1. 1 Anatomy of The Eye

2. 2 INTRODUCTION The Eye is the organ of vision. The Eye is the organ of vision. Composed of : Composed of : 1. Eyeball. 2. The adnexa.

3. 3 THE POSITION In the Predatory species: have set well forward In the Predatory species: have set well forward In Herbivores, Ruminant and rabbits: have eyes more laterally to have wide area of vision In Herbivores, Ruminant and rabbits: have eyes more laterally to have wide area of vision

4. 4 Terminology of the eye Cornea : the transparent part of the eyeball. Cornea : the transparent part of the eyeball. Anterior pole: the highest point on cornea. Anterior pole: the highest point on cornea. Posterior pole : the highest point on posterior surface. Posterior pole : the highest point on posterior surface. Optic axis: the straight line passing through both poles Optic axis: the straight line passing through both poles

5. 5 The Eyeball Equator :an imaginary line about the eyeball, which is the equidistant from the poles. Equator :an imaginary line about the eyeball, which is the equidistant from the poles. Meridian: is one of many lines passing from pole to pole that intersects the equator at right angles. Meridian: is one of many lines passing from pole to pole that intersects the equator at right angles. Optic nerve :leaves the eyeball slightly ventral to the posterior poleOptic nerve :leaves the eyeball slightly ventral to the posterior pole

6. 6 Eyeball The three tunics are: The three tunics are: I- An external fibrous tunic II- A middle vascular tunic III- An internal tunic

7. 7 Eyeball The three tunics are: The three tunics are: I. An external fibrous tunic: that gives form to and protects the eyeball; it’s the only complete tunic. II. A middle vascular tunic: that consist largely of blood vessels and smooth muscle concerned with the nutrition of the eyeball and the regulation of the shape of the lens and size of pupil. concerned with the nutrition of the eyeball and the regulation of the shape of the lens and size of pupil.

8. 8 Eyeball III. An internal tunic: that consists largely of nervous tissue III. An internal tunic: that consists largely of nervous tissue  concerned with vision and translation of visual stimuli into nerve impulses for interpretation by the brain.

9. 9 The Fibrous Tunic It consists of the sclera and the cornea, which meet at the limbus. It consists of the sclera and the cornea, which meet at the limbus. 1. The sclera is the opaque posterior part of the fibrous tunic and consists of a dense felt work of colagenous and elastic fibers and is generally white but in some species it contain pigment cells

10. 10 The fibrous tunic The cornea forms about one quarter of the fibrous tunic and bulges forward. It is composed off dense connective tissue arranged in lamellar form. The cornea forms about one quarter of the fibrous tunic and bulges forward. It is composed off dense connective tissue arranged in lamellar form. The cornea doesn’t contain blood vessels; nutrients for its cells permeate from vessels in the limbus or are carried to it its surface in the lacrimal fluid and aqueous humor. The cornea doesn’t contain blood vessels; nutrients for its cells permeate from vessels in the limbus or are carried to it its surface in the lacrimal fluid and aqueous humor.

11. 11 The vascular Tunic (uvea) Deep to the sclera, which it composed of three zones. Deep to the sclera, which it composed of three zones. 1) The choroids: lies on the sclera from the optic nerve to the limbus and contains a dense network of blood vessels embedded in heavily pigmented connective tissue 1) The choroids: lies on the sclera from the optic nerve to the limbus and contains a dense network of blood vessels embedded in heavily pigmented connective tissue

12. 12 The vascular Tunic (uvea) In the dorsal part of the fundus the choroids forms colored, light-reflecting area known as tapetum lucidum In the dorsal part of the fundus the choroids forms colored, light-reflecting area known as tapetum lucidum  is avascular layer (cellular in the carnivores, fibrous in ruminants and horses) between the capillaries and the vessels. The tapetum makes the eyes of animals shine when they look toward the light. The tapetum makes the eyes of animals shine when they look toward the light. Our eyes and those of the pig don’t have a tapetum so they don’t reflect the light. Our eyes and those of the pig don’t have a tapetum so they don’t reflect the light. This reflecting of light is a night vision adaptation because of stimulation of the light sensitive receptors in the retina. This reflecting of light is a night vision adaptation because of stimulation of the light sensitive receptors in the retina.

