A myotome is most often defined as a group of muscles that are innervated by a single spinal nerve root. The tissue can involve either whole or parts of a muscle. Myotomes are responsible for a significant number of the body's motor functions. In embryology, a myotome is also defined as a tissue group that develops along the body wall in vertebrate embryos. The tissue later develops into several striated muscle groups, excluding those of the heart.
Mytome innervation results in several essential body movements, including the bending and straightening of the knees and elbows. Myotomes are also responsible for fanning and bending fingers, rotating the foot, and flexing the hip. Other motor functions involve involuntary muscle movement in organs such as bowels, diaphragms, and genitalia.
Dermatomes, skin cells supplied by a single spinal nerve root, work hand-in-hand with myotomes to produce reflexes. External stimuli register the sensation of touch on one or several dermatones, which then sends impulses to the myotomes for the appropriate bodily reaction. For example, when a finger is put into an open flame, the dermatome will send signals to the brain indicating heat and pain. The brain will respond by innverating the myotome groups responsible for jerking the finger away from the flame.
Doctors refer to myotome maps to determine several symptoms of possible nerve damage. Along with reflex tests, muscle strength tests in areas supplied by myotomes can help diagnose any areas in which nerve cell activity is either deficient or absent. These tests are often used in patients who suffered injury to the spinal cord. Alternatively, doctors can also use a patient's reported symptoms to identify damaged nerves according to their locations on the myotome map.
In cases of serious nerve damage, physical therapists can use myotome maps to aid in speedier recovery. Stimulating areas of the body that cause myotomes to react can rehabilitate weakened nerves. The results of regular myotome testing can be used to monitor the effectiveness of the therapy, allowing therapists to make appropriate adjustments in case of deficiencies.
Embryological myotomes, on the other hand, are responsible for the development of back, abdominal, and limb muscles. The myotomes develop from somites in the body wall and divide into dorsal and ventral parts, which then become the different trunk muscles respective to their location. Deficiencies in myotome development can lead to birth defects, such as quadriplegia and leptokurtic, or hunched spinal formation.