres (round ligament of liver) extends from umbilicus to the liver ….. it is the remnant of the fetal umbilical vein Ligamentum venosum : connects the L branch of the portal vein and the IVC remnant of ductus venosus (separates the L lobe of the liver from the caudate lobe) Gallbladder: concentrates and stores bile produced in the liver … bile is used to digest fats …. Contraction of the gallbladder after a fatty meal forces bile into the cystic duct which is continuous with the common bile duct which then empties into the second portion of the duodenum 5 Pancreas : endocrine (insulin) and exocrine (Digestive enzymes that empty into duodenum via the common bile duct ) Spleen: largest lymph gland in body 1. Breaks down platelets and old RBCs 2. Its venous return empties into liver like the GI organs 3. Located in L superior abdomen (LUQ) just under L lower ribs Kidneys: “retroperitoneal” … located posteriorly (Gerota’s fascia around kidney) 1. “filter” blood 2. Large renal arteries enter from the Aorta 3. Large renal veins empty into IVC PERITONEUM: Closed serous membrane sac that lines walls of abdominal cavity ~ pleura of lungs Structures within its boundaries are called “intraperitoneal” Pathologic Conditions: Peritoneal cavity can become distended with fluid (ascites), blood (hemoperitoneum), bile and fecal material “Retroperitoneal” organs include most of GU system and Pancreas Specialized Portions of Peritoneum suspend and anchor the GI organs A double-layered mesentery carrying vessels and nerves suspends intestines from posterior abdominal wall A quadrupled-layered greater omentum drapes over the abdominal contents anteriorly. It contains fat and blood vessels and can act as a “drape” to wall off infection Parietal Peritoneum Greater Omentum 6 ARTERIAL BLOOD SUPPLY AND VENOUS RETURN OF ABDOMINAL VISCERA 1. Three unpaired and 1 paired set arteries ALL arising from Abdominal Aorta: Celiac Trunk, Superior mesenteric, Inferior mesenteric and Renals (paired) 2. Celiac trunk most superior lies just beneath diaphragm … branches into large splenic, a common hepatic and a small L gastric artery ….. serves the stomach, pancreas, spleen, liver, gallbladder and parts of the duodenum 3. Superior mesenteric … inferior to the celiac trunk …. Arises from descending aorta and serves the duodenum, jejunum, ileum, cecum, ascending colon and proximal 2/3 of transverse colon 4. Inferior Mesenteric ….. from inferior end of descending aorta …. Supplies the remaining part of the transverse colon, descending colon, sigmoid colon and rectum. 5. Paired renal arteries arise from about same level as the Superior mesenteric artery and are posterior to the renal veins v Paired gonadal arteries and paired lumbar arteries also come off the aorta between the Superior and Inferior mesenteric arteries VENOUS DRAINAGE 1. Most GI organs empty into hepatic portal vein to the sinusoids of the liver. 2. Venous sinusoids join to form the hepatic vein which empties into the Inferior Vena Cava 3. Obstruction in Portal System (cirrhosis of the liver) results in hepatic hypertension Venous blood in portal system flows in reverse direction ….. blood gets into caval system (there are NO VALVES in the venous gut system like there are in the extremities) Can lead to esophageal varices, ascites, caput medusa sign, and hemorrhoids Portal vein and its tributaries: 7