Eye Flashcards
7 bones that form the bony orbit
- Frontal
- Zygomatic
- Maxillary
- Sphenoid
- Lesser wing
- greater wing
- Ethmoid
- Lacrimal
- Palatine
Name the 3 aperatures of the posterior wall of the orbit: and what passes through them?
Optic canal • Optic nerve • Ophthalmic artery Superior orbital fissure • CNs III, IV, V1, VI • Superior ophthalmic v. Inferior orbital fissure • Infraorbital n. • Infraorbital a. & v
Name the 3 aperatures of the anteior wall of the orbit:
Bony rim of the orbit
Fossa for lacrimal sac & duct
Superior orbital foramen (or notch)
• Supraorbital n.
• Supraorbital a. & v
Name the 3 aperatures of the side walls of the orbit:
Ant. ethmoidal foramen • Ant. ethmoidal nerve • Ant. ethmoidal a. & v. Post. ethmoidal foramen • Post. ethmoidal nerve • Post. ethmoidal a. & v. Infraorbital Groove • Infraorbital nerve • Infraorbital a. & v
What are the parts of the eyelids? What is the space between the lids called?
Moveable skin flaps (palpebrae)
• Upper lid (palpebra superioris)
• Much more mobile than the lower lid (palpebra inferioris)
• Usually covers part of iris
• Palpebral fissure is the space between the lids
Explain location:
Medial & lateral palpebral commissures
Medial canthus & lateral canthus
Medial & lateral palpebral commissures - outside on skin near where the eye lids meet
Medial canthus & lateral canthus - on the inside edges of the eye lids where they meet
What makes up the deep part of the eyelids?
superior and inderior tarsal plates and medial and lateral palpebral ligaments
Describe the conjuntiva: N81
• Membranous sac (with aslit at the palpebral fissure)
• Transparent
• Bulbar part overlies sclera
• Palpebral part lines eyelids
• Bulbar conjunctiva stretches from the corneal
limbus to fornices
• Palpebral conjunctiva stretches from the fornices to the palpebral fissure
Describe the Lacrimal Gland & Apparatus N82
- Lacrimal gland
- Lacrimal lake with lacrimal caruncle
- Lacrimal papillae
- Lacrimal puncta
- Lacrimal canaliculi
- “Trail of tears”
- Lacrimal sac
- Nasolacrimal duct to nasal cavity
Orbicularis Oculi muscle attachments
• Origin from medial palpebral ligament (lacrimal bone & bony orbit)
• Inserts on skin & tarsal plates
• Functions to close the eyelids
Palpebral part – gentle closing of eyelids
(“blinking”)
Orbital part – tight closing of eyelids (“winking”)
• Innervated by CN VII (zygomatic & temporal branches)
Levator Palpebrae Superioris
Originates from the orbital roof and common tendinous ring
• Inserts into the superior tarsal plate 84N4
• Innervated by the superior division of CN III
• Functions to elevates upper lid under voluntary control
Superior Tarsal Muscle (of Mullër)
Superior Tarsal Muscle (of Mullër)
• Smooth muscle (involuntary)
• Originates off the levator palpebrae superioris m.
• Inserts on the superior tarsal plate
• Elevates tarsal plate
•Innervated by posynaptic sympathetics from carotid
plexus
•Contributes to the “wide-eyed”expression when the individual is excited
Muscles of eye innervated by CN III
- Medial rectus m.
- Superior rectus m.
- Inferior rectus m
- Inferior oblique
Muscles of eye innervated by abducens (VI)
lateral rectus
Muscles of the eye innervated by the trochlear n. (IV)
superior oblique
Which muscles insert on the Common tendinous ring (annulus of Zinn)
Gives origin to 4 “rectus”
extraocular muscles
and 1 “oblique”
extraocular muscle
Doesn’t do the inferior rectus muscles
Medial Rectus
- Originates from the Common Tendinous Ring
- Insertion into the medial eyeball at the 9 o’clock position in the left eyeball (3 o’clock in the right eyeball)
- Innervated by the inferior division of CN III
- Acts to adduct eyeball
Superior Rectus
• Originates from the Common Tendinous Ring
• Inserts into the superior eyeball at the 12 o’clock
position in both eyes
• Innervated by the superior division of CN III**
• Actions:
• To elevate eyeball
Less important:
• To adduct eyeball
• To medially rotate eyebal
Inferior Rectus
- Originates from the Common Tendinous Ring
- Inserts into the inferior eyeball at the 6 o’clock position in both eyeballs
- Innervated by the inferior division CN III
- 3 Actions:
- To depress eyeball
Less important
• To adduct eyeball
• To laterally rotate eyebal
Inferior Oblique
• Originates from the nasal walls of the orbital floor • Inserts into the posterolateral quadrant of inferior eyeball inferior to inferior rectus • Innervated by the inferior division of CN III • Actions: • To elevate eyeball • To abducts • To laterally rotate eyeball
Lateral Rectus
• Originates from the CommonTendinous Ring
• Inserts into the lateral eyeballat the 3 o’clock position in the left eyeball (at the 9 o’clock position in the right eyeball)
