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PARTITIONING OF THE ABDOMINAL REGION

BIG PICTURE

The abdomen typically is described topographically using two methods. The first method partitions the abdomen into four quadrants. The second method partitions the abdomen into nine regions.

FOUR QUADRANT PARTITIONS

To divide the abdomen into four quadrants, a transverse plane and a sagittal plane intersect through the umbilicus at the L3–L4 vertebral level (Figure 7-1A). The two intersecting planes divide the abdomen into right and left upper and lower quadrants. The four-quadrant system is straightforward when used to describe anatomic location. For example, the appendix is located in the lower right quadrant of the abdomen.

Figure 7-1:

A. Quadrant partitioning: right upper quadrant (RUQ); left upper quadrant (LUQ); right lower quadrant (RLQ); and left lower quadrant (LLQ). B. Regional partitioning: right hypochondriac (RH); right lumbar (RL); right iliac (RI); epigastrium (E); umbilical (U); hypogastrium (H); left hypochondriac (LH); left lumbar (LL); and left iliac (LI). C. Surface anatomy and dermatome levels. D. Fascial layers of the anterior abdominal wall.

NINE REGIONAL PARTITIONS

For more precise description, the abdomen is partitioned into nine regions created by two vertical planes, one each through the middle of each clavicle, and two horizontal planes, one each through the costal margin and the transtubercular plane (Figure 7-1B). The nine regions are:

  • Right hypogastric. Region under the right costal margin.

  • Right lumbar. Region on the right side of the abdomen.

  • Right iliac. Region over the right iliac region.

  • Epigastric. Upper central region of the abdomen.

  • Umbilical. Region overlying the umbillicus.

  • Hypogastric. Lower central region of the abdomen (suprapubic area).

  • Left hypogastric. Region under the left costal margin.

  • Left lumbar. Region on the left side of the abdomen.

  • Left iliac. Region over the left iliac region.

ABDOMINAL SURFACE LANDMARKS

The following structures are helpful anatomic surface landmarks on the anterior abdominal wall (Figure 7-1C):

  • Xiphoid process. The xiphoid process is the inferior projection of the sternum.

  • Umbilicus. The umbilicus lies at the L3–L4 vertebral level, within the T10 dermatome. A helpful mnemonic is “T10 for belly but-ten.”

  • Inguinal ligament. Formed by the inferior border of the external oblique muscle and its aponeurosis, where the aponeurosis attaches from the anterior superior iliac spine to the pubic tubercle. The inguinal ligament is revealed superficially as a crease on the inferior extent of the anterior abdominal wall. The inguinal ligament is the location of the dermatome level of L1.

Image not available. McBurney's point is the name given to a point on the lower right quadrant of the abdomen, approximately one-third the distance along an imaginary line from the anterior superior iliac spine to the umbilicus. McBurney's point roughly corresponds to the skin overlying the ...

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