Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
177 Cards in this Set
- Front
- Back
Describe the orbit:
|
Pyramidal shaped bony cavity
|
|
What 6 types of structures does the orbit contain?
|
-Eyeballs
-Muscles -Nerves -Vessels -Fat -Lacrimal apparatus |
|
How are the walls of the orbit oriented?
|
Medial walls are parallel to each other; (0' angle)
Lateral walls perpendicular (90' angle) |
|
What are the 4 orbit margins and what bones make up each margin?
|
1. Supraorb: frontal/sprbtlnotch
2. Lateral: frontal/zygomatic 3. Infraorb: zygomatic/maxilla 4. Medial: maxilla + frontal |
|
What composes the orbit roof and what is its special feature?
|
-Orbital plate of frontal bone
-Lacrimal fossa for lacrimal gland |
|
What composes the orbit lateral wall and what is its special feature?
|
-Zygomatic bone + greater wing of sphenoid
-Features the superior orbital fissure |
|
what two compartments communicate via the sup orb fissure?
|
Orbit + middle cranial fossa
|
|
What passes through superior orbital fissure?
|
CNs 3,4,V1,6
Opthalmic vein |
|
What does the orbit floor consist of?
|
Orbital plate of maxilla
|
|
What 2 features in the orbit floor are noteworthy?
|
-Inferior orbital fissure
-Infraorbital groove |
|
What bone has the following:
-Superior orb fissure -Inferior orb fissure |
Sup = ethmoid
Inf = maxilla (NOT sphenoid) |
|
What does the inferior orbital fissure allow to communicate?
|
Orbit + pterygopalatine fossa and infratemporal fossa
|
|
What passes through the inferior orbital fissure?
|
-V2 maxillary nerve
-Inferior opthalmic vein (going to the pterygoid plexus) |
|
What passes through the infraorbital groove?
|
V2 branch - infraorbital nerve
|
|
Components of medial orbit wall: (4)
|
-Maxilla
-Lacrimal bone -Orbital plate of ethmoid -Body of sphenoid |
|
Features of medial orbit wall (2):
|
-Lacrimal groove
-Optic canal |
|
What lies in lacrimal groove?
|
Lacrimal sac
|
|
What bone contains optic canal, what does it allow commun. w/?
|
-Sphenoid bone
-Communcn w/ mid cranial fossa |
|
What passes thru Optic canal:
|
Optic nerve - CN II
opthalmic artery |
|
What is the opening between the eyelids called?
|
Palpebral fissure
|
|
What are the corners of the eyes called?
|
Angles (canthi) - med/lat
|
|
What glands are in the eyelids skin?
|
Ciliary - sweat/sebaceous
|
|
4 Eyelid muscles:
|
-Orbicularis oculi
-Submusc. connectv tissue - contin w/ galea aponeurotica. -Levator palpebrae superioris -Superior tarsal |
|
Action of levator palebrae:
|
voluntarily raises upper eyelid - deep fibers insert into superior tarsal plate.
|
|
Superior tarsal muscle action:
|
Smooth muscle; widens eyes to their fullest extent via sympathetic innervation.
|
|
Function of glands in the tarsal plates:
|
Secrete oily substance over tear layer; causes tears to spill over when eyes fill.
|
|
What is the orbital septum?
|
Membranous sheet connecting tarsal plates to orbital rim; continuous w/ periosteum.
|
|
4 Main points re: conjunctiva:
|
1. Transparent mucous membrane
2. Palpebral (inner eyelids) 3. Bulbar (over eyeball) 4. Fornix (crease betwn above 2) |
|
6 Main parts of the Eyeball:
|
1. Lens
2. Anterior cavity 3. Posterior cavity 4. Fibrous tunic 5. Vascular tunic 6. Neural/Retinal layer |
|
Basic structure of the lens:
|
Transparent, biconvex;
Tightly packed lens fibers; Lens capsule = basement membrane surrounding fibers. |
|
What special structures facilitate change in lens shape during accommodation?
