Myotome

A myotome is the group of

The anatomical term myotome which describes the muscles served by a spinal nerve root, is also used in embryology to describe that part of the somite which develops into the muscles.^[3] In anatomy the myotome is the motor equivalent of a dermatome.

Function

Each muscle in the body is supplied by one or more levels or segments of the spinal cord and by their corresponding spinal nerves. A group of muscles innervated by the motor fibres of a single nerve root is known as a myotome.^[4]

List of myotomes

Myotome distributions of the upper and lower extremity are as follows;^[5][6]

• C1/C2: neck flexion/extension
• C3: Lateral Neck Flexion
• C4: shoulder elevation
• C5: Shoulder abduction
• C6: Elbow flexion/Wrist Extension
• C7: Elbow extension/Wrist flexion
• C8: Thumb extension
• T1: Finger Abduction & Adduction^{[citation needed]}
• L2
  : Hip Flexion
• L3
  : Knee extension
• L4
  : Ankle dorsi-flexion
• L5
  : Great toe extension
• S1: Hip extension/Ankle plantar-flexion/ankle eversion
• S2: Knee flexion
• S3–S4: anal wink

Clinical significance

In humans myotome testing can be an integral part of neurological examination as each nerve root coming from the spinal cord supplies a specific group of muscles. Testing of myotomes, in the form of

References