Astanga Hrudaya
आशयच्चादनौ तौ तु नितम्बौ तरुणास्थिगौ। अधःशरीरे शोफोऽत्र दौर्बल्यं मरणं ततः॥२१॥
the two areas above the ear-like projections of the pelvis (outside the buttocks), concealing the visceral organs and composed of delicate cartilages are two nitamba (marmas); injury to these leads to swelling and debility in the lower portion of the body and death.
english translation