60 OSTEOLOGY 



bones of the face partially surround the orbital cavity 

 and form the walls of the nasal and oral cavities. 

 The cranium has eight bones. 



(a) Unpaired: ^6) Paired: 



Occipital. Temporal. 



Sphenoid. Parietal. 



Ethmoid. 

 Frontal. 



The face has fourteen bones: 



(a) Unpaired: (6) Paired: 



Vomer. Nasals. 



Mandible. Maxillae. 



Lacrymals. 



Malars. 



Palates. 



Turbinates. 



The Bones of the Cranium. The Occipital Bone. 



This is situated in the back part and base of the skull, 

 is flattened, lozenge-shaped, bent on itself, presenting 

 an internal or cerebral surface, which is concave, and 

 an external or posterior surface, which is convex; four 

 borders and four angles. Below and in front the 

 bone shows a large oval opening, called the foramen 

 magnum, for the passage of the spinal cord and mem- 

 branes, spinal accessory nerves, and two vertebral 

 arteries. On either side of the anterior boundaries 

 of the foramen magnum are two condyles which 

 articulate with the atlas (first cervical vertebra). 

 Anteriorly a rough process of bone (the basilar) artic- 

 ulates with the body of the sphenoid and temporal, 

 and the posterior border of the occipital bone articu- 

 lates with the parietal Bones on either side. 



The Parietal Bones. These are paired one on either 

 side, together forming the median portion of the roof 



