Corpus: Thigh muscles

The term thigh muscles refers to all skeletal muscles in the thigh that surround the femur.

The thigh muscles are divided into functional groups based on their action at the knee joint: the ventral extensor group and the dorsal flexor group. Additionally, the adductor muscles, which act primarily on the hip joint, are often included as part of the thigh musculature. However, some authors classify them as hip muscles since, except for the gracilis muscle, they do not act on the knee joint.

2.1. Thigh extensors

The thigh extensors include the quadriceps femoris muscle, which has four muscle heads:

• Rectus femoris muscle
• Vastus intermedius muscle
• Vastus lateralis muscle
• Vastus medialis muscle

These muscles are located in the extensor compartment of the thigh (anterior compartment oft the thigh). The sartorius muscle, although located in this compartment, primarily causes flexion at both the hip and knee joints. All extensors and the sartorius muscle are innervated by the femoral nerve.

2.2. Femoral flexors

The flexors, also known as the ischiocrural muscles, include:

• Biceps femoris muscle
• Semitendinosus muscle
• Semimembranosus muscle

The popliteus muscle is also classified as a thigh muscle in some references.

These flexors are located in the posterior compartment of the thigh. All muscles in this group are innervated by the tibial nerve, with additional innervation to the biceps femoris from the common fibular nerve.

2.3. Thigh adductor muscles

The adductor muscles of the thigh include:

• Pectineus muscle
• Adductor longus muscle
• Adductor brevis muscle
• Adductor magnus muscle
• Gracilis muscle

These muscles are located in the medial compartment of the thigh (adductor compartment) and are innervated by the obturator nerve.

The extensors and flexors of the thigh act on two joints. Extensors extend the knee joint and flex the hip joint, while flexors flex the knee and extend the hip. The adductors primarily produce adduction of the thigh at the hip joint.