Myotome

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. 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. List of myotomes Myotome distributions of the upper and lower extremity are as follows; • 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 • L1/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 isometric resisted muscle testing, provides the clinician with information about the level in the spine where a lesion may be present. During myotome testing, the clinician is looking for muscle weakness of a particular group of muscles. Results may indicate lesion to the spinal cord nerve root, or intervertebral disc herniation pressing on the spinal nerve roots. ==References==