Force and Contraction Velocity of the Middle Ear Muscles in the Gat and the Rabbit

Contractions of the stapedius and the tensor tympani muscles in cats and rabbits have been elicited at controlled length by electric stimulation of their motor nerves at varying stimulus frequencies. Both muscles were stronger than found in previous investigations. The tetanic tension of the stapedius was an average of 13.9 g (cat) and 15.4 g (rabbit). The tetanic tension of the tensor tympani averaged 54.3 g (cat) and 32.3 g (rabbit). By comparing the data from cats with the findings of Wever and Bray (1937, 1942) each muscle developed sufficient tension to cause a reduction in the sound transmission of the middle ear of more than 20 dB. With a twitch contraction time between 20 and 30 ms both muscles must be classified as fast muscles. However, different degrees of submaximal stimulation gave evidence for an additional slow twitch component in the tensor tympani muscle.