Acromiotrapezius is the middle trapezius muscle. It covers the dorsal and lateral surfaces of the scapula. Its origin is the neural spines of the cervical vertebrae and its insertion is in the metacromion process and fascia of the clavotrapezius. Its action is to draw the scapula to the dorsal, and hold the two scapula together. [ http://en.wikipedia.org/wiki/Cat_anatomy#Acromiotrapezius ]