optometry education, Ophthalmology, optometrist, ocular anatomy

1. Anatomy of eye

2. Anatomy Tear film
The tear film has four
main functions:
optical, mechanical,
nutritional, and
Defensive
PH: 7.45

3. • Tear film has a total volume of 7–10 μL
• Normal basal tear production rate is 1–2 μl/min
• Reflex tear rate is >100 μl/min
• Normal tear volume turnover occurs every 5–7 min.

4. • Lipid Layer (0.1 μm):
- Meibomian glands with additional contributions from the glands of Moll and
Zeiss
• A rapid (<10 s) tear fi lm breakup time is a sign of lipid layer insufficiency.
Meibomian glands are 20-30 in numbers per tarsals. Content are holocrine
secretion.
• Meibomian secretion occurs on blinking due to contraction of the muscle of
Riolan.
• Its sebaceous gland
Glands of Moll: modified sweat glands. open into the eyelash hair follicle.
Glands of Zeiss: sebaceous glands. open at the lid margin or into eyelash

5. Aqueous Layer (7 μm):
• 95 % is from lacrimal gland secretion; 5 % from the accessory glands of Krause and
Wolfring.
• Sjogren syndrome

6. • Mucus Layer (3–30 μm):
- Mucins (glycoproteins) secreted by conjunctival goblet cells.
- Water and electrolytes secreted by conjunctival goblet and non – goblet epithelial cells.
• Mucin is stored in large secretory granules at apical surface of goblet cells.
• Goblet cell are Merocrine.(Eccrine). Density more at nasal conjunctiva.
• increased breakup of tears and symptoms of dry eye
• Glycocalyx is a membrane-bound network of mucins attached to
• The apical microvilli of corneal and conjunctival epithelial cells

7. • Lacrimal Gland:
- lobulated tubuloacinar gland . ( branced tubes)
- Divided into superior orbital part and an inferior palpebral part.
- acini consist of columnar secretory cells .
- produce IgA that is secreted in tears.
- parasympathetic fi bers from the lacrimal nucleus of the pons
Reflex tear secretion:
• Peripheral sensory stimulation (e.g., of the cornea, conjunctiva, nose) is
mediated by the trigeminal nerve.
• Central stimuli may be related to light (optic nerve as afferent arm) or
emotion (e.g., weeping).

8. Anatomy of Conjunctiva
• mucus for the tear film
• Protection of the ocular surface by barrier function
• Defense against pathogens as an element of the mucosa-associated
lymphoid tissue ( MALT )
• Provision of limbal stem cells to maintain and heal the corneal and
conjunctival epithelia.
• Epithelial stem cells located at the palisades of Vogt in the corneal
limbus

9. • bulbar conjunctiva lines the sclera; the palpebral conjunctiva lines the eyelid inner
surface.
• Conjunctiva consists of a surface epithelium and an underlying substantia propria .
Epithelium:
• two- to three-cell layer non-keratinized cuboidal stratified epithelium.
Substantia propria:
• substantia propria is highly vascular and contains immune cells (mast cells, plasma cells,
neutrophils, and lymphocytes)
• Two layers: Adenoid layer(contains lymphoid tissue and absent in infants)-no follicle and
Deep Fibrous Layer

10. Conjunctival Tear Film Contribution
• Crypts of Henle eyeball's conjunctiva, arranged in a ring around the
cornea, near the scleral junction. Secrete mucin. Its non goblet cell.
• glands of Krause are mostly forniceal; 20 in the superior and 6–8 in the
inferior fornix.
• glands of Wolfring are in the tarsal conjunctiva of the upper and
occasionally lower lid.