|
Zonule fibers - parasympathetic innervation
|
|
What common clinical problem occurs with the lens?
|
Cataracts
|
|
Where is Anterior cavity located; what does it contain?
|
-In front of lens
-Contains aqueous humor |
|
2 main areas of the anterior cavity:
|
1. Anterior chamber
2. Posterior chamber |
|
Where is the anterior chamber?
|
Between posterior surface of cornea, and anterior surface of lens/iris.
|
|
Where is the posterior chamber?
|
Between posterior surface of iris/lens, and suspensory ligament.
|
|
Where is the posterior CAVITY?
|
behind the lens
|
|
What does the posterior cavity contain?
|
Vitreous humor
|
|
What are the 2 components of the fibrous tunic?
|
1. Sclera (back 5/6)
2. Cornea (front 1/6) |
|
Main functions of the sclera:
|
-Maintains eyeball shape
-Insertion of extraocular muscles |
|
Main functions of cornea:
|
-Refraction
(transparent/avascular) |
|
3 structures found in the vascular tunic:
|
1. Choroid
2. Ciliary body 3. Iris |
|
What is the choroid?
|
-Dense capillary plexus w/ pigment cells
|
|
Where is the choroid found?
|
Between sclera/retina
|
|
What is the ciliary body?
|
The layer of the vascular tunic that produces aqueous humor and contains the ciliary muscle.
|
|
What is the purpose of aqueous humor?
|
provides nutrients to the avascular lens and cornea
|
|
Where does aqueous humor from the ciliary body go?
|
Passes through the pupil, drains into the venous sinus at the iridocorneal angle.
|
|
What common clinical problem is associated with the ciliary body and aqueous humor?
|
glaucoma
|
|
How is the ciliary muscle connected to the lens?
|
By zonule fibers.
|
|
What type of muscle is the ciliary m?
|
smooth muscle like a sphincter
|
|
What does the ciliary muscle do?
|
Controls the shape of lens.
|
|
How exactly does the ciliary m work?
|
1. Parasymp nerves stim it
2. Contraction decreases tension of zonule fibers 3. Lens curvature increases -> now u can see close up |
|
What is the iris?
|
A highly pigmented diaphragm extending over the anterior lens surface.
|
|
What is the pupil?
|
The hole in the middle of iris
|
|
What 2 muscles control the iris?
What kind of nerves innervate each? |
-Sphincter pupillae; parasymp
-Dilator pupillae; sympathetic |
|
What 2 types of layers make up the retina?
|
1. Retinal pigment epithelium
2. Nerve fiber layer - forms optic nerve. |
|
What are the 4 key components of the lacrimal apparatus?
|
1. Gland
2. Puncta 3. Sac 4. Nasolacrimal duct |
|
Where is the lacrimal gland and how is it situated there?
|
-Superolateral orbit angle
-Levator palpebrae superioris aponeurosis splits gland into: -Orbital part (in lacrimal fossa of zygomatic bone) -Palpebral part (lateral upper eyelid) |
|
Where does the lacrimal duct open into?
|
Fornix
|
|
Where does lacrimal fluid flow?
|
From lateral upper fornix to lower medial Lacrimal Lake.
|
|
What are lacrimal puncta?
|
Small apertures withn lacrimal papillae elevations along each eyelid.
|
|
Where does lacrimal fluid flow after entering lacrimal puncta?
|
Into lacrimal canaliculi -> lacrimal sac
|
|
What and where is the lacrimal sac?
|
In the lacrimal fossa of the lacrimal bone; the opening of the nasolacrimal duct.
|
|
Where does the nasolacrimal duct flow into?
|
The inferior nasal meatus.
|
|
What 2 major arteries feed the orbital region?
|
1. Internal carotid
2. External carotid |
|
What branch does the internal carotid send to the orbit?
|
Opthalmic artery via optic canal
|
|
What are the 6 main branches of the Opthalmic Artery?
|
1. Central artery of retina
2. Lacrimal artery 3. Supraorbital artery 4. Supratrochlear artery 5. Dorsal nasal artery 6. Post/ant ethmoidal aa. |
|
Where does the central artery of retina run?
