Myotome#Myosepta

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.{{cite book|last1=Larsen|first1=William J.|title=Human embryology|date=2001|publisher=Churchill Livingstone|location=Philadelphia, Pa.|isbn=0-443-06583-7|edition=3.|page=86}} In anatomy the myotome is the motor equivalent of a dermatome.

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.[http://www.apparelyzed.com/myo-dermatomes.html Apparelyzed: Myotomes & Dermatomes]

Myotome distributions of the upper and lower extremity are as follows;{{cite book|title=Orthopaedic Physical Assessment|last=Magee|first=David. J|publisher=Elsevier|year=2006|isbn=978-1-4160-3109-3|edition=4th|location=St. Louis|pages=121–181|chapter=3}}{{cite book|title=Orthopaedic Physical Assessment|last=Magee|first=David. J|publisher=Elsevier|year=2009|isbn=978-1-4160-3109-3|edition=4th|location=St. Louis|pages=467–566|chapter=9}}

• 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{{cn|date=November 2021}}
• 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

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.{{cite book|last=Magee|first=David. J|title=Orthopaedic Physical Assessment|year=2006|publisher=Elsevier|location=St. Louis|isbn=978-1-4160-3109-3|pages=1–63|edition=4th|chapter=1}} 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.

{{Reflist}}

• Neurology Textbook, edited by Professor L. Sokolva, M.D., D.Sc. 2012, {{ISBN|9789663824260}}

• {{EmbryologyUNSW|Notes/skmus7}}
• {{EmbryologyUNSW|Notes/week3_6}}
• {{EmbryologyUNC|mslimb|009}}

Category:Neurology