11. Lacrimal Drainage System
• punctum , a 0.3 mm opening located
on the medial eyelid margin
• canaliculus , a 10 mm tubule that
traverses the medial eyelid
• canaliculi are surrounded by
orbicularis oculi fibers.
• valve of Rosenmuller at the
common canaliculus opening
prevents to a variable extent reflux
from the sac.
• valve of Hasner is often present at
the nasal end of the duct to prevent
refl ux
• Tear goes to canaliculi by capillary
attraction and Lid movement

12. Anatomy of Cornea
• Prolate shaped, with a 12.6 mm
horizontal and a 11.7 mm vertical
diameter, central cornea is spherical.
• cornea transmits wavelengths 310 –
2500 nm
• Refractive index of 1.376.
• + 48.9 D from the anterior corneal
surface/tear film
• − 5.8 D from the posterior corneal
surface
• Total Power: + 43.18 diopters
• Corneal curvature:
- Anterior: 7.8 mm
- Posterior: 6.5 mm
• with-the-rule astigmatism
The central corneal thickness is 0.53 mm, whereas the corneal periphery is 0.71 mm thick

13. Corneal epithelium
• Stratified, non-keratinized, squamous
epithelium
• Five to seven cell layers deep
• Cell turnover, from basal cell division to
superficial cell sloughing, occurs in 7–10
days
• Three cell types (from surface to
basement membrane): superficial ,wing ,
and basal cells
Superficial cells have apical surface projections
(microvilli).
Basal cells form a single layer of cuboidal cells. Mitotic
activity an stem cells activity from this layer.
Basal cells rest on a basement membrane of type IV
collagen, laminin, fibronectin and fibrin
Cell-cell adhesion:
Desmosomes attach basal, wing, and superficial
cells to one another. (macula adherens)
Tight junctions encircle superficial cells. (zonula
occludens)
Gap junctions are numerous among basal and
wing cells. These allow intercellular
communication

14. Corneal
Stroma
• Makes up 90 % of corneal thickness.
• Bowman ’s layer is acellular non-regenerating membrane. It consists of is compact fibers from
stroma. Consists predominantly type I collagen.
• Stroma lamellae:
- 200 – 250 highly organized lamellae by collagen fibers.
- Parallel fibers centrally and orthogonal peripherally to give cornea stability.
- ground substance consisting of a proteoglycan matrix
- Keratocytes are the main stromal cell type and they synthesize fibrillar collagen and help in wound
healing.

15. Dua’s Layer:
Descemet’s Membrane:
• Descemet’s membrane is a 10–15 um thick basement membrane of the corneal endothelium.
• Type IV collagen
• Toughest layer and relatively resistant to proteolytic enzymes
• Thickened area of collagenous connective tissue may be seen at the membrane’s termination in the
limbus; this circular structure is called Schwalbe’s line
Endothelium:
• Endothelial cells generally do not replicate. Polymegatheism.
• Newborns have 5500 cells/mm 2 , while adults have 2500–3000 cells/mm 2 .
• A minimum of 400–700 cells/mm 2 is required for normal corneal function.
• Stressed or unstable endothelium demonstrates polymegathism (cells of varying size) and
pleomorphism(cells of varying shape)
• Periodic thickenings of endothelium in Descemet’s membrane located near the corneal periphery are
called Hassall-Henle bodies and located at central cornea are called corneal guttata
• FUCHS’ DYSTROPHY (see Figure 2-16) is a bilateral, noninflammatory loss of endothelial function

16. Corneal
Innervation
• Corneal nerves are non-myelinated.
• The cornea is innervated by the anterior ciliary nerves, branches of the ophthalmic nerve (V1).
• NEUROTROPHIC KERATITIS is a rare degenerative disease caused by the loss of corneal
sensory innervation.

17. Anatomy of Sclera
• The sclera is a tough , opaque collagen coat. Its relatively Avascular. collagen type I
• the sclera is opaque due to:
(a) Increased water content (70 %)
(b) Larger diameter and more interwoven collagen fibrils
• Episclera is a dense vascular connective tissue making up the superficial portion of the sclera
The posterior sclera contains perforations for the:
(a) Optic nerve (scleral canal and lamina cribrosa)
(b) Long and short posterior ciliary arteries
(c) Ciliary nerves
(d) Short ciliary veins
(e) The vortex veins

