N. axillaris, anatomy and motor function
- Runs out just below the shoulder joint and along the collum chirurgicum
- Innervates M. deltoideus and M. teres minor
- M. deltoideus
- Shoulder abduction > 20° (middle part), flexion and internal rotation (anterior part), extension and external rotation (posterior part)
- M. teres minor
- Shoulder external rotation, slight adduction, and pulls humerus up against glenoid fossa
M. deltoideus and M. teres minor (N. axillaris, C5)
N. axillaris, sensory function
Sensibility lateral shoulder
N. axillaris, injury
- Can be injured in fractures of the surgical neck, anterior shoulder dislocation, and pressure against the axilla
- Numbness in the lateral shoulder
- Weakness in shoulder abduction
- Muscle atrophy of the deltoid muscle
- Deformity
- Shoulder in adduction (weak deltoid muscle, normal pectoralis major)
- Shoulder in internal rotation (weak teres minor, normal subscapularis)