A N A 1 
of the upper part of the temporal bones on the lower part 
of the parietal, where, in both bones, there are a great 
many fmall rifings ahd furrows, which are indented into 
each other; though thefe iiiequaiities"do not appear till 
the bones are l'eparated. In tome fkulls, indeed, the in¬ 
dentations here are as confpicuous externally as in other 
futures; and what is commonly called the pofterior part 
of this fquamous future always has the evident ferrated 
form, and therefore is reckoned by fome a dillindt future, 
under the name of additamentum pofieriusJ'uturce fquamofcz. 
The bones of the (hull are joined to thofe of the face, 
by fchindylefis and futures. The fchindylefis is in the 
partition of the nofe. The futures hud to be common to 
the cranium and face are five, viz. the ethmoidal, fphe- 
noidal, tranfverfe, and two zygomatic. The elhmoidal and 
fpkcnoidal futures furround the bones of thefe names ; and 
in fome places help to make up other futures, particular¬ 
ly the fquamous and tranfverfe ; and in other parts there is 
but one future common to thefe twobones. The tranfveife 
future is extended quite acrofs the face, from the external 
canthus of one orbit to the fame place of the other, by 
linking from the canthus down the outfide of the orbit to 
its bottom ; then, mounting upon its infide, it is continued 
by the root of the nofe down to the internal part of the 
other orbit, and rifes up again on its outfide to the other 
canthus. The zygomatic futures are one on each fide, be¬ 
ing fhort and flanting from above obliquely downwards 
and backwards, to join a procefs of the cheek bone to one 
of the temporal bones,, which advance towards the face; 
fo that the two proeelfes thus united, form a fort of bridge 
or jugum, under which the temporal tnufcle palTes ; on 
which account the proeelfes, and future joining them, have 
been called zygomatic. 
It is alleged, that through the futures there is a tran- 
fpiration of fleams from the brain, which was the old doc¬ 
trine ; or fome communication of the velfels without and 
of thofe .within the ikull, larger here than in any other part 
of the cranium, according to Tome moderns; and therefore 
eucuphae, fomentations, cataplafms, cephalic plafters, 
blifters, are applied, and ilfues are eroded or cut in the 
head, at thofe places where the futures are longed in form¬ 
ing, and where the copneiStion of the bones is afterwards 
loofeft, for the cure of a phrenitis, mania, inveterate liead- 
ach, epilepfy, apoplexy, and other difeafes of the head. 
The favourers of the doffrine of tranfpiration, or com¬ 
munication of veffels at the futures, endeavour to fupport 
it by obfervations of perfons fubjecd to head-achs which 
caufed death, from the futures being too clofely united. 
The os fronds lias its name from its being the only bone 
of that part of the face we call the forehead, though it 
reaches a good deal farther. It has fome refemblance in 
ihape to the (hell of the concha bivalvis, commonly call¬ 
ed the cockle: for the greateft part of it is convex exter¬ 
nally, and concave internally, with a ferrated circular 
edge; while the fmaller part has procefles, and depref- 
fions, which make it of an irregular figure. Between the 
internal and external angular proeelfes on each fide, an 
arched ridge is extended, on which the eye-brows are pla¬ 
ced. Very little above the internal end of each of thefe 
fuperciliary ridges a protuberance may be remarked, where 
there are large cavities, called finufes. Between the inter¬ 
nal angular proeelfes a fmall procefs rifes, which forms a 
part of the nofe, and thence is named nafal. Some cb- 
ferve a protuberant part on the edge of the bone w hich 
they call temporal proeelfes; but thefe are inconfiderable. 
From the under part of the fuperciliary ridges, the frontal 
bone runs a great way backwards: thefe parts may juftly 
enough be called orbitar proeelfes, which, contrary to the 
reft of this bone, are concave externally, for receiving the 
globes of the eyes, with their inufcles,. fat, &c. In each 
of the orbitar proeelfes, behind the middle of the fuper¬ 
ciliary ridges, a conliderable finuolity is obferved, where 
the glanduia innominata Galeni, or lacrymalis, is lodged. 
