Lecture1 anatomy of the eye

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Lecture1 anatomy of the eye

  1. 1. ANATOMY AND PHYSIOLOGY OF THE EYE Department of Ophthalmology Fatima College of Medicine
  2. 2. ORBIT <ul><li>BONY CAVITY WHICH HOUSES THE EYEBALL </li></ul><ul><li>4 WALLS - ROOF,FLOOR, MEDIAL AND LATERAL WALL </li></ul><ul><li>30 mL in volume </li></ul><ul><li>HAS AN APEX WHERE NERVES AND VESSELS EMERGE </li></ul>
  3. 3. Orbital Walls
  4. 4. ORBITAL WALLS <ul><li>ROOF </li></ul><ul><ul><li>COMPOSED OF THE LESSER WING OF THE SPHENOID, AND ORBITAL PLATE OF THE FRONTAL BONE </li></ul></ul><ul><ul><li>INTIMATELY RELATED TO THE FRONTAL SINUS </li></ul></ul>
  5. 5. ORBITAL WALLS <ul><li>LATERAL WALL </li></ul><ul><ul><li>SEPARATED FROM THE ROOF BY THE SUPERIOR ORBITAL FISSURE </li></ul></ul><ul><ul><li>COMPOSED OF THE GREATER WING OF THE SPHENOID, ZYGOMATIC BONE </li></ul></ul><ul><ul><li>STRONGEST PART OF THE BONY ORBIT </li></ul></ul>
  6. 6. ORBITAL WALLS <ul><li>FLOOR </li></ul><ul><ul><li>SEPARATED FROM THE LATERAL WALL BY THE INFERIOR ORBITAL FISSURE </li></ul></ul><ul><ul><li>INTIMATELY RELATED TO THE MAXILLARY SINUS </li></ul></ul><ul><ul><li>COMPOSED OF MAXILLARY BONE, ZYGOMATIC BONE AND PALATINE BONE </li></ul></ul><ul><ul><li>ORBITAL CONTENTS CAN HERNIATE INTO THE MAXILLARY SINUS IN TRAUMA CASES </li></ul></ul>
  7. 7. ORBITAL WALLS <ul><li>MEDIAL WALL </li></ul><ul><ul><li>INTIMATELY RELATED TO THE ETHMOID AND SPHENOID SINUSES </li></ul></ul><ul><ul><li>COMPOSED OF THE ETHMOID BONE, SPHENOID BONE, LACRIMAL BONE AND MAXILLA </li></ul></ul>
  8. 8. ORBITAL APEX <ul><li>SERVES AS A PORTAL FOR NERVES AND VESSELS </li></ul><ul><li>SITE OF ORIGIN OF ALL EOMS EXCEPT INFERIOR OBLIQUE </li></ul>
  9. 9. Orbital Apex
  10. 10. SUPERIOR ORBITAL FISSURE <ul><li>LATERAL PORTION </li></ul><ul><ul><li>SUPERIOR OPHTHALMIC VEIN </li></ul></ul><ul><ul><li>LACRIMAL NERVE </li></ul></ul><ul><ul><li>FRONTAL NERVE </li></ul></ul><ul><ul><li>TROCHLEAR NERVE </li></ul></ul><ul><li>MEDIAL PORTION </li></ul><ul><ul><li>SUPERIOR AND INFERIOR DIV. OF OCULOMOTOR NERVE </li></ul></ul>
  11. 11. ORBITAL APEX <ul><li>OPTIC CANAL </li></ul><ul><ul><li>TRANSMITS OPTIC NERVE AND OPHTHALMIC ARTERY </li></ul></ul><ul><li>SUPERIOR ORBITAL FISSURE </li></ul><ul><ul><li>ALSO TRANSMITS THE INFERIOR OPHTHALMIC VEIN </li></ul></ul>
  12. 12. BLOOD SUPPLY OF THE ORBIT <ul><li>OPHTHALMIC ARTERY </li></ul><ul><ul><li>CENTRAL RETINAL ARTERY </li></ul></ul><ul><ul><li>LACRIMAL ARTERY </li></ul></ul><ul><ul><li>MUSCULAR BRANCHES </li></ul></ul><ul><ul><li>LONG AND SHORT POSTERIOR CILIARY ARTERY </li></ul></ul><ul><ul><li>MEDIAL PALPEBRAL ARTERIES </li></ul></ul>
  13. 13. Blood Supply of the Eyeball
  14. 14. BLOOD SUPPLY <ul><li>SHORT POSTERIOR CILIARY ARTERY </li></ul><ul><ul><li>CHOROID, OPTIC NERVE </li></ul></ul><ul><li>LONG POSTERIOR CILIARY ARTERY </li></ul><ul><ul><li>SUPPLY CILIARY BODY, ANASTOMOSE WITH EACH OTHER AND ANTERIOR CILIARY ARTERY TO FORM THE MAJOR ARTERIAL CIRCLE </li></ul></ul>
  15. 15. BLOOD SUPPLY <ul><li>Anterior ciliary artery </li></ul><ul><ul><li>derived from muscular branches of the rectus muscles </li></ul></ul><ul><ul><li>anterior sclera, episclera, limbus, conjunctiva </li></ul></ul>
  16. 16. Venous Drainage of the Orbit <ul><li>Superior and Inferior Ophthalmic Veins </li></ul><ul><li>Vortex veins </li></ul><ul><li>Anterior Ciliary Veins </li></ul><ul><li>Central retinal Veins </li></ul>