|
Within dural sheath of optic nerve's inferior surface; supplies the retina.
|
|
Where does the lacrimal artery go and feed?
|
To the lacrimal gland, conjunctiva and eyelids -> becomes the lateral palpebral artery.
|
|
What happens to the lacrimal artery ultimately?
|
Anastomoses w/ the zygomatic-orbital a. and facial artery (of external carotid)
|
|
What does the Supraorbital artery supply?
|
-Superior rectus m
-Levator palpebrae superioris |
|
Where does the supraorbital a ultimately end up?
|
Passes thru supraorbital notch to feed 6 things:
-forehead and scalp -medial canthus -diploe of frontal bone -periosteum & frontal sinus |
|
What is the supratrochlear artery and what does it feed?
|
Terminal branch of opthalmic artery; feeds forehead/scalp and pericranium.
|
|
What is important about the dorsal nasal artery?
|
-Supplies lacrimal sac and skin of the nose.
-Anastomoses with external carotid via infraorbital artery. |
|
What 3 branches to the orbit come from the external carotid?
|
1. Infraorbital artery
2. Zygomatico-orbital artery 3. Facial artery |
|
What is the infraorbital artery a branch of?
|
Maxillary
|
|
What 3 things does infraorbital artery supply?
|
1. Inferior rectus m
2. Inferior oblique 3. Lacrimal sac |
|
What does the infraorbital a anastomose with?
|
Dorsal nasal artery of internal carotid's opthalmic artery. Also the facial artery.
|
|
What is the zygomatico-orbital artery a branch of?
What does it supply? |
The superficial temporal artery.
-Supplies orbicularis oculi muscle. |
|
What does the zygomaticorbital artery anastomose with?
|
Lacrimal artery (from opthalmic artery)
|
|
What does the facial artery anastomose with?
|
-Dorsal nasal artery
-Infraorbital artery |
|
What 3 arteries does the transverse facial artery anastomose with?
|
1. Facial
2. Infraorbital 3. Lacrimal |
|
What are the 3 important veins of the orbit?
|
1. Central vein of the retina
2. Superior opthalmic vein 3. Inferior opthalmic vein |
|
Where does the central vein of the retina run/drain?
|
With the optic nerve; drains into cavernous sinus or superior opthalmic vein.
|
|
What does the superior opthalmic vein communicate w/?
|
-Facial vein
-Supraorbital vein |
|
What hole does the superior opthalmic v. pass through and where does it drain?
|
Passes through superior orbital fissure to drain into cavernous sinus.
|
|
What does the inferior opthalmic vein receive blood from?
|
Inferior/medial parts of the orbit.
|
|
What does the inferior opthalmic vein connect to and drain into?
|
-Connects w/ superior opthalmic vein and/or drains via inferior orbital fissure into pterygoid plexus.
|
|
What 2 sensory nerves carry optic information?
|
1. CN II - Optic
2. CN V1 - Opthalmic |
|
What functional modality is attributed to each optic sensory nerve?
|
Optic = special somatic afferent
Opthalmic = general somatic afferent |
|
How does the optic nerve begin?
|
-Axons of retinal ganglion cells form a nerve
-Nerve pierces sclera medial to posterior pole of eyeball |
|
What covers the optic nerve?
|
Meninges and CSF
|
|
What hole does the optic nerve run through and where does it go?
|
-Courses through optic canal of sphenoid bone
-Forms optic chiasm -Tracts terminate in lateral geniculate nucleus. |
|
Where does the opthalmic nerve (V1) arise from?
|
Sensory receptors which transmit info via peripheral processes.
|
|
What hole does the opthalmic nerve course through, and where does it go after that?
|
-Superior orbital fissure
-Through cavernous sinus to NCB's in trigeminal ganglion. |
|
What happens to CN V1 (opthalmic) at the trigeminal ganglion?
|
Its central nerve processes transmit sensation to 2 things: 1. Principle sensory nucleus
2. Spinal nucleus |
|
what are the 3 very important branches of the opthalmic nerve?
