Abdomen1

Abdomen: Viscera (Gut)

Stomach



• J-shaped enlargement of the gastrointestinal tract
• Chief function: enzymatic digestion
o Acidic gastric secretions convert food into liquid chime
o Passes fairly quickly into the duodenum
• Parts of the stomach
o Greater curvature: long, convex border
o Lesser curvature: short, concave border
o Cardia: surrounds cardial (esophageal) orifice
oFundus: dilated upper part
 Above the level of the esophageal orifice
 Dilated by fluid, food, but mainly gas
 Separated from esophagus by cardiac notch
o Body: between fundus and pyloric antrum
o Pyloric part
 Begins at level of angular incisure: indentation two thirds of the way along the lesser curvature
 Widest region: pyloric antrum
 Antrum leads to pyloric canal
 Pylorus:surrounds pyloric orifice
 Pyloric sphincter
a. Thick, circular middle layer of muscularis externa
b. Controls passage of chime into duodenum
c. Normally closed in tonic contraction, except during peristalsis
• Three muscle layers: outer longitudinal, inner circular, and innermost oblique
• Internal surface thrown into numerous longitudinal folds-rugae
o Gastric canal = longitudinal foldalong lesser curvature
o Forms during swallowing
o Accommodates the passage of liquid
• Covered by peritoneum except where blood vessels run over it, and over a small area posterior to the cardiac orifice
o Double layer of peritoneum extends between stomach and liver and duodenum and liver: lesser omentum
o Two layers of lesser omentum wrap around stomach and leave greater curvature as greatomentum
• Vascular supply (Section 4-6: Abdomen-Visceral Vasculature)
o Arteries
 Left gastric from celiac trunk
 Right gastric from common hepatic artery
 Right gastroepiploic (gastro-omental) from proper hepatic or gastroduodenal arteries
 Left gastroepiploic from splenic artery
 Short gastric arteries (four to five) from distal splenic artery
o Veins
 Follow the arteries
 Rightand left gastrics drain to portal vein
 Short gastrics and left gastroepiploic drain into splenic vein → superior mesenteric vein (SMV) → portal vein
 Right gastroepiploic drains to SMV
o Lymphatics
 Follow the arteries
 Drain into gastric, gastroepiploic, pancreaticosplenic, and pyloric nodes
• Innervation (Section 4-7: Abdomen-Innervation)
o Parasympathetic supply
 From anterior andposterior vagal trunks
 Increase peristalsis and relax pyloric sphincter
o Sympathetic supply
 From T6-T9 spinal cord segments via great splanchnic nerve to celiac plexus
 Inhibit peristalsis and contract pyloric sphincter

Duodenum



• First and shortest part of small intestine
• Follows a C-shaped course around the head of the pancreas
• Consists of four parts (parts 2 through 4are retroperitoneal)
o Superior (first) part: anterolateral to body of L1
 Ascends from pylorus
 Is connected to liver by hepatoduodenal ligament (part of lesser omentum)
 Portal vein, bile duct, and IVC located posteriorly
o Descending (second) part
 Descends along the right of L1-L3
 Contains major duodenal papilla on posteromedial wall = opening of hepatopancreatic ampulla
oHorizontal (third) part
 Crosses inferior vena cava (IVC), aorta, and L3 vertebra
 Is crossed by superior mesenteric artery (SMA) and SMV and root of mesentery
o Ascending (fourth) part
 Ascends to L2 on the left side
 Curves anteriorly at the duodenojejunal flexure
 Flexure is supported by the ligament of Treitz
• Vascular supply (Section 4-6: Abdomen-Visceral Vasculature)
o Arteries
Gastroduodenal artery, branch of common hepatic → superior anterior and posterior pancreaticoduodenal arteries
 SMA → anterior and posterior inferior pancreaticoduodenal arteries
 Important anastomoses between celiac trunk and SMA via duodenal arteries
o Veins
 Follow the arteries
 Drain directly or indirectly into the portal vein
o Lymphatics
 Follow the arteries
 Drain into...