  17. 17. Venous Drainage of the Eyeball
  18. 18. Venous Drainage <ul><li>The ophthalmic veins communicate with the cavernous sinus via SOF and the pterygoid venous plexus via the inferior orbital fissure. </li></ul><ul><li>The SOV is formed from the supraorbital and suparatrochlear veins which drain the skin. </li></ul><ul><li>* potential communication between skin infection and cavernous sinus causing thrombosis </li></ul>
  19. 19. Eyeball <ul><li>Roughly spherical </li></ul><ul><li>approximately 24.5 mm (less than an inch) in length </li></ul><ul><li>about 5mL in total volume </li></ul>
  20. 20. Eyeball
  21. 21. Histological Cross Section of the Eyeball
  22. 22. Conjunctiva <ul><li>Thin transparent mucous membrane which covers the posterior surface of the eyelid (palpebral conjunctiva) and the anterior surface of the sclera (bulbar conjunctiva) </li></ul><ul><li>composed of two to five layers of stratified columnar epithelial cells </li></ul><ul><li>contains glands which help in ocular lubrication </li></ul>
  23. 23. Conjunctiva <ul><li>Blood Supply </li></ul><ul><ul><li>anterior ciliary artery </li></ul></ul><ul><ul><li>palpebral aretries </li></ul></ul><ul><li>Nerve Supply </li></ul><ul><ul><li>first division of the trigeminal nerve </li></ul></ul>
  24. 24. Upper Eyelids
  25. 25. Lower Lid Retractors
  26. 26. Tenon’s Capsule <ul><li>A fibrous membrane that envelopes the globe from the limbus to the optic nerve </li></ul><ul><li>continuous with the EOM’s </li></ul><ul><li>thickens to form check ligaments </li></ul>
  27. 27. Sclera <ul><li>Fibrous outer protective coating of the eye </li></ul><ul><li>composed of dense bands of well hydrated connective tissue </li></ul>
  28. 28. Episclera <ul><li>Fine elastic tissue containing blood vessels and covers the anterior surface of the sclera </li></ul>
  29. 29. Cornea <ul><li>Transparent tissue which accounts for most of the refractive power of the eye </li></ul><ul><li>thicker at the limbus, and thinner at the center </li></ul><ul><li>5 layers </li></ul><ul><ul><li>epithelium </li></ul></ul><ul><ul><li>Bowman’s layer </li></ul></ul><ul><ul><li>Corneal stroma </li></ul></ul><ul><ul><li>Descemet’s layer </li></ul></ul><ul><ul><li>Endothelium </li></ul></ul>
  30. 30. Cornea
  31. 31. Cornea
  32. 32. Uveal Tract <ul><li>Iris </li></ul><ul><li>Ciliary Body </li></ul><ul><li>Choroid </li></ul>
  33. 33. Posterior View of Uveal Tissue
  34. 34. Iris <ul><li>Flat anterior extension of the ciliary body </li></ul><ul><li>has a central round aparture known as the pupil </li></ul><ul><li>divides the anterior from the posterior chamber </li></ul>
  35. 35. Iris
  36. 36. Ciliary Body <ul><li>Extends from the choroid to the iris </li></ul><ul><li>divided into the pars plicata and pars plana </li></ul><ul><li>point of suspension of the lens </li></ul><ul><li>produces aqueous humor </li></ul>
  37. 37. Aqueous Flow
  38. 38. Choroid <ul><li>Posterior segment of the uveal tract in between the retina and sclera </li></ul><ul><li>joins the ciliary body anteriorly </li></ul><ul><li>choroidal blood vessels nourish outer portion of the retina </li></ul>
  39. 39. Ora Serrata
  40. 40. Choroidal Circulation
  41. 41. Lens <ul><li>Biconvex, avascular, colorless and transparent structure </li></ul><ul><li>second most powerful refractive tissue </li></ul><ul><li>held in place by suspensory ligaments known as zonules </li></ul><ul><li>accommodates to facilitate near vision </li></ul>
