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Origin, insertion, innervation and functions of the quadriceps femoris muscle.
Hello again, everyone. This is Matt from Kenhub. And in this short tutorial, we’re going to talk about the origin, insertion, and function of the quadriceps femoris.
The quadriceps femoris muscle is a four-headed muscle of the thigh which almost completely covers the femur. The quadriceps is among the strongest muscles in the human body and significantly forms the lateral contours in the ventral side of the thigh.
Its innervation is carried by the femoral nerve. It consists of four separate muscles: the rectus femoris, the vastus medialis, the vastus lateralis, and the vastus intermedius. We will discuss the insertion and origin of each one individually.
The rectus femoris muscle has two origins at the anterior inferior iliac spine of the pelvis and the upper margin of the acetabulum. Distally, its fibers end in the common insertion tendon which is also known as the quadriceps tendon.
The vastus medialis muscle runs spirally around the shaft from the linea aspera and intertrochanteric line of the femur and merges with the quadriceps tendon for the most part. A second part referred to as medial patellar retinaculum bypasses the patella medially and inserts at the medial condyle of the tibia.
The vastus lateralis muscle originates at the linea aspera and greater trochanter of the femur, loops around the shaft, and mainly runs into the quadriceps tendon. Near inverted to the vastus medialis muscle, a small part goes around the patella laterally and inserts at the lateral condyle of the tibia, also known as the lateral patellar retinaculum.
The vastus intermedius muscle begins at the front side of the femur and ends in the common insertion tendon. In the height of the patellar base, a small part splits off and inserts at the suprapatellar recess of the knee joint capsule, also known as the articularis genus muscle. Even though it does not count as an independent muscle, it is sometimes considered as the fifth head of the quadriceps.
The quadriceps tendon runs above the ventral side, and through the periosteum of the patella, and finally inserts at the tuberosity of the tibia. The part below the patellar apex is referred to as the patellar ligament, seen here in green.
The quadriceps is the only extensor of the knee joint. It plays a key role in every movement involving the stretching of the knee. And in addition, it keeps the knee from buckling when standing.
Furthermore, the rectus femoris muscle forces a flexion of the hip joint. To a small extent, the vastus medialis muscle is involved in the internal rotation, and the vastus lateralis muscle in the external rotation of the knee joint. The articularis genus muscle is directly linked to the knee joint capsule and the suprapatellar bursa. During the knee extension, it pulls both structures proximally, and by this means, prevents their entrapment between patella and femur.