Myogenic tone

Muscle tone can be defined for any muscular tissue.
Tone: is a sustained contraction in the muscle and can be subdivided into Myogenic and Neurogenic.
source of Myogenic tone is muscle cells itself without any external innervation.
in contrast; source of the Neurogenic tone is innervation from central nervous system which is handled by "autonomic nervous system".
a good example for myogenic tone is the lower esophageal sphincter which close the lower end of the esophagus by 10 to 40 mmHg of pressure to prevent acidic gastric contents entering the lower esophagus.
upper esophageal sphincter also closes the upper end of esophagus to prevent air entering to esophagus, but this contraction is neurogenic tone by 100 to 200 mmHg of pressure.