Motor Units of Laryngeal Muscles

Abstract

DURING 'URING the last few years, work in our laboratory has been directed toward the fine neuromuscular substrate of muscles of the middle ear and the larynx. Our interest in these particular muscles is based on the following observations. First, the laryngeal and tympanic muscles are delicately interrelated in vocalization and hearing, especially in those animals which exhibit echolocation.^1,2Man is less dependent on sound for environmental orientation than other animals, but his speech and behavior patterns are greatly affected by acoustic feedback as the voice blends with other sounds of his internal and external environments. Second, laryngeal muscles, like those of the middle ear are derived from branchial arch mesoderm and are supplied by special visceral efferent motor neurons. The tensor tympani and stapedius muscles exhibit delicately coordinated contractions as they modify sound transmission across the middle ear. This behavior is apparently dependent upon a rich nerve supply