Elbow Anatomy and Biomechanics Mimi Renaudin, DPT University of Mississippi Medical Center

Objectives Describe the anatomy and joint articulations at the elbow Discuss the static and dynamic constraints acting at the elbow Identify the neurovascular contributions within the elbow joint

Elbow Snap Shot Trochoginglymoid joint Humerus Radius Ulna 2 Degrees of freedom Flexion/Extension and forearm rotation Humerus Radius Ulna

Anatomy Overview

Joint Articulations Humeroradial Humeroulnar Proximal Radioulnar

Anterior Muscular Component 9 muscles cross the anterior aspect of the joint Only 3 have primary action on the elbow Radioulnar joint - rotation Remaining 4 muscles arise from common flexor tendon on medial epicondyle

Elbow Flexors

Radioulnar Motion Supinator, pronator teres with assistance from pronator quadratus distally

Anterior Musculature Final 4 muscles attach on medial epicondyle Primary actions occur at the wrist and digits PL FCR FCU FDS

Posterior Muscular Component Elbow extensors: triceps, anconeus Triceps: 3 heads Long: crosses GH and elbow Medial/Lateral: only cross elbow Anconeus Common extensor tendon

Elbow Extensors

Lateral Epicondyle Attachments Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor carpi ulnaris Extensor digiti minimi

Capsuloligamentous Complex Medial collateral ligament Lateral collateral ligament

Medial Collateral Ligament Resists valgus stress Limits extension Taut throughout arch of motion Anterior fibers most taut in extension Posterior bundle is taut in flexion Transverse fibers provide valgus stability and help with joint approximation

Vascular Contribution

Normal Elbow Motion Normal ROM: Functional ROM: Elbow 0-145° Pronation: 80° Supination: 85° Functional ROM: Elbow 30-130° Pronation: 50° Supination: 50°

Carrying Angle Formed by valgus tilt of the axis of rotation (humeral articulation) and the valgus orientation of the ulnar shaft in reference to the olecranon

References DeLee, Drez. DeLee and Drez’s Orthopaedic Sports Medicine. 3rd ed. 2009. 2. Levangie PK, Norkin CC. Joint Structure & Function. 4th ed. 2005. 273-295. 3. Moore KL, Dalley AF, Agur AM. Clinically Oriented Anatomy. 6th ed. 2010. 734-762.

Questions