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Quadriceps Femoris Muscle Anatomy

The quadriceps femoris forms the main bulk of the anterior thigh muscles and collectively constitutes the largest and one of the most powerful muscles in the body. It covers almost all the anterior aspect and sides of the femur.

The quadriceps femoris consists of four parts: rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis. Collectively, the quadriceps is a two-joint muscle capable of producing action at both the hip and knee.

The tendons of the four parts of the quadriceps unite in the distal portion of the thigh to form a single, strong, broad quadriceps tendon. The patellar ligament (L. ligamentum patellae) is the continuation of the quadriceps tendon in which the patella, the largest sesamoid bone in the body, is embedded. Distally, the patellar ligament is attached to the tibial tuberosity.

The medial and lateral vasti muscles also attach independently to the patella and form aponeuroses, the medial and lateral patellar retinacula, which reinforce the joint capsule of the knee joint on each side of the patella en route to attachment to the anterior border of the tibial plateau. The retinacula also play a role in keeping the patella aligned over the patellar surface of the femur.

See Also: Quadriceps Tendon Rupture

Quadriceps Femoris Muscle Parts

Rectus Femoris

The rectus femoris received its name because it runs straight down the thigh (L. rectus, straight). Because of its attachments to the hip bone and tibia via the patellar ligament, it crosses two joints; hence, it is capable of flexing the thigh at the hip joint and extending the leg at the knee joint. The rectus femoris is the only part of the quadriceps that crosses the hip joint, and as a hip flexor, it acts with and like the iliopsoas during the preswing and initial swing phases of walking.

The ability of the rectus femoris to extend the knee is compromised during hip flexion, but it does contribute to the extension force during the toe off phase of walking, when the thigh is extended. It is particularly efficient in movements combining knee extension and hip flexion from a position of hip hyperextension and knee flexion, as in the preparatory position for kicking a soccer ball. The rectus femoris is susceptible to injury and avulsion from the anterior inferior iliac spine during kicking, hence the name “kicking muscle.” A loss of function of the rectus femoris may reduce thigh flexion strength by as much as 17%.

Origin	Straight head from anterior inferior iliac spine; Reflected head from groove just above acetabulum
Insertion	Base of patella to form the more central portion of the quadriceps tendon
Innervation	Muscular branches of femoral nerve (L2, L3, L4)
Blood Supply	Lateral circumflex femoral artery
Action	Extends the knee Accessory flexor of hip

Vastus Muscles

The names of the three large vastus muscles (pl., vasti) indicate their position around the femoral shaft.

Vastus lateralis, the largest component of the quadriceps, lies on the lateral side of the thigh.
Vastus medialis covers the medial side of the thigh.
Vastus intermedius lies deep to the rectus femoris, between the vastus medialis and vastus lateralis.

Vastus Lateralis

Origin	Superior portion of intertrochanteric line Anterior and inferior borders of greater trochanter Superior portion of lateral lip of linea aspera Lateral portion of gluteal tuberosity of femur
Insertion	Lateral base and border of patella; Also forms the lateral patellar retinaculum and lateral side of quadriceps tendon
Innervation	Muscular branches of femoral nerve (L2, L3, L4)
Blood Supply	Lateral circumflex femoral artery
Action	Extends the knee

Vastus Medialis

Origin	Inferior portion of intertrochanteric line Spiral line Medial lip of linea aspera Superior part of medial supracondylar ridge of femur Medial intermuscular septum
Insertion	Medial base and border of patella Also forms the medial patellar retinaculum and medial side of quadriceps tendon
Innervation	Muscular branches of femoral nerve (L2, L3, L4)
Blood Supply	Femoral artery Profunda femoris artery Superior medial genicular branch of popliteal artery
Action	Extends the knee

Vastus Intermedius

Origin	Superior 2/3 of anterior and lateral surfaces of femur; Also from lateral intermuscular septum of thigh
Insertion	Lateral border of patella; Also forms the deep portion of the quadriceps tendon
Innervation	Muscular branches of femoral nerve (L2, L3, L4)
Blood Supply	Lateral circumflex femoral artery
Action	Extends the knee

The small, flat articularis genu (articular muscle of the knee), a derivative of the vastus intermedius, usually consists of a variable number of muscular slips that attach superiorly to the inferior part of the anterior aspect of the femur and inferiorly to the synovial membrane of the knee joint and the wall of the suprapatellar bursa. The articularis genu muscle pulls the synovial membrane superiorly during extension of the leg, thereby preventing folds of the membrane from being compressed between the femur and the patella within the knee joint.

Quadriceps Femoris Muscle Function

The quadriceps is the great extensor of the leg. Concentric contraction of the quadriceps to extend the knee against gravity is important during rising from sitting or squatting, during climbing and walking up stairs, and for acceleration and projection (running and jumping) when it is lifting or moving the body’s weight. Consequently, it may be three times stronger than its antagonistic muscle group, the hamstrings.

In level walking, the quadriceps muscles become active during the termination of the swing phase, preparing the knee to accept weight. The quadriceps is primarily responsible for absorbing the jarring shock of heel strike, and its activity continues as the weight is assumed during the early stance phase (loading response). It also functions as a fixator during bent-knee sports, such as skiing and tennis, and contracts eccentrically during downhill walking and descending stairs.

The quadriceps femoris muscle is the most important muscle in stabilizing the knee joint, particularly the inferior fibers of the vastus medialis and lateralis.

See Also: Quadriceps Active Test
See Also: Thomas Test

Testing the quadriceps is performed with the person in the supine position with the knee partly flexed. The person extends the knee against resistance. During the test, contraction of the rectus femoris should be observable and palpable if the muscle is acting normally, indicating that its nerve supply is intact.

References & More

Clinically Oriented Anatomy – 8th Edition
Bordoni B, Varacallo M. Anatomy, Bony Pelvis and Lower Limb: Thigh Quadriceps Muscle. [Updated 2023 May 8]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK513334/
Murdock CJ, Mudreac A, Agyeman K. Anatomy, Abdomen and Pelvis, Rectus Femoris Muscle. [Updated 2023 Nov 13]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2024 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539897/