18. Anatomy of Lens:
• Biconvex, contained within capsule. (16-17 Diopters power).
Crystallin proteins.
• Anterior single layer of cuboidal epithelial cells.
• Radius of curvature: Anterior: 11.mm Posterior: −6.5mm
• Refractive index: Periphery to center: 1.362–1.406
• Anteroposterior diameter of lens: Young (20 yrs) 3.5–
4.0mm Old age ( 70 yrs) 4.5–5.0 mm
• The anterior suture is an upright- Y shape and the
posterior suture an inverted-Y shape, embryonic suture.
• The area occupied by the zonules is the canal of Hannover,
and the retrozonular space, the area from the most posterior
zonules to the vitreal face, is the canal of Petit

19. Lens Capsule
• lens capsule is an elastic basement membrane,
composed of type IV collagen.
• Thickest in the anterior midperiphery (21 μm). At the
anterior pole it is 13 μm; it is thinnest at the posterior
pole (4 μm).
Lens Epithelium:
• Epithelium is a monolayer of cuboidal cells inside the
anterior and equatorial capsule.

20. • Lens proteins: Crystallins make up 40 % of the wet weight of lens fibers.
• Alpha crystallin (30 % of total lens protein) and Beta/gamma crystallin (56 % of total lens protein).
• Glucose is the principal carbohydrate of the lens. It enters the lens from the aqueous by simple diffusion
and insulin-dependent facilitated transfer .
• Anaerobic metabolism is highly prevalent in the lens, compared to most body

21. Parasympathetic nerves
• The ciliary muscle is supplied by parasympathetic fibers of the oculomotor nerve.
• These originate in the midbrain Edinger-Westphal nucleus and synapse in ciliary
ganglion.
• Parasympathomimetic agents (e.g., pilocarpine) stimulate accommodation.
• Cycloplegic agents (muscarinic antagonists, e.g., cyclopentolate) block
Accommodation.

22. The Ciliary Body anatomy
• ciliary body is continuous with the iris anteriorly and the choroid. (uveal layer)
• The ciliary body has two main functions:
(a) Production of aqueous fluid
(b) Accommodation via ciliary muscle contraction
It consists of the ciliary muscle, ciliary stroma, and ciliary epithelium.
It extends anteriorly to the scleral spur, where it is firmly attached to the sclera.
It is divided into the anterior pars plicata and the posterior pars plana.

23. • The inner surface of the pars plicata is
corrugated, with ciliary processes
extending from 70 ridges.
• Aqueous fluid formation occurs over
the ciliary double epithelium.
• It has three smooth muscle fiber
groups: longitudinal (outer), radial,
and circular (inner).

24. The ciliary muscle
• It has three smooth muscle fiber groups:
longitudinal (outer), radial, and circular (inner).
• On accommodation all muscle groups contract,
releasing tension on the zonules.
The ciliary stroma
• highly vascularized, loose connective tissue.
• It contains multiple capillaries that have fenestrated
endothelium
• Fluid accumulates in the stroma by bulk flow across
the capillary endothelium.
• This fluid is the reservoir of ultrafiltrate from which
aqueous is secreted.
The ciliary epithelium
a. Outer pigmented epithelium (PE) cuboidal and
b. Inner non-pigmented epithelium Columnar. Highly
active and active secretion of Aqueous.

25. Aqueous Fluid
• Aqueous fluid is formed by the ciliary body and secreted
into the posterior chamber.
• The fluid traverses the pupil to enter the anterior chamber
and exits the eye through one of the two drainage
pathways
(a) The trabecular meshwork (TM) route
(b) The uveoscleral route
Aqueous fluid is formed through diffusion, ultrafiltration, and
active secretion
• Diffusion and ultrafiltration form a reservoir of plasma in
the ciliary stroma. (pressure dependent)
• Active secretion of aqueous from ultrafiltrate occurs across
the ciliary epithelium. (energy dependent)
The aqueous is produced at 2.6 μl/min

26. Aqueous Drainage from the
Eye
The trabecular meshwork route
• Aqueous traverses the TM, across the inner wall of Schlemm’s canal (SC) (50–75 %)
• From there it passes into collector channels, aqueous veins, and into episcleral veins.
The uveoscleral route
• This occurs freely as the anterior ciliary body and iris root lack an endothelial lining .
• The fluid then passes into the suprachoroidal space and exits the eye through the sclera via scleral
perforations or the vortex veins.
• Uveoscleral flow is IOP independent at IOP levels greater than 7 mmHg.
In the anterior chamber, the aqueous circulates in convection currents, moving down along the
cooler cornea and up along the warmer.

