Motor Exam

Aka: Motor Exam, Strength Grading, Muscle Strength, Myotomes, Motor Nerve, Motor Root, Motor Neurons, Motor Strength

1. Signs: Upper motor neuron lesion findings
   1. Muscle group weakness (not complete paralysis)
   2. Minimal muscle atrophy
   3. "Clasp-knife" spasticity
      1. Initial resistance to motion is strongest
      2. Once initial resistance gives-way, resistance to motion is less for remaining range of motion
   4. Hyperreflexia with or without Clonus
   5. Babinski reflex positive response
   6. Pathologic spread of reflexes
      1. Muscle contractions produce motions in muscles other than the one tested
   7. Precaution
      1. Cauda equina are all peripheral nerves
      2. Upper motor neuron findings for levels below T12 or L1 must be central lesions in the higher cord
         1. Strongly consider severe Cervical Spinal Stenosis
   8. Reference
      1. Robbins (2012) Board Review Express, San Jose
2. Exam: Muscle Strength Grading
   1. Grade 0: Total Paralysis
   2. Grade 1: Palpable or visible contraction
   3. Grade 2: Full range of motion with gravity eliminated
   4. Grade 3: Full range of motion against gravity
   5. Grade 4: Full range of motion with decreased strength
   6. Grade 5: Normal Strength
   7. NT: Not testable
3. Exam: Common Motor deficits
   1. Ulnar Nerve: Claw Hand
   2. Radial Nerve: Wrist drop
   3. Median Nerve: Cannot make 'OK' Sign
   4. Peroneal Nerve: Foot drop
4. Exam: Higher Cervical Cord
   1. C2: Breathing
   2. C3-4: Spontaneous breathing, Trapezius function
   3. C4-6: Shoulder Flexion, Extension
5. Exam: Upper Extremity Strength
   1. C5: Deltoid Abduction at Shoulder
   2. C6: Biceps Flexion at Forearm
   3. C6: Wrist Extension (extensor carpi radialis)
   4. C7: Wrist Flexion
   5. C7: Elbow Extension (Triceps)
   6. C7: Finger Extension
   7. C8: Fingers Flexion middle finger (flex dig profundus)
   8. T1: Small finger abductors (abductor digiti minimi)
   9. T1: Interossei - Spread Fingers
6. Exam: Lower Extremity Strength
   1. L2-3: Hip flexors (Iliopsoas)
   2. L3-4: Knee Extension (Quadriceps)
   3. L4: Ankle dorsiflexion (tibialis anterior)
   4. L4: Anterior Tibial - Foot Inversion
   5. L5: Great toe extension (Extensor hallucis longus)
   6. L5: Foot dorsiflexion (Extensor digitorum longus)
   7. L5: Weak heel walking, foot drop
   8. S1: Ankle plantar flexors (Gastrocnemius, Soleus)
   9. S1: Toe walking