The Abdomen and Pelvis (Revision) Flashcards
Surface Anatomy of the Abdomen
Xiphoid process: Base of the sternum.
Costal margin: Bottom edge of the rib cage.
Umbilicus: Central point located at L3/L4 vertebral level.
Iliac crest: Superior part of the ilium, prominent in the pelvis.
Abdominal and Pelvic Cavities
The diaphragm separates the thoracic cavity from the abdominal cavity. It has three main openings:
Caval hiatus (T8): Allows passage of the inferior vena cava
Esophageal hiatus (T10): Allows passage of the esophagus and vagus nerves.
Aortic hiatus (T12): Allows passage of the abdominal aorta
Muscles of the Anterolateral Abdominal Wall
External Oblique: Trunk rotation and lateral flexion
Internal Oblique: Works with the external oblique for trunk rotation.
Transversus Abdominis: Compresses abdominal contents; important for core stability.
Rectus Abdominis: Flexes the vertebral column and stabilizes the pelvis
Muscles of the Posterior Abdominal Wall
Psoas Major: Flexes the hip and stabilizes the lumbar spine.
Iliacus: Works with the psoas major to flex the thigh.
Quadratus Lumborum: Provides lateral stability to the lumbar spine.
Vascular Anatomy
Abdominal Aorta: Extends from T12 to L4, giving off key branches:
- Celiac trunk: Supplies the liver, stomach, and spleen.
- Superior mesenteric artery (SMA): Supplies the small intestine and part of the large intestine.
- Inferior mesenteric artery (IMA): Supplies the distal colon.
Venous Drainage: Inferior vena cava (IVC) collects blood from the lower body and abdominal organs; it runs from L5 to T8.
- Hepatic veins drain the liver into the IVC.
- Gonadal veins (testicular/ovarian) drain directly into the IVC (right side) or left renal vein (left side).
Peritoneum
A serous membrane that forms the lining of the abdominal cavity
- Parietal peritoneum: Lines the abdominal wall.
- Visceral peritoneum: Covers the abdominal organs.
Peritoneal cavity: A potential space between the two layers, reducing friction during organ movement.
- Intraperitoneal: SPLAT DJ
- Retroperitoneal: SAD PUCKER
Anatomy of Abdominal Organs
Stomach
- Cardia, fundus, body, pylorus
Small Intestine
- Duodenum, jejunum, and ileum
- Jejunum is primarily responsible for nutrient absorption
Large Intestine
- Cecum, colon (ascending, transverse, descending, sigmoid), and rectum
- Water absorption and waste formation
Liver
- Metabolism
- Detoxification
- Bile production
Gallbladder
- Stores and concentrates bile
Pancreas
- Endocrine (insulin production)
- Exocrine (digestive enzymes)
Spleen
- Filters blood
- Immune response
Kidneys and Ureters
- Urine production and transport
Mesentery
Definition
- A fold of peritoneum
- Attaches the intestines to the posterior abdominal wall
Function
- Supports intestines
- Supplies the intestines (blood vessels, nerves, lymphatics)
Composition
- Connective tissue
- Blood vessels
- Nerves
Types
- Mesentery Proper: Attaches the small intestine (jejunum and ileum) to the posterior abdominal wall
- Mesocolon: Attaches parts of the large intestine (e.g., transverse mesocolon, sigmoid mesocolon) to the abdominal wall.
Omentum
Definition
- A fold of peritoneum
- Attaches the stomach to other abdominal organs
Function
- Protects abdominal organs
- Fat storage
- Immune cells and lymph nodes for immune resopnse
Composition
- Fat deposits
- Blood vessels
- Lymphatic tissue
Types
- Greater Omentum: Extends from greater curvature of stomach, covering large intestine
- Lesser Omentum: Extends from lesser curvature of stomach to the liver
Functions of the Digestive System
Ingestion: Taking food into the mouth
Digestion: Breakdown of food into smaller molecules (mechanically and chemically)
Absorption: Nutrients are absorbed into the bloodstream, primarily in the small intestine
Compaction: Indigestible materials consolidated into feces
Defecation: Elimination of waste products
Stomach
Location
- Between the esophagus and the small intestine
Structure
- Cardia (near the esophagus)
- Fundus (upper curved part)
- Body (main part)
- Pylorus (narrowed region leading to the small intestine)
Function
- Mechanical and chemical digestion of food
- Secretes gastric juice (has HCl and pepsin)
Features
- Rugae: Folds in the stomach lining that allow for expansion as food enters.
- Pyloric Sphincter: Controls the passage of chyme from the stomach into the duodenum
Small Intestine
Structure
- Duodenum
- Jejunum
- Ileum
- Highly folded surface with villi and microvilli
Function
- Digestion and absorption of nutrients
- Via enzymes from the pancreas
- Via bile from the liver
Brunner’s Glands (Duodenum)
- In submucosa of the duodenum.
- Secrete alkaline fluid to neutralize gastric acid in chyme
- Creates an optimal pH
- Produce mucous to protect the intestinal lining
Liver
Location
- Anterior to the stomach
Function
- Bile Production: Fat emulsification
- Metabolism: Processes carbohydrates, fats, and proteins, and stores glycogen, vitamins, and minerals
- Detoxification: Filters and detoxifies blood
Special Features
- Hepatic Portal System: Blood from the digestive organs is transported to the liver via the hepatic portal vein for processing
Gallbladder
Location
- Beneath the liver
Function
- Stores and concentrates bile
Special Features
- Bile release stimulated by cholecystokinin (CCK)
- In response to fatty foods.
Pancreas
Location
- Posterior to the stomach
Function
- Produces digestive enzymes (e.g., amylase, lipase, proteases)
- Produces bicarbonate to neutralize stomach acid
- Secretes hormones like insulin and glucagon
Special Features
- Pancreatic Duct: Carries digestive enzymes to the duodenum
