The quadriceps tendon is derived from the muscular junction of the rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius muscles at the anterior superior pole of the patella. The quadriceps tendon, in combination with the patellar tendon and the patella bone, makes up the extensor mechanism of the lower leg. Structurally and biomechanically, the quadriceps tendon can withstand very high loads without rupture. The quadriceps muscle derives its neurovascular innervation from the femoral nerve and artery. Specifically, the rectus femoris, vastus intermedius, and vastus lateralis gain their arterial supply from the lateral femoral circumflex artery. The vastus medialis gains its arterial supply from the femoral artery, the superior medial genicular branch of the popliteal artery, and the profunda femoris artery. The vastus lateralis, vastus medialis, and vastus intermedius act both as knee extenders as well as assist with patellar tracking. The vastus lateralis is the largest of the quadriceps muscles. It helps pull the patella laterally. This action must be counterbalanced by the vastus medialis, which is the smallest of the quadriceps muscles and acts to pull the patella medially. The vastus intermedius acts to help stabilize midline tracking of the patella. The combined contraction of this group of anterior thigh muscles causes extension of the lower leg. The rectus femoris also plays a role in hip flexion. A rupture of this central tendon drastically hinders knee extension and directly affects functionality. The degree that a quadriceps tendon rupture limits lower leg extension is based on the severity of tendon damage. Minor tendon tears may have minimal impact on extensor function, while complete tendon tears may totally impede lower leg extension.