Ligaments of the Glenohumeral Joint.

There are several important ligaments in the shoulder. Ligaments are soft tissue structures that connect bones to bones. A joint capsule is a watertight sac that surrounds a joint. In the shoulder, the joint capsule is formed by a group of ligaments that connect the humerus to the glenoid. These ligaments are the main source of stability for the shoulder. They help hold the shoulder in place and keep it from dislocating. These are the glenohumeral ligaments (GHL)

Another ligament links the coracoid to the acromion - coracoacromial ligament (CAL). This ligament can thicken and cause Impingement Syndrome

Ligaments attach the clavicle to the acromion in the AC joint.

Two ligaments connect the clavicle to the scapula by attaching to the coracoid process, a bony ridge on the scapula - coracoclavicular ligaments (CCL)

Ligaments of the Shoulder Complex:

• CCL - coracoclavicular ligaments
• CAL - coracoacromial ligaments
• SGHL - Superior GlenoHumeral Ligament
• MGHL - Muperior GlenoHumeral Ligament
• IGHL - Inferior GlenoHumeral Ligament

Ligaments of the Rotator Cuff

The tendons of the rotator cuff are the next layer in the shoulder joint. Tendons are much like ligaments, except that tendons attach muscles to bone. Muscles move the bones by pulling on the tendons. One important tendon that travels through the shoulder joint is the biceps tendon . The biceps tendon actually begins at the top of the shoulder socket (the glenoid) and then passes across the front of the shoulder to connect to the biceps muscle. (The biceps is the muscle that weightlifters are always showing off).

The rotator cuff tendons are a group of four tendons that connect the deepest layer of muscles to the humerus.  They are the tendons of the rotator cuff muscles (left)

Tendons of the shoulder:

From front to back:

• Subscapularis
• Biceps Tendon
• Supraspinatus
• Infraspinatus
• Teres Minor

Muscles of the Shoulder

There are 30 muscles providing movement and support for the shoulder complex. 15 muscles move and stabilize the scapula; 9 muscles provide for glenohumeral joint motion; and 6 support the scapula on the thorax

There are three important groups of muscles around the shoulder:

1. Surface muscles (Extrinsic):

• The large deltoid muscle forms the outer layer of muscle. This is the largest, strongest muscle of the shoulder. The deltoid muscle takes over lifting the arm once the arm is away from the side.
• Pectoralis Major provides movement and support in the front of the shoulder

2. Deep muscles (Intrinsic):

• The rotator cuff tendons attach to the deep rotator cuff muscles. These 4 muscles are involved in raising the arm from the side and rotating the shoulder in the many directions. The rotator cuff mechanism also helps keep the shoulder joint stable by holding the humeral head in the glenoid socket. These muscles are: subscapularis, supraspinatus, infraspinatus and teres minor.

3. Back Muscles (Posterior):

• These muscles are at the back of the shoulder that stabilise and move the scapula on the trunk of the body. This group includes the trapezius, rhomboids, levator scapulae, and the serratus anterior muscles; and are concerned with stabilisation and rotation of the scapula.

Bursas of the Shoulder

Sandwiched between the rotator cuff muscles and the outer layer of large bulky muscles is a structure known as a bursa. Bursae are everywhere in the body. They are found wherever two body parts move against one another and there is no joint to reduce the friction. A bursa is simply a sac between two moving surfaces that contains a small amount of lubricating fluid.

Think of a bursa like this: If you press your hands together and slide them against one another, you produce some friction. In fact, when your hands are cold you may rub them together briskly to create heat from the friction. Now imagine that you hold in your hands a small plastic sack that contains a few drops of salad oil. This sack would let your hands glide freely against each other without a great deal of friction.