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Arm and Elbow Joint

OVERVIEW
• The elbow serves to position the hand in space.
• The muscles acting here are often denervated in brachial plexus and proximal peripheral nerve injury patterns.
• With dysfunction at the elbow, the upper extremity cannot be properly positioned in space to perform normal functions even if normal hand or other distal function is preserved.
• Restoration of elbow movement must be a priority in peripheral nerve injury patients.
DETAILS
Structures of the Elbow
• Bones:
• Humerus
• Radius
• Ulna
• The elbow joint is a hinge joint.
 
Movements of the Elbow
• Flexion and extension are movements about a coronal axis.
 
 Muscles of the Elbow (with detailed examination links)
Muscle Name Innervation Basic Action
 Biceps brachii Musculocutaneous nerve Elbow flexion, forearm supination.
 Brachialis Musculocutaneous nerve Elbow flexion.
 Brachioradialis Radial nerve Can assist in elbow flexion (with forearm in neutral position).
 Triceps brachii Radial nerve Elbow extension.
 Anconeus Radial nerve Elbow extension.
 Extensor carpi radialis longus Radial nerve Extends the wrist (weak assistance in elbow flexion).
 Pronator teres Median nerve Pronates the forearm (weak assistance in elbow flexion).
 Italics – Muscles that assist or may assist but are not the primary action of elbow joint flexion and extension. These include muscles that cross the elbow joint.
 
Muscles Originating from the Common Tendon of the Extensor Muscles
• Extensor digiti minimi
• Extensor digitorum
• Extensor carpi radialis brevis
• Extensor carpi ulnaris
 
Muscles Originating from the Common Tendon of the Flexor Muscles
• Palmaris longus
• Flexor digitorum superficialis
• Flexor digitorum profundus
• Flexor carpi radialis
• Flexor carpi ulnaris
• Pronator teres