1 Anatomy of the Glenohumeral Joint University of the People HS 2211-01 Human Anatomy and Physiology Dr. Pressley June 27, 2022
2 Introduction Joint pain is a common phenomenon in today's world, especially among athletes. Our joints play many roles in the overall function of the human body. Without joints our arms wouldn't bend, our fingers wouldn't grasp, and our legs wouldn't run. Mobility and flexibility are just two of the many benefits joints provide. In addition to these aspects our joints provide protection by preventing the scraping of our bones against bones when they move in our body. Joints are classified into the following categories based on the range of motion they provide: synarthrosis/immobile, amphiarthrosis/limited mobility, and diarthrosis/free mobility (OpenStax, 2018). The glenohumeral joint, more commonly known as the shoulder joint, is an example of a diarthrosis joint. An examination of the development, structure, movement, and function of the glenohumeral joint is necessary for a comprehensive understanding of its role in the human body. Development and Structure The glenohumeral joint is where the scapula (shoulder blade) connects to the humerus (arm). The bones of the shoulder are developed via ossification processes by which intramembranous ossification in the clavicle lays bone in the mesenchyme from which endochondral ossification forms the rest of the bony structures (Chan et al., 2022). The head of the humerus rests inside the glenoid cavity of the scapula forming a ball and socket joint (Chang et al., 2022). The diarthrosis glenohumeral joint allows for the most mobility compared to any other joint in the body. However, due to this free range of motion and the shallowness of the glenoid cavity, the shoulder joint is also the easiest joint to dislocate (OpenStax, 2018). The glenohumeral is a synovial joint which means that a layer of cartilage outlines the articulation of the two bones; articulation refers to where the two bones make contact. Synovial joints are also surrounded by
3 synovial fluid which provides extra protection by acting as a cushion between the bones. The Glenoid labrum is the name given to the fibrocartilage which extends around the outer glenoid cavity; this cartilage creates a small lip which serves to slightly deepen the cavity (OpenStax, 2018). The Articular capsule, containing the synovial and fibrous membranes, is located between the two bones and diminishes friction as they move past each other. There are several ligaments, tendons, and muscles which serve to provide structural support for the joint and allow for the arm to move without falling out of its socket. Ligaments connect bone to bone while joints connect bone to muscles. The shoulder joint has four ligaments: the coracohumeral ligament and three glenohumeral ligaments. The purpose of these ligaments are to support the superior and anterior capsule walls (OpenStax, 2018). The supraspinatus, infraspinatus, teres minor, and subscapularis are a group of supporting muscles whose tendons serve to support the joint by thickening the capsule. These tendons are collectively known as the rotator cuff (OpenStax, 2018). The glenohumeral joint also