Shoulder Joint Capsule Definition

The shoulder joint capsule refers to the group of ligaments that encapsulate the shoulder’s ball-and-socket joint. These ligaments connect the humerus (the upper arm bone) to the glenoid (the shoulder’s socket) and stabilize the joint. The shoulder’s joint capsule can become overstretched and loose after a trauma or as the result of participating in repetitive, overhead activities, such as baseball, swimming, and painting. Some people naturally have laxity (looseness) in the shoulder joint capsule.