• Innervated by CN VI
• Acts to abduct the eyeball
84N4
Superior Oblique
• Origin from roof of bony orbit& common tendindous ring
• Its tendon passes through a trochlea (Greek for
“pulley”)
• Inserts into the posterolateralquadrant of superior eyeball inferior to superior rectus “X”on the diagram)
• Innervated by CN IV
• Actions:
• To depress eyeball
• To abduct eyeball
• To medially rotate eyeball
•“Down and out”muscle
Inside Common Tendinous Ring
- Optic nerve
- Ophthalmic artery
- Superior division CN III
- Inferior division CN III
- CN VI (abducens)
- Nasociliary nerve
Outside CommonTendinous Ring
- Lacrimal nerve
- Superior Ophthalmic vein
- Frontal nerve
- Trochlear nerve
LOFT
3 Coats of the eyeball:
- Fibrous
- Vascular
- Neural
3 Chambers of the eyeball
- Anterior chamber
- Posterior chamber
- Vitreous chamber
4 Refractive bodies of the eye ball
- (Air)
- Cornea
- Aqueous humor
- Lens
- Vitreous Body
Fibrous Coat
• Outermost layer of globe •Sclera -White & fibrous - Posterior 5/6 of eyeball - Protection & support • Cornea - Clear elevated part - Anterior 1/6 of eyeball - Refractive element (most of the refractio of light occurs at the interface of the air and surface of the cornea)
Name contents of vascular coat, which layer is it?:
Middle layer
- Choroid
- Ciliary body
- Iris
•Describe the Choroid Layer of vascular coat
- Vascular
- External to retina
- Terminates near ciliary body
Describe the Ciliary body
vascular coat - deep to choroid layer • Ciliary (smooth) muscle • Ciliary processes • Contains glands that produces “aqueous humor”(fluid of the anterior and posterior chambers)
Describe the ciliary muscle actions/innervations:
Relaxation = lens is stretched Contraction = lens is thickened = more refraction
- Ciliary muscle is a sphincteric-type smooth muscle
- Action is to pull ciliary body anteriorly and inward
- Releases tension on suspensory ligament, allowing the lens to thicken
- Postsynaptic parasympathetics (CN III) innervate ciliary muscle
Pupil is opening at the center of the iris (Greek for “rainbow”); what does the ______ do and what is it innervated by?
• Dilator pupillae
• Sphincter pupillae
Which coat is this located in?
- Dilator pupillae– postsynaptic sympathetics = bigger aperature
- Sphincter pupillae– postsynaptic parasympathetics = smaller aperature
vascular coat
Describe the Neural Coat
- Retina (mostly)
- Neurosensory layer that converts light photons into electrical impulses “phototransduction”
- Optical axis
- Macula lutea “yellow spot”
- Fovea centralis (absolute center of your visual field) - in macula
Name the insides of the occular chambers:
Anterior
Posterior
Vitreous
Anterior chamber - Aqueous humor (watery)
•Posterior chamber - Aqueous humor (watery)
•Vitreous chamber - Vitreous body (gelatinous)
Where is light bent that goes through the eye?
- Air -> Cornea(chief refractive interface)
- Cornea -> Aqueous humor (minor)
- Aqueous humor -> Lens *
- Lens -> Vitreous Body *
** The two surfaces of the lens change shape under parasympathetic control)
Name the ocular vessels
- Ophthalmic artery
- Superior ophthalmic vein
- Inferior ophthalmic vein
Name the branches of the opthalmic artery
- Central artery of retina*
- Anterior ciliary aa.
- Posterior ciliary aa.
- Lacrimal a.
- Supraorbital a.
- Muscular branches
- Anterior ethmoidal a.
- Posterior ethmoidal a.
Describe the venous drainage of the eye
• Superior ophthalmic vein superior to CN II
• Inferior ophthalmic vein inferior to CN II
(associated with pterygoid plexus of veins)
Corneal Reflex(Somatic – i.e., efferent fibers are branchial motor in type)
- Touch cornea with cotton wisp - Afferent (sensory) limb
- Reflexive blink - Efferent limb
- Afferent (sensory) limb - Long & short ciliary nn of nasociliary branch of CN V1
- Efferent (motor) limb - Orbicularis oculi (palpebral portion) via CN VII
Pupillary Light Reflex(Visceral – i.e., efferent fibers are visceral motor in type
• Shine light into one - Afferent (sensory) limb
• Reflexive constriction of pupil - Efferent limb
- Ipsilateral pupil -“direct”
- Contralateral pupil -“indirect”or “consensual”
Afferent (sensory) limb • CN II Efferent (visceral motor) limb • Inferior division of CN III • Parasympathetic root of the ciliary ganglion • Synapse within ciliary ganglion • Short ciliary nerves • Parasympathetic innervation of pupillary constrictor m.
Summary: Innervation of Eyeball
Special sensory
•CN II
Somatic sensory
•CN V1
•CN V2
Somatic (not branchial) motor!
•CN III
•Superior division
•Inferior division
•CN IV
•CN VI
Visceral motor
•Parasympathetics
•CN III
•Nervous intermedius of CN VII
•Parasympathetic ganglia
•Ciliary ganglion
•Pterygopalatine ganglion
•Sympathetics
•(Internal) carotid plexus
