Anatomy of the Abdominal Region

Introduction

• Misconception: Common mistake is to call the abdomen the stomach.
• Purpose: Discuss the anatomy of the abdominal region using cadavers.
• Goal: Understand what you're feeling when you experience abdominal pain.

Musculoskeletal Borders of the Abdomen

Key Structures

• Rib Cage: Includes ribs 1-10 with cartilage attachment to the sternum; ribs 11 and 12 lack such cartilage.
• Clavicles: Useful for certain anatomical demarcations.
• Vertebral Column: Particularly the lumbar region (L1-L5); transitions into the sacrum.
• Oscoxy (Hip Bone): Composed of ilium, ischium, and pubis. Iliac crest is crucial for defining borders.

Division of the Abdomen

Four Quadrant Scheme

• Method: A vertical line through the xiphoid process to pubic symphysis; horizontal line through the umbilicus.
• Quadrants: Right Upper, Left Upper, Right Lower, and Left Lower.
• Usage: Adequate for basic anatomy teaching.

Nine Region Scheme

• Lines:
  • Midclavicular lines (right and left)
  • Intertubercular line from iliac crest's tubercle
  • Subcostal or Transpyloric lines
• Regions: Epigastric, Umbilical, Hypogastric, Right and Left Hypochondriac, Right and Left Lumbar, Right and Left Inguinal.
• Clinical Relevance: More precise for diagnosing pain locations.

Muscular Wall of the Abdomen

Anterior Wall

• Rectus Abdominis: Flexes lumbar column; enveloped in the rectus sheath.
• Linea Alba: Central white line in the rectus abdominis.

Lateral Wall

• External Oblique: Fibers run towards the midline.
• Internal Oblique: Fibers run perpendicular to external oblique.
• Transversus Abdominis: Fibers in the transverse plane; compresses abdomen.

Posterior Wall

• Quadratus Lumborum: Provides lateral stability.

Internal Anatomy

Diaphragm

• Function: Separates thoracic and abdominal cavities; crucial for respiration.
• Position: Above the liver.

Peritoneum

• Parietal Peritoneum: Lines abdominal cavity walls.
• Visceral Peritoneum: Covers abdominal organs.
• Greater Omentum: Example of a peritoneal reflection.

Abdominal Organs

• Liver: Usually in the right upper quadrant; affected by metastasized colon cancer.
• Stomach, Pancreas, Spleen: Mostly in the left upper quadrant.
• Intestines: Spread across lower quadrants; small intestines are intraperitoneal.
• Kidneys, Adrenal Glands, Pancreas, Duodenum: Mostly retroperitoneal.

Clinical Implications

Diagnosing Pain

• Epigastric Pain: Indicates possible stomach issues like gastritis.
• Right Inguinal Pain: Correlates with appendicitis.

Referred Pain

• Nature: Pain felt in different areas due to poor visceral innervation.

Conclusion

• Takeaway: Detailed anatomical understanding aids in diagnosing abdominal pain.
• KenHub: Mentioned as a resource for further learning about human anatomy.