An elderly woman sustains a completely displaced intracapsular fracture of the femoral neck. The blood supply to the femoral head is jeopardised mainly because the principal source of supply travels:

• A Along the ligamentum teres through the artery of the ligamentum teres
• B Retrograde along the femoral neck through the ascending cervical branches of the medial circumflex femoral artery ✓
• C Through the nutrient artery of the femoral diaphysis
• D Through the lateral circumflex femoral artery entering the piriform fossa

Explanation

In adults the femoral head is supplied predominantly by the medial circumflex femoral artery, whose ascending cervical (retinacular) branches run along the posterosuperior neck beneath the capsule. Displacement of an intracapsular fracture tears these vessels, causing avascular necrosis. The artery of the ligamentum teres contributes little in adults, which is why option A is tempting but incorrect.

Reference: Gray's Anatomy, 42nd ed.

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Written and medically reviewed by the StethoPrep medical team.