THE OCCIPITAL BONE 33 



THE BONES OF THE HEAD 



The skull is divided into two parts, the cranium and face; 

 the former protects the brain; the face surrounds the mouth, 

 nasal cavities, and orbits in part. There are twenty-two bones 

 forming the skull as a whole. 

 The cranium has eight bones. 



(a) Unpaired: (b) Paired: 



Occipital. Temporal. 



Sphenoid. Parietal. 



Ethmoid. 

 Frontal. 

 The face has fourteen bones. 



(a) Unpaired: (6) Paired: 



Vomer. Nasals. 



Mandible. Maxillse. 



Lacrymals. 

 Malars. 

 Palates. 

 Turbinates. 



THE BONES OF THE CRANIUM 



The Occipital Bone 



The occipital bone, situated in the back part and base of 

 the skull, is flattened, lozenge-shaped, and bent on itself, 

 presenting two surfaces, four borders, and four angles. The 

 internal or cerebral surface is concave; the posterior or external 

 is convex. It articulates with six bones two parietal, two 

 temporal, the sphenoid, and atlas. 



Below and in front the bone is pierced by the foramen mag- 

 num, a large oval opening with its long axis anteroposteriorly 

 placed (foramen occipitale), for the passage of the spinal cord 

 and membranes, spinal portions of the spinal accessory nerves, 

 and two vertebral arteries. The part behind the foramen is 

 the tabular portion, in front is the basilar portion, at the sides 

 are the condylar portions. 



The tabular portion presents posteriorly near the centre 

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