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Functional Anatomy Review of the Shoulder Complex . Objectives • Review specific functional anatomy of the shoulder complex. • Understand the biomechanics of the shoulder complex. • Identify sources of pain • Not all anatomical illustrations are completely accurate General Principles of the Shoulder • • • • Shoulder is complex Cuff insertion is anterior Cuff is always activated Tendon of cuff is less vascular • Small muscle for long lever arm = mechanical disadvantage • Many other structures can affect the shoulder (ie neck and scapula) Roof and Floor Roof Floor Functional Anatomy of the Shoulder Complex • 25%-30% of the humerus contacts the glenoid. • Glenoid is shallow • Why is there an unstable bony configuration? • Muscular activity is very important Superficial Muscles How often do you see a tear of these? Bony Shoulder Anatomy Bony Posterior Shoulder Anatomy Anterior Orientation Muscles - Dynamic Stabilizers Capsular Tissue Cuff/Capsule Capsule Capsule Biceps Tendon • Can be both intraarticular and extraarticular • Long head depresses humerus • Long head tears more Biceps-Labrum A-C Joint Tender A-C joint Horizontal adduction painful Pain and swelling Degenerates quickly Cuff path. vs. A-C jt. degen. Spurs can sever the cuff. A-C Joint Spur Vascularity Angle of Inclination Rotator Cuff Position Posterior Capsule • Thin • Close assoc. with cuff. • Contract cuff= tightening of capsule • Tight posterior cuff can cause impingement at the subacromial space • Demo. Coracohumeral Ligament Suspends humerus. Little function. Thoracic kyphosis increase laxity = cuff works harder R-C Function (cont.) Compresses the G-H joint. Elevates IR & ER Accelerates and decelerates the arm Hammock Effect Inverted Hammock Humeral Head Depression Massive Rotator Cuff Tear Neuromuscular Inhibition Pain Swelling Instability Functional Stability of the Shoulder Shoulder Dynamic Stability Knee Static Stability