Amyotome is the group ofmuscles that a singlespinal nerve innervates.[1] Similarly adermatome is an area ofskin that a single nerve innervates with sensory fibers. Myotomes are separated bymyosepta (singular:myoseptum).[2] Invertebrateembryonic development, a myotome is the part of asomite that develops into muscle.
Structure
editThe anatomical term myotome which describes the muscles served by a spinal nerve root, is also used in embryology to describe that part of thesomite which develops into the muscles.[3] In anatomy the myotome is the motor equivalent of adermatome.
Function
editEach 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
editMyotome 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]
- 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
editIn 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 ofisometric resisted muscle testing, provides the clinician with information about the level in the spine where a lesion may be present.[7] 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, orintervertebral disc herniation pressing on thespinal nerve roots.
References
edit- ^Dorland's Illustrated Medical Dictionary 2012 Page 1226
- ^"Medical Definition Of MYOSEPTUM". 2018. Merriam-Webster.Com.https://www.merriam-webster.com/medical/myoseptum.
- ^Larsen, William J. (2001).Human embryology (3. ed.). Philadelphia, Pa.: Churchill Livingstone. p. 86.ISBN 0-443-06583-7.
- ^Apparelyzed:Myotomes & Dermatomes
- ^Magee, David. J (2006). "3".Orthopaedic Physical Assessment (4th ed.). St. Louis: Elsevier. pp. 121–181.ISBN 978-1-4160-3109-3.
- ^Magee, David. J (2009). "9".Orthopaedic Physical Assessment (4th ed.). St. Louis: Elsevier. pp. 467–566.ISBN 978-1-4160-3109-3.
- ^Magee, David. J (2006). "1".Orthopaedic Physical Assessment (4th ed.). St. Louis: Elsevier. pp. 1–63.ISBN 978-1-4160-3109-3.
Further reading
edit- Neurology Textbook, edited by Professor L. Sokolva, M.D., D.Sc. 2012,ISBN 9789663824260