Corpus: Quadriceps femoris muscle: Unterschied zwischen den Versionen

The quadriceps femoris muscle is located on the ventral side of the thigh and lies above the articulatio genus muscle. It consists of four parts: the rectus femoris muscle, the vastus intermedius muscle, the vastus medialis muscle and the vastus lateralis muscle.

Musculus rectus femoris

from Latin: rectus - right, upright

The rectus femoris muscle has two muscle heads. Its caput rectum originates from the anterior inferior iliac spine, the spina iliaca anterior inferior. The caput reflexum, which is highly variable, originates from the upper edge of the acetabulum. The tendon of the muscle begins about ten centimetres cranial to the kneecap. As this part of the muscle is bi-articular, it also provides flexion in the hip joint in addition to extension in the knee joint.

Musculus vastus intermedius

from Latin: vastus - wide

The vastus intermedius muscle originates from the frontal and lateral surfaces of the upper two thirds of the thigh bone. Approximately in the middle of the bone, the muscle fibres progressively merge into a tendon. As a rule, this part of the muscle is completely covered by the rectus femoris muscle.

The vastus lateralis muscle

The vastus lateralis muscle generally has the largest muscle mass of the four heads of the quadriceps femoris. It essentially originates from a broad aponeurosis, which is attached to the cranial part of the linea intertrochanterica, the greater trochanter and the linea aspera of the femur. A smaller part of the fibres originate from the lateral intermuscular femoral septum.

The vastus medialis muscle

The vastus medialis muscle originates from the medial side of the femur, the upper part from the linea intertrochanterica. The origin follows the medial lip of the linea aspera caudally to the linea supracondylaris medialis.

The common tendon of the four muscle parts inserts at the upper pole of the kneecap (patella). Some fibres extend over the kneecap and thus enclose the patella as a sesamoid bone. The force is transmitted to the lower leg via the patellar ligament, which inserts at the tibial tuberosity of the tibia.

Innervation is provided by the femoral nerve (segments L2-L4) from the lumbar plexus.

The quadriceps femoris muscle is the only extensor of the knee joint and is therefore of immense importance for straightening the body (e.g. from a squatting position). As it works against gravity, it significantly exceeds the strength of the hamstrings. The rectus femoris muscle can also flex in the hip joint, but its effect is relatively weak. The muscle can only achieve its full extension capacity in the knee joint when the hip joint is extended because the rectus femoris muscle becomes insufficient when the hip is flexed.

The four muscles are also responsible for ensuring that the kneecap remains in its gliding groove. If they are unevenly developed, this can lead to dislocation of the kneecap.