Human eyes are special sense
organs for the sense of vision and are called as photoreceptor organs. They are
spherical structures present in the bony socket of the skull. The bony socket
of skull is called as orbital cavity and it remaining filled with fatty tissues
the movement of eye ball in the orbital cavity is regulated by rectus muscles
and oblique muscles. The rectus muscles are anterior rectus, posterior rectus,
superior rectus and inferior rectus while the oblique muscles are superior
oblique and inferior oblique. Each eye is of about 2.5 cm diameter.
The eye ball remains protected by upper and lower
eye lids. The eyebrows and eyelashes also protect the eyeball.
The eye ball gets secretions of meibomian gland,
harderian gland, glands of Zeis and lacrimal gland. The secretion of meibomian
and harderian glands is oily and lubricates the eyelids and cornea while the
lacrimal gland secretes watery fluid, the tears. It makes eye ball moist, soft,
clean and free from bacteria. The glands of Zeis are present at the base of eye
lashes and their secretion keep eye lashes soft and smooth.
Internal
Structure
The
internal structure of eye can be studied with the help of its vertical section.
It consists of three concentric layers of tissues which are outer layer, middle
layer and inner layer.
