Eye Anatomy-Histology Correlate. By: Michael Lu, Class of ‘07.
Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.
By: Michael Lu, Class of ‘07
The superficial features of the eye and eyelids are detailed here. The palpebral fissure (not labeled )is the opening of the eye itself. The lateral and medial commissures (canthus or angles) form the lateral and medial corners of the eyes. The medial commissure contains the plica semilunaris (semilunar fold) and the lacrimal caruncle.
Some parts of the lacrimal apparatus were described earlier. The lacrimal gland is located superior and lateral to the eyeball. It is divided into orbital and palpebral parts by the levator palpebrae superioris muscle. The gland secretes tears directly into the superior conjunctival fornix. The tears are distributed across the eye by blinking, collected in the lacrimal lake, and drained by the superior and inferior lacrimal papillae through puncta (pores). The tears are drained via the canaliculi into the lacrimal sac. There is a suction action when the lids are closed due to attachments of the orbicularis oculi muscle into the lateral wall of the sac. From there, they drain via the nasolacrimal duct into the nasopharynx.
The ciliary body contains ciliary muscle that is composed of smooth muscle. Contraction and relaxation of the ciliary muscles change the tension of the zonular fibers, or suspensory ligaments, of the lens. This allows the lens to change shape, a process known as accommodation.
The iris is detailed here in higher magnification. Note the anterior and posterior chambers to help orient yourself.
Now we will look at the other portions of the eyeball. The eye can essentially be divided into 3 layers:
The 3 layers of the eye are shown here again. Note the retina, the choroid, and the sclera. The top panel also indicates an extraocular muscle and some orbital fat.
The top panel shows the retina as viewed through the ophthalmoscope (with much practice). The numbered areas are magnified in the histological slides.
The eyeball itself is directly connected with, or part of, the optic nerve(CN II).
The arterial supply to the eyeball, orbit, and eyelid comes primarily from the ophthalmic artery, which branches off the internal carotid artery.