|
1. Lacrimal nerve
2. Frontal nerve 3. Nasociliary nerve |
|
what are the 3 branches of the Frontal nerve (of CN V1)?
|
1. Supratrochlear
2. Supraorbital 3. Nerve to the frontal sinus |
|
What are the 5 branches of the Nasociliary nerve?
|
1. Anterior/posterior ethmoidal nerves
2. Infratrochlear nerve 3. Meningeal nerve 4. Long ciliary nerves 5. Short ciliary nerves |
|
What 3 nerves give motor innervation to the orbit?
|
1. CN III - Oculomotor
2. CN IV - Trochlear 3. CN VI - Abducent |
|
What type of functional modality are the 3 orbit motor nerves?
|
General somatic efferent
|
|
Where do the axons of CN III arise?
|
From neurons in midbrain oculomotor nucleus
-Located near median plane, at the midbrain-pons junction. |
|
What is the route of CN III in going from the oculomotor nucleus to the eye muscles?
|
-Passes between posterior cerebral and superior cerebellar arteries
-Passes thru cavernous sinus -Thru Superior orbital fissure -Within common tendinous ring |
|
What are the 2 divisions formed from the oculomotor nerve?
|
1. Superior
2. Inferior |
|
What is innervated by the Superior Oculomotor Nerve? (2 things)
|
1. Levator Palpebrae superioris
2. Superior rectus |
|
What is innervated by the Inferior Oculomotor Nerve? (3 things)
|
1. Medial rectus
2. Inferior rectus 3. Inferior oblique |
|
What does the trochlear nerve innervate?
|
Superior oblique
|
|
What is unique about the trochlear nerve?
|
Axons originate from nuclei in the DORSAL brainstem surface.
|
|
How does the trochlear nerve get to the orbit?
|
Thru cavernous sinus, then thru Superior Orbital Fissure
|
|
How does the Abducent nerve get to the orbit?
|
Same way that the trochlear does, except from ventral brainstem side.
|
|
What orbit structures receive autonomic innervation? Which get parasympathetic and which get sympathetic?
|
Lacrimal gland = both
Sphincter pupillae - para Ciliary muscle - para Dilator pupillae = sympathetic Superior tarsal = sympathetic |
|
What is the 2 neuron system like -For parasympathetic neurons?
-For sympathetic neurons? |
PARA: long preganglionic + short post-ganglionic neuron
SYMP: short preganglionic + long postganglionic neuron. |
|
Where are the preganglionic parasympathetic NCBs for the lacrimal gland located?
|
In the superior salivatory nucleus
|
|
How do the preganglionic parasymp fibers for lacrimal gland get to it?
|
-Emerge from brain w/ Nervous Intermedius (CN VII)
-Pass thru geniculate ganglion -Continue as Greater Petrosal -Join Deep Petrosal nerve |
|
What do the Greater Petrosal + Deep Petrosal nerves combine to form?
|
Nerve of the Pterygoid Canal
|
|
Where do the preganglionic parasymp fibers for the lacrimal gland synapse?
|
At the Pterygopalatine ganglion
|
|
How do postganglionic parasymp fibers from the Pterygopalatine ganglion get to the Lacrimal gland?
|
-Travel w/ Zygomaticotemporal nerve + Lacrimal nerve
|
|
What happens once parasymp nerves get to the Lacrimal gland?
|
They stimulate secretion.
|
|
What happens when SYMPATHETIC nerves get to the lacrimal gland?
|
They stimulate Vasoconstriction of blood vessels.
|
|
Where are the preganglionic SYMPATHETIC NCB's for the lacrimal gland?
|
In the lateral horn of the spinal cord gray matter - just like for all other sympathetic preganglionic neurons.
|
|
Where do preganglionic sympathetic lacrimal fibers synapse?
|
Superior Cervical Ganglion
|
|
What structure is formed by postganglionic sympathetic lacrimal fibers?
|
Internal Carotid nerve
|
|
How does the internal carotid sympathetic nerve get to the lacrimal gland?
