Elbow and Forearm Flashcards
Humeroradial Joint and Humeroulnar Joint
Part of the elbow complex. Interrelated joints where the humerus meets the radius or ulna. These joints are involved in flexion/extension.
Proximal Radioulnar Joint
Part of the elbow complex. Where the radius meets the ulna and both rotate against the humerus. This joint is involved in forearm pronation/supination.
Elbow Joint Type
Hinge or Synovial joint. Motions only in the sagittal plane: Flexion and Extension only.
Stability of Elbow Joint
Joint is not very mobile (Flex/Ext only), and is therefore more stable.
• Withstands forces 1-3x the bodyweight.
• Less movements do make it more susceptible to repetitive stress injuries (RSI), however.
Arc of Motion for the Elbow
0˚ extension to ~145˚ flexion (biceps stop the flexion range).
Can hyperextend ~10-15˚ due to laxity of ligaments or shortened olecranon process.
Motion needed for ADLs: 30˚ to 130˚.
Motions of Forearm
Rotary motions of Supination and Pronation only. Also prone to repetitive stress injury (RSI).
Interosseous Membrane
The tough, thin membrane that holds together the radius and ulna. Strengthens forearm against fractures from falls, etc.
Rotation of Radius and Ulna in supination/pronation
Ulna is held stable while radius rotates around it.
REMEMBER: (R)ADIUS = (R)OTATES
ROM norms for Supination/Pronation
0˚ to 80˚ for pronation and supination.
0˚-50˚ needed for ADLs (total Arc of Motion of 100˚).
Carrying Angle
Angle formed by long axis of humerus and long axis of forearm. To accommodate anatomy and to help angle hand toward mouth. Seen in anatomical position. Women’s hands extend out to sides more than men due to hips.
Women: 10-15˚, Men: 5˚
Cubital Varus vs. Cubital Valgus
Irregular carrying angles.
Cubital Varus = (inward) carrying angle less than 5˚. Also called “gun stock deformity.” Mal-alignment from supracondylar fractures.
Cubital Valgus = (outward) carrying angle greater than 15˚. Caused by fracture, Turner syndrome or Noonan syndrome. Can cause neuropathy and ulnar nerve palsy.
Musculocutaneous Nerve
Terminal nerve of the lateral cord of brachial plexus (C5-C7).
Innervates:
- Biceps (flexion and supination)
- Brachialis (flexion)
Radial Nerve
From posterior cord of brachial plexus; runs along radial side of arm (C5-C8).
Innervates:
- Triceps (extension)
- Anconeous (extension)
- Brachioradialis (flexion)
Posterior Interosseous Radial Nerve
Runs along radial side of arm (C6). Innervates:
- Supinator (supination)
Median Nerve
Has many “exits” along the arm. Runs along palmar side of arm. (C7-C8).
Innervates:
- Pronator Teres (pronation)