1. origin: greater trochanter and the lateral lip of linea aspera of the femur
insertion: patella via the quadriceps femoris tendon
action: Extends and stabilizes knee
how to locate: Palpate the muscle below the greater trochanter and above the lateral femoral condyle. Divide the muscle into thirds and administer the injection into the middle third of the muscle lateral to the midpoint of the thigh.
2. origin: lateral part of the clavicle, spine, and acromion process of the scapula
insertion: deltoid tuberosity of the humerus
action: arm abduction, flexion, and extension
how to locate: Palpate the acromion and trace an imaginary inverted triangle below the shoulder. The injection should be given 3-5cm below the acromion, in the middle of the triangle.