Which is a part of the insertion of the external oblique?

• A. Anterior part of iliac crest
• B. Central tendon
• C. Last rib
• D. Medial sacral crest

Answer: (A)

The main concept here is where the external oblique attaches to the skeleton. The external oblique is a broad muscle on the lateral abdominal wall whose fibers angle downward and medially, ending in an aponeurosis that contributes to the rectus sheath and the inguinal region. A primary insertion point is the anterior part of the iliac crest, which helps anchor the lower lateral abdominal wall and supports movements like trunk rotation and lateral flexion. The other options don’t describe insertion points for this muscle: the central tendon is not part of the external oblique; the last rib is a source of origin for the muscle, not an insertion; and the medial sacral crest is not involved with the external oblique. Thus, the anterior part of the iliac crest is the correct insertion site.