Behind each internal angular procefs, a fmall pit may be 
remarked, where the cartilaginous pully of the mufculus 
O M Y. ^ 531 
obliquus major of the eye is fixed. Between the two or¬ 
bitar proeelfes,. there is a large dileontinuation of the bone, 
in which the cribriform part of the os ethmoides is incafed. 
The foramina, or holes, obfervable on the external iur- 
face of the frontal bone, are three in each fide. One in 
each fuperciliary ridge, a little removed from its middle 
towards the nofe; through w'hich a twig of the ophthalmic 
branch of the fifth pair of nerves palfes out of the orbit, 
with a fmall artery from the internal carotid, to be diftri- 
buted to the teguments and mufcles of the forehead. 
Thele velfels, in fome fkulls, make furrows in the os fron- 
tis, efpecially in the bones of children, as has alio been 
obferved of another conliderable velfel of this bone near 
its middle; and therefore we ought to beware of tranf¬ 
verfe incifions on either fide of the os frontis, which might 
either open thefe veffels, or hurt the nerves, while they 
are yet in part within the bone: for, when velfels are thus, 
wounded, it is difficult to flop the haemorrhage, becaule 
the adhelion of a part of the artery to the bone hinders its- 
contraftion, and confequently ftypticscan have little eftedl; 
the lides of the furrow keep off compreffing fubftances- 
from the artery; and we would with to ftiun cauteries or 
efcharotics, becaule they make the bone carious; and 
nerves, when thus hurt, fometimes produce violent Symp¬ 
toms. Near the middle of the infide of each orbit, hard- 
by or in the tranfverfe future, there is a fmall ho!e for the: 
paffage of the nafal twig of the firll branch of the fifth 
pair of nerves, and of a branch of the ophthalmic artery. 
This hole is fometimes entirely formed in the os frontis ; 
in other fkulls, the fides of it are conipoled of this lalt 
bone and of the os planum. It is commonly known by 
the name of orbilarium internum, through antcrius fhould 
be added, becaule of the next, which is commonly omit¬ 
ted. This, which may be called orbitarium internus pojte- 
rius, is fuch another as the former; only fmaller, and 
about an inch deeper in the orbit. Through it a fmall 
branch of the ocular arteiy paffes to the nole. 
The internal furface of the os frontis is concave, except 
at the orbitar proeelfes, which are convex, to fupport the 
anterior lobes of the brain. This furface is not lofmooth 
as the external; for the larger branches of the arteries of 
the dura mater make fome furrows in its fides and back 
parts. The linuofities from the luxuriant rifings of the 
brain are often very obfervable on its upper part; and 
its lower and fore parts are marked with the contortions of 
the anterior lobes of the brain. Through the middle of 
this internal furface, where-always in children, and fome¬ 
times in old people, the bone is divided, either a ridge 
Hands out, to which the upper edge of the falx is fatten¬ 
ed, or a furrow runs, in which the upper fide of the fu- 
perior longitudinal finus is lodged; on both thefe accounts, 
chirurgical authors juftly forbid the application of the tre¬ 
pan here. 
The os frontis is compofed of two tables, and an inter¬ 
mediate diploe, as the other bones of the cranium are. 
It is of a mean thicknefs between the os occipitis and the 
parietal bones; and is nearly equally denfe throughout, 
except at the orbitar proeelfes, where, by the action of 
the eye on one lide, and preliure of the lobes of the brain 
on the other, it is made extremely thin and diaphanous,, 
and the meditullium is entirely obliterated. In this place 
there is fo weak a defence for the brain, that fencers clleem 
a puffi in the eye mortal. The diploe is aifo exhauftedin 
that part above the eye-brows, where the two tables of 
the bone i’eparate, by the external being protruded out¬ 
wards, to form two large cavities, called finus frontaks. 
Thefe are divided by a middle perpendicular bony parti¬ 
tion. Their capacity in the fame fubjeiT is feldom equal; 
in fome the right, in others the left, is largeft: In fome 
fkulls, belides the large perpendicular feptum, feveral bo¬ 
ny pillars, or fhort partitions, are found in each finus: in 
others thefe are wanting. For the moll part the feptum 
is entire ; at other times it is difeontinued, and the two ji. 
nufs communicate. When the finufes are feen in fuch 
fkulls as have the frontal bone divided by the fagittal fu¬ 
ture.;, 
