1. Patient: 2-month-old infant
Site of injection: Anterolateral thigh
Targeted muscle/s: Vastus lateralis
Origin: Greater trochanter and linea aspera of femur
Insertion: Patella via quadriceps tendon, and tibial tuberosity via patellar ligament
Action: Extend leg at knee joint
How to locate: The injection site for the vastus lateralis muscle is around halfway (thigh) going up from the knee, and around the anterolateral region
2. Patient: 65-year-old grandfather
Site of injection: Upper arm
Targeted muscle/s: Deltoid
Origin: Acromial extremity of clavicle, acromiom of scapula, and spine of scapula
Insertion: Deltoid tuberosity of humerus
Action: Abduct arm at shoulder joint, and flex, extend, and rotate arm at shoulder joint
How to locate: The injection site for the deltoid muscle is around 2 inches below the acromion process, just above the level of the armpit, and at the central part of the arm.