Table of ContentsView AllTable of ContentsHow Myotomes WorkMyotomes vs. DermatomesTypesTestingBenefits
Table of ContentsView All
View All
Table of Contents
How Myotomes Work
Myotomes vs. Dermatomes
Types
Testing
Benefits
Myotomes are groups of muscles that receive signals from a singlespinal nerve root. These muscle groups work together to perform a specific motor function.
If you have signs of nerve damage, your healthcare provider orphysical therapistmay do myotome testing. Along with reviewing your history and a physical examination, these tests help determine the nerve root(s) that could be causing problems.
Once the area of your spine is identified, your provider can target treatment to alleviate the pain and heal the damage.
Nazar Abbas Photography / Getty Images
How Myotomes Function
Myotomes are part of the somatic (voluntary) nervous system, which is part of yourperipheral nervous system. The peripheral and central nervous systems communicate with one another.
The motor nerve roots are responsible for muscle movement. They branch out from the different parts of the spinal cord. A myotome is the group of muscles on one side of the body that receive signals from one nerve root.
Each nerve cell innervates (provides signals to) several muscle fibers.A single nerve and its corresponding muscle fibers comprise amotor unit. Every fiber that is part of a motor unit contracts (shortens) to move when its respective nerve is fired.
All this is signaling happens at the microscopic level. A many-fibered muscle contains an innumerable collection of motor units.
Myotomes are often assessed alongside dermatomes.
Types of Myotomes
Researchers have mapped specific muscle movements to specific myotomes.These include cervical (C), thoracic (T), lumbar (L), and sacral (S) myotomes.
How Myotome Testing Works
Myotome testing helps identify muscle weakness in certain muscle groups. This information can help your healthcare identify the specificspinal nerve(s)that may be causing muscle weakness.
During myotome testing, the examiner will ask you to perform certain movements. They will use resistance to determine the strength of each muscle group.
For example, if you have difficulty resisting downward pressure when raising your arm and shoulder, you likely have an injury in the C5 nerve root.
Grading Muscle FunctionDuring myotome testing, motor strength is graded on a scale of 0 to 5 with 0 indicating total paralysis and 5 indicating normal movement.
Grading Muscle Function
During myotome testing, motor strength is graded on a scale of 0 to 5 with 0 indicating total paralysis and 5 indicating normal movement.
Benefits of Myotome Testing
Identifying the nerve root correlated to specific injuries or pain allows healthcare providers to target therapies to treat those specific areas.
Spinal treatments may involve nonsurgical options such as physical therapy, medications, orepidural steroid injectionor surgical procedures such asfusion of spinal discsordiscectomy(removal of a damaged disc).
Summary
Myotomes are groups of muscles that receive signals from a specific spinal nerve root. If you have damage in one of these nerve roots, you may have weakness in the associated muscle group.
During myotome testing, you’ll be asked to perform certain movements while the examiner provides resistance. The results of this test can help your healthcare provider identify the nerve root where the injury occurred and the severity of the problem.
4 SourcesVerywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8:293. doi:10.3389/fncel.2014.00293Hong CG, Nam WD.Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy.Neurospine. 2022;19(4):1006-1012. doi:10.14245/ns.2244194.097Van Straaten MG, Cloud BA, Morrow MM, Ludewig PM, Zhao KD.Effectiveness of home exercise on pain, function, and strength of manual wheelchair users with spinal cord injury: a high-dose shoulder program with telerehabilitation.Arch Phys Med Rehabil. 2014;95(10):1810-1817.e2. doi:10.1016/j.apmr.2014.05.004Roberts TT, Leonard GR, Cepela DJ.Classifications In Brief: American Spinal Injury Association (ASIA) Impairment Scale.Clin Orthop Relat Res. 2017;475(5):1499-1504. doi:10.1007/s11999-016-5133-4Additional ReadingBarkhaus, P., M.D., et. al.EMG Evaluation of the Motor Unit - Electrophysiologic Biopsy. Medscape. Aug 2013.Magee, David, J. Orthopedic Physical Assessment. 4th Edition. Saunders Elsevier. St. Louis, MO. 2006.
4 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8:293. doi:10.3389/fncel.2014.00293Hong CG, Nam WD.Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy.Neurospine. 2022;19(4):1006-1012. doi:10.14245/ns.2244194.097Van Straaten MG, Cloud BA, Morrow MM, Ludewig PM, Zhao KD.Effectiveness of home exercise on pain, function, and strength of manual wheelchair users with spinal cord injury: a high-dose shoulder program with telerehabilitation.Arch Phys Med Rehabil. 2014;95(10):1810-1817.e2. doi:10.1016/j.apmr.2014.05.004Roberts TT, Leonard GR, Cepela DJ.Classifications In Brief: American Spinal Injury Association (ASIA) Impairment Scale.Clin Orthop Relat Res. 2017;475(5):1499-1504. doi:10.1007/s11999-016-5133-4Additional ReadingBarkhaus, P., M.D., et. al.EMG Evaluation of the Motor Unit - Electrophysiologic Biopsy. Medscape. Aug 2013.Magee, David, J. Orthopedic Physical Assessment. 4th Edition. Saunders Elsevier. St. Louis, MO. 2006.
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read oureditorial processto learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8:293. doi:10.3389/fncel.2014.00293Hong CG, Nam WD.Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy.Neurospine. 2022;19(4):1006-1012. doi:10.14245/ns.2244194.097Van Straaten MG, Cloud BA, Morrow MM, Ludewig PM, Zhao KD.Effectiveness of home exercise on pain, function, and strength of manual wheelchair users with spinal cord injury: a high-dose shoulder program with telerehabilitation.Arch Phys Med Rehabil. 2014;95(10):1810-1817.e2. doi:10.1016/j.apmr.2014.05.004Roberts TT, Leonard GR, Cepela DJ.Classifications In Brief: American Spinal Injury Association (ASIA) Impairment Scale.Clin Orthop Relat Res. 2017;475(5):1499-1504. doi:10.1007/s11999-016-5133-4
Stifani N.Motor neurons and the generation of spinal motor neuron diversity.Front Cell Neurosci. 2014;8:293. doi:10.3389/fncel.2014.00293
Hong CG, Nam WD.Reliability and Diagnostic Accuracy of Standard Dermatomes and Myotomes for Determining the Pathologic Level in Surgically Verified Patients With Cervical Radiculopathy.Neurospine. 2022;19(4):1006-1012. doi:10.14245/ns.2244194.097
Van Straaten MG, Cloud BA, Morrow MM, Ludewig PM, Zhao KD.Effectiveness of home exercise on pain, function, and strength of manual wheelchair users with spinal cord injury: a high-dose shoulder program with telerehabilitation.Arch Phys Med Rehabil. 2014;95(10):1810-1817.e2. doi:10.1016/j.apmr.2014.05.004
Roberts TT, Leonard GR, Cepela DJ.Classifications In Brief: American Spinal Injury Association (ASIA) Impairment Scale.Clin Orthop Relat Res. 2017;475(5):1499-1504. doi:10.1007/s11999-016-5133-4
Barkhaus, P., M.D., et. al.EMG Evaluation of the Motor Unit - Electrophysiologic Biopsy. Medscape. Aug 2013.Magee, David, J. Orthopedic Physical Assessment. 4th Edition. Saunders Elsevier. St. Louis, MO. 2006.
Barkhaus, P., M.D., et. al.EMG Evaluation of the Motor Unit - Electrophysiologic Biopsy. Medscape. Aug 2013.
Magee, David, J. Orthopedic Physical Assessment. 4th Edition. Saunders Elsevier. St. Louis, MO. 2006.
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