BONES OF THE CRANIUM. 193 



of Ingrassias. These end in a point and mark the position 

 of the fissure of Sylvius, or the division between the ante- 

 rior and middle lobes of the cerebrum. These lesser wings 

 have processes projecting backwards towards the posterior 

 clinoid, and sometimes uniting with them, called the an- 

 terior clinoid processes. These are thick tubercles, and have 

 in their base a large foramen for transmitting the optic 

 nerve and ophthalmic artery. 



From the posterior and inferior part of the sides of the 

 body, proceed outwards, upwards, and forwards, the alee- 

 majores or greater wings. These processes present three 

 surfaces, an Anterior or orbital, an external or temporal, and 

 an internal or cerebral. The orbital surface or process , assists 

 in forming the outer wall of the orbit, is smooth and some- 

 what square. The temporal surface or process is divided by 

 a transverse ridge, called the crest, into two portions, that 

 above the crest helping to form the temporal fossa, that 

 below entering into the formation of the zygomatic fossa. 

 The^ inner or cerebral surface is concave, and with the 

 temporal bone, receives the middle lobe of the cerebrum. 



From the junction of the greater wings with the body, 

 descend the pterygoid processes. Each process is divided 

 into an external and an internal plate. The external plate 

 has the pterygoideus externus muscle attached to its outer 

 side, and the pterygoideus internus to its inner side. The 

 internal plate ends in a curved hook-like process, called the 

 hamular process, is covered by a bursa, and over it the tendon 

 of the circumflexus palati muscle plays. Between the two 

 plates is the pterygoid-fossa, occupied by the Eustachian 

 tube, and the tensor palati muscle. The space between the 

 two pterygoid plates at their lower extremity, is filled by 

 the pterygoid process of the palatine bone. Through the 

 base of the pterygoid process runs the Vidian canal, which 

 gives passage to the pterygoid branch of the fifth pair of 

 nerves. 



The angle between the squamous and petrous portions of 

 the temporal bone is occupied by a process called the spi- 

 nous, which projects from the posterior part of each wing, 

 13 



