The Quadriceps, commonly known as the “quads,” are located on the anterior compartment of the thigh. The four-headed muscle is made up of the Rectus Femoris, Vastus Lateralis, Vastus Intermedius, and the Vastus Medialis. While the Vastus muscles originate on the upper region of the femur, the Rectus Femoris originates on the Ilium (hip). The fibers in each muscle have distinct paths from these origination sites that run in some fashion toward the knee, eventually converging into a single tendon that crosses over the patella and inserting on the Tibial Tuberosity. Because of these attachment sites, direction of the fibers, and the joints involved, the Quadriceps are responsible for knee extension and hip flexion (Rectus Femoris).
Superficial, posterior aspect of the hip joint.
Rectus Femoris - Anterior inferior iliac spine; supraactabular groove of ilium.
Vastus Lateralis - Introchanteric line, greater trochanter, gluteal tuberosity, linen aspera of femur.
Tensor Vastus Intermedius - Proximally from the anterolateral aspect of the greater trochanter.
Vastus Intermedius - Anterior surface of femoral shaft.
Vastus Medialis - Introchanteric line, pectineal line of femur, linea aspera, medial supracondylar line of femur.
Tibial tuberosity, via the quadriceps tendon and patellar ligament.
Hip Flexion (Rectus Femoris only)
SHORT AND LONG POSITION
When considering the short and long position for the Quadriceps, we must direct our attention to Rectus Femoris. This is due to the sole fact that Rectus Femoris is the only one of the quad muscles to cross over two joints, the hip joint and knee joint. The Vastus muscles only cross one joint, the knee joint. This means that if we were to focus on the knee joint ONLY, we would be neglecting the function of approximately a quarter of this group of muscles. Taking Rectus Femoris into consideration means that the short position of this group can be found when the hip is in flexion and the knee is in extension. To get this group into its long position would require the hip to be in extension and the knee to be in flexion.
Currently, the prevailing thought is that the Hamstring Complex is the antagonist to the Quadriceps. This is in large part due to the fact that the group of muscle perform opposing functions. With that said, there is a direct opposite for EACH muscle of the Quadriceps. With the discovery of the 5th Quadricep, the direct opposites are currently under review by Danielle Hamlin. Once the direct antagonists of each muscle has been determined, this blog entry will be updated.
Quadriceps = Hamstring Complex