Bones of the Skull. 



15 



Squama front al is 



Facies frontalis 



Tuber frontale 



Margo 

 parietalis 



Facies 

 temporalis 



Linea temporalis 



Site of former sutura frontalis _^ 



Glabelhi 



1'rooessus zygomaticus 

 \ Margo supraorbitalis 

 \ Foramen supraorbitale 

 \ Incisura frontalis 

 v 'Arcus superciliaris 

 -Spina frontalis 



[_ Margo _] 

 nasalis 



A 

 Pars nasalis 



16. Frontal bone, os frontale, from in front. 



The unpaired OS frontale (frontal bone) (see also Figs. 17, 18, 5558, 61 66, 

 68 71, and 73) closes the cerebral skull in front and lies above the facial skull. It has 

 four parts, the unpaired squama frontalis and pars nasalis, and the paired partes orbitales. 



The squama frontalis (see also Figs. 17, 18, 5558 and 6166) is curved sagittally 

 and transversely so as to be convex in front. Its largest posterior serrated margin, margo 

 parietalis , unites with the frontal margin of the parietal bone to form the sutura coronalis. 

 The inferior boundary is formed in the middle by the pars nasalis, lateral from this on each 

 side by the margo supraorbitalis; the latter runs out lateral ward into the proc. zygomaticus, 

 which unites, by means of a rough surface, with the proc. frontosphen. of the zygomatic bone 

 to form the sutura zygomatico frontalis. 



In the medial part of the margo supraorbit. there is often a shallow notch, incisura 

 frontalis (rarely a foramen frontale} (for the a. frontalis; r. frontal, n. frontal.) and lateralward 

 from this a foramen supraorbitale or an incisura supraorbitalis (for the a. supraorbit.; 

 n. supraorbit.). The anterior, convex surface, fades frontalis, is smooth and sometimes presents, 

 in the median plane, signs of the sutura frontalis (always present at birth) ; lateralward from 

 this on each side lies the tuber frontale (0. T. frontal eminence) and lateralward from this 

 the linea temporalis, ascends backward and upward from the zygomatic process, bounding the 

 flat, nearly sagittally placed, fades temporalis (for the m. temporal.). Close to the inferior 

 border, near the median plane on each side, begins a ridge, arcus superciliaris (0. T. super- 

 ciliary ridge), which passes upward and lateralward, flattening as it proceeds; the depressed 

 surface lying between the medial ends of these ridges is called the glabella. 



