1.) For infants, vaccines like the pneumococcal conjugate vaccine (PCV) and the pentavalent vaccine (Penta) are usually injected in the Vastus Lateralis muscle which is located in the anterolateral side of the thigh.
VASTUS LATERALIS
Origin: Greater trochanter. It also attaches to the lateral lip of linea aspera of femur.
Insertion: Quadriceps tendon to base of patella and onto tibial tuberosity via the patellar ligament.
Action: Extends leg at knee
How to locate?
To locate the vastus lateralis, palpate the muscle below the greater trochanter and above the lateral femoral condyle (knee joint). Afterwards, divide the muscle into thirds and inject into the middle third of the muscle.
2.) The preferred site for IM injection on a 65-year-old male would be in the deltoid muscle. The deltoid muscle crowns the shoulder and is overlying the glenohumeral joint.
DELTOID
Origin: Acromial extremity of clavicle (anterior fibers), acromion of scapula (lateral fibers), and spine of scapula (posterior fibers).
Insertion: Deltoid tuberosity of humerus
Action: Lateral fibers abduct arm at shoulder
joint; anterior fibers flex and medially rotate arm at shoulder joint; posterior fibers extend and laterally rotate arm at shoulder joint.
How to locate?
To locate, the patient's arm from shoulder to the top of the elbow should be visible as she sits comfortable. Afterwards, palpate the acromion (outer edge of the scapula) and trace an imaginary inverted triangle below the shoulder.
References:
Intramuscular Injections. The Royal Children’s Hospital Melbourne. (n.d.). https://www.rch.org.au/rchcpg/hospital_clinical_guideline_index/Intramuscular_Injections/
Pirie, E. (n.d.). Deltoid muscle. Kenhub. https://www.kenhub.com/en/library/anatomy/the-deltoid-muscle
Tortora, G. J., & Derrickson, B. (2017). Principles of anatomy and physiology. Wiley Custom Learning Solutions.
Vaskovi, J. (n.d.). Quadriceps femoris muscle. Kenhub. https://www.kenhub.com/en/library/anatomy/the-quadriceps-femoris-muscle