Muscle spindles in nonhuman primate extrinsic auricular muscles.

Muscle spindles were sought in peri-auricular muscles of several primate species (rhesus monkey, woolly monkey, and baboon). Transverse sections cut at 10 mu and stained primarily by a silver impregnation technique were examined using light microscopy. Spindles were identified on the basis of standard criteria. Posterior and/or superior auricular muscles of each species were found to contain spindles. At least some muscles innervated by facial nerve have classical spindles as component structures.