The attic space--its development and some species differences.
The attic space of the rat has been described. The lateral attic compartment is connected with the rest of the middle ear through a narrow opening--the isthmus tympanicus. Part of this lateral compartment seems to correspond to Prussak's space in the human. The attic space develops later than the rest of the middle ear cavity and is not fully developed until the external auditory canal is established. Most mammals seem to have an attic space similar to that of the rat. The size of pars flaccida relative to that of pars tensa, however, differs between species. It is interesting to note that an extremely earthbound animal such as the hedgehog has an extremely large pars flaccida, whereas guinea pig, emanating from high altitude life, has its pars flaccida converted into bony lamella. In this context it is also noteworthy that the bird investigated has only a rudimentary pars flaccida. On the basis of the presented findings it is tempting to speculate that the attic space is of importance for the pressure-equilibration of the middle ear cavity. The space needs to be ventilated. If not sufficiently ventilated, pathological conditions affecting this part of the middle ear cavity may start. To obtain conclusive evidence for these suppositions, further research is needed. Such studies are already in progress.
D000818:Animals; D002645:Chickens; D004424:Ear Canal / Q000196:embryology; D004432:Ear, Middle / Q000033:anatomy & histology*; D005260:Female; D005865:Gestational Age; D006168:Guinea Pigs; D006364:Hedgehogs; D051381:Rats; D013045:Species Specificity