Assertion: mastoid process's portion | /r/MadeOf | tympanic sulcus
Facets:
Source sentences:
text: Its middle portion contains the tympanic sulcus, a groove that attaches to the tympanic membrane, better known as the eardrum.
text: Its middle portion contains the tympanic sulcus, a groove that attaches to the tympanic membrane, better known as the eardrum.