THE SKULL AS A WHOLE 



75 



extreme anterior part is the fossa for the lacrimal sac. Behind this there is a small 

 depression in which the inferior oblique muscle of the eye arises; here the plate 

 which Separates the orbit from the maxillary sinus is very thin. The dorsal wall 

 (Pari^ dorsalis) is formed by the frontal and to a small extent by the lacrimal bone. 

 It pr^ents the supraorbital foramen, which perforates the root of the supraorbital 

 process. The ventral wall (Paries ventralis) is very incomplete, and is formed by 

 the malar, the zygomatic process of the temporal, and to a small extent by the max- 

 illa. The lateral wall (Paries lateralis) is the supraorbital process. At the extreme 

 posterior part is the orbital group of foramina. Four are situated in front of the 

 pterygoid crest. Of these, the uppermost is the ethmoidal foramen, which trans- 



Fig. 4S. — Cranial and Obbital Regions of Skull of Hoetse; Lateral \'rEW. The Zygomatic Arch and Supra- 

 orbital Process Have Been Sawn Off. 

 iS.o., Squamous part of occipital; P, parietal; S, squamous temporal; B.o., basilar part of occipital; B.s., body of 

 sphenoid; A.t., temporal wing of sphenoid; A.o., orbital wing of sphenoid; Pt.p., pter^-goid process of sphenoid; P.p., 

 perpendicular part of palate bone; F, F', facial and orbital parts of frontal bone; L, L', orbital and facial parts of lacri- 

 mal bone; M, facial part of malar bone; M.x., maxilla; o, parieto-occipital suture; b, squamous suture; c, d, spheno- 

 squamous suture; e, fronto-palatine suture; /, fronto-lacrimal suture. 1, Occipital condyle; 2, condyloid fossa; 3, 

 paramastoid process; 4, nuchal crest; 5, external occipital protuberance; 6, external acoustic meatus; 7, mastoid 

 process; 8, hyoid process; 9, stylomastoid foramen; 10, muscular process; 11, foramen lacerum; 12, postglenoid 

 process; 13, glenoid cavity; 14, temporal condyle; 15, pter3''goid groove; 16, alar canal of pterygoid process indicated 

 by arrow; 17, alar foramen; 18, ethmoidal foramen; 19, optic foramen; 20, foramen orbitale; 21, maxillary fora- 

 men; 22, sphenopalatine foramen; 23, posterior palatine foramen; 24, supraorbital foramen (opened); 25, fossa for 

 lacrimal sac; 26, depression for origin of obliquus oculi inferior; 27, facial crest; 28, maxillary tuberosity; 29, alveolar 

 tuberosity; 30, hamulus of pterygoid bone. 



mits the ethmoidal vessels and nerve. The optic foramen is situated a little lower 

 and further back; it transmits the optic nerve. Immediately below the optic is 

 the foramen orbitale,, which transmits the ophthalmic, third; sixth, and sometimes 

 the fourth nerve; commonly there is a very small trochlear foramen in the crest 

 for the last-named nerve. The foramen rotundum is below the foramen orbitale, 

 from which it is separated by a thin plate; it transmits the maxillarj^ nerve. The 

 alar canal opens in common with the foramen rotundum, and the anterior opening 

 of the pterygoid canal is also found here. The foramen alare parvmn is just be- 

 hind the pterygoid crest and on a level with the foramen orbitale. It is the upper 

 opening of a canal which leads from the alar canal, and through it the anterior deep 



