Sunday, October 11, 2009

The Eye and Eyeball

The eyeball is contain in the cavity of the orbit. In this situation it is surely protected from injury, whilst position in such as to ensure the most extensive range of sight. It is acted upon by nemerous muscles, by which it is capable of being directed to different parts: It is applied by vessel and nerves and is additionally protected in front by several appendages, such as the eyebrow, eyelids, etc.

The eyeball is imbedded in the fat of the orbit, but is surrounded by a thin membranous sac. the capable of tenon, which isolate it, so as to allow of free movement.

The capsule of tenon consist of a thin membrane which envelope the eyeball of the optic nerve to the eilliary region, separating it from the orbital fat and forming a socket in which it plays. Its inner surface is smooth, and is in contact with outer surface of the selerotic, the perisclerotic lyph space only intervening. This lymph-space is continuous with the subdural and subarachnoid spaces, and in tranversed by delicate bands of connective tissue which extend between the capsule and the selerotic. The capsule is perforated behind by the ciliary vessels capsule and nerves and by the optic nerve, being continuous with the sheath of the latter.

In front it blends with the ocular conjunctiva, and with it is attached to the ciliary region of the eyeball. It is perforated by the muscle which move the eyeball and on each it sends a tubular sheath. The sheath of the Superior oblique is carried as far as the fibrous pulley of the muscle; that on the inferior oblique reaches as far as the floor of the orbit, to which it gives off a slip.

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