Myotomes, Dermatomes and Reflexes

Myotomes

Upper Limb Myotomes

MovementNerve Root Segments
Shoulder girdle elevationC3/4
Shoulder flexion / abductionC5
Elbow flexionC5/6
Elbow extensionC7/8
Wrist flexion / extensionC6/7
Finger flexion / extensionC7/8
Finger abduction / adductionT1

Lower Limb Myotomes

MovementNerve Root Segments
Hip flexionL2/3
Hip extensionL4/5
Hip adductionL2/3
Hip abductionL4/5
Knee extensionL3/4
Knee flexionL5/S1
Ankle DorsiflexionL4/5
Great toe extensionL5
Ankle plantarflexionS1/2

Testing Power

Use the Oxford Scale

Oxford GradeDescriptor
0No signs of activity
1Flicker of activity, no movement
2Full active range of motion, across gravity
3Full active range of motion, against gravity
4Moderate resistance
5Maximal resistance

 

Dermatomes

Charts showing areas of skin where you would expect altered sensation following nerve root lesion

Upper Limb

Lower Limb

 

 

Chart showing where you might expect radicular pain to radiate

Reflexes

Upper Limb Reflexes

ReflexNerve Segments
Biceps JerkC5/6
Triceps JerkC7/8
Brachioradialis JerkC6/7

Lower Limb Reflexes

ReflexNerve Root Segments
Knee JerkL3/4
Ankle JerkS1/S2

Babinski Test

  • The Babinski test (“plantars”) can be abnormal in the present of upper motor neuron damage.
  • A normal response is flexion of the toes
  • An abnormal response involves dorsiflexion of the great toe and fanning of the other toes