SPINAL CORD FUNCTIONING AT C3

• The nerve root of C3 runs between vertebrae C3 and C4. 

• Motor function includes:

  • weak diaphragm

  • usually unable to sustain ventilation

  • weak neck movement (sternocleidomastoid present, weak trapezius) 

What Sensory Function is Consistent with C3?

• C3 provides sensation for lower neck. 

Assessment of C3 Motor Function

• Evaluate ability to contract neck muscles (NOTE: cervical spine immobilization limits ability to assess during acute phase).
• Place examiner's hand over trapezius and ask patient to shrug shoulder.  Assess motor function.  C3 function will provide only weak neck function.
• Assess ability to turn cheek from side to side (sternocleidomastoid). NOTE: only assess after cervical immobilization has been discontinued.  Muscle strength can be assessed by having patient turn cheek against examiner's resistance.

Assessment of C3 Sensory Function

• Test one side, then test same spot on opposite side
• Always apply the same amount of pressure to each side
• Ask patient to compare sensation on side A to side B
• Conceal test from the patient
  • Light touch:
    • use wisp of cotton or tissue; touch neck on either side and assess sensatio
  • Sharp or temperature touch:
    • use safety pin, cap of pen or ice cube (do not use needle); assess neck on either side

Expected Outcome

• swallowing
• speaking
• usually ventilator dependent