1) SITES OF INJECTION: Outer thigh/anterolateral aspect of the thigh
MUSCLE TARGETED: Vastus lateralis
ORIGIN: Greater trochanter and linea aspera of femur
INSERTION: Patella via quadriceps tendon and then tibial tuberosity via patellar ligament
ACTION: Extends leg at knee joint
HOW TO LOCATE:
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Position the patient lying down.
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Palpate the muscle below the great trochanter and above the lateral femoral condyle (knee joint).
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Divide the muscles into thirds and administer the injection into the middle third of the muscle, in the outer anterolateral aspect.
2) PREFERRED SITE FOR IM INJECTION: 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:
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Position the patient so they are sitting comfortably with their arm visible from the shoulder to the top of the elbow.
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Palpate the acromion (outer edge of the scapula) and trace an imaginary inverted triangle below the shoulder.
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The injection should be administered in the middle of the triangle.