ANATOMY OF THE EYELIDS, LACHRIMAL APPARATUS AND ORBIT.pptx

Anatomy of the eye

1. ANATOMY OF THE EYELID, LACRIMAL APPARATUS AND ORBIT Structures making the eyelid Conjunctiva Tarsal plate Orbicularis oculi muscles Levator muscle Skin Muller s muscle Septum and mucus glands etc

2. Eye lids The lids protect the eye and keeps it moist. Each time a person blinks, the tear film is spread across the surface of the cornea, the upper eyelid is more important than the lower one. The conjunctiva is a thin membrane which lines inner surface of the eyelid and the outer of the eyeball. It is divided into three(3) Bulbar conjunctiva Fornix conjunctiva Tarsal conjunctiva The tarsal plate is a fibrous structure, which keeps the eyelid rigid and contains meibomian glands.

3. The eyelid Beneath of the epithelial surface, the conjunctiva contains many islands of lymphoid tissues especially in the fornex and many goblet cells which secret mucus Orbicularis oculi muscle fibre are in front of the tarsal plate, supplied facial nerve. Its function is to close the eyelid. The levator muscle is also attached the tarsal plate of the eyelid. This muscle is responsible for lifting (opening) the eyelid. This is partly supplied by the 3 rd cranial nerve The eyelids have a very good blood supply. Eyelashes are specialized hairs. They have numerous sweat and sebaceous glands near their roots.

4. Lacrimal apparatus Lacrimal apparatus comprises of the following structures: Lachrimal gland. Accessory gland Lacrimal puncta Canaliculi Sac Nasolacrimal duct

5. Lacrimal apparatus Lacrimal apparatus. The function of lacrimal apparatus is to produce and drain the tears. Tears form a thin film of fluid on the surface of the conjunctiva and cornea Tears film is vital for the health and transparency of the cornea. Tears film contains mucus which is secreted by conjunctival goblet cells which helps the tear film to stick to the surface of cornea and keep it moist. Meibomian glands secret waxy secretion which becomes on top of tear film to prevent tears from drying.

6. THE EXTRA OCULAR MUSCLES There are six extra ocular muscles which control eye movements. They form a cone which passes backwards from the eye to the apex of the orbit. The action of the muscles are rather complex. The names of muscles are as follow: Superior rectus Inferior rectus Lateral rectus Medial rectus Superior oblique and Inferior oblique

7. THE MUSLES AND NERVES MUSCLES ACTION NERVE SUPPLY Orbicularis oculi Close the eye Facial (7) Levator palpebrae superioris Open the eye Oculomotor (3) Superior rectus Looks up Oculomotor (3) Medial rectus Looks in ,, Inferior rectus Looks down ,, Lateral rectus Looks out Abducens (6) Superior oblique Looks down and in Trochlear (4)

8. MUSCLE AND NERVES conti … MUSCLES ACTION NERVE SUPPY Inferior oblique Looks up and in Oculomotor (3) Ciliary muscle Accomodation ,, Pupil constrictor Constrict pupil ,, Pupil dilator Dilate pupil sympathetic

9. ANATOMY OF THE ORBIT

10. BONES OF THE ORBIT The orbit is a cavity or socket in the skull in which the eye globe and it’s appendeges are situated.

11. THE ORBIT The orbit is made up of seven orbital bones. Four facial and two cranial bones. These are: Maxilla bone Zygomatic bone Cranial bone Palatine bone Frontal bone Ethmoid bone and Sphenoid bone

12. The base of this pyramid opens anteriorly onto the face while the apex is pointed posteromedially towards the centre of the skull.

13. FUNCTION OF THE ORBIT The orbit is a bony structure of the skull that house the eye globe, extraocular muscles, nerves, blood vessels, lacrimal apparatus and adipose tissues. Each orbit protects the eye globe, while the supportive tissues allow the globe to move in three dimensions. Horizontal, vertical and torsional.