The dumbbell armpit row is a rare exercise that targets your lateral deltoid. Your posterior deltoid and various arm and back muscles act as synergists.
Seated Dumbbell Lateral Raises For Firm and Shapely Shoulders by Team FitRx
An isolation and push exercise. Synergistic muscles: Lateral Deltoid, Clavicular Pectoralis Major, Serratus Anterior, Middle Trapezius, and Lower Trapezius.