94 SPECIAL ANATOMY OF THE SKELETON 







wing is connected to the side of the body by two roots, the upper thin and flat, the 

 lower thicker, obliquely directed, and presenting on its outer side, near its junction 

 with the body, a small tubercle, for the attachment of the common tendon of origin 

 of three of the Extrinsic muscles of the eye. Between the two roots is the optic 

 foramen (J'oramen opticum), for the transmission of the optic nerve and ophthal- 

 mic artery. 



The Pterygoid Processes (processus pterygoidei}. The pterygoid processes, 

 one on each side, descend perpendicularly from the place where the body and 

 greater wing unite (Fig. 59). Each process consists of an external and an 

 internal lamina or plate, which are joined together by their anterior borders 

 above, but are separated below, leaving an angular cleft, the pterygoid notch 

 (fissura pterygoidea), in which the pterygoid tuberosity of the palate bone is 

 received. The two plates diverge from each other from their line of connec- 

 tion in front, so as to form in conjunction with the tuberosity of the palate 

 bone a V-shaped fossa, the pterygoid fossa (fossa pterygoidea). The external 

 pterygoid plate (lamina lateralis processus pterygoidei) is broad and thin, turned 

 a little outward, and, by its outer surface, forms part of the inner wall of the zygo- 

 matic fossa, giving attachment to the External pterygoid; its inner surface forms 



FIG. 59. Sphenoid bone. Posterior surface. 



part of the pterygoid fossa, and gives attachment to the Internal pterygoid. The 

 posterior border of this plate frequently has one or more rough projections, to 

 one of which is attached the pterygospinous ligament, when this is present. The 

 internal pterygoid plate (lamiria medialis processes pterygoidei} is much narrowef 

 and longer, curving outward, at its extremity, into a hook-like process of bone, 

 the hamular process (hamulus pterygoideus}, around which turns the tendon of the 

 Tensor palati muscle. The outer surface of this plate forms part of the pterygoid 

 fossa, the inner surface forming the outer boundary of the posterior aperture of 

 the nares. The posterior border of this plate gives attachment to the pharyngeal 

 aponeurosis throughout its entire length. The Superior constrictor muscle of 

 the pharynx arises from its lower half. Projecting backward from the middle 

 of this border is a spine (processus tubarius}, which supports the pharyngeal end 

 of the Eustachian tube. Above this the border divides into two lips; the space 

 between is the scaphoid fossa (fossa scaphoidea}. In this fossa arises the Tensor 

 palati muscle. The anterior margin articulates with the posterior border of the 

 perpendicular plate of the palate bone. 



Superiorly, the internal pterygoid plate has a thin lamina of bone, the vaginal 

 process, which runs inward on the under surface of the body of the sphenoid 

 nearly to the rostrum. In the groove between the two in the articulated skull 



