Anatomy of Shoulder Problems
By Chad Evans PT
Anatomy of Shoulder Problems
Working as a physical therapist in an outpatient rehab clinic it is fairly common to treat patients with various shoulder problems. The majority of issues involve some level of dysfunction related to the soft tissue structures in the shoulder. Some issues are related to the bones of the shoulder. To better understand common problems seen in the shoulder, it makes sense to discuss the anatomy of the shoulder.
The shoulder has many different muscles that cross over the joint and influence how the shoulder functions. They generate arm movement and provide dynamic stability of the shoulder joint. They are the following: Biceps, Triceps, Deltoids, Latissimus Dorsi, Pectoralis Major, Coracobracialis, Teres Major, and the group of muscles called the Rotator Cuff (Supraspinatus, Infraspinatus, Subscapularis, and Teres Minor).
The main ligaments that help connect the ball and socket joint are: The glenohumeral ligaments and the coracohumeral ligaments. Another prominent ligament in the front of the shoulder is the transverse ligament. The ligaments function to help provide stability by preventing separation of the bones they connect.
There are three bones that comprise the shoulder. The arm bone (humerus), the shoulder blade (scapula) and the collar bone (clavicle).
Most people think of the shoulder joint as a ball and socket joint given the shape and structure of the bones in the shoulder. At the end of the arm bone (humerus) is a ball-shaped structure known as the humeral head. It articulates with a socket shaped indention on the side of the shoulder blade called the glenoid. Officially this is called the glenohumeral joint.
There is also a second joint in the shoulder known as the acromioclavicular joint. This joint is formed on top of the shoulder where the collar bone (clavicle) and acromion process (projection on top portion of scapula) meet.
Common Injuries and Pathologies
By design the shoulder joint (glenohumeral) has plenty of mobility as the arm is able to move in multiple planes. This allows for reaching in many directions. Unfortunately this mobility can also make it easier for the shoulder to have injuries.
Injuries to the Bones of the Shoulder
Dislocation of the shoulder usually refers to an episode where the humeral head becomes dislodged from the socket (glenoid). This can occur when someone falls on an outstretched arm.
Subluxation of the shoulder describes an episode where the humeral head partially slides out of the socket but does not come out completely.
Fractures occur when the bones are overloaded from some type of external force, resulting in cracks and breaks in the bone matrix.
Injuries to the Soft Tissue of the Shoulder
Shoulder Impingement is a condition where the tendons get pinched between the bones of the shoulder. Usually, this occurs in the space between the humeral head and acromion process. Rotator cuff tendons can get pinched here if the humeral head is migrating upward due to increased laxity, weak stabilizing muscles or from bony abnormalities of the acromion process.
Rotator Cuff Tears are common injuries in the shoulder where the rotator cuff tendons have torn. This can occur from trauma or can slowly develop over time from chronic shoulder impingement. They can be categorized based on the amount of tearing that has occurred.
Labral Tears describe tearing or fraying of the lip of cartilage that surrounds the glenoid cavity. This often occurs when the shoulder has been dislocated or has had multiple episodes of subluxation.
JOI Physicians are currently offering ASAP fracture and injury care. This is a new option for patients who would like to avoid the emergency room if they have suffered a fracture or soft tissue injury. To learn more about this service, read this article about fracture and injury care. Make an appointment by calling (904)JOI-2000.
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