An urologist plans a lumbotomy approach to the kidney and identifies the lumbar triangle of Petit in the posterolateral abdominal wall. Which set of boundaries correctly defines this triangle?

• A External oblique medially, teres major laterally, latissimus dorsi inferiorly
• B Internal oblique posteriorly, rectus abdominis medially, inguinal ligament inferiorly
• C Latissimus dorsi medially, serratus anterior laterally, twelfth rib superiorly
• D Latissimus dorsi posteriorly, external oblique anteriorly, iliac crest inferiorly ✓

Explanation

Petit's triangle lies in the flank with the free posterior border of latissimus dorsi behind, the free posterior border of external oblique in front, and the iliac crest forming its base inferiorly. Its floor is internal oblique, and it has been used for loin access to the kidney. Option C describes the triangle of auscultation region bounded by the twelfth rib, and option A mixes muscles of the axillary and scapular regions, none of which bound a lumbar triangle.

Reference: Moore's Clinically Oriented Anatomy, 9th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.