Shoulder Anatomy.Information for patients.

Dr Geoffrey SmithImages courtesy of www.biodigital.com

Bones

• The shoulder (glenohumeral joint) is a ball and socket joint.

• The ball is at the top of the arm bone (the humerus).

• The socket is the glenoid which is part of the shoulder blade (scapula).

Humerus Scapula

Soft tissue

• The glenohumeral joint is surrounded by a sleeve of tissue (the capsule).

• The capsule is thick in places & forms ligaments.

Capsule

Tendons

• Outside the capsule are the tendons of the rotator cuff.

• Tendons are where muscles attach to bone.

• Muscle pulling on bones through tendons produces movement at joints.

Rotator Cuff

• The rotator cuff is composed of 4 tendons

• Subscapularis (at the front)

• Supraspinatus and infraspinatus (at the top)

• Teres minor (at the back).

Subscapularis

Supraspinatus

Infraspinatus

Teres Minor

Subacromial space

• Above the rotator cuff is the acromion which is the bone you can feel on the top of your shoulder.

• The acromion is part of the shoulder blade (scapula).

• The subacromial space is between the undersurface of the acromion and the upper surface of the rotator cuff.

• The subdeltoid or subacromial bursa (a sac of fluid) occupies the subacromial space.

Acromion

Subacromial bursa

Clavicle and AC joint

• At the front of the shoulder the acromion articulates with the collar bone (clavicle) at the acromioclavicular joint (ACJ)

• The ACJ is stabilised by the ACJ capsule and the coracoclavicular ligaments

Clavicle

Acromion AC joint

CoracoclavicularLigaments

ACJ capsule

Biceps tendon

• The biceps muscle (the strong muscle at the front of the arm) has two tendons.

• One (long head or LHB) is attached to the top of socket of the shoulder joint.

• The second tendon is attached to the coracoid process (part of the scapula). This is a finger-like projection of bone that you can feel about 4 cm below the outer part of your collar bone.

• The two tendons join together to form the biceps muscle at the top of the arm

LHB

Coracoid process

Biceps Muscle