The area where your arm connects to your shoulder is the glenohumeral joint.
Understanding the Glenohumeral Joint
The glenohumeral joint, also known as the shoulder joint, is where the head of the humerus (your upper arm bone) meets the glenoid fossa (a shallow cavity) of the scapula (your shoulder blade). This is a ball-and-socket joint, allowing for a wide range of motion. Its flexibility comes at the cost of stability; the joint relies heavily on surrounding muscles and ligaments for support.
Key Features of the Glenohumeral Joint:
- Ball-and-socket structure: This design enables flexion, extension, abduction, adduction, internal rotation, and external rotation of the arm.
- Rotator cuff muscles: These muscles (supraspinatus, infraspinatus, teres minor, and subscapularis) play a crucial role in stabilizing the joint and facilitating controlled movement.
- Tendons: Tendons of the biceps and triceps brachii also contribute to the joint's stability and function.
- Joint capsule: A fibrous capsule surrounds the joint, providing further stability and containing synovial fluid for lubrication.
The glenohumeral joint's intricate structure allows for the remarkable dexterity and mobility of the human arm, making actions like throwing, reaching, and lifting possible. However, this same flexibility also makes it prone to injuries such as dislocations and rotator cuff tears.
