Relationships between spindle density, muscle architecture and fibre type composition in different parts of the rabbit masseter.
The occurrence of muscle spindles was studied in the masseter muscle of rabbits by light-microscopy of whole muscle sections. The distribution of the spindles appeared to be heterogeneous. Most spindles lay in the anterior/deep and mid-parts of the masseter. The lateral/superficial part contained only a few muscle spindles. The distribution of the spindles is correlated to the distribution of slow twitch (type I) extrafusal fibres. This means that spindles, like type I fibres might be involved in the control of fine movements and posture. Spindle density and type I fibre density increase with distance from the temporomandibular joint. This could mean that spindles are involved in controlling bite force.
Bredman
J J
JJ
Department of Functional Anatomy, Academic Centre for Dentistry Amsterdam (ACTA), The Netherlands.
Weijs
W A
WA
Brugman
P
P
D000818:Animals; D008297:Male; D008406:Masseter Muscle / Q000033:anatomy & histology*; D009470:Muscle Spindles / Q000033:anatomy & histology*; D011817:Rabbits