Lecture Notes: Elbow Movement and Muscles

Primary Elbow Flexors

Brachialis

• Strong elbow flexor
• Effective regardless of the type of load (external or internal) or speed of movement
• Strongest in elbow flexion at 100°
• Weak in assisting with pronation and supination

Biceps Brachii

• Multi-joint muscle crossing the elbow, forearm, and shoulder
• Most efficient at 90° of elbow flexion and forearm supination
• Nearly inactive when forearm is in pronation

Brachioradialis

• Origin near end of humerus and insertion on radial bone
• Helps in elbow flexion, pronation, and supination
• Most effective when forearm is in neutral position

Primary Elbow Extensors

Triceps Brachii

• Three heads: long head, lateral head, medial head
• Active in resistive concentric or eccentric movements
• Long head less efficient when elbow and shoulder are both in extension
• Medial head stronger in unresisted elbow extension

Anconeus

• Small muscle but important for initiating and maintaining elbow extension
• Stabilizes the joint

Range of Motion and Functional Limits

• Flexors are stronger than extensors
• Normal range: 0° to 140-150°
• Functional range: 30° to 130°
• Most ADLs (Activities of Daily Living) require an elbow arc from 60° to 120°
• End feel: soft for flexion, hard for extension

Elbow Measurement and Carrying Angle

• Best elbow flexion achieved with forearm in neutral position
• Measurement: shoulder adducted, arm close to body
• Carrying angle (cubitus valgus): 5° in men, greater in women

Elbow Joint Composition

• Three joints: humeroulnar, humeroradial, and proximal radioulnar
• Surrounded by ligaments
  • Medial collateral ligaments
  • Lateral collateral ligaments
  • Annular ligament (stabilizes radial head for pronation/supination)