![Page 1: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/1.jpg)
Visual System: (deliberately) Basic Anatomy and Physiology of The Eye
Tom Fearnley Clinical Fellow Ocular Oncology, OculoplasDcs and Orbital Surgery
![Page 2: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/2.jpg)
Lecture Outline
• Gross Structure • Layers of the Eye • Muscles
• Adnexal Tissues • Arterial Supply • Venous drainage • LymphaDcs
![Page 3: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/3.jpg)
Shameless plug
• Ophthalmology is one of the most rewarding careers in medicine offering an unrivalled mix of medicine and surgery
• Cataract surgery is the most frequently performed operaDon in the UK (>300 000/yr)
• At the very limit of surgical finesse • Which of your senses would you least like to lose? • You will see lots of eye disease • Ophthalmologists regularly feature near the top of the “happiest physicians” table
![Page 4: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/4.jpg)
The Gross Structure of the Eye – in relaDon to its funcDon
• The eye is a hallow sphere (2 chambers) -‐ evolved to focus light to a fine point
• The amount of light allowed into the eye is controlled by pupil size • Light is refracted by 2 surfaces
• Cornea • Lens
• The light sensiDve Dssue at the back of the eye is called the ReDna • Contains specialised cells responsible for converDng light energy (photons) into
a cell membrane potenDal for neurotransmission
• The globe is protected within the orbit • The adnexal Dssues (lids, lacrimal apparatus etc) protect and
moisturise the ocular surface • The extra-‐ocular muscles move the eyes in synchrony to maintain
binocular single vision and allow depth percepDon (stereopsis)
![Page 5: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/5.jpg)
The layers of the Eye
• Outer Layer (protecDon) • Sclera & Cornea
• Middle Layer (nutriDon) • Uvea
• Iris • Choroid • Ciliary Body
• Inner Layer (detecDon) • ReDna
![Page 6: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/6.jpg)
Sclera
• The tough white outer coat of the eye • Covered by ConjuncDva and Tenon’s • Allows abachment of extraocular muscles
![Page 7: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/7.jpg)
Cornea
• Transparent window (you put your contact lenses on it) • Transmits light • Protects intraocular contents • 2/3rds of focusing power of the eye (refracDve index) • Thinner in the centre (500µm), Thicker at the edge (700µm) • Avascular – nutriDonal requirements from tear film and aqueous
• InnervaDon via Trigeminal nerve – 400 xs that of skin • In conDnuity with the sclera at the limbus • Must remain relaDvely dehydrated (or becomes cloudy) • Epithelium replaced conDnually by Limbal Stem Cells • Endothelium must last a lifeDme
![Page 8: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/8.jpg)
The layers of the Cornea
1: Epithelium 2: Bowman’s Layer 3: Stroma 4: Descemet’s Membrane 5: Endothelium
![Page 9: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/9.jpg)
![Page 10: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/10.jpg)
The Uveal Tract
• Grape (hangs from opDc nerve following dissecDon from sclera)
• Highly vascular • Highly pigmented (melanin)
• 3 anatomically and funcDonally disDnct parts • Iris • Ciliary Body • Choroid
![Page 11: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/11.jpg)
Iris • Thin contracDle diaphragm – the coloured part of the eye • Central aperture (pupil) • Directly overlies the lens • 2 muscles control pupil size
• Dilator pupillae (dilates) • Radial • Outer • SympatheDc
• Spincter pupillae (constricts) • CircumferenDal • Pupil margin • ParasympatheDc
• Pupil reflexes • Light • Near (constricDon plus accomodaDon) • SympatheDc
![Page 12: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/12.jpg)
![Page 13: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/13.jpg)
![Page 14: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/14.jpg)
Ciliary Body
• CircumferenDal structure surrounding the lens • Produces Aqueous from glandular epithelium (acDve secreDon and ultrafiltraDon)
• Smooth muscle in stroma allows: • AccomodaDon (AlteraDon of lens convexity)
• AlteraDon of aqueous oullow via abachment to trabecular meshwork
![Page 15: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/15.jpg)
A word about Aqueous
• Circulates from the posterior to the anterior chamber through the pupil
• Similar to plasma (lower glucose and protein, higher ascorbate and lactate)
• Provides nutrients to cornea and lens • Maintains IOP (balance between producDon and drainage)
• Drains (mostly) via the trabecular meshwork • Specialised Dssue in the anterior chamber angle (between the iris and the cornea)
![Page 16: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/16.jpg)
Aqueous Drainage
![Page 17: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/17.jpg)
The Choroid
• Thin, highly vascular structure between reDna and sclera
• Vascular supply to outer reDna
![Page 18: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/18.jpg)
The Lens
• Flexible (change in shape alters refracDve power) • Biconvex • Held in place by suspensory zonules • Crystal like • 1/3rd focusing power of eye • Lens fibres progressively laid down over life (thickens) • Adult diameter 9-‐10mm • Allows eye to change focus from distance to near
(accomodaDon) – lost as we age • Pathological opacificaDon = CATARACT
• Accounts for 48% of world blindness • 18 million people
![Page 19: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/19.jpg)
![Page 20: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/20.jpg)
![Page 21: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/21.jpg)
![Page 22: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/22.jpg)
![Page 23: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/23.jpg)
Vitreous
• thick, gel-‐like substance that fills the posterior chamber
• 99% water + Hyaluronic acid • Collagen scoffold – degrades with age • 80% (4ml) of the volume of the globe • Strongly adherent to anterior few mm of reDna (detachments)
• Embryological support for vessels delivering nutrients to lens
• Best avoided during cataract surgery!
