| Structure/Space | Description/Boundaries | Significance |
|---|---|---|
| arcuate line | anatomical feature on the inner surface of the abdominal wall; a fascial line in the transverse plane approximately 1/2 of the distance from the umbilicus to the pubic symphysis | arcuate line is the point at which the posterior lamina of the rectus sheath ends and transversalis fascia lines the inner surface of the rectus abdominis m. |
| epigastric region | an area on the anterior abdominal wall between the midclavicular lines, superior to the transpyloric line | one of 9 regions of the abdomen |
| hypochondriac region | an area on the anterior abdominal wall lateral to the midclavicular line, superior to the transpyloric line | one of 9 regions of the abdomen; bilateral |
| hypogastric region | an area on the anterior abdominal wall between the midclavicular lines, inferior to the intertubercular line | one of 9 regions of the abdomen; also known as: pubic region |
| inguinal region | anterior abdominal wall lateral to midclavicular line, inferior to intertubercular line | one of 9 regions of the abdomen; also known as: iliac region |
| intercristal line | an imaginary line drawn in the horizontal plane at the upper margin of the iliac crests | intercristal line locates the level of the L4 vertebra; a useful landmark in spinal tap procedure |
| intertubercular line | an imaginary line drawn in the horizontal plane at the upper margin of the iliac tubercles | intertubercular line locates the level of the L5 vertebra; used with midinguinal and transpyloric lines to divide the abdominal wall into 9 regions |
| linea alba | anatomical feature on the midline of the anterior abdominal wall; an aponeurotic band that extends from the xiphoid process to the pubic symphysis; | linea alba is formed by the combined abdominal muscle aponeuroses; it is used for midline abdominal incisions to avoid major nerves or vessels |
| lumbar region | an area on the anterior abdominal wall lateral to the midclavicular line, inferior to transpyloric line, superior to intertubercular line | one of 9 regions of the abdomen; also known as: lateral region |
| McBurney's point | a point on the anterior abdominal wall which is 1/3 of the distance along a line from the right anterior superior iliac spine to the umbilicus | McBurney's point is the approximate location of the vermiform appendix; point of tenderness in appendicitis |
| midaxillary line | an imaginary vertical line passing through the middle of the axilla | used as a surface landmark for descriptive purposes |
| midclavicular line | an imaginary vertical line passing through the midshaft of the clavicle | used as a surface landmark for descriptive purposes |
| midinguinal line | an imaginary vertical line passing through the midpoint of inguinal ligament | used with the transpyloric and intertubercular lines to divide the abdomen into 9 regions |
| quadrant, inferior left | a region on the anterior abdominal wall defined by the midline and the transumbilical line | one of 4 abdominal quadrants |
| quadrant, inferior right | a region on the anterior abdominal wall defined by the midline and the transumbilical line | one of 4 abdominal quadrants |
| quadrant, superior left | a region on the anterior abdominal wall defined by the midline and the transumbilical line | one of 4 abdominal quadrants |
| quadrant, superior right | a region on the anterior abdominal wall defined by the midline and the transumbilical line | one of 4 abdominal quadrants |
| semilunar line | an anatomical feature of the anterior abdominal wall; the lateral edge of the rectus abdominis m. | semilunar line is formed by the fused aponeuroses of the abdominal wall mm. at the lateral margin of the rectus sheath |
| transpyloric line | an imaginary horizontal line 1/2 of the distance between the jugular notch and the pubic crest | transpyloric line is used with the midinguinal and intertubercular lines to divide the abdominal wall into 9 regions; the fundus of the gall bladder lies at the intersection of the transpyloric line with the right 9th costal cartilage; the pylorus of the stomach is located at this plane; a horizontal plane through the transpyloric line locates the level of the L1 vertebra |
| transumbilical line | an imaginary horizontal line through the umbilicus | transumbilical line is used with the midline to divide abdomen into 4 quadrants |
| transverse lines | anatomical features in the anterior abdominal wall; folds in the anterior abdominal wall (usually 3) | transverse lines are creases that overlie the tendinous intersections in the rectus abdominis m. |
| umbilical region | a region on the anterior abdominal wall between the midclavicular lines, inferior to the transpyloric line, superior to the intertubercular line | one of 9 regions of the abdomen |
| umbilicus | remnant of the attachment of the umbilical cord to the anterior abdominal wall | umbilicus marks the approximate level of the L3/L4 intervertebral disc in non-obese individuals |