lesson 2: abdominal cavities and abdominal wall (1)

Abdominal Quadrants and Regions

• The left lower quadrant contains the left ureter and reproductive organs
• The four abdominal quadrants contain portions of the small and large intestines
• The right hypochondriac region contains the liver, gallbladder, right kidney, and portions of the small and large intestine
• The epigastric region contains portions of the liver, stomach, pancreas, duodenum, spleen, and adrenal glands
• The left hypochondriac region contains the spleen, large/small intestines, left kidney, pancreas, stomach, and tip of the liver
• The right lumbar region contains portions of the ascending colon, small intestine, and right kidney
• The umbilical region contains the duodenum, small intestine, and transverse colon
• The left lumbar region contains parts of the descending colon, small intestine, and left kidney
• The right iliac region contains the appendix, cecum, ascending colon, and small intestine
• The hypogastric region contains the bladder, portions of the sigmoid colon, small intestine, and reproductive organs
• The left iliac region contains parts of the sigmoid colon, descending colon and small intestine

Abdominopelvic Cavity

• Also known as the peritoneal cavity
• Lined by the peritoneal membrane/peritoneum
• Located in the abdominal cavity and pelvis
• Bordered by muscles and bones
• Superior border - Diaphragm
• Inferior border - Pelvic Floor
• Posterior - spine, muscles
• Anterior - abdominal wall

Peritoneal Cavity

• Parietal peritoneum forms a closed sac
• Visceral peritoneum covers the organs
• Intraperitoneal organs: liver (except the bare area), gallbladder, spleen, stomach, transverse colon, small bowel, ovaries (in females), and fallopian tubes (in females)
• Retroperitoneal organs: great vessels (aorta and inferior vena cava), pancreas, kidneys, urinary bladder, rectum, and majority of duodenum

Organs and Ligaments

• Ligaments and mesentery hold organs in place
• Greater omentum attaches the stomach to adjacent abdominal organs
• Lesser omentum attaches the lesser curvature of the stomach to the porta hepatis
• Double layer of peritoneum that extends from the stomach to adjacent abdominal organs

Abdominal Wall and Muscles

• Muscles: external oblique, internal oblique, transversus abdominis, and rectus abdominis
• Anterior border: laterally - 3 muscles (external oblique, internal oblique, and transversus abdominis), medially - rectus abdominis
• Aponeuroses of the external oblique, internal oblique, and transverse abdominis muscles form the rectus sheath
• Linea alba: tough band of connective tissue in midline
• Sonographic appearance of muscle: medium level echogenicity, may see high echogenicity fibrous strands within

Diaphragm

• Shape: curvilinear or dome-shaped
• Contour: smooth
• Echogenicity: muscles of diaphragm seen as thin, hypoechoic band
• Interface between liver (or spleen) appears as a thin echogenic line
• Interface between diaphragm and lung thicker echogenic line
• Crura anchor the diaphragm to the spine and join in midline