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Abdominal surface anatomy

Dr Pradeep A Wijayagoonawardana et al.

Abdominal Surface Anatomy

The abdomen, when looking from front is divided into 9 regions by imaginary planes (vertical and horizontal, two each). The nine regions are of clinical importance when examining and describing pathologies related to the abdomen. The horizontal planes are of further importance as they provide useful landmarks on cross sectional imaging such as CT.

The dividing planes are based on lines drawn between easily palpable bony points. The two horizontal lines are:

Subcostal plane : a plane corresponding to a line drawn joining the lowermost bony point of the rib cage - usually 10^th costal cartilage

This corresponds the level of the body of the L3 vertebra. The origin of the superior mesenteric artery and 3^rd part of the duodenum lie on this plane

Trans-tubercular plane : a plane corresponding to a line uniting the two tubercles of the iliac crests.

The upper border of the L5 vertebra corresponds to this plane long with the confluence of the common iliac veins (i.e. commencement of the Inferior Vena Cava).

The two vertical planes are similar on each side and follow a line joining the mid clavicular point to the mid inguinal point. It passes just lateral to the tip of the ninth costal cartilage - which is palpable as a distinct step along the costal margin. It roughly corresponds to the lateral border of the rectus abdominis muscle

The above lines intersect and divide the abdomen into 9 regions.