Shoulder Anatomy

Clavicle

The clavicle is the collarbone.  It connects the shoulder to the rest of the skeleton and acts as a strut.  At its lateral (outer) end it forms the Acromioclavicular joint.  At its medial (inner) end it forms the sternoclavicular joint.

Glenoid

The glenoid is part of the scapula (shoulder blade) that forms the shoulder joint with the humerus.  It is a shallow cup that is deepened by a rim of fibrocartilage called the labrum.

Humerus

The humerus is the upper arm bone. It runs between the elbow and the shoulder joint.

Rotator Cuff Anatomy

The rotator cuff is a highly specialized arrangement of four main tendons in the shoulder.  It allows an extraordinary range of motion overhead with precise control.  The rotator cuff is formed by the tendons of the subscapularis, supraspinatus, infraspinatus, and teres minor muscles.

Subacromial Bursitis Anatomy

A bursa is a potential space filled with a film of fluid.  They are associated with joints and allow smooth gliding movement between structures around a joint.  The subacromial bursa lies between the acromion (point of the shoulder) and the rotator cuff.  It allows the rotator cuff to slide smoothly under the acromion when you raise your arm over your head.

Acromion

The Acromion is part of the scapula (shoulder blade).  It is a projection of bone that curves over the top of the glenohumeral joint (shoulder joint).  It provides a scaphold for muscle attachment for the deltoid muscle and forms the Acromioclavicular joint with the clavicle.

Acromioclavicular Joint

The Acromioclavicular joint is formed the clavicle (collar bone) meets the scapula (shoulder blade) at the acromion.  It has a fibrocartilagenous disc that lies within the joint between the bone ends.  It acts as a pivot joint which allows the arm to be raised overhead.

Glenohumeral Joint

The glenohumeral joint is the shoulder joint.  It is formed between the humerus (upper arm bone) and the scapula (shoulder blade).  Its structure allows great range of motion that conversely predisposes it to instability.

Articular Shoulder Capsule

The articular capsule is the lining membrane of the joint.  This is a thin pliable membrane.  In the shoulder the capsule has thickenings in it that form ligaments (superior, middle and inferior glenohumeral ligaments) that help the to give stability to the shoulder.