Bones of the Skull 



Incisura parietalis 

 Sutura squamosomastoidea 



Canalis facialis 



Spina tympanica minor 

 Spina tympanica major,. _ 



Entrance to the 

 antrum tympanicum 



-- Spina tympanica major 

 r- Spina tympanica minor 



Non- ossified area 



Sulcus tympanicus 



12. Right temporal bone, os temporale, at the 7 th or 8 th 



year of life, seen from without and somewhat from below. 



(The pars tympanica has been shelled out and drawn separately in the lower part of the 

 figure; on the right it is seen from the outside, on the left from within.) 



The canaliculi caroticotympanici (for the r. caroticotympanicus a. carotis internae; 

 nn. caroticotympanici superior et inferior) usually two in number, are openings or short canals 

 which pass from the posterior wall of the canalis caroticus immediately over the foramen 

 caroticum extemum to the cavum tympani and open in the latter on its anterior wall (see 

 Organ of Hearing). 



The pars tympanica (see also Figs. 7 and 905) a platelet of bone hollowed out behind 

 and above in the form of a groove, a nearly flat plate in front and below, presents normally, 

 during the early years of life, a non-ossified portion. The pars tympanica forms the whole 

 anterior, the inferior and a part of the posterior wall of the meatus acusticus externus as well 

 as the porus acusticus externus. The posterior limb of the groove lies upon the anterior 

 surface of the proc. mastoideus and often forms there the fissnra tympanomastoidea. The 

 anterior limb of the groove is attached to the inferior margin of the squama temporalis just 

 behind the fossa mandibularis ; lateral ward it is fused for a short distance with the squama, 

 but medianward there exists between the two a narrow platelet of bone , processus inferior 

 tegminis tympani (Fig. 9), which proceeds from the anterior margin of the facies anterior 

 pyramidis and which , with the pars tympanica, forms the fissura petrotympanica / Glaseri] 

 (0. T. Glaserian fissure). The latter presents several small openings for the a. tympanica an- 

 terior , vv. tympanicae , chorda tympani and the lig. mallei anterius. Below, surrounding the 

 root of the styloid process from in front like a sheath, is a process of the pars tympanica 

 called the vagina processus styloidei (0. T. vaginal process). 



The superior posterior surface of the pars tympanica is smooth and contains near its 

 anterior medial extremity a groove, bounded by two ridges, the sulcus tympanicus (for the 

 membrana tympani), the plane of which looks backward, upward and medianward; at each of 

 the upper angles of the pars tympanica it runs out into a small pointed extremity, the an- 

 terior being called the spina tympanica major, the posterior, the spina tympanica minor. 

 The space between these two spines is not entirely filled up by the attachment of the pars 

 tympanica to the squama temporalis; on the contrary, there remains an indentation called 

 the incisura tympanica [Rivini] (see Organ of Hearing). 



