What Motor Function is Consistent with 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 



Barr, M, and Kiernan, J. (1993). The Human Nervous System: An Anatomical Viewpoint. Philadelphia: Lippincott. pp 84-85.

Keppler, J. (1987). Acute spinal cord injury. Critical Care Clinics. July. 3:3. pp. 638-641.

Netter, F. (1989). Atlas of Human Anatomy. New Jersey: Novartis.

Waxman, S. (1996). Correlative Neuroanatomy. 23rd Ed.  Stamford: Lange. pp 46-52, 352-355, 370.

Brenda Morgan
Clinical Nurse Specialist, CCTC
May 11, 2001. Updated: January 15, 2019