13. 13 The vascular Tunic (uvea) 2) The ciliary body : toward the limbus the choroids thickness to form it. toward the limbus the choroids thickness to form it. 3) The Iris: the smallest part of the vascular tunic, which extends from the cornea to the lens.  It attached to sclera and ciliary body by pectinate ligament.  the opening in the center is the pulpi

14. 14 The vascular Tunic (uvea) The iris divided the space between the lens and cornea into anterior and posterior chambers tat communicate through pupil and filled with, aqueous humor (a clear watery fluid). The iris divided the space between the lens and cornea into anterior and posterior chambers tat communicate through pupil and filled with, aqueous humor (a clear watery fluid). The color of the iris determines the color of the eye The color of the iris determines the color of the eye  depends on the number of the pigmented cells present in its stroma  the type of the pigment in the cells.

15. 15 The internal tunic The internal tunic of the eyeball contains the light-sensitive receptor cells (known as retina). The internal tunic of the eyeball contains the light-sensitive receptor cells (known as retina).  It’s an extension of the brain to which remains connected by the optic nerve.

16. 16 The internal tunic The layers in retina are: A single layer of pigmented cells. A single layer of pigmented cells. Aneuroepithelialm layer containing the receptor cells, rods and cones and their nuclei. Aneuroepithelialm layer containing the receptor cells, rods and cones and their nuclei.  the rods for black and whit  the cones for the color vision. A layer of bipolar ganglion cells. A layer of bipolar ganglion cells. A layer of multipolar ganglion cells nonmyelinated axons lying internal to the cells and pass to the optic disc where they form the optic nerve. A layer of multipolar ganglion cells nonmyelinated axons lying internal to the cells and pass to the optic disc where they form the optic nerve. The optic disc is a blind area because there is no receptor cell. The optic disc is a blind area because there is no receptor cell.

17. 17  The adnexa of the eye 1. The orbital fasciae : a. The periorbital: is attached near the optic foramen at the apex of the cone. a. The periorbital: is attached near the optic foramen at the apex of the cone. b. The superficial muscular fascia: lies within the periorbital. It’s loose and fatty. And envelops in the levator palpebrae superioris and the lacrimal gland. b. The superficial muscular fascia: lies within the periorbital. It’s loose and fatty. And envelops in the levator palpebrae superioris and the lacrimal gland. c. The deep muscular fascia: is more fibrous and arises from the eyelids and from the limbus of the eyeball. c. The deep muscular fascia: is more fibrous and arises from the eyelids and from the limbus of the eyeball.

18. 18  The adnexa of the eye 2. The muscles of the eyeball: The rectus muscles: dorsal, ventral, medial and lateral are inserted anterior to the equator by wide but very thin tendons. The rectus muscles: dorsal, ventral, medial and lateral are inserted anterior to the equator by wide but very thin tendons. The ventral and dorsal oblique muscles: attach to the eyeball near the equator. The ventral and dorsal oblique muscles: attach to the eyeball near the equator.

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20. 20  The adnexa of the eye 2. The muscles of the eyeball: The retractor bulbi arises from the vicinity of the eyeball and inserted on the eyeball posterior to the equator. The retractor bulbi arises from the vicinity of the eyeball and inserted on the eyeball posterior to the equator. The levator palpebrae superioris: striated muscle within the orbit that doesn’t attach to the eyeball but passes over it to enter and elevate the upper eyelid The levator palpebrae superioris: striated muscle within the orbit that doesn’t attach to the eyeball but passes over it to enter and elevate the upper eyelid

21. 21  The adnexa of the eye 3. The eyelids and conjunctiva : The eyelids (palpebrae) are two musculofibrous folds of which the upper is the more extensive and more mobile. The eyelids (palpebrae) are two musculofibrous folds of which the upper is the more extensive and more mobile. The free margins of the lids are meet at the medial and lateral angles of the eye and bound an opening known as the palpebral fissure. The free margins of the lids are meet at the medial and lateral angles of the eye and bound an opening known as the palpebral fissure.

22. 22  The adnexa of the eye 3. The eyelids and conjunctiva : They are consist of three layers: They are consist of three layers: 1.The skin: is thin and delicate and is covered with short hairs: it may also carry a few prominent tactile airs. 2.The musculofibrous layer: is formed by the orbicularis oculi, the orbital septum, the aponeurosis of the levator muscle and the smooth tarsal muscle. 3.The mucous (palpebral conjunctiva) a thin, transparent mucous membrane

23. 23  The adnexa of the eye 3. The eyelids and conjunctiva : The third eyelid is supported by a T-shaped piece of cartilage. The third eyelid is supported by a T-shaped piece of cartilage. Bar lies in the free edge of the fold and stem points backward into the orbit medial to the eyeball. Bar lies in the free edge of the fold and stem points backward into the orbit medial to the eyeball. The stem of cartilage is surrounded by lacrimal gland (the gland of the third eyelid). The stem of cartilage is surrounded by lacrimal gland (the gland of the third eyelid).