  42. 42. Lens Accommodation
  43. 43. Lens in the Young
  44. 44. Lens in the Aged
  45. 45. Anterior Chamber Angle <ul><li>Schwalbe’s line </li></ul><ul><li>Schlem’s canal </li></ul><ul><li>Trabecular meshwork </li></ul><ul><li>Scleral spur </li></ul>
  46. 46. Anterior Chamber Angle
  47. 47. Trabecular Meshwork
  48. 48. Aqueous Flow
  49. 49. Optic Nerve Cupping
  50. 50. Retina <ul><li>Thin, semitransparent, multilayered sheet of neural tissue </li></ul><ul><li>lines the inner aspect of the posterior two thirds of the globe </li></ul><ul><li>terminates anteriorly as the ora serrata </li></ul>
  51. 51. Fundus
  52. 52. Posterior Pole
  53. 53. Layers of the Retina <ul><li>1. Internal limiting membrane </li></ul><ul><li>2. Nerve fiber layer </li></ul><ul><li>3. Ganglion cell layer </li></ul><ul><li>4. Inner plexiform layer </li></ul><ul><li>5. Inner nuclear layer </li></ul><ul><li>6. Outer plexiform layer </li></ul><ul><li>7. Outer nuclear layer </li></ul><ul><li>8. External limiting membrane </li></ul><ul><li>9. Photoreceptor layer (rods and cones) </li></ul><ul><li>10. Retinal pigment epithelium </li></ul>
  54. 54. Retinal Layers
  55. 55. Macula <ul><li>Center of the posterior retina </li></ul><ul><li>responsible for fine central vision </li></ul><ul><li>has yellow pigment (xantophyll) </li></ul><ul><li>histologically empty space tends to the accumulation of extracellular material that cause thickening </li></ul>
  56. 56. Photoreceptors
  57. 57. Blood Supply of the Retina <ul><li>Choriocapillaries </li></ul><ul><ul><li>outer third of the retina </li></ul></ul><ul><li>Central Retinal Artery </li></ul><ul><ul><li>inner two thirds of the retina </li></ul></ul>
  58. 58. Embryonic Eye
  59. 59. Embryonic Eye
  60. 60. Vitreous <ul><li>Clear, avascular, gelatinous body </li></ul><ul><li>comprises 2/3 of the volume of the eye </li></ul><ul><li>99% water ; 1% hyaluronic acid and collagen </li></ul><ul><li>firmly attached to the pars plana and ora serrata </li></ul>
  61. 61. Eyeball
  62. 62. External Anatomic Landmarks <ul><li>Limbus - point of referance , site of incision for basic cataract extraction </li></ul><ul><li>Ora Serrata - 6mm from the limbus on the nasal side ; 7mm from the limbus on the temporal side </li></ul><ul><li>Pars plana - 4mm from the limbus </li></ul><ul><li>Pars plicata - 2-3 mm from the limbus </li></ul>
  63. 63. Extraocular Muscles <ul><li>Rectus Muscles </li></ul><ul><ul><li>superior rectus </li></ul></ul><ul><ul><li>inferior rectus </li></ul></ul><ul><ul><li>medial rectus </li></ul></ul><ul><ul><li>lateral rectus </li></ul></ul><ul><li>Oblique Muscles </li></ul><ul><ul><li>Superior oblique </li></ul></ul><ul><ul><li>Inferior oblique </li></ul></ul>
  64. 64. Extraocular Muscles
  65. 65. Nerve Supply of EOMS <ul><li>Oculomotor nerve innervates medial, inferior and superior rectus muscles as well as the inferior oblique muscle </li></ul><ul><li>Abducens nerve innervates the lateral rectus muscles </li></ul><ul><li>Trochlear nerve innervates the superior oblique muscle </li></ul>
  66. 66. Blood Supply of the EOMS <ul><li>Muscular branches of the ophthalmic artery </li></ul><ul><li>Lateral rectus also receives additional supply from lacrimal artery </li></ul><ul><li>Inferior oblique also receives additional supply from the infraorbital artery </li></ul>
