Structure of the Middle Ear and Auditory Tube in the House Musk Shrew, <i>Suncus murinus</i>

Abstract

Anatomical features of the middle ear and auditory tube (AT) in the house musk shrew, Suncus murinus, were examined by dissection and light microscopy. The tensor veli palatini (TVP) and tensor tympani (TT) have no connections with the wall or cartilage of the AT although they are connected by the intermediate tendon. None of the levator veli palatini (LVP) muscle bundles are attached to the AT. The salpingopharyngeus (SA) alone has its origin on the caudal edge of the tubal cartilage. The origin extends to the pharyngeal two thirds of the cartilage. The SA originates perpendicular to the AT and runs caudomedialward. Some SA muscle bundles intermingle with those of the palatopharyngeus to end on the dorsal wall of the pharynx. The observations provide no evidence that the TVP, LVP and TT have any role in AT function. The only muscle affecting the AT function in S. murinus is the SA, and it would be the AT dilator.

Structure of the Palate and Pharynx in the House Musk Shrew <i>(Suncus murinus)</i>

“…The aperture of the auditory tube opening at the lateral wall of the nasopharynx is close to the nasopharyngeal hiatus. Air can be conveyed into or out of the ME through the auditory tube opened by its only muscle, the salpingopharyngeus [Yoshida et al, 2000]. The ME enclosure of S. murinus is a thin, inflated covering of connective tissue with a bassinet-shaped framework.…”

“…The ME enclosure of S. murinus is a thin, inflated covering of connective tissue with a bassinet-shaped framework. The LVP, TVP, stylohyoideus and pterygoideus medialis of S. murinus [Yoshida et al, 2000] are fastened by sheets of tough connective tissue on the outer wall of the membranous ME enclosure. The structural relationship indicates that compression of the ME enclosure by the action of the four muscles brings an increase of air pressure in the ME.…”