The primary blood supply to the femoral head, which is most vulnerable in a displaced fracture of the femoral neck, is derived from the:

Explanation

The medial circumflex femoral artery (MCFA), a branch of the profunda femoris artery, is the most important blood supply to the femoral head, particularly its retinacular branches (posterior superior and posterior inferior). These vessels run along the femoral neck and are highly susceptible to disruption in displaced femoral neck fractures, leading to avascular necrosis. The lateral circumflex femoral artery contributes less significantly. The obturator artery supplies the foveal artery (artery of ligamentum teres), which is a minor contributor, especially in adults. The superior gluteal artery supplies the gluteal muscles.