Introduction to Anatomy of the Abdomen The region between: Diaphragm and pelvis. Boundaries: • Roof: Diaphragm • Posterior: Lumbar vertebrae, muscles of the posterior abdominal wall • Infrerior: Continuous with the pelvic cavity, superior pelvic aperture • Anterior and lateral: Muscles of the anterior abdominal wall Topography of the Abdomen (PLANES)..1/2 TRANSVERSE PLANES • Transpyloric plane : tip of 9th costal cartilages; pylorus of stomach, L1 vertebra level. • Subcostal plane: tip of 10th costal cartilages, L2-L3 vertebra. • Transtubercular plane: L5 tubercles if iliac crests; L5 vertebra level. • Interspinous plane: anterior superior iliac spines; promontory of sacrum Topography of the Abdomen (PLANES)..2/2 VERTICAL PLANES • Mid-clavicular plane: midpoint of clavicle- mid-point of inguinal ligament. • Semilunar line: lateral border of rectus abdominis muscle. Regions of the Abdomen..1/2 4 2 5 9 regions: • Umbilical (1) 8 1 9 • Epigastric (2) • Hypogastric (Suprapubic) (3) • Right hypochondriacum (4) 6 3 7 • Left hypochondrium (5) • Right Iliac (Inguinal) (6) • Left Iliac (Inguinal) (7) • Right lumbar (8) • Left lumbar (9) Regions of the Abdomen..2/2 1 2 4 Quadrants: • Upper right quadrant (1) 3 4 • Upper left quadrant (2) • Lower right quadrant (3) • Lower left quadrant (4) Dermatomes Skin innervation: • lower 5 intercostal nerves • Subcostal nerve • L1 spinal nerve (ilioinguinal+iliohypogastric nerves). Umbilical region skin = T10 Layers of Anterior Abdominal Wall Skin Fascia: • Superficial fascia: • Superficial fatty layer(CAMPER’S fascia) • Deep membranous layer (SCARPA’S fascia) • Deep fascia: a thin layer underneath the deep 1 membranous layer External oblique muscle (1) 2 3 Internal oblique muscle (2) Transversus abdominis muscle (3) Transversalis fascia The Stomach Cardia Fundus Esophagus Muscularis externa Serosa • Longitudinal layer • Circular layer Body • Oblique layer Lesser Lumen curvature Rugae of mucosa Greater curvature Pyloric Pyloric Duodenum canal antrum Pyloric sphincter Falciform ligament Gallbladder Stomach Ligamentum teres Greater omentum Small intestine Cecum An intraperitoneal digestive organ located between the oesophagus and the duodenum. It has a ‘J’ shape, and features a lesser and greater curvature. The anterior and posterior surfaces are smoothly rounded with a peritoneal covering. It lies mainly in the epigastric and umbilical regions, but its exact size, shape and position can vary from person to person and with position and respiration. General Features..1/4 Cardiac end: • Lies at the level of 7th costal cartilage 2 cm to the left of the midline • Has no anatomical sphincter General Features..2/4 Pyloric end: • Lies in the transpyloric plane 1.5 cm to the right o the midline. • The circular muscle layer in its wall become thickened to form the pyloric sphincter • The pyloric sphincter can be identified by the presence of the prepyloric vein (of Mayo). General Features..3/4 Greater curvature • Forms the long, convex, lateral border of the stomach. • Arising at the cardiac notch, it arches backwards and passes inferiorly to the left. • It curves to the right as it continues medially to reach the pyloric antrum. • The short gastric arteries and the right and left gastro- omental arteries supply branches to the greater curvature. General Features..4/4 Lesser curvature • Forms the shorter, concave, medial surface of the stomach. • The most inferior part of the lesser curvature, the angular notch (incisura angularis), indicates the junction of the body and pyloric region. Relations of the stomach..1/2 Anterior surface • This surface is related to the: • Diaphragm • Left lobe of the liver • Anterior abdominal wall Relations of the stomach..2/2 Posterior surface • This surface is separated from the following structures by the cavity of the lesser sac: • Left suprarenal gland • Spleen • Left kidney • Splenic artery • Body of the pancreas • Transverse mesocolon • Transverse colon • diaphragm Arterial supply of the 3 stomach 1 1- Left gastric artery from the coeliac axis) 2 5 2- Right gastric artery (from the hepatic artery) 3- Short gastric arteries (5-6) also known as vasa brevia (from the splenic artery) 4- Right gastroepiploic artery (from the 4 hepatic artery) 5- Left gastroepiploic artery (from the splenic artery) Venous drainage of the stomach 1- Right gastric vein 2 3 3 2- Left gastric vein 4 1 3- Short gastric veins 4- Right gastroepiploic vein 5 5- Left gastroepiploic vein Lymph drainage of the stomach 1- Left gastric lymph nodes 2- Pancreatico-splenic lymph nodes 3- Right gastro-epiploic lymph nodes 4- Pyloric lymph nodes Nerve supply of the stomach Coeliac plexus, Formed of: • Sympathetic from the greater splanchnic nerve • Parasympathetic: Vagi nerves (CN X) The Duodenum Lies in the epigastric and umbilical regions on the posterior abdominal wall It is ~ 25 com long from the pylorus to the duodeno-jejunal junction. It is C shaped the concavity is directed to the left. Its concavity is occupied by the head of the