5 
le, which transmits to the orbit the third, fourth, the first 
of the fifth, and the sixth pair of nerves, and the opthalmic 
eyond this fissure, proceeding backwards, there is a round 
hole which gives passage for the second branch of the fifth pair of — 
nerves ; and the oval hole through which the third branch of the fifth 
pait of nerves passes. Near the oval hole is the spinous hole through 
which the spinous artery of the outer membrane of the brain passes. 
Between the oval hole and the posterior couch-like process, there 
is a large ragged aperture or canal, which in the fresh subject 
is partly filled with cartilage, and is the entrance of the carotid 
or head artery, and the exit of the great nerve for the ribs. A pro- 
jecting part of the bone next presents itself, called the rocky por- 
tion of the temple bone. It has on its posterior surface an oval” 
opening, the internal hearing canal, through which the nerve for the 
organ of hearing and the nerve of the face enter, ly be- | 
FOREHEAD BONE. 
The forehead bone is situated in the anterior part of the skull, 
forming the forehead and upper part of the orbits. Its shape is like 
a cockle shell. There are two forehead eminences which mark the 
centres of ossification; two forehead excrescences which are situa- _ 
ted over the two forehead canals; two eye-brow ridges, which give © 
origin to the forehead muscles, and whose extremities are called the 4 
angular or orbital processes ; an external forehead spine, On which — 
the bones of the nose rest ; and an internal forehead spine, to which 
the outer membrane of the brain adheres; and the two orbit 
plates which separate the orbits from the cavity of the sk 
__ The cavities are: the brain cavity, which contains the 
of the brain; a large notch between the orbitar plates for 
tion of the perforated plates of the sieve bone; two 
ee he sierg Soaeg ee: 
within the bone above th 
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