iy 
ANATOMY. : a 
of the blood from the side canals into the jugular vein, and the exit 
of the eighth pair of nerves; a large groove leading to the above 
notches, in which the side canals are placed. The internal surfaee 
has also four considerable depressions, formed by the cross-shaped 
' spine ; the two upper contain the posterior lobes of the brain, and 
the two lower, the two lobes of the hinder brain. a as 
This bone is joined to the wedge-shaped bone by the wedge pro-_ 
cess, in the adult by a bony concretion growing between them; but 
in youth they are united by an intervening cartilage ; with the side 
and temple-bones by the back suture; and with the first and second 
vertebrz of the neck by a cartilage. ar : 
The hinder bone constitutes the posteriorand lower part of the 
skull; contains the posterior lobes plctpaabsninetisacback brain and 
the oblong marrow ; and joins*th® head to the back bone. 
WEDGE-SHAPED BONE. 
This bone derives its name from being fixed in the middle of the 
base of the skull like a wedge, and extends underneath from one — 
temple to the other. Its shape is irregular, being compared toa 
bat with the wings expanded. LS a 2 eee 
its external processes are, two large wings, the front part of which 
forms part of the orbit, the inner surface supports a portion of the 
middle lobe of the bra, and the whole external. surface is covered 
by the muscle of the temple. Two spinous pro 
point projecting behind the spinous hole, The 
See week the plough-share, or bone separating the nostrils 
‘wo pen-shaped processes, each of which is distinguished into 
root and two extended plates or wings; one external, which on S 
outer surface gives rise to the external pen-shaped muscle, and on 
its internal surface to the internal pen-shaped muscle; the other __ 
internal: "Two hook-like processes, one on the end of the internal 
wing of each pen-like process, over which the tendon of the muscle, 
called the stretcher of the palate, turns. The internal processes 
are, two smaller wings which form the upper part of the superior 
— fissures; four couch-shaped processes, two front and two 
__ The external cavities are, the w e-shaped pituitary itary canal, which 
is in the middle of the bone, has SS ecg with the nostrils, 
and is divided by an intermediate partition. Two pen-shaped de- 
pressions, One between each greater and lesser wing, for the rece 
tion of a part of the palate bone. Two holes, each leading to a canal 
. Inthe root of the pen-shaped process, through which the recurrent 
branch of the fifth pair of nerves passes into the skull, The internal 
Cavities are, the cavity containing the pituitary or nose gland ; » 
two optic holes ; two grooves, one on each side of the pituitary gle 
formed by the pulsation of the head arteries; two upper o1 
holes, between each greater and lesser wing, through 
fourth, first branch of the fifth, and the sixth pair 
artery, pass out of the skull ; | 
