Final answer:
The acromioclavicular ligament joins the acromion process of the scapula to the clavicle, forming part of the acromioclavicular joint which facilitates the movement of the shoulder and transmits forces from the upper limb.
Step-by-step explanation:
The ligament that joins the acromion process of the scapula to the clavicle is the acromioclavicular ligament. This ligament is part of the acromioclavicular joint, which is the articulation between the acromion of the scapula and the acromial end of the clavicle. The acromion is the flattened bony process that extends laterally from the scapular spine to form the bony tip of the shoulder. The lateral end of the clavicle, known as the acromial end of the clavicle, articulates with the acromion of the scapula to form this joint.
The acromioclavicular joint is responsible for transmitting forces from the upper limb to the clavicle, but it is important to note that the ligaments around this joint are relatively weak. Direct trauma to the shoulder can lead to a 'shoulder separation' or dislocation of the acromioclavicular joint. The scapula, also referred to laterally as a part of the pectoral girdle, plays a key role in connecting the upper limb to the axial skeleton.