Eye And Orbit

Front 1

Bony orbit

Back 1

pyramidal or funnel shape, inferior to anterior cranial fossa and anterior to middle cranial fossa
- Apex: optic foramen - II with retinal vessels, ophthalmic a., projects posteriorly
- Base: (orbital margin) anterior perimeter
- roof, floor, medial and lateral walls
BONES (7)
- frontal: margin, roof, med wall, frontal air sinus may project over the orbit
- zygomatic: margin, lat wall
- maxilla: margin, floor
- lacrimal: small part of medial wall
- ethmoid: medial wall
- sphenoid: great wing, lat wall
- lesser wing: roof, med wall
- palatine: small part of floor

- optic canal: pierces the lesser wing sphenoid

- superior orbital fissure: lies b/w the greater and lesser wing sphenoid, communicates with middle cranial fossa: III, IV, VI, V1 (3 branches), ophthalmic veins

- inferior orbital fissure and infraorbital groove: V2 infraorbital nreves, infraorbital vessels, vein to pterygopalatine plexus, fissure extends inferiorly, the groove ends as the infraorbital foramen

- supraorbital foramen (notch): supraorbital nerves and vessel

Front 2

Periosteum (periorbita)

Back 2

- lines orbit and extends into eyelids as the orbital septum, extends posteriorly
- is continuous with periosteal layer of dura at optic canal and supraorbital fissure
- continuous with fascia of extraocular muscles and eyeball (bulbar sheath), extends into eyelids as the orbital septum and reflects off the bone to be continuous with extraocular muscles
- the thickening is called the tendinous ring and that is the apex of the orbit

Front 3

Eyelids

Back 3

- skin vry thin: "black eye"
- medial and lateral angles of the eye = canthi
- palprebral fissure
- lashes: sebaceous glands,superior and inferior eyelids are lined
- styes: infection of the duct
- Medial angle: are devoid of lashes surrounds the lacrimal lake and caruncle, there is a mound of flesh in the corner of the eye
- lacrimal papillae and punctum [hole that is an opening into the nasal lacrimal duct]
- papillae fissure - where the two eyelids meet

Front 4

orbital septum

Back 4

periosteum extends into eyelids and forms protective barrier when eyelid is closed [preventing things from piercing into the orbit], attaches to the tarsal plates

Front 5

tarsal plates

Back 5

deep CT plates in lids deep to orbicularis oculi muscle [inside the upper and lower eyelids], attach to orbital septum and medial and lateral palpebral ligaments
- tarsal glands: secrete a viscous soln., helps spead lacrimal fluid over the eye
- chalazion (inside lid): blockage or infection of the tarsal glands, causes a bump on the inside

Front 6

orbicularis oculi muscle

Back 6

- innervated by CN VII, when it contracts helps expel lacrimal fluid from the lacrimal gland
-palprebral portion: extends into the eyelid
-orbital portion
-lacrimal portion

Front 7

levator palprebrae superioris

Back 7

- innervated by CN III
- inserts by broad aponeurosis to tarsal plate

Front 8

superior tarsal muscle

Back 8

- symp. innervation [autonomic innerv.]
- assists the levator palprebrae in elevating the eye

Front 9

horner's syndrome

Back 9

- injury to symp. trunk in neck, problems with the SNS
- partial ptosis due to loss of tarsal muscle innerv.
- miosis [pupil constriction]
- enopthalmos [retraction of the eye]
- ipsilateral anhydrosis
- vasodilation

Front 10

conjunctiva

Back 10

thin mucous memb that covers the surface of the eye
- superior and inferior conjunctival fornices
- conjunctival sac

Front 11

lacrimal apparatus

Back 11

- gland: divided by the levator palprebra tendon, secretes into a series of lacrimal ducts
- lacrimal ducts: secrete lacrimal fluid onto the eye
- lacrimal lake: accumulation of lacrimal fluid
- lacrimal punctum: a hole in lacrimal papillae, where the fluid drains
- lacrimal caniculi: tiny ducts that extend down from the papillae
- lacrimal sac/ nasolacrimal duct: nasal cavity, a dilated sac that is continuous with the nasolacrimal duct
- orbicularic oculi contraction forces fluid into nasolacrimal duct, relaxation creates suction, drawing fluid into the lake

Front 12

blood supply

Back 12

- internal carotid a. to ophthalmic a.
- branches of ophthalmic a.
-- orbital branches [supply the orbit itself']: lacrimal a., supraorbital a. [goes through the supraorbital foramen], ant. and post. ethmoidal, muscular
--- supratrochlear and dorsal nasal (terminal braches)
-- ocular branches: long and short posterior ciliary, anterior ciliary, central a. of the retina
-- central a. of the retina: travels in the optic n., occlusion results in blindness
- Venous Drainage: superior and inferior opthalmic veins receive blood from the eye, orbit, angular v. and that unites and drains into the cavernous sinus or pterygoid plexus of veins, this can act as a route for infection spread

Front 13

Extraocular skeletal muscles

Back 13

SO4LR6AO3
superior orbital - CN 4
Lateral Rectus CN 6
all other - CN 3

Front 14

common tendinous ring

Back 14

CT cuff that surrounds the optic canal and part of the superior orbital fissure: provides origin for 4 rectus muscles and superior oblique, it lies posterior and medial to the eyeball

Front 15

bulbar sheath (fascia bulbi)

Back 15

CT sheath around the eye, ends at the cornea, blends with CT sheaths of inserting extraocular muscles. All extraocular muscles insert on the bulbar sheath

fascia of extraocular muscles form medial and lateral cheek ligaments and suspensory ligament of the eye, keep the eye in check so it doesnt role in or out

