An exceptionally high density of muscle spindles in a slow-tonic pigeon muscle.
Histochemical and histological observations on the tiny wing muscle, M. coracotriceps, of the pigeon revealed a remarkably high density of muscle spindles (14,582 +/- 2,302/g of muscle)--approximately 15 times the highest densities hitherto reported for any muscle. Furthermore, all of the extrafusal fibers of this muscle were of the slow-tonic variety. This unique muscle probably functions as a mechanoreceptor extremely sensitive to changes in its own length.
D000818:Animals; D010856:Columbidae / Q000033:anatomy & histology*; D008322:Mammals; D008465:Mechanoreceptors / Q000502:physiology; D009119:Muscle Contraction; D009470:Muscle Spindles / Q000648:ultrastructure*; D009132:Muscles / Q000502:physiology / Q000648:ultrastructure