|
Travels w/ Deep Petrosal nerve; Joins Greater Petrosal nerve;
Travels w/ Nerve of Pterygoid Canal |
|
So how do both sympathetic AND parasympathetic postganglionic nerve fibers get to the lacrimal gland?
|
By traveling with the Zygomaticotemporal and Lacrimal nerves.
|
|
What type of innervation do Sphincter pupillae and ciliary muscles receive?
|
Parasympathetic
|
|
Where do preganglionic parasymp fibers for Sphinct. pupillae and ciliary muscles arise? How do they get where they're going?
|
From Edinger-Westphal nucleus in midbrain; travel w/ CN III to the ciliary ganglion.
|
|
What happens to parasymp preganglionic fibers at the ciliary ganglion?
|
Synpase and send postganglionic fibers via SHORT CILIARY NERVES (V1 branches) to Sphincter pupillae and ciliary mm.
|
|
What happens when the postganglionic parasymp fibers of Short Ciliary Nerves reach their muscles?
|
-Pupil constriction
-Lens thickening (accommodation) |
|
What type of innervation do Dilator pupillae and Superior tarsal muscles receive?
|
Sympathetic
|
|
Where do preganglionic symp fibers for Dilator pupillae and Superior tarsal muscles arise? How do they get where they're going?
|
From spinal cord; enter the sympathetic trunk and synapse in Superior Cervical Ganglion.
|
|
What happens to postganglionic sympathetic fibers for Dilator pupillae and Superior tarsal muscles?
|
Form Internal Carotid nerve plexus; pass uninterrupted thru ciliary ganglion.
|
|
What V1 branch carries sympathetic innervation to Dilator pupillae and Superior tarsal muscles after passing thru the ciliary ganglion?
|
Long Ciliary nerves (V1)
|
|
What happens when sympathic nerves stimulate Dilator pupillae and Superior tarsal muscles
|
-Pupils widen
-Palpebral fissure widens all the way. |
|
What are the 3 AXES of the eye?
|
1. Vertical
2. Horizontal/transverse 3. Anteroposterior |
|
What 3 actions occur around the vertical axis?
|
1. Abduction
2. Neutral 3. Adduction |
|
What 3 actions occur around the horizontal axis?
|
1. Elevation
2. Neutral 3. Depression |
|
What 3 actions occur around the anteroposterior axis?
|
1. Extorsion
2. Neutral 3. Intorsion |
|
What is extorsion?
What is intorsion? |
Extorsion: 12 o'clock on eye twists laterotemporally.
Intorsion: 12 o'clock on eye twists medionasally. |
|
Levator palpebrae superioris:
-Innervation -Action |
Innervation: CN III
Action: raises the eyelid |
|
Medial rectus:
-Innervation -Action around axes |
Innervation: CN III
Vertical axis: adduction Horizontal ax: nothing Antpost axis: nothing |
|
Lateral rectus:
-Innervation -Action around axes |
Innervation: CN VI
Vertical axis: abduction Horizontal ax: nothing Antpost axis: nothing |
|
Superior rectus:
-Innervation -Action around axes |
Innervation: CN III
Vertical axis: adduction(2') Horizontal ax: Elevation (1') Antpost axis: Intorsion (3') |
|
Inferior rectus:
-Innervation -Action around axes |
Innervation: CN III
Vertical axis: adduction(2') Horizontal ax: Depression(1') Antpost axis: Extorsion (3') |
|
Superior oblique
-Innervation -Action around axes |
Innervation: CN IV
Vertical axis: abduction Horizontal ax: Depression Antpost axis: Intorsion |
|
Inferior oblique
-Innervation -Action around axes |
Innervation: CN III
Vertical axis: abduction Horizontal ax: Elevation Antpost axis: Extorsion |
|
Why does SO cause depression around horizontal axis?
|
Because it elevates the posterior aspect of the eye
|
|
Why does IO cause elevation around the horizontal axis?
|
Because it depresses the post aspect of eye.