Front 16

muscle actions: described in reference to axes of the eye

Back 16

- movement around the vertical and horizontal axis: adduction [medial movement - eye moving in], abduction [lateral - eye moving out], elevation, depression
- movement around the anteroposterior axis: medial rotation (intortion) and lateral rotation (extortion), keep eyes level when head tilts
- 4 rectus muscles arise from common tendinous ring at apex of orbit, apex of orbit is medial to central axis of the eye. Muscles insert on anterior eye
-- Lateral Rectus (VI): abduct [out]
-- Medial Rectus (III): adduct eye [in], bulkiest and strongest

- Superior and Inferior Rectus muscles arise from tendinous ring that is medial to axis of eye so these muscles also act to pull eye medially (inward)
-- Superior Rectus (III): elevation and adduction (up and in)
-- Inferior Rectus (III): depression and adduct (down and in)

**NOTE: the primary action of the combined rectus muscles is to pull the eye inward, the superior oblqiue counter balances the rectus muscle actions

Front 17

Superior Oblique (IV)

Back 17

- arises from the tendinous ring, and pass along the medial orbit roof, tendon passes through the trochlea, crosses eye post-lat under the superior rectus, and inserts on the superior posterior lateral eye
- primary action is intorsion, acts as a counter balance, secondary action is to depress and abduct (down and out)

Front 18

inferior oblique (III)

Back 18

smallest of the eye muscles, only one that does not arise form the common tendonous ring
-arises from the anterior medial floor and it crosses the eye posteriolateral and deep to the inferior rectus and inserts on inferior posterior lateral eye
- primary action is elevation extortion, elevation and abduct

Front 19

elevation of eye

Back 19

IO
SR

Front 20

depression of eye

Back 20

SO
IR

Front 21

Adduction

Back 21

SR
MR
IR

Front 22

abduction

Back 22

IO
LO
LR

Front 23

intortion

Back 23

SO
SR

Front 24

extortion

Back 24

IO
IR

Front 25

Testing extraocular muscle integrity

Back 25

"H"
- MR and LR: track finger horizontally
- other muscles bring axis of eye in alignment with long axis of muscle; SR and IR: track finger laterally (abduct) and then down
- SO and IR: track finger medially (adduct) then up (IO) or down (SO)

Front 26

CN II

Back 26

vision

Front 27

CN III

Back 27

levator palprebrae superioris, SR, IR, MR, IO [extraoccular innervation], parsympathetic motor to cilliary muscle and construictor papillae

Front 28

CN IV

Back 28

SO

Front 29

CN VI

Back 29

LR

Front 30

CN VII

Back 30

motor to orbicularis oculi, parasymp motor to lacrimal gland

Front 31

V1 and V2

Back 31

sensory eye, eyelid, conjunctiva, orbit, forehead, lacrimal gland

Front 32

Cranial Nerve III:

Back 32

- occulomotor nerve
- has motor component to skeletal muscle and a parasympathetic component
- it starts in the brainstem nuclei and its axons exit midbrain - pons junction, then it passes in between the post cerebral artery and the super cerebellar a.then it goes to the cavernous sinus and then to the superior orbital fissure, it has two divisions:
-- Superior division: levator palprebrae, SR
-- Inferior division: IO, IR, MR

-- its parasympthatic motor roots to cillary ganglion go to the short cillary nerves

Front 33

Cranial Nerve IV:

Back 33

trochlear nerve
- Brain stem nucleus, its axons cross in midbrain and exit on the posterior aspect of the brain and wrap around to emerge b/w the pons and temporal lobe [travels with the occulomotor nerve] then it is b/w the posterior cerebral and super cerebellar aa. then to the cavernous sinus and then to the superior orbital fissure and then to the superior oblique

Front 34

Cranial Nerve VI:

Back 34

- brain stem nucleus in pons in floor of the IV ventricle, CN VII axons loop around it
- exits b/w pons and medullary pyramids [basilar a. and pontine branches] then to the subarachnoid space in the cranial fossa then pierces dura and run along petrous temporal bone then to cavernous sinus then to superior orbital fissure and then to lateral rectus

Front 35

Visceral Parasympathetics of CN III

Back 35

- edinger-westphal nucleus in the brain stem [preganglionic neurons] travel through the occulomotor nerve and goes to the ciliary ganglion then the postganglionic neurons travel to the short ciliary nerve which goes to the ciliary muscle and constrictor pupillae
- the ciliary ganglion is located at the apex of the orbit

Front 36

Accomodation reflex of CN III

Back 36

- adaption reflex of eye for near vision, coordinated by the visual cortex
- from CN II to the visual cortex to the III motor nucleus to the medial rectus muscle which causes convergence of the eye then to the edinger-westphal to the ciliary muscles which contract causing a decreased tension on the lens and the constrictor pupillae caused the pupil to constrict

Front 37

pupillary light reflex

Back 37

- direct: response in the illuminated eye
- consenual: response in contralateral eye
- from CN II to pretectal area then sends signals bilateral then to the constrictor pupillae

Front 38

sympathetic innervation of eye and orbit

Back 38

- head and neck region
- postganglionics travel along blood vessels and CN V
- superior cervical ganglion travel along the ophthalmic artery branch to the superior tarsal muscle then it go two different ways:

1. may travel through a branch of CN V go through the ciliary ganglion to the short ciliary nerve to the dilator pupillae

2. along the carotid plexus to the deep petrosal nerve and then to the lacrimal gland

Front 39

pathology resulting in damage to III, IV, VI

Back 39

- cavernous sinus lesion, superior oribital fissure fractures: III, IV, VI
- aneurysms post cerebral or superior cerebellar arteries: III, IV
- aneurysms Basillar a., pontine branches: VI
- IV ventricle: VI
- Intracranial pressure: can compress VI