The eustachian tube caliber and craniofacial skeleton in guinea pigs.

The temporal bone and eustachian tube (ET) keep developing up to adulthood in conjunction with facial growth, and the researchers considered that insufficient tubal function in childhood might be related to size, shape and position of the ET. In this study, we performed correlation and stepwise regression analyses between craniofacial skeletal parameters and diameter of the cartilaginous ET in 90 guinea pigs. Data showed that, not the potency of the lumen at the superior part of the cartilaginous ET, but the configuration of the cartilage surrounding the superior part of the ET, and position of the lateral lamina appeared to be significantly associated with the balance of the growth potentials between the naso-premaxillary unit, maxillo-zygomatic unit and the anterior cranial base. Therefore, we may hypothesize that the balance between these subunits of the developing craniofacial skeleton has determinative effect on tensor veli palatini muscle (TVPM).

Anatomy of the guinea pig temporal bone.

The middle ear of guinea pigs has long been used for experimental studies, but no detailed information about its temporal bone anatomy is available. In 18 adult guinea pigs, the temporal bone, eustachian tube, and inner ear anatomy, in addition to the anatomy of the middle ear, were investigated under the dissection microscope. In addition to properties of the eardrum, ossicles, air cell system, and cochlea previously described, the appearance of Huschke's foramen and the crista stapedis in an adult guinea pig ear, the structure of the eustachian tube, the architecture of the internal auditory canal, and the communication of the mastoid cells with the tympanic bulla are described. Differences and similarities among guinea pigs, other experimental animals, and humans are discussed to show the advantages and disadvantages of the guinea pig ear for experimentation.