Trapezius, upper portion
/ Middle deltoid m i§f§B ' Triceps watm, lateral head \ ||||||f /, ;
Trapezius, middle portion
Infraspinatus Teres minor Trapezius, lower portion Rhomboid
Triceps brachii, long head
Spine of scapula
Sulcus for radial nerve
Long head Lateral head Medial head
Sit facing the machine, with the torso against the back pad, arms forward, gripping the handles: • Inhale and separate the arms, squeezing the shoulder
Both of these muscles arise from the posterior surface of the scapula (shoulder blade), pass onto the scapulohumeral articulation, adhering to its articular capsule, and insert at the greater tubercle of the humerus. They play an Important role in external rotation of the arm and reinforce the action of the shoulder ligaments by actively reinforcing the attachment .of the arm to the chest.
! Comment: In some people, the teres minor and infraspinatus are fused, forming one muscle.
blades together at the end of the movement, • Exhale.
This exercise mainly engages the posterior deltoid, infraspinatus, and teres minor and, at the end of the movement, when the shoulder blades squeeze together, the trapezius .and rhomboids.
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The use of dumbbells gives you a much more comprehensive strengthening effect because the workout engages your stabilizer muscles, in addition to the muscle you may be pin-pointing. Without all of the belts and artificial stabilizers of a machine, you also engage your core muscles, which are your body's natural stabilizers.