Lower Digestive System Anatomy Quiz

Lower Digestive System (Abdomen)

• The lower digestive system includes the esophagus (a very short part in the abdomen), stomach, intestines, liver, and pancreas.
• The abdomen is divided into 3 regions: cranial (epigastric), middle (mesogastric), and caudal (hypogastric).
• Each region is further divided into smaller regions (e.g., hypochondriac, xiphoid, flank, umbilical, inguinal, pubic).
• The stomach is a musculo-glandular sac-like structure between the esophagus and duodenum. Its shape and size vary based on the type of food.

Stomach Classification

• Monolocular Stomach: A single-compartment stomach. Subdivided into simple (lined with glands) and compound (lined with glands and non-glandular mucus membrane).
• Multilocular Stomach: More than one compartment; only the last part is glandular. The glandular part is further divided into cardiac, fundic, and pyloric regions based on gland types and includes a nonglandular esophageal or proventricular part.

Stomach Anatomical Features

• Orifices: Cardiac (esophagus entrance) and pyloric (exit to the duodenum).
• Borders: Lesser curvature (concave, dorsal border) and greater curvature (larger, ventral border).
• Surfaces: Visceral (faces the intestine and greater omentum) and parietal (faces the diaphragm).

Stomach Fixation

• Greater omentum: Attaches to the stomach's greater curvature to the dorsal abdominal wall.
• Lesser omentum: Attaches the lesser curvature to the liver.
• Gastrophrenic ligament: Attaches parietal surface to the diaphragm.
• Gastrosplenic: Attaches the greater curvature to the spleen.

Comparative Stomach Features (Examples: Dog, Pig, Horse)

• Dog: Monolocular simple stomach, located in the left hypochondriac region; empty stomach resembles the letter "U"; moderate full stomach is "C" shaped; has a deep angular notch on the lesser curvature, and related to the diaphragm, liver, intestine, pancreas, and left kidney; pyloric sphincter.
• Pig: Monolocular compound stomach in the left part of the abdominal cavity; the stomach shape changes according to the fill and contains a blind conical diverticulum, called ventricular or gastric diverticulum; the pyloric sphincter is well developed; the mucosa has a non-glandular region folded around the cardia.
• Horse: Monolocular compound stomach in the dorsal part of the intrathoracic cavity; its shape never reaches the abdominal floor; the fundus bulges dorsally forming a blind sac; contains a deep angular border; the non-glandular mucosa lines the saccus caecus and separated from the glandular membrane by the Margo plicatus.

Peritoneum

• A serous membrane lining the abdominal cavity. Composed of parietal (lining the wall) and visceral (covering the abdominal viscera) layers.
• Connects parietal and visceral layers and forms folds like mesenteries, omenta, and ligaments.
• The greater and lesser omentum are connective tissue associated with the greater and lesser curvatures of the stomach.
• There's a greater peritoneal cavity (between partial and visceral layers) and a lesser peritoneal cavity (Omental bursa).

Test your knowledge of the lower digestive system anatomy, including the regions of the abdomen and classification of the stomach. This quiz covers both structural and functional aspects, ensuring a comprehensive understanding of digestive physiology.