Vastus lateralis muscle
Origin: Greater trochanter and linea aspera of femur
Insertion: Patella via quadriceps tendon and then tibial tuberosity via patellar ligament
Action: All four heads extend leg at knee joint; rectus femoris muscle acting alone also flexes thigh at hip joint.
It is located in the middle part of a thigh (outer top portion)
Deltoid muscle
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
It is located two finger widths below the acromion process