Temporomandibular joint and correlated fissures: anatomical and clinical consideration

An anatomical study of the fissures related to the temporomandibular joint (TMJ) was performed in 40 dry human skulls. The length of the squamotympanic fissure (X), as well as those of the petrotympanic fissure (Y) and the (descending part of) the petrosquamous fissure (Z), into which the first of them (as a rule) branches, was measured. The distances between the point of this bifurcation and the deepest point of the glenoid fossa (A), the articular tubercle (B), and the styloid process (C) of the TMJ were also measured. The distances measured presented a significant variability among different specimens. In particular, the lengths (X, Y, and Z) of some fissures measured twice as great compared to other ones. All distance measurements were expressed in mm. Dysfunction of the TMJ may lead to a variety of ear symptoms, i.e., otalgia, tinnitus, hearing loss, possibly vertigo and, less often, to tongue symptoms (collectively characterized as temporomandibular syndrome). These symptoms often relate to the important anatomic structures (anterior malleolar ligament, anterior tympanic artery and chorda tympani nerve) coursing (mainly) through the petrotympanic fissure, whose length and position may exert considerable impact. The measured distances (hardly assessable through a plain radiogram) may also be considered as parameters that need to be taken into account in view of an eventual replacement of a poorly functioning TMJ by a suitable prosthesis.