Shrugging the shoulders (scapula elevation) requires the use of levator scapulae and Trapezius. Fixation of the scapula by other muscles, allows the levator scapulae muscles to work together to aid cervical extension, or independently to laterally flex (side bend) the neck towards the side of the working muscle.
Origin - Transverse processes of C1-4
Insertion - Medial border of the scapula above the level of the scapula spine.
Actions - Scapula elevation, Lateral flexion of the cervical spine (each side independently), Extension of the cervical spine (each side independently)
Which nerves supply this muscle? - Cervical nerve, Dorsal scapular nerve