The Skull as a Whole. 



129 



major and minor, and the digastricus, the suspensory ligament of the 

 lesser cornu of the hyoid also being included in the ligament of the 

 stylohyoideus minor. The nuchal surface is separated from the 

 dorsal surface of the skull by a shield-shaped promontory and 

 crest (crista nuchae). The lateral continuation of this crest is the 

 superior nuchal line (linea nuchae superior). It forms a curved 

 ridge, the position of which indicates the dorsal limit of the occipital 

 musculature. The posterior, somewhat tri-radiate tip of the 



p.E. a. 



a.p.— 



, Fig. S9- Lateral surface of the skull: AS, alisphenoid (ala magna) ; BO, basioccipital 

 (basilar portion of occipital); BS, basisphenoid (body of posterior sphenoid); F, frontal; 

 I, interparietal; L, lacrimal; M, maxilla; MS, mastoid portion of petrosal (petroraastoid); 

 N, nasal; OS, orbitosphenoid (ala parva); P, parietal; PL, palatine; PM, premaxilla; 

 SO, supraoGcipital (squamous portion of occipital); SQ, squamosal; T, tympanic; ZY, 

 zygomatic. / 



a.p., piriform aperture of nose; d.i., i^icisor teeth; d.m., molars; d.pm., premolars; 

 f.i., infraorbital foramen; f.mx., maxillary fossa; f.o., optic foramen; f.s., stylomastoid 

 foramen; f.t., temporal fossa; l.l.,laterallaminaof pterygoid process; l.m., medial lamina; 

 m.a.e., osseous portion of external acoustic meatus; p.a., alveolar process of maxilla; 

 p. e., ethmoidal portion of orbitosphenoid; p.f., frontal process of premaxilla; p. j., jugular 

 process of occipital; p.m., mastoid process of mastoid; p.mx., maxillary process of frontal ; 

 P.O., orbital process of maxilla; p.o.e., external occipital protuberance; p.s., squamosal 

 process of parietal; p.s.a., and p.s. p., anterior and posterior supraorbital processes of 

 frontal; p.z., zygomatic process of squamosal;., p.z.m., zygomatic process of fhaxilla; 

 s, sphenoorbital process of maxilla; s.m., spina masseterica; sq., squamosal process of 

 squamosal. 



projection, together with a thin ridge extending ventrad from it, is 

 the external occipital protuberance (protuberantia occipitalis 

 externa), an important median point of attachment for the occi- 

 pital muscles and the ligamentum nuchae. 



The ventral wall of the cranial portion is the basal portion 

 (basicranium) of the entire skull. Its axial line, the basicranial 

 axis, continues, in general, that of the bodies of the vertebrae, 

 and its posterior portion is equivalent, morphologically, to vertebral 



