FIU - Eye Anatomy.ppt

8/14/2019 FIU - Eye Anatomy.ppt

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Eye AnatomyOrthopedic Assessment IIIHead,

Spine, and Trunk with LabPET 5609C
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2/23

Clinical Anatomy

Orbit:

Cavity or socket of the skull which houses the

eye

Protects and stabilizes the eye

Serves as attachment site for extrinsic muscles

Orbital Marginsbases which open in the face

(4 borders) Supraorbital marginfrontal bone

Inraorbital marginzygomatic and maxilla bones

Lateral marginzygomatic and frontal bones


3/23

Clinical Anatomy

YellowFrontalBone

BlueZygomaticBone

PurpleMaxillaBone
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4/23

Clinical Anatomy

Orbital Anatomy:Anterior aspect or roof

Frontal Bone

Posterior aspect Sphenoid Bone

Medial aspect

Lacrimal, ethmoid, maxillary, and sphenoid bones

Lateral aspect

Zygomatic and sphenoid bones

Orbit is thickest


5/23

Clinical Anatomy

Frontal Bone

Zygomatic

Bone

LacrimalBone

Ethmoid

Bone

Maxilla Bone

Sphenoid

Bone


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7/23

Clinical Anatomy

Superior Orbital Fissure Opening between lesser and

greater wings of sphenoidbone

Allows cranial nerves,arteries, and veins tocommunicate with eye

Optic Canal Foramen which the optic

nerve passes to reach thebrain

Optic Nerve

Cranial nerve II

Transmits visual informationfrom the retina to the brain


8/23

Clinical Anatomy

Superior

Orbital Fissure

Optic Fissure


9/23

Clinical Anatomy

Sclera: White of the eye

Tough, opaque tissue that servesas the eye's protective outer

Optic nerve is attached to the

sclera at the very back of the eye Pupil:

Opening in center of iris

Size of the pupil determines theamount of light that enters theeye

Pupil size is controlled by thedilator and sphincter muscles ofthe iris

Neurological Functionpupilsreaction to light


10/23

Clinical Anatomy

Iris: Colored part of the eye

Controls light levels inside the eye

Divides the anterior chamber fromposterior chamber

Color comes from microscopicpigment cells (melanin)

The color, texture, and patterns ofeach person's iris are as unique as afingerprint

Muscles acting on Iris: Sphincter muscle:

In bright light, the sphinctercontracts, causing the pupil toconstrict

Dilator muscle: Dilates the eye in dim lighting


11/23

Clinical Anatomy

Conjunctiva: Thin mucous membrane that

covers the outer surface of the

eye (sclera)

Lines inside of the eyelids

Anteriorly - continous with

the cornea

Nourished by tiny blood

vessels (nearly invisible to thenaked eye)

Secretes oils and mucous that

moisten and lubricate the eye


12/23

Clinical Anatomy

Cornea: Transparent, dome-

shaped window coveringthe front of the eye

(normally clear with ashiny surface)

Powerful refracting surface(provides 2/3 of the eye'sfocusing power)

Extremely sensitive More nerve endings in the

cornea than anywhere elsein the body


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Clinical Anatomy

Ciliary Body: Lies behind the iris

Attached to the ciliary body are tinyfiber ligaments (zonules)suspendthe lens

Produces aqueous humor (clear fluidthat fills the front of the eye)

Controls accommodation to light bychanging the shape of the lens Ciliary body contracts - zonules relax

and lens thicken, the eye's ability tofocus up close

Ciliay body relaxes - zonules contractand lens becomes thinner, adjustingthe eye's focus for distance vision

Lens: Located just behind the iris

Focuses light onto the retina


14/23

Clinical Anatomy

Retina: Multi-layered sensory tissue that

lines the back of the eye

Contain millions of

photoreceptors that capture lightrays and converts them into

electrical impulses

Impulses: Optic nerve to Brain

(images)

Cones(6 million) Bright light (help us

differentiate color)

Rods(125 million)

Peripheral and night vision


15/23

Blink Reflex

Corneal Reflex - Blink Reflex Involuntary blinking of the eyelids elicited by

stimulation (touching or a foreign body) of the cornea,or bright light

Should elicit response of the opposite eye also

Time = 0.1 second

Purpose - protect the eyes from foreign bodies andbright lights

Controlled by: Cranial nerve V (trigeminal nerve) - senses the stimulus on the

cornea, lid, or conjunctiva.

Cranial nerve VII (facial nerve)initiates motor response

Use of contact lenses may diminish or abolish this reflex


16/23

Clinical Anatomy

Muscular Anatomy:

Inferior Rectus

Superior Rectus

Medial Rectus Lateral Rectus

Inferior Oblique

Superior Oblique


17/23

Clinical Anatomy

Eye Movement Terminology:

Ductionmovement of one eye by itself

Versionmovement of the 2 eyes in the same direction

Adductioneye looks toward the nose Abductioneye looks toward the ear

Dextroversionboth eyes look to the right

Levoversionboth eyes look to the left

Supraversionboth eyes upgaze

Infraversion- downgaze


18/23

Clinical Anatomy

Medial Rectus: Strongest of the extra-

ocular muscles

Most mass of EOMs

Most anterior insertion(extra leverage)

ActionAdduction(eyes move towards the

nose) Lateral Rectus:

Action- Abduction


19/23

Clinical Anatomy

Superior Rectus:

Actionelevation,

upward rotation

Rotationanglesnasally toward site of

origin

Tendon of the Superior

Oblique muscle passes

underneath the SR


20/23

Clinical Anatomy

Inferior Rectus:

Actiondepression,

downward rotation,

adduction


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Clinical Anatomy

Superior Oblique: Keeps the eyeballs level

as the head tilts

Longest of the EOMs

Passes through apully called thetrochlea

Redirects the action

Action:Abduction of globe

Depression of globe

Rotation of globe


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Clinical Anatomy

Inferior Oblique:

Passes underneath the

inferior rectus

Action: Elevation of globe

Adduction of globe

Rotation of globe

Keeps the eyeballslevel as the head tilts


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Muscle Action Origin Insertion Innervation

Inferior

Rectus

Depression,

Downward

Rotation

From a tendinous

ring on posterior

aspect of orbit

Middle of the

inferior aspect of

anterior globe

Oculomotor

Superior

Rectus

Elevation, Upward

Rotation

From a tendinous

ring on posterior

aspect of orbit

Middle of the

superior aspect of

anterior globe

Oculomotor

Medial

Rectus

Medial Rotation

(Adduction)

From a tendinous

ring on posterior

aspect of orbit

Middle of the

superior aspect of

anterior globe

Oculomotor

Lateral

Rectus

Lateral Rotation

(Abduction)

From a tendinous

ring on posterior

aspect of orbit

Middle of the

superior aspect of

anterior globe

Abducens

Inferior

Oblique

Adduction,

Elevation of globe,

Rotation of globewhen abducted

From the periosteum

of the maxilla

Inferolateral

quadrant of the

globe

Oculomotor

Superior

Oblique

Abduction,

Depression of

globe, Rotation of

globe when

adducted

Greater wing of the

sphenoid

Superolateral

quadrant of the

globe

Trochlear

FIU - Eye Anatomy.ppt

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