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Dermatomes and Myotomes
Dermatomes are areas on the surface of the skin that are control by specific nerve roots
from the spinal cord
Myotomes correspond to muscles that are controlled by specific nerve roots from the
spinal cord

Cranial Nerves branch out off the brain (12)
info.med.yale.edu/ caim/cnerves/

Nerve Roots branch out off the spinal cord (31)
www.informeddecision.com/options/ lowback/dclmlama.htm
These nerve roots branch out to form a plexus which is a network of intersecting nerves
which travel to different parts of the body, they are both motor and sensory
Cervical Plexus
C1-C4 nerve roots innervate the diaphragm, shoulder and neck.
info.med.yale.edu/
Brachial Plexus
C5-T1 nerve roots innervate the upper limbs
Lumbosacral Plexus L1- L5, S2 nerve roots innervate the lower extremity
depts.washington.edu/anesth/ regional/femoralimage.html

Skin (sensation) is innervated by a single nerve roots called the dermatomes

Muscles (movement) are innervated by singe nerve roots called myotomes

Nerves and nerve roots are typically injured by compression or stretching forces

When a nerve root is damaged a deficit may occur in the corresponding limb

The evaluation of nerve root damage can be done by testing dermatomes and
myotomes

Nerve root trauma should always be inspected by a physician
Dermatomes

Test for abnormalities in sensitivity by using a pinwheel, paper clip or finger nail

The athlete should close his/her eyes and give the therapist feedback with regards
to various stimuli

All tests should be compared bilaterally
Nerve Root
Dermatome Patterns
Upper Extremity
C1
C2
C3
C4
C5
C6
C7
C8
T1
Top of head
Temporal & occipital regions of head
Neck and posterior cheek
Superior shoulder and clavicle
Deltoid patch & lateral arm
Lateral forearm, thumb and index finger
Posterior lateral forearm & middle finger
Medial forearm, ulna border & ring/little fingers
Medial side of forearm & upper arm
Lower Extremity
L1
L2
L3
L4
L5
S1
S2
Back, hip and groin
Anterior superior thigh, medial thigh above knee
Back, anterior thigh and medial knee
Lateral thigh/knee, anterior medial lower leg to
medial aspect of big toe
Lateral knee and lateral lower leg and top of foot
Buttocks, posterior lateral thigh and lateral plantar
surface of foot
Buttocks, posterior medial thigh and medial plantar
surface of foot
Myotomes

Test with resistive exercises

The trainer will check for weakness in strength

All tests should be compared bilaterally
Upper Extremity Nerve Routes
C4
C5
C6
C7
C8
T1
tested with resisted shoulder shrugs/elevation
tested with resisted shoulder abduction
tested with resisted elbow flexion
tested with resisted wrist flexion
tested with resisted thumb extension
fingers abduction & adduction
Lower Extremity Nerve Routes
The quick test for the lower extremity, to rule out a nerve root injury is to have the athlete
do a squat.
L1-L2
L3
L4
L5
S1/S2
tested with resisted hip flexion
tested with resisted knee extension
tested with resisted foot dorsi flexion
tested with resisted great toe extension
tested with plantar flexion