40 BONES OF THE HEAD. 



spongy bones, dips forwards and downwards, and is connected with the 

 vomer. A thin edge, the sphenoidal crest, extends from the rostrum to the 

 ethmoidal spine, and articulates with the central plate of the ethmoid. 



The sphenoidal spongy bones, cornua sphenoidalia, or bones of Bertin, are 

 a pair of thin curved plates, whose closest anatomical relationship in the 

 adult is with the sphenoid bone, but which are originally distinct, and are 

 frequently united by earlier or stronger anchylosis with the ethmoid or 

 palate bones, so as to adhere, at least in part, to either of these in dis- 

 articulation of the skull, and thus to lay open the sinuses of the sphenoid. 

 The anterior part of each looks forwards, and leaves a considerable round 

 opening by which the sinus communicates with the nasal cavity ; the lower 

 and posterior part is of a triangular form, with the apex directed backwards. 



At the anterior and outer angle of the sphenoidal spongy bone is a small part 

 which enters into the formation of the inner wall of the orbit, articulating in front 

 with the ethmoid, behind with the sphenoid, above by a small angle with the frontal, 

 and below with the orbital process of the palate bone. It is most frequently fused in 

 the adult with the sphenoid or ethmoid, often, however, with the palate bone only, 

 and sometimes it remains free. (See Cleland in Trans, of Roy. Soc. for 1862.) 



The GREAT WINGS, alee majores, project outwards and upwards from the 

 sides of the body. The lower and back part of each, horizontal in direction, 

 occupies the angle between the petrous and squamous portions of the temporal 

 bone ; from its pointed extremity it sends downwards a short and sharp 

 projection, the spinous process. The upper and fore part is vertical, and 

 three-sided, lying between the cranial cavity, the orbit, and the temporal 

 fossa. The cerebral surface of the great wing is concave, and forms part of 

 the middle fossa of the base of the cranium. The external surface (temporo- 

 zygomatic) is divided by a ridge into an inferior part, which looks down- 

 wards into the zygomatic fossa, and an elongated superior part, looking 

 outwards, which forms a part of the temporal fossa. The anterior surface 

 looks forwards and inwards, and consists of a quadrilateral orbital portion, 

 which forms the back part of the external wall of the orbit, and of a smaller 

 inferior portion which overhangs the pterygoid process, looks into the spheno- 

 maxillary fossa, and is perforated by the foramen rotundum. Posteriorly, 

 the cerebral and external surfaces are separated by the margins which 

 articulate with the temporal and parietal bones ; anteriorly, the superior 

 divisions of the external and anterior surfaces are separated by the margin 

 which articulates with the malar bone, while their inferior divisions come into 

 contact with each other, and form the upper part of the posterior boundary 

 of the pterygo-maxillary fissure ; internally, the cerebral and orbital surfaces" 

 come into contact at the outer border of the sphenoidal fissure ; and 

 superiorly, all three surfaces abut against the triangular area which articu- 

 lates with the frontal bone. 



The SMALL WINGS, alee minores, or wings of Ingrassias, extend nearly 

 horizontally outwards from the fore part of the superior surface of the body. 

 The extremity of each is slender and pointed, and comes very close to, but 

 not into actual contact with, the great wing. The superior surface forms 

 part of the anterior fossa of the base of the cranium, the inferior overhangs 

 the sphenoidal fissure and the back of the orbit. The anterior border, thin 

 and serrated, passes directly outwards, and articulates with the orbital plate 

 of the frontal bone. The posterior border is prominent and free, and forms 

 the boundary between the anterior and middle cranial fossae : it is pierced 

 at its base by the optic foramen, and immediately beyond that projects 