27. Trabecular Meshwork and Schlemm’s Canal
• The TM is located at the angle of the eye
near the insertion of the iris root.
• It extends from Schwalbe’s line anteriorly to
the scleral spur posteriorly.
• It has three parts: the uveal (inner),
corneoscleral, and juxtacanalicular
(outer)layers

28. • Average adult IOP is 10-21 mmHg
• IOP demonstrates diurnal variation with a typical mid-morning increase by 5 mmHg;
this may be related to early morning cortisol levels

29. Anatomy of the Iris
• The iris contains two muscles: the sphincter and dilator pupillae .
• pupil size to vary from 1 to 9 mm.
• The iris consists of an anterior stromal layer and a posterior double-layered epithelium
• The sphincter(parasympathetic Nerves) and dilator muscles(sympathetic Nerves) are located
within the stroma.
Iris epithelium-
• 2 iris-pigmented epithelial layers
• Anterior is continuous with the outer pigmented ciliary body epithelial layer.
• The posterior is continuous with the inner non-pigmented ciliary body epithelial layer.

30. The Pupil
• The light reflex is a
parasympathetic-mediated
pupillary constriction to
light.
• The neural pathway consists of
afferent , interneuron , and
efferent divisions
• Direct vs Consensual light
reflex.

31. Afferent division
• Photoreceptor cells
• intrinsically photosensitive ganglion cells (ipRGC)
• Optic nerve
Interneuron division
• equal bilateral projections to the Edinger-Westphal (E-W)
nuclei
Efferent division
• Oculomotor nerve
The Near Reflex
• triad of ocular convergence ,
pupillary constriction , and
accommodation

32. Horner’s syndrome-
• Horner’s syndrome is caused by a
lesion in the sympathetic pathway
to the eye
• 1% Phenylnephrine test: Miosed
pupil affected and dilated after the
drop.

33. Adie’s tonic pupil- iris sphincter denervation
Relative afferent pupillary defect (RAPD)-The swinging flashlight, or Marcus
Gunn test, aims to detect inequality of visual input from either eye (a RAPD)
Light-near dissociation(Agryll Robertson Pupil)- Accommodation Reflex
present

34. Anatomy of Retina
Retinal Pigment Epithelium
Neurosensory Retina

36. Macula Lutea:
• Antioxidant carotenoid pigments (lutein and zeaxanthin) give the macula a yellow hue.
a) Fovea centralis
• fovea centralis is a small depression at the central macula that provides highest visual acuity.
• The depression is due to centrifugal displacement of inner retinal cells to maximize image clarity.
• Vessels are absent from the central fovea ( foveal avascular zone ) to minimize light scattering.
b) The parafovea
• The fovea is surrounded by the parafovea which is in turn surrounded by perifovea.
• With increasing eccentricity the density of cones decreases while the density of rods rises to peak
at approximately 20 0 off fixation

37. Photoreceptor
Cells
• Photoreceptor cells convert light into neural
signal by phototransduction .
Outer Segment and Inner Segment
• Cone outer segments (OS) are conical with a
tapered end; rod outer segments are non-
tapered.
• The outer segments consist of 600–1000 disks
made of bilayered lipid membrane.
• Rod Spherules Cone pedicels.
• Resting membrane Potential of −50 mV

42. ARMD

43. RPE ( Retinal Pigment Epithelium)
- Pigmented layer of retina attached to choroid.
- Prevents scattering of light increasing contrast and visual sensitivity.
- Tapetum in cat, dog, tigers etc. night glow.

44. Horizontal Cells
• Horizontal cells (HCs) have long branching
dendritic processes that form interconnections
between photoreceptor cells and bipolar cells.
• Use the inhibitory neurotransmitter GABA .
• Involved in feedback mechanism based on
Photoreceptor response.
• Send inhibitory response to Photoreceptor and
Bipolar cells.

