166 ANTHROPOLOGY. 
The obliquus superior or trochleator arises from the sheath of the optic 
nerve, and from the inner margin of the optic foramen. It passes forwards 
and ends in a round tendon, which passes through the cartilaginous pulley 
attached by a movable fibrous ligament to a depression behind the inner 
angle of the os frontis; the tendon then passes backwards and outwards, 
and is inserted into the posterior part of the sclerotic coat between the 
superior and external recti. In some instances the pulley is bony instead 
of cartilaginous. 
The inferior oblique muscle is the shortest of the group, and the only one 
that is not connected to the apex of the cavity, being situated at the 
inferior and anterior part of the orbit, behind the lower eyelid. It arises 
from a rough ridge within the orbital margin of the superior maxillary bone 
external to the lachrymal sac, and endsin a broad thin tendon which 
ascends between the eye and the external rectus, becoming inserted into 
the posterior external part of the sclerotic. The two oblique muscles are 
adapted to rotate the eye on its axis. The recti muscles are adapted to 
change the position of the axis of the eye with reference to the axis of the 
orbit, and by the combination of the two sets of muscles, the axis of the 
eye can be turned with ease and precision to any object in front of the 
body. 
5. Bioop-vesseLs or THE Orsit. The arteries are the ophthalmic artery 
and its ramifications, assisted by small vessels from the facial, temporal, 
and internal maxillary arteries. The ophthalmic artery, as the principal, 
arises from the internal carotid, just after the latter has emerged from the 
cavernous sinus, and is curving upwards by the side of the anterior clinoid 
process. It immediately becomes attached to the sheath of the optic 
nerve, and passing into the orbit, sends off numerous branches to supply 
the optic apparatus. The principal vein is the ophthalmic, which escapes 
from the orbit by the inner wide portion of the sphenoid fissure; it then 
enters the cavernous sinus, whence the blood is carried by the petrous 
sinuses to the internal jugular veins. 
6. Nerves or tHE Eye. The nerves of the eye are large and numerous, 
no less than four entire nerves and a portion of three others being distributed 
to this organ. These nerves are the second, third, fourth, and sixth; one 
division of the fifth, and branches of the seventh or facial, and of the sympa- 
thetic. Each of the cerebral nerves arises from a distinct part of the ner- 
vous system, and ministers to some distinct and special purpose. 
Pi. 131, fig. 1, well formed left eye of a middle-aged man, seen from the 
front: abc, eye-brow; d, upper eye-lid; erm, palpebral fissure; e fg hi, 
inner canthus of the eye, with the lacus and the lachrymal caruncle ; #/, line 
showing the difference in height between the two canthi of the eye ; m to gq, 
lower eye-lid ; r, outer canthus; stvuw, iris. Fig. 2, female eye, for com- 
parison with the male. ig. 39, lateral view of the eye. Fig. 3, left eye, 
as shown during a quiet sleep; abc, eye-brow; ode /, depressed upper eye- 
lid; ef, completely closed rima; g, lashes of both lids; h to.o, translucent 
portion of the eye-lid; p, fold of the lower eye-lid. Fig. 4, eye-lids removed, 
and seen from behind: a, portion of the orbicularis muscle; 6, rima_palpe- 
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