Orbit Flashcards by Meghan May

Drainiage via Inferior Orbital Fissure: then to pterygoid plexus

Inferior Ophthalmic Vein

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Superior Ophthalmic V drains to

Superior Orbital Fissure

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Special about venous supply of eye?

you have arteries coming in one way, but the veins exit a different path

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uses optic canal along w/ CN II

*branch of internal carotid

Opthlamic Artery

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seen when you section optic nerve (pierces it and supplies portions or retina)

Central artery of retina

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heads superior and medial to lacrimal gland

Lacrimal artery

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7 branches of Opthalmic artery

Central artery of retina:
Lacrimal artery:
Supraorbital artery
Supratrochlear artery: terminal branch
Doral nasal artery: terminal branch
Poster & anterior ethmoidal artery: medially pierce ethmoid bone
Short and long ciliary arteries penetrate sclera of eye

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Contributes to eye via branch called Infraorbital artery via infraorbital foramen

External Carotid

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Two main arterial supplies in eye

External Carotid + Opthalmic Artert

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Path of External Carotid

external carotid branch→ Maxillary Artery branch→ Infraorbital artery

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What supplies: inferior rectus

	- inferior oblique
	- lacrimal gland

Infraorbital artery

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What three branches does Infraorbital artery anastomose with?

anastomosis with dorsal nasal artery (thus have anastomosis btwn internal/external carotids via infraorbital artery (external)—Dorsal Nasal artery (internal) and the Facial Artery

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How is there an anastomotic connection bewteen external and internal carotids in the orbit?

anastomosis with dorsal nasal artery (thus have anastomosis btwn internal/external carotids via infraorbital artery (external)—Dorsal Nasal artery (internal)

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Three branches of External Artery in the eye

a. Facial~ anastomose w/ Dorsal facial artery
b. Transverse Facial anastomose w/ the infraorbital and lacrimal arteries
c. Infraorbital

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Drainage of lacrimal gland

Drains→ superior fornix (where conj folds over)

flows inferiorly and medially toward papilla

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Passage of lacrimal drainage

openings in lacrimal papillae →lacrimal caruncle→lacrimal canaliculi→ lacrimal sac→ nasolacrimal duct→ inferior nasal meatus which extends posteriorly through posterior aspect of cavity→ pharnyxn→ esophagus (too much teasrs = tears out the nose!

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Where does nasolacrimal duct lie?

w/in nasolacrimal canal

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CC to CN II

Visual Field Defects

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Brach that supplies Somatic Sensory (pain/temp/pressure from globe of eye and highly innervated cornea)
a. From forehead and skin of medially aspect of face~ tip of nose

Opthalmic region of the Trigeminal = CN V1

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Pathway of V1 sensory branch

Peripheral processes trasmit sensation from sense neurons→ through SOF→ through Cavernous Sinus
Synaspse @ NCB in Trigeminal Ganglion→ then transmits central processes Central Processes transmit sensation to Principap Sensory Nucleus and Spinal nucleus of V From here, these central processes will send info to cortex for processing so you can tell where the sensation is located

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Special about V1

VIP branches of Opthalmic (V1) **ALL SENSORY V1 is SENSORY

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Branch of V1 that innervates the lacrimal gland

Lacrimal Nerve

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Has these three subdivision
Supratrochlear nerve (most medial)
-supraorbital nerve (middle) (divides further to medial and lateral branches)
-nerve to Frontal sinus (dives deep)

Frontal nerve

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Frontal nerve comes from

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Branches of Nasociliary nerve

- Anteroior and Posterior Ethmoidal Nerves - Infratrochlear nerve - Meningeal Nerve - Long Ciliary Nerve: pierces sclera - Short Ciliary nerve: pierce sclera and goes to ciliary ganglion

Origin of nasociliary nerve

Muscles innervated by CN III

Levator palpebrae, Superior rectus, Inferior Rectus, Medial Rectus, Inferior Oblique

Location on Pregang NCB of III

upper brain stem in oculomotor nucleus = location of NCB

Pathway of CN III

origintaes in upper brain stem in oculomotor nucleus = location of NCB→ - emerges near median plane at jnx of midbrain and pons - then passes btwn posterior and superior cerebellar arteries→ - through cavernous sinus→ through SOF of sphenoid bone: has superior and inferior branch - Passes w/in tendinous ring where rectus m.s originate

Ptosis (eyelid droops), resting eye ‘down and out’ bc of unopposed action of superior oblique and lateral rectus, pupil is fixed and dialated

CC to oculumotor

Cause of 'down and out' eye

unopposed action of superior oblique and lateral rectus

Location on Pregang NCB of Trochlear IV

Neurons in Trochlear nucles in midbrain of brainstem

Only nerve to go Dorsally over the midbrain

Trochlear

Path of Trochlear IV

-Neurons in Trochlear nucleus in midbrain of brainstem -goes dorsally (only one) from midbrain -enter cavernous sinus→ SOF of sphenoid -passes OUTSIDE tendinous ring Muscles: Superior Oblique m.

