Vision: Anatomy of the Eye (Nursing)

00:01 Let's take a look at the structures of the eye starting with the accessory structures.

00:07 We have the eyebrows, the eyelid and the eyelashes.

00:12 Also not depicted here, we have the lacrimal apparatus which is responsible for tear production and also the extrinsic eye muscles which are responsible for the movement of the eye.

00:26 The palpebral muscles are going to control the eyelid movements and the extrinsic eye muscles are going to be responsible for moving the eyeball itself in all directions.

00:38 The conjunctiva of the eye is a thin protective mucous membrane that lines the eyelids and covers the sclera.

00:47 This is what gets infected during conjunctivitis or pink eye.

00:54 The tarsal plate is a fold of connective tissue that gives form to the eyelids.

01:01 It also contains a row of sebaceous glands called tarsal gland or Meibomian glands that keeps the eyelids from sticking together.

01:14 Now let's look at the lacrimal apparatus.

01:18 The lacrimal apparatus is going to be responsible for the production and draining of tears.

01:25 If we look at the pathway of tear production, we find that it starts at the lacrimal gland superior to the eye.

01:34 From there, the secretions of this gland go to the lacrimal ducts and then into the lacrimal puncta that are medial to the eye.

01:46 From there, we go to the lacrimal canaliculi and finally to the lacrimal sac.

01:53 From the lacrimal sac, we go to the nasolacrimal ducts that are going to carry our tears into the nasal cavity.

02:05 Now let's take a look at some of the anatomy of the eyeball.

02:09 Starting with the structures responsible for our eye movements, the eyeball contains six extrinsic eye muscles that move the eyes in almost any direction.

02:21 pThey include the superior rectus, the inferior rectus, the lateral rectus, the medial rectus, the superior oblique muscles and the inferior oblique muscles.

02:34 The eyeball also contains two different layers or tunics.

02:39 On the outer portion, you have the fibrous tunic which is going to consist of the cornea and the sclera of the eye and then in the inner layer, we have the vascular tunic which is going to include the choroid, the ciliary body, and the iris of the eye.

02:58 The iris is a structure that is going to control the size of the pupil based on our autonomic reflexes.

03:06 This is the colored portion of the eyeball.

03:10 In bright light, circular muscles are going to contract and the pupil will constrict.

03:16 In normal light, this structure will be at a normal diameter.

03:21 In dim light, the radial muscles will contract and the pupil will dilate.

03:29 Another structure in the eye is the retina.

03:33 The retina is going to line the posterior three-quarters of the inner layer of the eyeball.

03:40 The optic nerve is actually visible from the retina.

03:46 The optic nerve comes out or exits the eye at a spot known as the optic disc or our blind spot.

03:55 The exact center of the retina is referred to as the macula lutea.

04:01 The center of this structure is the fovea centralis and this is the area of the retina that has the highest visual acuity and where we hope for light to concentrate on as it comes into the eye The eye is divided into different chambers: an anterior chamber and a posterior chamber.

04:24 They are divided by the iris.

04:28 In the anterior chamber, which is between the iris and the cornea, we have a liquid known as aqueous humour.

04:37 This is a very watery liquid.

04:40 In the posterior chamber, which is going to be behind the iris but in front of the lens, it's going to also be filled with aqueous humor In the posterior portion or posterior cavity also referred to as the vitreous chamber of the eye, we have another liquid but it is a little more solid or gelatinous.

05:03 This is referred to as vitreous humour.