Atlas of Human Anatomy by Netter

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Costal margin: Formed by the medial borders of the 7th through 10th costal cartilages

Rectus sheath

From xiphoid process and 5th through 7th costal cartilages → pubic symphysis and pubic crest

Contains rectus abdominis muscle (Section 4-2: Abdomen-Body Wall)

Linea alba

A slight indentation that can sometimes be seen extending from the xiphoid process to the pubic symphysis

A fibrous raphe where the aponeuroses of the external and internal abdominal oblique and the transversus abdominis muscles on

either side unite.

Semilunar line (linea semilunaris)

Vertical indentation seen as a curved line from the tip of the ninth rib cartilage to the pubic tubercle on each side in well-muscled

individuals

Represents the lateral edge of the rectus abdominus muscle

Tendinous intersections

Transverse attachments between the anterior rectus sheath and rectus abdominis muscle

May be seen as transverse grooves in skin on either side of midline (six-pack)

Inguinal ligament

From ASIS to pubic tubercle of pelvis

Folded inferior edge of external abdominal aponeurosis

Separates abdominal region from thigh

Umbilicus

At approximate level of intervertebral disc between the L3 and L4

Marks the T10 dermatome

Liver

Mainly in the right upper quadrant, behind ribs 7 through 11 on the right side

Crosses the midline to reach towards the left nipple (Section 4-5: Abdomen-Viscera (Accessory Organs))

Spleen

Beneath ribs 9 through 11 on the left side

10th rib is axis of spleen

Kidneys

Located in loin region

Left kidney is higher than right (pelvis at L1/2 on left and L2/3 on right) (Section 4-8: Abdomen-Kidneys and Suprarenal Glands)

Abdominal contents
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Gastrointestinal tract

Stomach

Duodenum

Ileum

Jejunum

Cecum and appendix

Ascending, transverse and descending colon

Part of the sigmoid colon

Accessory digestive organs

Liver

Gallbladder

Pancreas

Spleen

Suprarenal glands

Urinary system-kidneys and ureters

Kidneys are the only organs developing beneath the parietal peritoneum

Never have a mesentery

Thus are primarily retroperitoneal

Organs that develop within the abdominal cavity and then become retroperitoneal

Are called secondarily retroperitoneal

Pancreas

Two thirds of the duodenum

Ascending and descending colon.

All the rest of the organs are peritoneal

Lie within the peritoneal cavity

Covered by a layer of visceral peritoneum

Visceral peritoneum is continuous with the parietal peritoneum lining the cavity via a mesentery.

Abdominal regions

Abdominal quadrants

Clinicians usually divide the abdomen is into four quadrants for descriptive purposes, using the following planes:

Median plane: imaginary vertical line following the line alba from the xiphoid process to the pubic symphysis

Transumbilical plane: imaginary horizontal line at the level of the umbilicus

These lines or planes create four quadrants

Right upper

Left upper

Right lower

Left lower

Abdominal regions