Joints+of+the+Shoulder

=__Joints of the Shoulder__=

There are three joints of the shoulder: The [|glenohumeral], [|acromioclavicular], and the [|sternoclavicular] joints. 

Glenohumeral joint
The [|glenohumeral joint] is the main joint of the shoulder and the name that is known as the "shoulder joint". It is a [|ball and socket joint] that allows the arm to rotate in a circular motion or to hinge out and up away from the body. It is formed by the joining between the head of the humerus and the lateral scapula. The "ball" of the joint is the rounded portion, 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 a large amount of movement, 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 the lateral scapula and are collectively called the glenohumeral ligaments.

The [|capsule] is a soft tissue 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 three other ligaments attaching the lesser tubercle of the humerus to lateral scapula and are collectively called the glenohumeral ligaments. Semicirculare humeri is also a ligament which is a transversal band between the posterior sides of the tuberculum minus and majus of the humerus. This band is one of the most important strengtening ligaments of the joint capsule.



Acromioclavicular joint
The [|acromioclavicular] (AC) joint is located between the [|acromion] process of the scapula (part of the scapula that forms the highest point of the shoulder) and the distal end of the clavicle. The capsule of this joint is reinforced by the coracoclavicular ligament between the scapula and clavicle at the point of articulation. The coracoclavicular ligament in further detail is created by the conoid ligament, medial from the coracoid process of the scapula and inserts on the conoid tubercle of the clavicle. Lateral to the conoid ligament is the trapezoid ligament, which runs from the coracoid process of the scapula to the trapezoid line of the clavicle. One more ligament, the coracoacromial ligament, running from the corocoid process to the acromion of the scapula contributes to the integrity of the acromioclavicular joint. 

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.

picture courtesy of: 1) eoarthopod.com 2) Medicalook.com

Wiki by: Heather L. & Ji Yoon K. Faith lutheran January 8, 2008