Knowledge Base

Anatomy of upper body muscles, innervation and their action

• Shoulder abduction/deltoid: (C5,6)
• Shoulder adduction/:
• Elbow flexion/biceps: (C5,6)
• Elbow extension/triceps: (C6,7,8)
• Wrist flexion/ :
• Wrist extension/: (C6,7,8)
• Finger abduction: (C8,T1) Ulnar nerve
• Thumb opposition: (C8,T1) Median nerve

Upper arm innervation

• Ulnar
• Radial
• Median

Distributionand degree of weakness as a diagnostic clue to site of lesion

• Segmental (Nerve root)
• Territory of (One peripheral nerve)
• Proximal (Myopathies)
• Distal (Neuropathy)
• One sided (Upper motor neurone)
• Spinal level /paraplegia (Spinal cord)
• Generalized (Wasting disorders)

Diseases causing lesions of nerve or muscle

• Nerve root: (Herniated disc)
• Peripheral nerve: (Trauma, mononeuritis, diabetes, distant malignant manifestation)
• Muscle: (Myopathy, myasthenia, muscular dystrophy)
• Upper motor neurone: (CA, intracranial space occupying lesion)
• Spinal cord: (Injury, transverse myelitis, multiple sclerosis)
• General: (Malnutrition, thyrotoxicosis, malignancy, prolonged bed rest)

Ref:

1. Bates, A Guide to Physical Exam....485-495.
2. Review Dr. McNulty's lesson, "Master Muscle List".
3. Castro, Mosby's....Neuroscience, 146-8.