pancreas. It is divided into 4 parts. First Part of the Duodenum ..1/3 It is 5 cm in length and begins 1.5 cm to the right of the median plane in the transpyloric line, The first 2.5 cm is intraperitoneal and gives attachment o the lesser and greater omenta. Passes to the right and upwards and backwards. It ends at the level of the neck of the gallbladder. It bends sharply downwards to continue as the second part. First Part of the Duodenum ..2/3 Relations of the first half of the first part of the of the duodenum: • Anteriorly: • The quadrate lobe of the liver • Posteriorly: • Separated from the neck of the pancreas by the cavity of the lesser peritoneal sac First Part of the Duodenum ..3/3 Relations of the 2nd half of the first part of the of the duodenum: • Anteriorly: • The body of the gallbladder • Posteriorly: • Gastroduodenal artery • Bile duct • Portal vein • Inferior Vena cava • Inferiorly: • The head of the pancreas • Superiorly: • Epiploic foramen of Winslow Second Part of the Duodenum ..1/3 It is 7.5 cm long. Begins at the level of L1 and descends vertically to the level of L3 The opening of the major pancreatic duct and the common bile duct open in its middle on the ampulla of Vater. The ampulla of Vater is surrounded by smooth muscle fibres known as sphincter of Oddi. The minor pancreatic duct opens 2-3 cm above the ampulla of Vater. Second Part of the Duodenum ..2/3 The 2nd part of the duodenum is related to the following: Anteriorly: • The transverse colon • Right lobe of the liver and body of the gallbladder • Coils of the small intestine Second Part of the Duodenum ..3/3 Posteriorly: • Hilum of the right kidney • Right psoas major muscle Medially: • Head of the pancreas • Pancreatico-duodenal arteries Laterally: • Right colic flexure (hepatic) Third part of the duodenum ..1/3 It is the longest part of the duodenum (10 cm) 3rd part of Runs horizontally across the duodenum posterior abdominal wall towards the left at the level of the 3rd lumbar vertebra It crosses the inferior vena cava and aorta then curves upwards Third part of the duodenum ..2/3 Anteriorly: • Root of mesentery • Superior mesenteric vessels • Coils of small intestine • Transverse colon Third part of the duodenum ..3/3 Posteriorly: • Right psoas major • Inferior vena cava • Aorta • Right ureter • Right gonadal artery • Inferior mesenteric artery Superiorly: • Head of the pancreas Fourth Part of the Duodenum ..1/2 It is the shortest part of the duodenum (2.5 cm) It curves upwards on the left side of the aorta It ends at the level of the 2nd lumbar vertebra 2.5 cm to the left of the midline. Fourth Part of the Duodenum ..2/2 Anteriorly: • Coils of the small intestine • Transverse colon and mesocolon Posteriorly: • Left psoas major • Left sympathetic chain • Left gonadal vessels • Inferior mesenteric vein Medially: • Head of the pancreas • Aorta Laterally: • Left kidney Arterial Supply of the Duodenum 1- Supraduodenal artery (branch from the hepatic artery) 2- Superior pancreatico-duodenal artery 3- Inferior pancreatico-duodenal artery (branch from the superior mesenteric artery) 4- The first part of the duodenum receive additional blood supply from the right gastric and right gastroepiploic arteries. The Small Intestine Composed of 3 parts; duodenum, jejunum and ileum The duodenum is the fixed part of the small intestine The jejunum and ileum are mobile because they have a mesentery that suspends them from the posterior abdominal wall The small intestine is coiled and occupies the central and lower parts of the abdominal cavity No clear demarcation between the jejunum and ileum; the next table shows points for differentiation Jejunum Ileum The proximal 2/5 of the small intestine The distal 3/5 of the small intestine Vascularity Greater vascularity; appears dark red Less vascularity; appears pale with with simple arterial arcades and long complex arcaded and short vasa recta vasa recta Wall Thick; due to the presence of numerous Thin; few plica circularis plica circularis Lumen Empty Contains some liquid food Lymph nodules Solitary Aggregated; Peyer’s patches Fat in the mesentery Few More Jejunum Ileum Blood Supply of the Small Intestine The arterial blood supply for the small intestine comes from the celiac trunk and the superior mesenteric artery (SMA). The superior pancreaticoduodenal artery is a branch from the gastroduodenal artery (from the proper hepatic artery). It anastomoses with the inferior pancreaticoduodenal artery, which comes from the SMA, to supply blood to the duodenum. The jejunum and ileum receive their blood supply from a rich network of arteries that travel through the mesentery and originate from the SMA. The multitude of arterial branches that split from the SMA is known as the arterial arcades, and they give rise to the vasa recta that deliver the blood to the jejunum and ileum. The venous blood mimics that of the arterial supply, which unite to form the superior mesenteric vein (SMV), which then joins with the splenic vein to form the portal vein.