Middle Trapezius

Origin: C7-T3

Insertion: Scapula (Acromion & Superior Spine) 

Action: Scapular Retraction, Shoulder Horizontal Abduction

Innervation: C3,4 and CNXI (Accessory Nerve)

EMG Studies: Townsend et al., 1991 &  Reinold et al., 2004