THE BONES. 57 



3. Vertical Diameter from the anterior border of the for. magnum to the cen- 

 tre of the s. sagittalis = 3^ inches. 



The circumference is in children proportionnbly greater than in adults; in 

 the male sex and in the Caucasian Race larger than in the female and other 

 Races. 



The circumference of the skull stands in an inverse relation with that of 

 the face. Vide the facial angle of Camper. 



57. 4. The Cranial cavity, cavum cranii. 



a. Basis 5 rests upon the Atlas ; contains three terrace-like gently descending 

 fossae, fossa crauii. 



1. Anterior, most elevated, but the smallest, supports the anterior cerebral 

 lobes, is formed of: 



Ethmoid. Frontal, and the lesser wings of the Sphenoid tone : 



Presents, anteriorly, for. ccecum, Crista Galli, and c. frontalis internet, (for Falx 

 cerebri). 



In the centre, foramina cribrosa (for olfactory nerve?) : posteriorly, for. Optica 

 (for Optic nerve and Ophthalmic artery') Proc. clinoid. anter. 



The sharp posterior border, before the fossa Sylvii and sinus Ophthalmicus. 



2. Central, supporting the middle cerebral lobes and base of the great brain, 

 formed by the greater wings and the body of the sphenoid, by the squamous 

 and the petrous portions of the temporal bones: posterior limit: Jlnguli Petrosi 

 and the posterior edge of the Setta Tunica ; 



Presents, in the centre, the Sella turcica (for the Hypophysis, [pituitary 

 gland], Infundibulum, circular sinus of Ridley: with, proc. clinoid. medii (for 

 the commissure of the Optic nerve) ; proc. clinoid. poster, (for the corpora mam- 

 millaria) ; next the sulcus caroticus (sinus cavernos., carotis) ; for. lacerum an- 

 terius. 



At the sides, anteriorly, Fissura orbitale superius (for nerv. oculomotor, troch- 

 learis, ram. ophthalmic, n. trigemini, n. abducens, ven. ophthalmica) . 



Farther backwards, for. rotundum (for nerv. maxillar. superior*). 



Externally, for. ovale (for n. maxillar. inferior') ; 



for. spinosum (for art. meningea med.} ; and 

 hiatus canal. Fallopice, and for. tympanicum. 



3. Posterior, the lowest, but largest (for the cej-ebellum and Medutt. Oblon- 

 gota). 



Formed, by the Petrous and Mastoid portions of the Temporal bones and 

 by the Os occipitis ; 



Bounded, before by the anguli petrosi, behind by the sulcus transversus; 

 presents in the middle line, anteriorly, fossa basilaris (for Pons Varolii, medulla 

 oblongata') ; has therein,ybraw. magnum (for Spinal cord and n. access. iVillisii, 

 the art. spinal, and vertebral), foram. condyloidea anteriora (for nerv. Hypogloss.')- 



Posteriorly, spina and crista occipit. int. (for Falx cerebelli, torcula Herophili)- 



At the sides, anteriorly, for. jugulare (for the nerv. glosso-pharyng. vagus, 

 accessorius Will., and vena jugular is), with the termination of the siilc. trans- 

 versus (for sinus transversus} ; 



More externally and above, meat us audilorius intern, (for nerv. facialis and 

 acusticus, and Af/useducf. Vestibuli) ; 



Lastly ; tineas Iransversse (for tentorium Cerebelli), with sulcus transversus. 



b. The Cranial arch,fornix, the smooth roof above the convex surface of 

 the brain ; formed of frontal, parietal, and occipital bones. 



