Abstract Volume 114 Issue 2 (1997) pp 371-376
T. S. Miles, A. V. Poliakov
Abstract During chewing, the force exerted by the jaw-closing muscles
must constantly adapt to changing resistances between the teeth, as the
food is broken down. In the present study, the changes in biting force resulting
from small, controlled displacements imposed on isometrically contracting
jaw-closing muscles were measured. We found that the force changes resulting
from small loading and unloading movements were normally highly symmetrical.
The initial force change was linear, and preceded the onset of reflex changes
in muscle activity. Later changes in force were the result of both short-
and long-latency reflexes in the jaw-closing muscles, the long-latency component
being quantitatively greater. The long-latency unloading reflex in the jaw-closing
muscles has not been described hitherto. The symmetry of force increase
with loading and decrease with unloading was absent in one subject with
atypical stretch and H-reflexes.
Key words Stretch; Unloading; Reflex; Stiffness