elbow anatomy and biomechanics

Elbow Anatomy and Biomechanics

Mimi Renaudin, DPTUniversity 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

– 2 Degrees of freedom Flexion/Extension and forearm rotation

• Humerus• Radius • Ulna

Anatomy Overview

Joint Articulations

Humeroulnar

Proximal Radioulnar

Humeroradial

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:

– 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

References1. 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