150 OSTEOLOGY 





portion of the temporal and presents at its apex a downwardly directed process, 

 the spina angularis (sphenoidal spine). 



Surfaces. The superior or cerebral surface of each great wing (Fig. 145) forms 

 part of the middle fossa of the skull; it is deeply concave, and presents depressions 

 for the convolutions of the temporal lobe of the brain. At its anterior and medial 

 part is a circular aperture, the foramen rotundum, for the transmission of the maxil- 

 lary nerve. Behind and lateral to this is the foramen ovale, for the transmission 

 of the mandibular nerve, the accessory meningeal artery, and sometimes the 

 lesser superficial petrosal nerve. 1 Medial to the foramen ovale, a small aperture, 

 the foramen Vesalii, may occasionally be seen opposite the root of the pterygoid 

 process; it opens below near the scaphoid fossa, and transmits a small vein from 

 the cavernous sinus. Lastly, in the posterior angle, near to and in front of the spine, 

 is a short canal, sometimes double, the foramen spinosum, which transmits the 

 middle meningeal vessels and a recurrent branch from the mandibular nerve. 



The lateral surface (Fig. 146) is convex, and divided by a transverse ridge, the 

 infratemporal crest, into two portions. The superior or temporal portion, convex 

 from above downward, concave from before backward, forms a part of the tem- 

 poral fossa, and gives attachment to the Temporalis; the inferior or infratemporal, 

 smaller in size and concave, enters into the formation of the infratemporal fossa, 

 and, together with the infratemporal crest, affords attachment to the Pterygoideus 

 externus. It is pierced by the foramen ovale and foramen spinosum, and at its 

 posterior part is the spina angularis, which is frequently grooved on its medial 

 surface for the chorda tympani nerve. To the spina angularis are attached the 

 sphenomandibular ligament and the Tensor veli palatini. Medial to the anterior 

 extremity of the infratemporal crest is a triangular process which serves to increase 

 the attachment of the Pterygoideus externus; extending downward and medialward 

 from this process on to the front part of the lateral pterygoid plate is a ridge which 

 forms the anterior limit of the infratemporal surface, and, in the articulated skull, 

 the posterior boundary of the pterygomaxillary fissure. 



The orbital surface of the great wing (Fig. 146), smooth, and quadrilateral in 

 shape, is directed forward and medialward and forms the posterior part of the 

 lateral wall of the orbit. Its upper serrated edge articulates with the orbital plate 

 of the frontal. Its inferior rounded border forms the postero-lateral boundary of 

 the inferior orbital fissure. Its medial sharp margin forms the lower boundary 

 of the superior orbital fissure and has projecting from about its center a little 

 tubercle which gives attachment to the inferior head of the Rectus lateralis oculi; 

 at the upper part of this margin is a notch for the transmission of a recurrent 

 branch of the lacrimal artery. Its lateral margin is serrated and articulates with 

 the zygomatic bone. Below the medial end of the superior orbital fissure is a 

 grooved surface, which forms the posterior wall of the pterygopalatine fossa, 

 and is pierced by the foramen rotundum. 



Margin (Fig. 145). Commencing from behind, that portion of the circum- 

 ference of the great wing which extends from the body to the spine is irregular. 

 Its medial half forms the anterior boundary of the foramen lacerum, and presents 

 the posterior aperture of the pterygoid canal for the passage of the correspond- 

 ing nerve and artery. Its lateral half articulates, by means of a synchondrosis, 

 with the petrous portion of the temporal, and between the two bones on the 

 under surface of the skull, is a furrow, the sulcus tubae, for the lodgement of the 

 cartilaginous part of the auditory tube. In front of the spine the circumference 

 presents a concave, serrated edge, bevelled at the expense of the inner table below, 

 and of the outer table above, for articulation with the temporal squama. At 

 the tip of the great wing is a triangular portion, bevelled at the expense of the 



1 The lesser superficial petrosal nerve sometimes passes through a special canal (canaliculus innominatus of Arnold) 

 situated medial to the foramen spinosum. 