  67. 67. Ocular Adnexa <ul><li>Eyebrows </li></ul><ul><ul><li>thickened skin covered with hair </li></ul></ul><ul><li>Eyelids </li></ul><ul><ul><li>modified folds of skin </li></ul></ul><ul><ul><li>closes to protect the eyeball </li></ul></ul><ul><ul><li>blinks to lubricate cornea </li></ul></ul>
  68. 68. Eyelids
  69. 69. Eyelids <ul><li>Skin Layer </li></ul><ul><li>Orbicularis Oculi </li></ul><ul><li>Areolar tissue </li></ul><ul><li>Tarsal plate </li></ul><ul><li>Palpebral conjunctiva </li></ul>
  70. 70. Orbicularis Muscle
  71. 71. Lid Margins <ul><li>Eyelashes </li></ul><ul><li>Glands of Zeis </li></ul><ul><li>Glands of Moll </li></ul><ul><li>Meibomian glands </li></ul><ul><li>lacrimal punctum </li></ul>
  72. 72. Palpebral Fissure <ul><li>Elliptical space between the two eyelids </li></ul><ul><li>terminates at the lateral and medial canthi </li></ul>
  73. 73. Orbital septum <ul><li>Fascia behind the portion of orbicularis muscle and serves as a barrier between the lid and the orbit </li></ul>
  74. 74. Eyelids
  75. 75. Eyelid Anatomy
  76. 76. Lid retractors <ul><li>Responsible for opening the eyelids </li></ul><ul><ul><li>levator palpebrae superioris muscle </li></ul></ul><ul><ul><ul><li>aponeurosis </li></ul></ul></ul><ul><ul><ul><li>meuller’s muscle </li></ul></ul></ul><ul><ul><li>Lower lid retractor </li></ul></ul><ul><ul><ul><li>inferior rectus, extends with the inferior oblique and insert into the lower border of the tarsal plate </li></ul></ul></ul>
  77. 77. Upper Eyelids
  78. 78. Lower Lid Retractors
  79. 79. Nerve Supply of the Eyelid <ul><li>First and second division of the trigeminal nerve </li></ul><ul><li>Ophthalmic </li></ul><ul><ul><li>lacrimal, supraorbital, supratrochlear,infratrochlear, external nasal nerves </li></ul></ul><ul><li>Maxillary </li></ul><ul><ul><li>Infraorbital, zygomaticofacial, zygomaticotemporal nerves </li></ul></ul>
  80. 80. Eyelids <ul><li>Blood Supply </li></ul><ul><ul><li>lacrimal and ophthalmic areteries </li></ul></ul><ul><li>Venous drainage </li></ul><ul><ul><li>ophthalmic vein </li></ul></ul><ul><li>Lymphatic drainage </li></ul><ul><ul><li>Temporal eyelids - pre-auricular and parotid nodes </li></ul></ul><ul><ul><li>Nasal eyelids - submandibular nodes </li></ul></ul>
  81. 81. Lacrimal Apparatus <ul><li>Lacrimal glands </li></ul><ul><li>accessory lacrimal glands of Krauss and Wolfring </li></ul><ul><li>Puncta </li></ul><ul><li>Canaliculi </li></ul><ul><li>Lacrimal sac </li></ul><ul><li>Nasolacrimal duct </li></ul>
  82. 82. Lacrimal Apparatus
  83. 83. Lacrimal Gland <ul><li>Blood supply - lacrimal artery </li></ul><ul><li>Venous drainage - ophthalmic vein </li></ul><ul><li>Lymphatic drainage - preauricular lymph nodes </li></ul><ul><li>Nerve supply - lacrimal nerve, great superficial petrosal nerve, sympathetic nerves </li></ul>
  84. 84. Lacrimal Apparatus
  85. 85. Optic Nerve <ul><li>Consists of 1 million axons from ganglion cells of the retina </li></ul><ul><li>emerges from the sclera on the nasal portion of the globe </li></ul><ul><li>25 - 30mm long in the orbital segment </li></ul><ul><li>goes through optic canal </li></ul><ul><li>10mm intracranial course </li></ul><ul><li>joins optic chiasm </li></ul>
  86. 86. Optic Nerve
  87. 87. Vascular Supply of the Optic Nerve
  88. 88. Visual pathway <ul><li>Retina </li></ul><ul><li>Optic nerve </li></ul><ul><li>Optic chiasm </li></ul><ul><li>Optic tract </li></ul><ul><li>Optic radiation </li></ul><ul><li>Occipital lobe (Visual center) </li></ul>
  89. 89. Visual Pathway

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