**5.17 The extensors of the knee**

• M. quadriceps: Intramuscular injections can be administered in this muscle that consists of four parts. All insert into the basis of the patella.

M. rectus femoris: The origin is just dorsal to the acetabulum (**Figures 25** and **37**).

M. vastus lateralis: This part of the quadriceps muscle arises from the greater trochanter of the femur.

M. vastus medialis: This muscle arises from lesser trochanter of the femur (**Figure 37**).

M. vastus intermedius (formerly described as the m. crureus): This deep muscle arises from the proximal three-fourths of the shaft of the femur (**Figure 37**).

• M. tensor fasciae latae: The origin of this muscle is the ilium and the fascia overlying the gluteus medius muscle. The muscle is inserted into the fascia lata (**Figures 25**, **26**, and **36**).
