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Recap Muscles Of The Anterolateral Abdominal Wall
  • Pectoralis major
    • Sternocostal part
  • Internal intercostals
    • Sternum
  • Serratus anterior
  • Pectoralis major (abdominal part)
  • External oblique
    • External oblique aponeurosis
  • Rectus sheath, anterior layer
  • Linea alba
  • Umbilicus
  • Inguinal ligament
  • Superficial inguinal ring
  • Spermatic cord, cremaster muscle
  • Fundiform ligament of the penis
  • Costal cartilage
  • Xiphoid process
  • Rectus abdominis
  • Internal oblique
    • Internal oblique aponeurosis
  • Transversus abdominis
  • Tendinous intersections
  • Pyramidalis
Muscles Of The Anterior And Posterior Abdominal Wall
  • Rectus Abdominis (Anterior)
  • Quadratus Lumborum (Posterior)
Divisions Of The GI Tract
  • Foregut:
    • Oesophagus to middle of duodenum
  • Midgut:
    • Middle of duodenum to proximal two thirds of transverse colon
  • Hindgut:
    • Distal one third of transverse colon to anus
Abdominal Vs Peritoneal Cavity
  • Abdominal cavity:
    • Actual space; boundaries include:
    • Superior = diaphragm
    • Inferior = continuous with pelvic cavity
    • Anterolateral = abdominal muscles
    • Posterior = lumbar vertebrae
  • Peritoneal cavity:
    • Potential space lined with peritoneum
Important Terminology
  • Parietal peritoneum:
    • Lining of abdominal wall, upper pelvis, and inferior diaphragm
  • Visceral peritoneum:
    • Covers organs (viscera)
  • Intraperitoneal:
    • Encapsulated organs suspended by a double layer of peritoneum (e.g., liver, stomach)
  • Retroperitoneal:
    • Organs outside peritoneal cavity, in contact with posterior body wall (e.g., kidneys)
    • Lack of mesentery restricts movement
  • Secondarily retroperitoneal:
    • Organs that develop with mesentery but adhere to posterior abdominal wall during growth (e.g., ascending and descending colon)
The Dorsal Mesentery
  • Mesentery:
    • Double-layered fold of peritoneum allowing for organ movement and a route for vessels and nerves
    • Necessary for the developing gut tube to grow longer than body cavity
  • Dorsal mesentery:
    • Separates gut tube from body wall; important for aorta and other structures in the abdomen
Organs That Retain Their (Dorsal) Mesentery
  • Small intestine:
    • Jejunum and ileum have mesentery running from upper left to lower right
  • Transverse colon:
    • Mesentery runs horizontally across posterior abdominal wall
    • Mesocolic shelf separates peritoneal cavity into:
    • Supracolic compartment
    • Infracolic compartment
Organs That Lose Their (Dorsal) Mesentery
  • Regions of the GI tract that become secondarily retroperitoneal:
    • Ascending and descending colon (paracolic gutters)
The Peritoneal Cavity
  • Divided into 2 compartments:
    • Greater sac: main peritoneal cavity, including supracolic and infracolic compartments
    • Lesser sac (omental bursa): between stomach and posterior abdominal wall
    • Linked by the epiploic foramen
The Ventral And Dorsal Mesentery
  • Foregut: has ventral and dorsal mesentery, free border at duodenum's level
  • Midgut and Hindgut: have dorsal mesentery only
Formation Of The Greater And Lesser Sacs
  • As stomach rotates around craniocaudal axis:
    • Creates lesser sac behind it
    • Remaining cavity termed greater sac
  • Epiploic foramen connects both sacs
Formation Of Ligaments During Development
  • Liver and spleen develop in ventral and dorsal mesentery respectively
  • Ligaments formed:
    • Lesser sac
    • Greater sac
    • Epiploic foramen
    • Splenorenal ligament, Gastrosplenic ligament, Falciform ligament,
    • Lesser omentum:
    • Hepatogastric lig
    • Hepatoduodenal lig
The Greater Omentum
  • Hangs anterior to the intestines along greater curvature of stomach
The Lesser Omentum
  • Formed by:
    • Hepatogastric ligaments (from lesser curvature)
    • Hepatoduodenal ligaments
Supracolic And Infracolic Compartments
  • Supracolic compartment: includes
    • Falciform ligament
    • Subphrenic recess
    • Coronary ligaments
    • Hepatorenal recess
    • Lesser omentum
    • Infracolic compartment: includes
    • Paracolic gutters
    • Mesentery
    • Sigmoid mesocolon
Learning Objectives

After this lecture, combined with practical classes:

  1. Describe the greater and lesser omentum
  2. Understand formation of ventral and dorsal mesentery and the ligaments formed
  3. Describe formation of greater and lesser sacs
  4. Describe supracolic and infracolic compartments