Shoulder Information

working on a shoulder in pt

humeral head and glenoid
The humeral head and glenoid
which make up the shoulder.
The shoulder is made up of three bones: the clavicle (collarbone), the scapula (shoulder blade), and the humerus (upper arm bone) as well as associated muscles, ligaments and tendons. The articulations between the bones of the shoulder make up the shoulder joints. The major joint of the shoulder is the glenohumeral joint (Shoulder joint). In human anatomy, the shoulder joint comprises the part of the body where the humerus attaches to the scapula.The shoulder is the group of structures in the region of the joint.

There are two kinds of cartilage in the shoulder.

  1. The white cartilage on the ends of the bones (called articular cartilage) which allows the bones to glide and move on each other. When this type of cartilage starts to wear out (a process called arthritis), the joint becomes painful and stiff.
  2. The labrum is a second kind of cartilage in the shoulder which is distinctly different from the articular cartilage. This cartilage is more fibrous or rigid than the cartilage on the ends of the ball and socket. Also, labrum cartilage is also found only around the socket where it is attached.

The shoulder must be mobile enough for the wide range actions of the arms and hands, but also stable enough to allow for actions such as lifting, pushing and pulling. The compromise between mobility and stability results in a large number of shoulder problems not faced by other joints including Unstable Shoulder,Frozen Shoulder, Rotater Cuff Injuries and Shoulder Impingement.

Joints of the Shoulder

Glenohumeral Joint

the restraining ligaments of the shoulder
The restraining ligaments of the
shoulder or gleno-humeral joint.
The glenohumeral joint is the main joint of the shoulder and the generic term "shoulder joint" usually refers to it. It is a ball and socket joint that allows the arm to rotate in a circular fashion or to hinge out and up away from the body. It is formed by the articulation between the head of the humerus and the lateral scapula (specifically-the glenoid fossa of the scapula). The "ball" of the joint is the rounded, medial anterior surface of the humerus and the "socket" is formed by the glenoid fossa, the dish-shaped portion of the lateral scapula. The shallowness of the fossa and relatively loose connections between the shoulder and the rest of the body allows the arm to have tremendous mobility, at the expense of being much easier to dislocate than most other joints in the body.

The capsule is a soft tissue envelope that encircles the glenohumeral joint and attaches to the scapula, humerus, and head of the biceps. It is lined by a thin, smooth synovial membrane. This capsule is strengthened by the coracohumeral ligament which attaches the coracoid process of the scapula to the greater tubercle of the humerus. There are also three other ligaments attaching the lesser tubercle of the humerus to lateral scapula and are collectively called the glenohumeral ligaments.

There is also a ligament called semicirculare humeri which is a transversal band between the posterior sides of the tuberculum minus and majus of the humerus. This band Jis one of the most important strengthening ligaments of the joint capsule.

Sternoclavicular Joint

The sternoclavicular occurs at the medial end of the clavicle with the manubrium or top most portion of the sternum. The clavicle is triangular and rounded and the manubrium is convex; the two bones articulate. The joint consists of a tight capsule and complete intra-articular disc which ensures stability of the joint. The costoclavicular ligament is the main limitation to movement, therefore, the main stabiliser of the joint. A fibrocartilaginous disc present at the joint increases the range of movement. Sternoclavicular dislocation is rare,[4] however it can be caused by direct trauma.

Rotator Cuff

The rotator cuff is an anatomical term given to the group of muscles and their tendons that act to stabilize the shoulder. It is composed of the tendons and muscles (supraspinatus, infraspinatus, teres minor and subscapularis) that hold the head of the humerus (ball) in the glenoid fossa (socket).

Two filmy sac-like structures called bursae permit smooth gliding between bone, muscle, and tendon. They cushion and protect the rotator cuff from the bony arch of the acromion.

From Wikipedia, the free encyclopedia

This information is provided by Orthopedic Spine and Sport Medicine Center as basic information about a specific orthopedic topic. It is not intended as a personal reply to your specific questions or concerns. It is hoped that the contents of this instruction will help you understand the nature of your orthopedic problem and the possibilities of treatment. The final decision regarding treatment, however, must take into account the possibilities of outcomes and complications and should be made only after consideration and further discussion with your physician. For more information, please contact Orthopedic Spine and Sports Medicine Center at 201-587-1111.


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