![Page 24: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/24.jpg)
ReDna
• Lines innermost surface of the eye and contains photoreceptors
• Cells responsible for converDng light into nerve impulses
• Fovea centralis – a depression, or pit, in the center of the reDna that contains only cones
• most accurate vision & color sensiDvity
![Page 25: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/25.jpg)
![Page 26: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/26.jpg)
![Page 27: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/27.jpg)
![Page 28: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/28.jpg)
Photoreceptors
– Rods: • about 100 million, operate in grayscale, are mostly around the periphery
• most sensiDve to 500nm which appears “bluish-‐green” • allow us to see in low light and provide for peripheral vision
– Cones: • about 5 million • 3 varieDes (trichromaDc) • Each sensiDve to parDcular wavelength of light (short, medium & long)
• Greatest concentraDon at fovea
![Page 29: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/29.jpg)
Rods & Cones
![Page 30: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/30.jpg)
Basic phototransducDon
• Photoreceptors convert photon energy into membrane potenDal that ulDmately results in a reducDon of neurotransmiber release
• Photoreceptors contain light sensiDve visual pigments
• AbsorpDon of light leads to an isomeric alteraDon of the visual pigments which in turn hyperpolarises the photoreceptor cell due to movement of calcium ions
![Page 31: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/31.jpg)
![Page 32: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/32.jpg)
Extraocular Muscles • 6 per eye
– 4 recD • Arise from Annulus of Zinn at apex
– 2 obliques • Superior – arises from back of roof of orbit • Inferior – arises from anterolateral orbital floor
• DucDons • Monocular – eg adducDon
• Versions • Binocular same direcDon (conjugate) – eg right gaze (dextroversion)
• Vergences • Binocular opposite direcDon (disconjugate) – eg convergence
• InnervaDon • Lateral rectus – 6th CN • Superior Oblique – 4th CN • All the rest – 3rd CN
• Deliver blood supply to anterior segment of eye via anterior ciliary arteries
![Page 33: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/33.jpg)
Adnexal Tissues
• Lids • ConjuncDva • Lacrimal apparatus
• Orbit
![Page 34: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/34.jpg)
Lids
• Glide over the front surface of the eye
• Protect • Distribute tears
• Anterior Lamella • Skin and muscle (orbicularis -‐ closure)
• Posterior Lamella • Tarsal plate (rigid) • ConjuncDva
![Page 35: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/35.jpg)
ConjuncDva
• Clear covering over the sclera • Several regions
• Tarsal (back of lid) – Dghtly adherent • Fornix (recess behind lids) – lots of glands • Bulbar (over globe – loosely adherent – allows eye to move freely
• Goblet cells secrete mucous
• LymphaDcs • Immune response
![Page 36: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/36.jpg)
Lacrimal Apparatus
• Lacrimal gland produces tears
• Drain inferonasally • Puncta (upper and lower) • Cannalicular system
• Lacrimal Sac
• Nasolacrimal duct
• Inferior meatus (nose)
![Page 37: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/37.jpg)
Tears
• 3 layers • Anterior lipid (meibomium glands)
• Middle aqueous (lacrimal glands)
• Posterior mucous (goblet cells)
• ProtecDve • AnDbacterial • Smooth surface
• NutriDon to cornea
![Page 38: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/38.jpg)
Orbit
![Page 39: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/39.jpg)
Arterial Supply • Internal caroDd artery
– Ophthalmic artery • Central reDnal artery
– OpDc nerve – Arcades – nourish inner reDna
• Posterior Ciliary arteries (short and long) – Choroidal circulaDon –
nourishes outer reDna • Lacrimal artery
– Lacrimal gland • Anterior and posterior
Ethmoidals
• External caroDd – Facial artery
• angular artery – Medial lid and orbit
![Page 40: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/40.jpg)
![Page 41: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/41.jpg)
Venous drainage
• Inner reDna • Branch reDnal veins
– Ophthalmic veins
» Cavernous sinus
• Outer reDna and Choroid
• Vortex veins – Ophthalmic veins
» Cavernous sinus
![Page 42: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/42.jpg)
LymphaDcs
• Not well understood • None within the eye itself
• Accepted pabern – Lower medial and central lid to submandibular
– Upper lid, medial canthus and lateral lower lid to pre-‐auricular
![Page 43: Visual’System:’(deliberately)’Basic’ Anatomy’and ... · The’Gross’Structure’of’the’Eye’–in’ relaon’to’its’funcDon’ • The’eye’is’a hallow&sphere&(2’chambers)’[’evolved’to’focus](https://reader036.vdocuments.us/reader036/viewer/2022071007/5fc490d45173f96cc8273e04/html5/thumbnails/43.jpg)
QuesDons?