Targeting medical students

1. Anatomy of the eye

3. Orbit anatomy

5. The roof: the lesser wing of the sphenoid, the orbital plate of the frontal.
The lateral wall: the greater wing of the sphenoid, Zygomatic.
The floor: Zygomatic, Maxillary, Palatine.
The Medial wall: Maxillary, Lacrimal, Ethmoid, Sphenoid.

9. Lid anatomy
Anterior lamella Posterior lamella
• Skin
• Orbicularis
• Tarsus
• Conjunctiva

10. Eyelid Structure
1. Orbicularis oculi (sphincter muscle); closes eyelids.
2. Levator muscle of the upper eyelid (striate muscle); opens eyelids.
3. Tarsal plate (connective tissue); contributes to eyelid form and support.
4. Locus of tarsal plate; set as a requirement for eyelid manipulation

12. Orbicularis oculi
Two main parts:
• Orbital part: plays a role when the eyelids need to be tightly shut.
• Palpebral portion that plays a role in winking and blinking.
Nerve supply: facial nerve

13. Levator Palpebrae Superioris
Origin: Roof of the orbit, above the optic foramen
Insertion: Anterior surface of superior tarsus and upper eyelid
Innervation: Oculomotor nerve (CN III)
Action: Retraction and elevation of eyelid.

14. Blood Supply of the Lid

15. Conjunctiva
Palpebral Bulbar
Fornix

17. Blood supply of Conjunctiva
Arterial supply of conjunctiva derives from
(1) Peripheral Tarsal arcades
(2) Marginal Tarsal arcades
(3) The anterior ciliary arteries

20. Lymphatics
Lateral Side Preauricular Lymphnode
Medial Side Submandibular Lymphnode

21. Lacrimal System
Lacrimal System
Secretory part
Main lacrimal gland
Accessory lacrimal glands
Drainage part

22. Lacrimal gland
• Located within the lacrimal fossa in the superior and
outer edge of the orbital roof.
• The tendon of the levator palpebrae muscle divides the
lacrimal gland into a larger orbital part (2/3) and a smaller
palpebral part (1/3).
• Parasympathetic secretomotor nerve supply comes from
the nervus intermedius.
• Blood supply: lacrimal artery (a branch of the ophthalmic
artery

26. Tear drainage
The superior and inferior puncta lacrimales collect the
tears, which then drain through the superior and inferior
lacrimal canaliculi into the lacrimal sac. From there they
pass through the nasolacrimal duct into the inferior
concha

27. CoRNEA

28. The cornea is the transparent tissue that covers the front
of the eye, forms anterior 1/6th of the outer coat of
eyeball.
• Diameter 11.5 mm. (11.7 mm * 11mm).
It forms 3/4th of the total refractive power of eye.
• Refractive power: 45D.
• Refractive index: 1.376.

29. Microscopic Anatomy of cornea

30. FACTORS AFFECTING CORNEAL TRANSPERANCY
Anatomical factors:
• Uniform and regular arrangement of corneal
epithelium
• regular arrangement of corneal stromal lamellae.
• Corneal avascularity.
Physiological factors:
• Relative state of corneal dehydration.

31. Uveal Tract
Iris
Ciliary Body
Choroid

32. Iris
• Iris is the anterior-most part of the uveal tract.
• It is a thin, circular structure, forms a diaphragm like structure in
front of the crystalline lens.
• It has a central aperture known as the pupil.
• The pupil determines the amount of light entering the eye.

33. Muscles in iris
Sphincter pupillae: circular muscle, 1 mm wide, encircles the pupil.
 Innervated by the parasympathetic system.
 Contraction of the sphincter causes the pupil to constrict (miosis).
Dilator pupillae: extends radially from the iris root to the sphincter.
 innervated by the sympathetic system
 Contraction of the dilator muscle causes the pupil to dilate
(mydriasis).

34. Ciliary body
The ciliary body is the middle part of the uveal tract forms a ring-
shaped structure that projects posteriorly from the scleral spur.
Anteriorly: it is confluent with the periphery of the iris (iris root).
Posteriorly: it has a scalloped periphery, known as ora serrata, where
it is continuous with the choroid and retina.

36. Ciliary muscle
Nonstriated muscle primarily situated in the anterior 2/3 of
the ciliary body stroma.
The muscle has three parts: Outer longitudinal portion,
Middle oblique portion, Inner circular portion.
Action: Accommodation
Nerve supply: The parasympathetic stimulation activates
the muscle for contraction, whereas sympathetic innervation
likely has an inhibitory effect.

37. Pars plicata: the portion of the ciliary body that contains finger-like
projections (ciliary processes), extend into the posterior chamber.
Pars plana: the smooth part of the ciliary body, terminates at the
ora serrata, which is the transitional zone between the ciliary body
and choroid.

38. Physiology of aqueous humor circulation

40. Choroid
• The choroid is a thin but highly vascular layer, lining the inner
surface of the sclera.
• It extends from ora serrata anteriorly to the optic nerve posteriorly.
• The outer surface is attached to the sclera at the optic nerve and at
the exit of the vortex veins, The inner surface is attached to the
retinal pigmented epithelium (RPE).

41. Microscopic structure of choroid

42. Blood supply of uveal tract:
The blood supply of the uveal tract is mainly from three
arteries namely
• Short posterior ciliary arteries
• Long posterior ciliary arteries
• Anterior ciliary arteries.
The posterior ciliary arteries are branches of the
ophthalmic artery

43. Blood Supply of Uveal Tract

44. Retina

48. The optic disc lies a 3 mm medial to the center of the macula
(fovea). There are no normal retinal layers in this zone (blind spot)
as ganglion cell axons from the retina pierce the sclera to enter the
optic nerve.

49. Vascular supply to the retina
The inner layers of the retina (the internal limiting membrane
through the inner nuclear layer) are supplied by the central
artery of the retina. This originates at the ophthalmic artery,
enters the eye with the optic nerve, and branches on the inner
surface of the retina. It is a terminal artery without
anastomoses and divides into four main branches
Because the central artery is a terminal artery, occlusion will
lead to retinal infarction.
The outer layers (outer plexiform layer through the pigment
epithelium) contain no capillaries. They are nourished by
diffusion primarily from the richly supplied capillary layer of the
choroid.

50. diagram of the human visual pathways and their neuronal components.

52. Extra-ocular muscles