Dermatomes and Myotomes
Dermatome and Myotome Video!!
A major component of musculoskeletal assessment is determining the distribution of peripheral nerves and dermatomes. A dermatome is an area of skin that is innervated by the sensory fibers of a single spinal nerve or cranial nerve. A myotome is a muscle or group of muscles innervated by a specific motor nerve.
Testing a dermatome:
Superficial sensation:
-touch with cotton
Superficial pain:
-touch with pin
Deep pressure pain:
-squeeze a muscle
Sensitivity of temperature:
-touch with ice cube
Sensitivity of vibration:
-touch with tuning fork
Position sense:
-move toes passively and ask athlete to indicate direction
Lower Body Myotomes:
L2/L3: Hip flexion, adduction
L3/L4: Knee extension
L4/L5: Hip extension, abduction, ankle dorsiflexion
L5: Great toe extension
L5/S1: Knee flexion
S1/S2: Ankle plantar flexion
Lower Body Reflexes
Knee Jerk
-L3/L4
Ankle Jerk
-S1/S2
