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Updated: Aug 10, 2026

Muscle Receptor Organs in the Crayfish Abdomen: A Student Laboratory Exercise in Proprioception
Published on: November 18, 2010
Muscle spindles in the inferior constrictor pharyngis muscle of the crab-eating monkey (Macaca irus)
Abstract:
Pharyngeal muscles were considered to be lacking in spindles. A search was made for the same in the inferior constrictor pharyngis muscle of the crab-eating monkey (Macaca irus). Muscle spindles were found for the first time in this muscle. Transverse serial sections and teased preparations were obtained from this muscle belonging to six such animals, and these tissues were stained by Masson's trichrome and Ranvier's gold method, respectively. Both the methods were successful in revealing these receptors. The potential significance of this finding was discussed in relation to the activities of the pharyngeal muscles and a suggestion for a thorough re-investigation of the so-called spindleless muscles was made.
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