184 



HEALTH AND DISEASE 



Occiput. This bone is situated at the superior extremity of the 

 cranium, and, as we have already pointed out, furnishes two large con- 

 dyles, by which it articulates with the atlas, or first bone of the neck 



(15, fig. 289). Above, it forms 

 the crest or prominence between 

 the ears, while below it gives off 

 a process (basilar process) which 

 passes forward to assist in form- 

 ing the base of the skull. Be- 

 hind, it forms the superior boun- 

 dary of the . cranium, where it 

 presents two rounded projections 

 or condyles. Between these is a 

 large opening (foramen magnum), 

 through which the brain is con- 

 nected with the spinal cord. On 

 the outer side of the occipital con- 

 dyles a bony projection (styloid 

 process) is found. This, like other 

 parts of the bone, affords attach- 

 ment to important muscles. 



Parietal. The parietal bones 

 are two, situated immediately be- 

 neath the bone last described and 

 above the frontal bones. They are 

 united by the sagittal suture in the 

 middle line of the cranium, and 

 serve to form the roof of that cavity. 



Temporal Bones. - - These 



are four in number, two pairs, dis- 

 tinguished from each other as the 

 squamous and the petrous tem- 

 poral bones, the former having a 

 shell-like structure, while the latter 

 are of great density and hardness. 

 The petrous temporal bones con- 

 tain the organs of hearing. 



Squamous Temporal. These are two flattened portions of bone 

 situated at, and forming the sides of, the brain cavity. From the outer 

 part, near the middle, a long bony eminence proceeds in a downward direc- 

 tion to unite with the orbital process of the frontal bone above, and the 



Fig. 287. Skull (Front Aspect) 



1 Occipital Tuberosity. 2 Parietal Bone. 3 Squamous 

 Temporal Bone. 4 Superior Orbital Foramen. 5 Lach- 

 rymal Bone. 6 Malar Bone. 7 Inferior Orbital Foramen. 

 8 Foramen Incissivum. 9 Anterior Maxillary Bone. 10 Nasal 

 Suture. " Superior Maxillary Bone. J2 Frontal Bone. 

 13 Frontal Suture. 14 Temporal Fossa. 15 Sagittal Suture. 



