In ophthalmology orbit is the main cavity which contains the
eyeball and many other structures related to ocular functions.
Lacrimal fossa contains the lacrimal sac, nasolacrimal canal contains
the nasolacrimal duct whereas the fossa for the lacrimal gland
contains the lacrimal gland. There is no difference between lacrimal
fossa and fossa for the lacrimal gland. As two different structures
had to be described this artificial difference has been made. The
optic canal transmits the optic nerve and through supra-orbital
notch pass the the supra-orbital nerve and vessels. Cavities are
not necessarily hard like bony cavities. There could be soft cavities
also which are cystic in nature and usually contain some fluid.
Thus, the eyeball itself contains three soft cavities namely anterior
chamber, posterior chamber and vitreous cavity. The anterior and
posterior chambers contain aqueous humor whereas the vitreous
cavity contains vitreous humor. The soft cavities can be static or
dynamic performing some specific function. All bony cavities are
static but soft cavities like anterior chamber, posterior chamber
and conjunctival sac, or conjunctival cavity are dynamic . In the
former two there is circulation of aqueous humor and in the latter,
there is circulation of tears (Table 1).
All cranial cavities are hard cavities and mainly include the
anterior cranial fossa, middle cranial fossa and the posterior cranial
fossa and contain anterior frontal lobe, middle parietal lobe and the
posterior occipital lobe which perform their respective functions.
In the center of the middle cranial foss is situated the pituitary fossa
which contains the pituitary gland which is of great importance.
Besides these there are cranial arteries, veins and nerves.