Definition of AC joint

AC joint: Acromioclavicular joint located between the acromion (a projection of the scapula that forms the point of the shoulder) and the clavicle (the collar bone). This is a gliding type of joint.
The ligaments that serve to support and strengthen this joint are called the capsular; superior and inferior acromioclavicular; articular disk; and coracoclavicular (trapezoid and conoid) ligaments.