45. Bipolar Cells
• Bipolar cells (BCs) carry signal from
photoreceptor cells to ganglion cells
and amacrine cells .
• use glutamate as their
neurotransmitter.
• BCs can be classified into cone and
rod Bipolar Cells.
• There are at least 11 cone bipolar
types which contact cones and a
single type of rod bipolar cell which
contact rods.

46. Amacrine Cells
• There are at least 40 types of amacrine cell.
• Receive excitatory signal from Bipolar and provide inhibitory input to
Bipolar, other amacrine and ganglion cells.
• Release of glycine or GABA
• Some are dopaminergic , projecting widely and facilitating light adaptation
in the retina.
• Helps in Edge Detection.

47. Ganglion Cells
• 14–20 morphological GC types exist.
• P (midget) and M (parasol) channels
Midget Ganglion (P-ganglion) (Parvocellular Pathway)
- Color vision, contrast and fine vision (VA)
Parsol (M-ganglion) (Magnocellular Pathway)
- Temporal vision.
- Larger in size , affected first in glaucoma. Give results to Frequency doubling Visual field
test.
IpRGC (Intrinsic Photosensitive Retinal Ganglion cell):
- Photosensitive (like rods and cones)
- Control Circardian rhythm

48. Optic Nerve
Optic Tract
Lateral Geniculate Body

49. Lateral Geniculate Body
• Third order neurons of vision
• Consists of six layers of neurons alternating with white matter(formed by
optic fibres).
• Dorsal 4: Parvocellular layer
• Ventral 2: Magnocellular Layer
• Middle layers: Konio-cellular layers

51. VISUAL CORTEX
• Primary visual cortex:V1,striate cortex,Brodman area 17
• Horizontal calcarine fissure divides the medial surface of the occipital lobe.
• Its the visuosensory area.
• Impulses originating from corresponding points of two retina meet here.
51

53. Neurotransmitters
Glutamate: Glutamate is the predominant excitatory neurotransmitter within the retina.
GABA and glycine: Gamma-aminobutyric acid ( GABA ) and glycine are inhibitory
neurotransmitter
Dopamine: Dopamine is a modulatory retinal neurotransmitter
• Acetylcholine: Acetylcholine is a fast excitatory neurotransmitter released by starburst
amacrine cells

54. Anatomy of the Orbit
• The skull bones can be
divided into two parts: the
cranial bones and the facial
bones
• Total 22 bones
• Cranial: 8
• Facial: 14
Orbit: 7 bones

56. ORBITAL WALLS:
a) Roof: orbital plate of the frontal bone in front and
lesser wing of the sphenoid contributes a small
posterior portion.
- Lateral of Frontal bone: fossa for the lacrimal gland.
- Medial of the Frontal bone : trochlea.
b) Floor: orbital plate of the maxillary bone, orbital
plate of the zygomatic bone in front and the small
orbital process of the palatine bone behind.
Commonly affected in blow-out fracture.
c) Medial Wall: formed by the frontal process of the
maxilla, the lacrimal bone, the orbital plate of the
ethmoid, and a part of the body of the sphenoid.
Thinnest Wall.
d) Lateral Wall: zygomatic bone in front and of the
greater wing of the sphenoid bone behind

57. superior orbital fissure is the gap between the lesser wing and the greater wing
of the sphenoid bone.
The optic foramen or the optic canal, lies in the lesser wing of the sphenoid.
The lacrimal bone (one in each orbit) is the smallest bone of the face and
articulates with the maxillary bone, ethmoid bone, and frontal bone.
Total Bones in Orbit: 7
Sphenoid, Frontal, Zygomatic, Ethmoid, Lacrimal, Maxilla, Palatine
• Orbit Volume: 30 cc
• 35 mm high and 45 mm wide
• Rim to the orbital apex measures 40 to 45 mm in adults
• Lateral walls of the two orbits are set at approximately a right angle from one

58. Optic Nerve and Pathway
• Second Cranial Nerve (Afferent) : 5 to 6 cm long
The optic nerve consists of:
(a) Retinal ganglion cell (RGC) axons
(b) Supportive glial tissue
(c) Vascular tissue
• It is surrounded by three layers of meningeal tissue (pia, arachnoid, and dura).
• Each nerve covered by oligodendrocyte rather than Schwan cell (hence Retina is called Part of
Brain) and affected in Multiple Sclerosis.

