What joint is formed by the acromion and the clavicle?

The acromioclavicular joint is the articulation between the acromion, which is a bony process on the scapula, and the clavicle. This joint plays a crucial role in shoulder mechanics, as it allows for the movement and stability of the shoulder region. It enables the arm to move freely while maintaining stability during various activities such as reaching overhead or lifting.

The acromioclavicular joint supports the connection between the upper limb and the trunk, contributing to the overall function of the shoulder girdle. This joint is often a focus in discussions about shoulder injuries, particularly in sports medicine, as it can be a site for injuries such as separations or sprains.

The other options refer to different joints in the body: the glenohumeral joint is the main shoulder joint which connects the humerus to the scapula, the sacroiliac joint connects the sacrum to the ilium of the pelvis, and the humeroulnar joint is part of the elbow joint complex. Each of these joints serves different functions and has unique characteristics, further highlighting the specificity of the acromioclavicular joint in the context of shoulder mobility and stability.