Sensory activity of the mandibular muscle receptor organ ofHomarus gammarus(L)

Abstract

The mandibular muscle receptor organ (Mand. M.R.O.) of Homarus gammarus (L) exhibits increased activity to receptor muscle (R.M.) contraction (decrease in length) and to stretch (increase in length). The sensory units of this receptor differ in their threshold to R.M. tension and in the frequency change they exhibit for a given increment in tension. The units fire tonically during maintained tension once their threshold has been reached. Both the number of active units and their frequency increase with R.M. tension. The Mand. M.R.O. is velocity sensitive and exhibits a higher degree of activity during rapid stretch. This dynamic response increases with rate of R.M. stretch. The activity of the Mand. M.R.O. sensory neurones is compared with that of other M.R.O.’s and the authenticity of some aberrant units is discussed.