Superior Oblique m. innervated by

Trochlear IV

Can’t look down when eye is adducted→ causes Diplopia d/t cavernous sinus injury

CC to Trochlear IV

lateral rectus = abducts the eyeball innervated by:

Abducent VI

Location of NCB of Abducent VI

NCB in the abducent nucleus and emerge at median plane near medulla/pons

Pathway of Abducent VI

NCB in the abducent nucleus and emerge at median plane near medulla/pons→ -pass through Cavernous Sinus and SOF of sphenoid -passes w/in tendinous ring Muscle: Lateral Rectus Muscle

Horizontal diplopia (double vision), imparied eye Abduction, eye turns medially

CC to Abducent

← straight that way | testing:

Right Lateral Rectus (VI) | Left Medial rectus (III)

→straight that way | testing:

Right Medial rectus (III) | -Left lateral recuts (VI)

Patient look Laterally first | -patient looks up =

Superior Rectus

Patient look Laterally first | -patient looks down =

Inferior Rectus

Patient Look Medially first (Goofy one) | -patient looks up=

Inferior Oblique

Patient Look Medially first (Goofy one) | -patient looks down=

Superior Oblique

Truly testing Superior Recuts muscle CN III

align axis of gaze with muscle thus have them look laterally to be in line with the long line of the super rectus muscle—thus we wipe out help from inferior oblique muscle (it can’t help when eye is in this position)

Truly testing the Inferior rectus muscle

align axis w/ muscle so that is’ lateral then you know you knock out help from Superior Oblique -then we can test the ability of the inferior rectus muscle to depress the eye

Action of Superior Oblique muscle (IV)

depression, abduction, intorsion

Truly testing Superior obliuque muscle

aling w/ long axis of muscle by having patient looking medially so that the tension of Superior oblique is aligned and now can depress up eyeball towards nose

Truly testing Inferior rectus

patient looks medially and then can they look up. If they can then we know that inferior oblique is in good condition to elevate the eye

*Ptosis Explanation: paralysis of Levator Palpebrae Sup. *A resting eye that’s ‘Down and Out’ Explanation: paralysis of Medial Rectus and Superior Rectus→ unopposed action of lateral rectus m and Superior Oblique m.

CC of CN III

Causes of CN III

* Intracranial aneurysm * trauma * inflammation (syphallis, diabetic neuopathy) * Cav.Sin thrombosis

Inability to look down(depression) and Nasally (Adduction)

CN IV injury

Cause of CN IV injury

trauma or cavernous sinus thrombis

Explanation of CC IV injury manifestations

Explanation: paralysis of Superior Oblique m. *Head tilt Explanation: (pt tilts head to shoudler opposite affected eye) Injured eye is extroted, tiliting head toward opp side of injury→intorsion of normal eye→ realignment of gaze

Impaired eye Abduction | *Tendancy for eye to turn medially

CC to CN VI

Explanation for CN VI clinical symptoms

Explanation: paralysis of Lateral Rectus m. →unopposed action of medial rectus m.

Cause of injury to CN VI

Cavernous sinus injury

Horners Syndrome

-pupil constriction (Miosis) → d/t ≠dilator pupillae→ unopposed sphincter pupillae m -ptosis (drooping eyelid) → d/t ≠superior tarsal m. -Anhydrosis (lack of sweating) →d/t loss of head and neck sweat gland innervation -Erythematosis (blushing skin) → d/t blood vessel dialation (PNS takes over)

Horners syndrome is damage to what?

SNS of ANS

CNVII (involving Greater Petrosal N)→

loss of Lacrimation (dry cornea)

CNIII | Parasympathetic fibers knocked out

-pupil dialation →d/t paralysis of sphincter pupilae w/ unopposed dialator pupillae m -Pupil fixation/loss of accomidation to light reflex →d/t paralysis of ciliar m. and sphincter pupillae m.

Symptom: -Pupil fixation/loss of accomidation to light reflex

→d/t paralysis of ciliar m. and sphincter pupillae m.

Symptom: pupil dialation

→d/t paralysis of sphincter pupilae w/ unopposed dialator pupillae m

Symptom: -pupil constriction (Miosis)

-pupil constriction (Miosis) | → d/t ≠dilator pupillae→ unopposed sphincter pupillae m

Symptom: -ptosis (drooping eyelid)

→ d/t ≠superior tarsal m.

Symptom: -Anhydrosis (lack of sweating)

→d/t loss of head and neck sweat gland innervation

Symptom-Erythematosis (blushing skin)

→ d/t blood vessel dialation (PNS takes over)