ANATOMY. 
moulded to the form of its contents, instead 
of influencing them, as we might have ex- 
pected a priori. Hence the convolutions 
of the brain, the vessels, which ramify on 
its surface, &c. all leave prints on the inner 
table. The ordinary thickness varies from 
about the fifth of an inch to almost a mere 
line. 
The common number of the bones of the 
cranium is, as we have already stated, 7 ; but 
this is often increased by small portions 
formed between the others, and surrounded 
by distinct sutures. These are called ossa 
triquetra, or wormiana. 
The form of the cranium is elliptical, and 
pretty regularly so, particularly on the front, 
upper and back part, and sides. The smal- 
ler circle of the ellipse is in front, and the 
larger behind. It is tolerably smooth ex- 
ternally, except its basis, and it is almost 
entire or unperforated, except at the same 
part. In this situation, however, itpossesses 
numerous holes, or as they are technically 
named, foramina, which transmit blood-ves- 
sels to the brain, and the nine pairs of 
nerves, which arise from that organ. 
The upper and lateral parts of the cranium 
constitute a bony vault or arch, for protect- 
ing the brain ; this part is distinguished by 
the name of the skull cap. 
Individual bones of the head. — The os 
frontis forms the upper and anterior part of 
the skull ; the eyebrow, and the roof of the 
orbit. 
The ossa parietalia are called also ossa 
bregmatis, since the fontanelles or breg- 
mata are formed between their edges. They 
compose the whole upper and most of the 
lateral parts of the skull ; and possess an ir- 
regularly quadrangular figure. 
The ossa temporum compose the lower 
part of the sides, and the middle of the basis 
of the cranium. They are divided into a 
squamous portion, a mamillary, and a pe- 
trous portion. The former of these has a 
process contributing to the zygoma, or bony 
arch, at the side of the cranium, under 
which the temporal muscle passes. The 
second is also remarkable, by forming a 
large nipple-like protuberance towards the 
basis cranii. The third, which projects 
into the cavity of the skull, contains the or-, 
gan of hearing. 
The os spheno-occipitale has generally 
been described as two bones. The occipi- 
tal portion forms the posterior portion of 
the basis cranii, and a part also of the back 
of the bony case. 
The sphenoid portion is situated in the 
middle of the base of the skull, and extends 
across it from one temple to another. It is 
extremely irregular in its figure, and di- 
vided into a body placed in the middle, two 
aim on the sides, and two pterygoid pro- 
cesses projecting downwards. 
The os ethmoides occupies the middle of 
the forepart of the basis cranii. It lies in 
the interval between the two orbits, and 
contributes - to the cavity of the nose. It 
consists of an irregular assemblage of bony 
cells, and processes of a very thin and deli- 
cate formation. It has a cribriform or hori- 
zontal plate towards the brain ; a nasal or 
perpendicular plate ; 2 turbinated bones ; 
cells ; and two orbital plates. 
The sutures joining these are the coronal, 
between the os frontis and the two ossa pa- 
rietalia; the sagittal, between the two ossa 
parietalia ; the lambdoidal, joining the ossa 
parietalia to the os occipitis ; the squamous, 
between the temporal and parietal bones. 
The foramina occurring in the cranium, 
for the transmission of nerves are ; 1, those 
of the cribriform plate of the ethmoid bone : 
2, f. optica : 3, f. lacera orbitalia : 4, f. ro- 
tunda : 5, f. ovalia : 6, meatus auditorii in- 
tend: 7, f. lacera in basi cranii: 8, f. 
condylpidea anteriora : 9, foramen magnum. 
Those which transmit blood vessels are ; 
1, canales carotici : 2, f. spinosa : 3, f. la- 
cera in basi cranii : 4, f. magnum. 
Bones of the face.—' The ossa nasi consti- 
tute the arch of the nose. The ossa lacy- 
malia or unguis are placed at the forepart of 
the inner edge of the orbits, and contain an 
excavation which holds the laerymal bag. 
The ossa malarum form the prominence* 
of the cheeks. 
The ossa maxillaria superiora form the 
largest portion of the upper jaw, and most of 
the bony palate, or roof of the mouth ; they 
contain also the upper teeth. 
The ossa palati form the back part of the 
bony palate. 
The ossa turbinata inferiora are situated 
in the cavity of the nose. 
The former completes, with the nasal por- 
tion of the ethmoid, the septum that divide* 
the two nostrils. 
The maxilla inferior is articulated to the 
basis cranii, and holds the lower teeth. 
The bones of the cranium and face com- 
pose the two orbits, or pyramidal bony ca- 
vities, holding the organs of vision ; to each 
of these, seven bones contribute. They 
also form the cavity of the nose, which is 
very extensive, and includes portions of 
nearly all the bones of the face, and some of 
the skull. It has various cells, formed in the 
bones of the skull and face, opening into it, 