59. • RGC axons from the RNFL turn 90° to dive into
the disc to form the neuroretinal rim.
• RGC axons exit the eye through pores of the
lamina cribrosa , a perforated portion of sclera
that provides structural support to the optic nerve
head.
• Intraocular portion (0.7 to 1 mm)
• Intraorbital portion (30 mm)
• Intracanalicular(6 to 10 mm)
• Intracranial portion (10 to 16 mm).

60. Topographic Organization
• Superior and inferior fibers are segregated by the
horizontal raphe (H) which divides the inferior and
superior visual fields .
• Temporal macular fibers (T) course around the fovea
(F) to enter the disc superiorly or inferiorly.
• Nasal macular fibers travel in the papillomacular
bundle (P) to enter the temporal aspect of the optic
disc.

61. • 90% of which will terminate in the LGN. Approximately 10% project to areas controlling pupil
responses or the circadian rhythm.
• LGN: conscious visual perception .
Pretectal nucleus:
• Each pretectal nucleus (in the dorsal midbrain) receives bilateral optic nerve projections.
• Each projects bilaterally to the Edinger–Westphal nuclei.
• They are involved in controlling the pupillary light reflex

65. • Superficial nerve fiber: Central Retinal Artery
Occasionally from the Cilioretinal Artery
• The posterior ciliary arteries each provide a
variable, segmental supply to portions of the optic
nerve below its head.
• Distal portions: arterial plexus.
• Within optic canal: internal carotid artery
• Intracranial segment: internal carotid, anterior
cerebral, or anterior communicating arteries

66. Hyaloid artery develops as a bud from Bergmeister’s Papilla (from center of optic
disc)
The ISNT rule is an easy way to remember how the optic nerve is supposed to look in a normal eye.

67. Anatomy of eyelids
• Barrier function
• Maintenance of globe position
• Ocular surface integrity
•
• Eyelid glands
• Normal interpalpebral fissure height is 8–11 mm;
• Horizontal Palpebral fissure length is 27–30 mm.
• The upper lid margin rests 1.5–2 mm below the
limbus; the lower rests on the limbus

68. Two Parts:
a) Anterior Lamellae
a) Posterior Lamellae

69. Anterior Lamellae
• Skin, muscle (orbicularis
oculi (OO)), and associated
glands
• Cilia: There are 100–150 on
the upper lid and 75 on the
lower lid and are replaced
every 3–5 months.

70. Posterior Lamellae:
Tarsal plate, conjunctiva, and associated glands
• Tarsal Plate: Dense fibrous tissue 1–1.5 mm thick and 25
mm wide.
- Upper lid the height varies from 8 to 12 mm, in the lower lid 3–
4 mm
- The tarsal plate contains the Meibomian glands, 25 in the
upper and 20 in the lower lid.

71. Eyelid movements
Opening:
- Levator palpebrae superioris muscle (innervated by 3rd
nerve) elevates the upper eyelid approximately 15 mm.
- Muller’s muscle (smooth muscle, sympathetically
innervated) contributes an additional 1–2 mm of upper lid
elevation.
- The lower lid is moved inferiorly (5 mm) by the inferior
retractors linked to the inferior rectus and inferior oblique by
the capsulopalpebral fascia.
Closing:
- Closure is due primarily to Orbicularis Oculi contraction.
(innervated by 7th nerve)
Horner’s syndrome: partial (1–2 mm) ptosis due to loss
of Muller’s muscle function.
Oculomotor (third) nerve palsy: Complete Ptosis
LAGOPHTHALMOS refers to incomplete closure of the
eyelids

