Shape of trapezium muscle is
Triangular
Quadrilateral
Trapezium
Quadrangular
*Trapezius is triangular muscle present in upper back region. *Attachments & Origin: Origin: Superior nuchal line, external occipital protuberance, ligamentum nuchae, spinous processes of C7-T12 Inseion: Lateral 1/3rd of clavicle, acromion, spine of scapula. Innervation: Motor - Accessory nerve (CN-11) Proprioception - C3, C4. FUNCTION: Assists in laterally rotating scapula during abduction of humerus above horizontal *Upper fibers - Elevation of scapula *Middle fibers - Adduct scapula *Lower fibers - Depress scapula All fibers together rotates scapula laterally so glenoid cavity projects upwards taking humerus upwards. (Overhead Abduction)