

THE OCCIPITAL BONE 



129 



In the Basle nomenclature, certain bones developed in association with the nasal 

 capsule, viz., the inferior nasal conchae, the lacrimals, the nasals, and the vomer, 

 are grouped as cranial and not as facial bones. 



The hyoid bone, situated at the root of the tongue and attached to the base 

 of the skull by ligaments, is described in this section. 





THE CRANIAL BONES (OSSA CRANE). 

 The Occipital Bone (Os Occipitale). 



The occipital bone (Figs. 129, 130), situated at the back and lower part of the 

 cranium, is trapezoid in shape and curved on itself. It is pierced by a large oval 

 aperture, the foramen magnum, through which the cranial cavity communicates 

 with the vertebral canal. 



Highest 

 nuchal line. 



Hypoglossal canal 



Constrictor pharyngis 

 superior 



isilarParb 



i 



FIG. 129. Occipital bone. Outer surface. 



The curved, expanded plate behind the foramen magnum is named the squama; 

 the thick, somewhat quadrilateral piece in front of the foramen is called the 

 basilar part, whilst on either side of the foramen is the lateral portion. 



The Squama (squama occipitalis) . The squama, situated above and behind 

 the foramen magnum, is curved from above downward and from side to side. 



Surfaces. The external surface is convex and presents midway between the 

 summit of the bone and the foramen magnum a prominence, the external occipital 

 protuberance. Extending lateralward from this on either side are two curved 

 lines, one a little above the other. The upper, often faintly marked, is named 

 le highest nuchal line, and to it the galea aponeurotica is attached. The lower 

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