Skull and Hyoid 191 



the parietal above, the frontal above and in front, and below this with one of the face 

 bones, the malar. The malar is the bone at the outer side of the orbit which we have 

 seen articulating with the external angular process of the frontal above and with 

 the zygomatic process of the temporal externally and behind. If we look inside the 

 orbit we can see the malar articulating with the frontal above, and, below this, by its 

 posterior border, with the great wing of the sphenoid, but this is the orbital surface of 

 the great wing. 



Looking at the side of the skull as a whole, we can see that a large part of it is 

 depressed, deep to the level of the zygomatic arch, forming the temporal fossa. The 

 floor of this fossa is made by the squama, great wing oi sphenoid, lower part of parietal, 

 and, in front, a small part of the frontal and malar. 



The fossa contains the temporal muscle, which arises from its floor, and it is limited 

 above by the superior temporal crest which forms an indefinite curved roughness on the 

 parietal, passes from this on to the frontal, where it becomes a prominent ridge leading 

 to the external angular process, and from this passes on to the sharp margin of the 

 malar. 



At about the level of the zygoma the floor of the temporal fossa is found to become 

 abruptly continuous with the base of the skull, forming a sharp border, the inferior 

 temporal crest : the tendon of the temporal muscle passes between this crest and the 

 zygoma to reach the lower jaw. 



If we trace the zygoma back we find that a slightly curved ridge, the upper root 

 of the zygoma, can be followed along the lower and back part of the squama, where it 

 forms a lower boundary of the temporal fossa. Below the root of the zygoma, and 

 just in front of the mastoid process, is the opening of the ear, the external auditory 

 meatus, and the lower jaw articulates with the under surface of the bone just in front 

 of this. 



All the cranial bones that have been mentioned so far, with the exception of the 

 parietals, are concerned also by their other parts in the formation of the base of the 

 cranial cavity in fact, there are no other bones there, with the exception of the 

 ethmoid, which fills in the interval between the orbital plates of the frontal. 



The basal view (norma basalis) of the skull shows us the constituent bones with 

 a little examination : they are not so clearly defined as on the other aspects, because 

 the basal surface, being that looking towards the neck, is covered by processes and 

 roughnesses for attachments of various structures and pierced by numerous holes 

 for the passage of vessels and nerves (Fig. 161). 



, Starting from the back, we notice that the occipital bone turns forward below, 

 presents the large foramen magnum for the passage of the central nervous axis and its 

 appendages, and narrows in front of this to a thick bar of bone. In the adult skull 

 this bone is continuous with the central portion of the sphenoid and has to be separated 

 by the saw, but the termination of the occipital can be taken as about an inch or less 

 in front of the margin of the foramen magnum. 



The different parts of the occipital bone can now be recognised : the portion in 

 front of the foramen is the basi-occipital ; the part that projects outwards on each side 

 of the foramen is the ex-occipital, frequently termed the jugular process, because it 

 forms the back wall of the jugular foramen, from which the internal jugular vein and 

 certain nerves leave the skull. The part behind the foramen is the post-occipital, 

 and this is seen to be roughened by aponeurotic attachments, showing upper and lower 

 curved lines and an external occipital crest running down from an external tuberosity. 



This is the basal part of the bone, but behind the superior curved line the bone 

 turns up on the back of the skull between the parietals, and this part is often termed 



