162 ANTHROPOLOGY. 
orbits, eyebrows, eyelids, conjunctiva, lachrymal apparatus, muscles of the 
eye, and ocular fascia, with their several blood-vessels and nerves. 
Tur Orsirs. These are conical bony recesses, the sides of unequal 
length, and joined to each other at angles so as to form quadrangular pyra- 
mids; seven bones enter into their formation, the frontal, sphenoid, ethmoid, 
malar, maxillary, unguis, and palate. The axis or central line of the orbits 
leads obliquely from the apex forwards and upwards and a little downwards. 
If, therefore, the axes of both orbits be produced, they will diverge con- 
siderably in front, but meet rapidly behind, intersecting at the back of the 
body of the sphenoid bone. ‘These lines are not parallel to the axes of the 
eyeballs, which lead more directly forwards and are nearly horizontal. 
The foramina in the orbit are: 1. The optic, which transmits the optic 
nerve, and beneath this the ophthalmic artery. 2. The foramen lacerum 
superius or sphenoidal fissure, the larger inner end of which corresponds to 
the axis of the orbit, and transmits the third, fourth, ophthalmic division of 
the fifth, and the sixth cerebral, and filaments of the sympathetic nerves. 
Beneath these the ophthalmic vein escapes from the orbit to join the cavern- 
ous sinus. The external part of this foramen is closed by membrane, 
through which a small artery from the middle meningeal sometimes passes 
and assists in supplying the lachrymal gland. 3. The lacerum inferius or 
spheno-maxillary fissure is in the inferior external angle of the orbit, and 
transmits small nerves and vessels from the orbit to the zygomatic fossa. 
4. Internal orbital foramina, generally two, but sometimes more, are in the 
superior internal angle ; the anterior transmits the nasal twig of the ophthal- 
mic nerve; the posterior, the ethmoidal branch of the ophthalmic artery. 
1. Tue Superciuia, or eyebrows, bound the superior eyelids ; they 
correspond to the superciliary ridge of the frontal bone, which partly causes 
their prominence. The hairs of the eyebrows are mostly directed in a 
slanting manner outwards, and are placed in two rows, the superior directed 
downwards and outwards, the inferior upwards and outwards; both rows 
converge in a median ridge, which causes a greater fulness and an even, 
regular appearance. The eyebrows are of use in shading the eye from 
very strong light, and protecting it from particles of dust and from perspira- 
tion and other fluids. They can be moved in three directions: upwards, 
by the occipito-frontalis muscle ; downwards, by the orbicularis ; down- 
wards and inwards, by the corrugators. 
2. Pavpesra, or Eyeuips. These are the two movable semilunar 
curtains, or folds of skin, placed in front of each orbit, convex and rounded, 
with horizontal wrinkles, and exactly moulded to the eye. The opening 
between them is called the palpebral fissure or rima. When the lids are 
open, they circumscribe an aperture more or less elliptical, on the size of 
which the apparent magnitude of the eye greatly depends. Its extremities 
are called canthi. The outer canthus is an acute angular commissure 
a little rounded, about a quarter of an inch distant from the edge of the 
orbit, to which it is attached by a dense fibrous membrane. The inner 
canthus extends for a short distance inwards towards the side of the nose, 
the edges being a little rounded ; externally it presents a small tubercle on 
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