72. Blinking:
- spontaneous, reflex, or voluntary.
a) Spontaneous blinking:
- This occurs at rate of 10-20 times/minute.
Affected by:
- Environment (dry, moist, dust, bright), Emotional state (anxiety, concentration), Some disease(e.g.,
Parkinson’s disease)
b) Reflex blinking:
- Tactile: (touch), Optical: dazzle (bright lights) , Auditory (menace)
- For Tactile reflex trigeminal nerve (afferent arm) and facial nerve (efferent arm).
C) Voluntary blinking:

73. Madarosis (loss of eyelashes)
Trichiasis (misdirected growth of eyelashes)
Distichiasis (extra row of eye lashes)
Lagophthalmos refers to incomplete closure of the eyelids
Poliosis: White eyelash
Blood Supply by:
- Medial and Lateral palpebral arteries are branches of the ophthalmic and lacrimal arteries,
respectively.

74. Cranial Nerves
Oculomotor: 3rd
Trochlear: 4th
Trigeminal: 5th
Abducens: 6th
Facial: 7th

75. Nerve 3,4: Midbrain
Nerve 5: Pons
Nerve: 6,7: Junction between Medulla and Pons

76. 6thCavernous Sinus:
3, 4,5 nerve: wall of Cavernous Sinus
6th nerve: Floor of Cavernous Sinus
- Hence easily affected with raised ICP and
carotid artery pressure

77. Oculomotor: 3rd Nerve
• Motor Nerve
• LPS and all extra ocular muscles except lateral rectus and superior oblique (LR6SO4)
Components:
Somatomotor Component: Supply Extraocular muscles ( from oculomotor Nucleus)
Visceromotor(Parasympathetic): Ciliary body and Sphincter pupillae (Edinger Westphal Nucleus)
General somatic afferent: for proprioceptive impulses from the medial rectus muscle

79. Superior Branch: Ptosis (pupil unaffected), Hypotropia
Inferior Branch : Exotropia, Hypertropia, Pupillary reaction absent (But no ptosis)
Both Branch affected (Complete 3rd nerve Palsy): EOM restriction, Ptosis, Pupillary reaction
absent

80. Trochlear: 4th Nerve
• Motor Nerve
• Innervates only Superior Oblique muscle
• Only cranial nerve that exits from the dorsal (rear) aspect
of the brainstem.
• Smallest Cranial nerve based on number of axons.
• Longest intracranial length.
• Most commonly affected due to head trauma.
• Supply contralateral side
Palsy:
- Esotropia
- Hypertropia
- Excyclotropia

81. Trigeminal: 5th Nerve
• Mixed nerve (motor/sensory)
• Only nerve to grow from organ to
brain

82. Three Branches:
Ophthalmic
Mandibular
Maxillary

83. Ophthalmic Branch:
- sensory innervation
• Frontal nerve:
(Largest Branch of three)
• Lacrimal nerve:
(Smallest Branch of three)
• Nasociliary nerve
Supraorbital Upper eyelid and conjunctiva, Scalp
Supratrochlear
Upper eyelid and conjunctiva,
Forehead
• Sensory innervation of lacrimal gland, upper eyelid and
conjunctiva.
• Contains parasympathetic fibers to lacrimal gland.
Long ciliary nerves
Sensory innervation to eye (cornea, ciliary
bodies, iris)
Contains sympathetic fibers to dilator
pupillae muscle.

84. Abducens: 6th Nerve
• Motor nerve
• Supply Lateral Rectus muscle
• Somatic efferent: for lateral movement of the eye
• General somatic afferent: for proprioceptive
impulses from the lateral rectus muscle.
• Raised ICP affects 6th nerve first.
• Lesions of the intracavernous part of sixth nerve
may cause Tolosa-Hunt Syndrome.
Palsy:
- Esotropia

85. Facial: 7th Nerve
• Mixed (Sensory and Motor)
• General visceral efferent : parasympathetic
supply of the lacrimal gland.
- Reflex Tearing
• Somatic motor fibers
• Eye closure (orbicularis oculi)
Bells Palsy:
Hemifacial Paresis