TEMPOEAL BONE. 



37 



situated at its base ; it is known as the form7irn ccccinn, and transmits a 

 minute vein from the nasal Ibss^e. The upper and greater part of the 



Fig. 32. 



Fig. 32.— The Frontal Bone 



FROM BEHIND AND BELOW, 

 SHOWING THE INTERNAL CERE- 

 BRAL .Surface and the llooi^ 

 OF THE Orbits. (A. T.) ^ 



2, 4, and 5, as in the 2)recediug 

 figure ; 9, internal or cerebral 

 surface, slightly marked by cere- 

 bral convolutions and glandular 

 pits ; 10, groove of the superior 

 longitudinal sinus, ending below 

 in, 11, the internal frontal crest, 

 which leads down to, 13, the 

 foraraen ca?cum ; 12, the orbital 

 jjlate, the number is placed in 

 the depression for the lachrymal 

 gland; 14, the opening of the 

 frontal sinus ; 15, jilaced on 

 the roof of the orbit internally, 

 is near the opening of the an- 

 terior ethmoidal or internal 

 orbital foramen. 



edge encompassing the 

 cerebral surface of the 

 bone is deeply serrated, 



and articulates with the parietal bones in the coronal suture ; the lower 

 transverse part is thin and uneven, and articulates with the greater and 

 lesser wings of the sphenoid in the transverse suture. The adult 

 frontal bone is sometimes divided into two parts Ijy a median suture, 

 the frontal suture which may be regarded as the persistence of the 

 original fcctal condition. 



THE TEMPORAL BONE. 



The temporal bone (os temporis) takes part in the construction of 

 the side and base of the skull, and contains in its interior the organ of 

 hearing. It is usually described in three parts, viz., an expanded 

 anterior and superior part, the squamous portion with the zygomatic 

 process, a thicker posterior portion, the mastoid, and below and 

 between these the petrous portion, a three-sided pyramid, exhibiting 

 at its base externally the aperture of the ear, and projecting forwards 

 and inwards into the base of the skull. With these is combined in the 

 adult the styloid process or bone. 



It articulates posteriorly and internally with tlie occipital bone, supe- 

 riorly with the parietal, anteriorly with the sphenoid, by the zygomatic 

 process with the malar, and by the glenoid cavity with the inferior 

 maxillary bone. 



The scfiiamous portion, or squamo-zygomatic, extends forwards 

 and upwards from its connection with the other portions, and presents 

 superiorly an arched border which describes about two-thirds of a circle. 



The inner surface is marked by cerebral impressions, and by meningeal 

 grooves. At its upper border, the outer table is prolonged considerably 

 beyond the inner, foiTning a thin scale with the fluted surface looking 



