The structures of the auditory tube in horses were investigated in res
pect to the opening mechanism. Macroscopic preparation techniques were
used and the results were compared with the findings of endoscopical
inspection of the nasopharynx. As for macroscopic anatomy the shape an
d the position of the cartilage of the auditory tube as well as its su
rrounding mucous membrane are presented. Close to the pharyngeal orifi
ce ol the auditory tube, the mucous membrane forms a distinct plica, w
hich is functionally important, but until now only sparsely documented
. Further the position and the course of the adjoining M. tensor veli
palatini, M. levator veil palatini, Mm. pterygo- and palatopharyngeus
are demonstrated. The endoscopical investigation indicates that - with
regard to the opening mechanism of the auditory tube - the M. pterygo
pharyngeus is the main actor: muscle contraction causes the large cart
ilage flap to bend and thus the pharyngeal orifice is widened. In the
initial phase, the M. tensor veli palatini and M. levator veli palatin
i assist in this process.