24. 24  The adnexa of the eye 4. The lacrimal apparatus: This consists of lacrimal gland proper This consists of lacrimal gland proper  The lacrimal gland is flat and lies between the eyeball and the dorsolateral wall of orbit. The glands associated with the third eyelids The glands associated with the third eyelids several small accessory glands several small accessory glands duct system that conveys the lacrimal fluid after it has washed over the eye into the nasal cavity for evaporation.duct system that conveys the lacrimal fluid after it has washed over the eye into the nasal cavity for evaporation.

25. 25  The blood supply of the eye: The arteries can be divided into three groups: The arteries can be divided into three groups: 1. THOSE SUPPLY EYEBLL 2. SUPPLY OCULR MUSCLES 3. THOSE LAEVING THE ORBIT TO SUPPLY ADJCENT STRCTURES. The external ophthalmic artery carries the principle supply of the blood to the eye, which is a branch of the maxillary artery. The external ophthalmic artery carries the principle supply of the blood to the eye, which is a branch of the maxillary artery.

26. 26  The blood supply of the eye: 1) The branches of the external ophthalmic for the eyeball penetrate the sclera to reach the vascular tunic and retina. 1) The branches of the external ophthalmic for the eyeball penetrate the sclera to reach the vascular tunic and retina. -Short posterior ciliary a. / supply the adjacent choroids in addition to branches to the optic nerve. -Short posterior ciliary a. / supply the adjacent choroids in addition to branches to the optic nerve. -Long posterior ciliary a. /pass close the sclera closer to the equator. -Long posterior ciliary a. /pass close the sclera closer to the equator. -The anterior ciliary a. / supply the anterior potion of the choroids, the ciliary body and the iris -The anterior ciliary a. / supply the anterior potion of the choroids, the ciliary body and the iris These arteries anastomose to form the greater arterial circle of the iris. These arteries anastomose to form the greater arterial circle of the iris.

27. 27  The blood supply of the eye: 2) The arteries that supply the ocular muscles. Which the absence of the large vessels in distal ends reduces bleeding when the muscles are cut during the enucleating.

28. 28  The blood supply of the eye: 3) The arteries that leave the orbit: -The lacrimal a. / supply the lacrimal gland in route. -The lacrimal a. / supply the lacrimal gland in route. -The supraorbital a. / send branches to the upper eyelids -The supraorbital a. / send branches to the upper eyelids -The malar a. /supply the eyelids and also adjacent area of the face. -The malar a. /supply the eyelids and also adjacent area of the face. -The external ethamoid a. / supply the ethamoid labyrinth of the nasal cavity. -The external ethamoid a. / supply the ethamoid labyrinth of the nasal cavity.

29. 29  The nerve supply of the eye: The optic nerve II: enters the orbit through the optic foramen and passes to the light receptor cells in the retina. The optic nerve II: enters the orbit through the optic foramen and passes to the light receptor cells in the retina. It allows the movements of the eye and is covered by meninges that it acquired during its development. It allows the movements of the eye and is covered by meninges that it acquired during its development.

30. 30  The nerve supply of the eye: The Oculomoter nerve III: control the movement of the eyeball. it enters the orbit through the orbital fissure. The Oculomoter nerve III: control the movement of the eyeball. it enters the orbit through the orbital fissure.  Supply: dorsal, medial, ventral Rectus muscle  Ventral oblique muscle  Part of retractor muscle The abducent nerve VI: enters through the orbital foramen and innervates most of retractor bulbi and lateral rectus muscles. The abducent nerve VI: enters through the orbital foramen and innervates most of retractor bulbi and lateral rectus muscles.

31. 31  The nerve supply of the eye: The trochlear nerve IV: innervate The trochlear nerve IV: innervate  Dorsal oblique muscle The trigeminal nerve V: send branches to the eye. The trigeminal nerve V: send branches to the eye.  Opthalmic division Give sensory branches to: 1- long ciliary nerve of the eye, lacrimal and supraorbital nerves.  Maxillary division  Zygomatic branch supply ventrolateral segment of the eyelids and conjunctiva

32. 32  The nerve supply of the eye: The facial nerve VII: The facial nerve VII:  passes between the eye and the ear gives auriculopalpebral branch  innervates the orbicularis oculi