|
|
Which muscles achieve eye movement in the horizontal plane only?
|
Medial and lateral rectus mm.
|
|
What muscles achieve eye elevation or depression?
|
Superior oblique
Inferior oblique Superior rectus Inferior rectus |
|
What 2 conditions regarding the axis of gaze are achieved by eye ABDUCTION?
|
1. Axis aligned w/ long axis of rectus muscles
2. Axis perpendicular to long axis of oblique muscles. |
|
What is achieved by abducting the eye?
|
-Rectus muscles are optimally positioned to elevate or depress
-Oblique muscle contribution is minimal |
|
What 2 conditions regarding the axis of gaze are achieved by eye ADDUCTION?
|
1. Axis perpendicular to long axis of rectus muscles
2. Axis aligned w/ long axis of oblique muscles |
|
What is achieved by adducting the eye?
|
-Rectus muscles contribute minimally
-Oblique muscles optimally positioned to elevate/depress |
|
What mnemonic is useful for remembering what direction to tell the patient to look when testing extraocular muscles?
|
O's toward the nose and upside down.
|
|
What is a common clinical complaint seen in eye motor nerve injuries?
|
Diplopia - double vision.
|
|
What 2 general types of neural problems can cause diplopia?
|
-Central lesions - in brainstem nuclei
-Peripheral lesions - injuries to the nerves. |
|
What is ptosis?
What is lateral strabismus? |
Ptosis = drooping eyelid
Lat Strabismus = eye turning down and laterally |
|
Damage to what nerve causes ptosis, and why?
|
CN III - because the levator palpebrae superioris is paralyzed.
|
|
Why does lateral strabismus occur in CN III damage?
|
Medial rectus and Superior rectus muscles are paralysed; leaves LR6(SO)4 unopposed.
|
|
What are 4 possible casues of CN III injury?
|
-Intracranial aneurysm
-Trauma -Inflammation (syphilis, diabetic neuropathy) -Cavernous sinus thrombosis |
|
What will a CN IV lesion result in?
|
Inability to look down and nasally (depress/adduct)
|
|
Why is depress/adduction inhibited by CN IV lesion?
|
Superior Oblique is paralysed
|
|
What is a clinical sign of CN IV injury?
|
Head tilt - toward opposite side of eye injured
|
|
Why do patients w/ injured CN IV tilt their head?
|
Because the normal eye intorts, realigning the axis of gaze with the extorted injured eye.
|
|
What are 2 common causes of CN IV injury?
|
-Trauma
-Cavernous sinus thrombosis |
|
What is a common sign of CN VI injury? Why?
|
Medial strabismus - medial rectus m is unopposed b/c lateral rectus is paralyzed
|
|
What is the most common cause of CN VI injury?
|
Cavernous sinus thrombosis
|
|
What nerve injury would result in a loss of lacrimation?
|
CN VII - w/ greater petrosal nerve involved too.
|
|
What nerve is associated with Horner's syndrome?
|
CN III sympathetic fibers
|
|
What are 4 symptoms of Horner's Syndrome?
|
-Miosis (pupil constriction)
-Ptosis (drooping eyelids) -Anhydrosis (lack sweating) -Erythematosis (skin blushes) |
|
What causes miosis in horner's syndrome?
|
Dilator pupillae paralysis - unopposed sphincter pupillae
|
|
What causes ptosis in horner's syndrome?
|
Paralysis of superior tarsal m
|
|
What causes anhydrosis in horner's syndrome?
|
Loss of head/neck sweat gland innervation
|
|
What causes erythematosis in horners syndrome?
|
Blood vessel dilation
|
|
What 2 conditions can result from CN III parasymp fiber lesion?
|
-Loss of accommodation to light reflex
-Pupil dilation |
|
Why do pupils dilate in CN III Parasymp fiber lesions?
|
Sphincter pupillae muscles are paralysed so dilator pupillae m are unopposed.
|
|
Why is accomodation to light reflex impaired by CN III lesion?
|
B/c the ciliary m and sphincter m are paralyzed.
|