06c: Orbit Flashcards
Eyelids are composed of (X), which are sandwiched by (Y) anteriorly and (Z) posteriorly.
X = small tarsal plates Y = skin and muscle (orbicularis oculi) Z = conjunctiva
Tarsal glands are located in/on (X) and function to (Y).
X = in tarsal plate Y = produce fluid that prevents eyelids from sticking together
Black eye develops as result of:
Extravasated/accumulated blood into subcutaneous tissue and skin of eyelids
T/F: Tears are continuously produced by lacrimal glands.
True
Blinking wipes tears in which direction? List the progressive structures into which they drain.
Lateral to medial;
- Superior and inferior lacrimal puncta
- Superior and inferior lacrimal canaliculi
- Lacrimal sac
- Nasolacrimal duct
- Inferior nasal meatus
What’s the explanation for blinking causing increased tear production?
Lacrimal gland divided into orbital/palpebral parts by levator palpebrae superioris tendon; blinking “milks” tears from gland
Parasympathetics to lacrimal gland via (X) have which effects?
X = CN 7
Secretomotor to gland and vasodilation
Sympathetics to lacrimal gland via (X) have which effects?
X = sympathetic trunk
Vasoconstriction
List pathway of pre-ganglionic parasympathetic fibers to lacrimal gland prior to synapse on (X).
X = pterygopalatine ganglion
- CN 7 (Greater petrosal)
- Nerve to pterygoid canal
List pathway of post-ganglionic parasympathetic fibers to lacrimal gland following synapse on (X).
X = pterygopalatine ganglion
- Zygomatic nerve
- Zygomaticotemporal nerve
- Lacrimal nerve
(Pre/post)-ganglionic sympathetics for CN 7 enter skull via (X) and become (Y).
Post;
X = internal carotid plexus
Y = deep petrosal nerve
Deep petrosal nerve carries (X) and joins (Y) on its path, just prior to (Z).
X = sympathetics to lacrimal gland Y = greater petrosal nerve Z = synapse on pterygopalatine ganglion
T/F: Nerve of pterygoid canal carries sympathetics to lacrimal gland.
True - both parasympathetic (greater petrosal) and sympathetic (deep petrosal)
Tears spilling over inferior eyelid is indicative of (X) nerve damage. Explain.
X = CN 7
Orbicularis oculi loss of function; abnormal blinking results in excessive lacrimation and abnormal tear drainage.
List the muscles involved in moving eyelid. Include the nerve(s) innervating each.
- Orbicularis oculi (CN VII)
- Levator palpebrae superioris (CN III)
- Superior tarsal muscle (sympathetics)
Damage to CN 3 causes ptosis, aka (Y), due to loss of innervation of (Z).
Y = drooping eyelid Z = levator palpebrae superioris
Action of superior tarsal muscle.
Elevates eyelid during sympathetic response (ex: fear)
Which nerves involved in afferent and efferent pathways for corneal (blink) reflex?
Afferent: CN V (V1) to cornea via short/long ciliary nn
Efferent: CN VII to orbicularis oculi
What’s the periorbita?
Periosteum of orbit (lining inner surface)
List the bones that make up the orbit.
- Frontal
- Sphenoid
- Ethmoid
- Maxilla
- Zygomatic
- Lacrimal
- Palatine
T/F: Temporal bone contributes to orbit.
False
T/F: Palatine bone contributes to orbit.
True
T/F: Nasal bone contributes to orbit.
False
Infraorbital groove is in close proximity with (X) (fissure/foramen). It’s a landmark on which bone?
X = inferior orbital fissure
Maxilla
Orbital margin is strong, so a “blowout fracture” may typically impact (X) wall of orbit instead. Which spaces affected?
X = medial/inferior
Medial: ethmoidal/sphenoid sinuses
Inferior: maxillary sinus
Many structures traveling between interior skull and orbit pass through (X). List the nerves that pass through.
X = cavernous sinus
CN 3, 4, 5 (V1, V2), 6
(Axes of orbits/optical axes) diverge at (X) degrees.
Axes of orbits;
X = 45
Direction/line of sight is represented by (X) axes, which are parallel to each other.
X = optical
Base of orbit is (anterior/posterior) and apex is (anterior/posterior).
Anterior; Posterior
(X) of orbit is site of entry for neurovascular structures.
X = apex
Most muscles attach (anteriorly/posteriorly) at (base/apex) of orbit.
Posteriorly; apex
List the extra-ocular muscles. Star those with nerve supply that differs from the typical (X) nerve.
X = CN III
- Lev. palpebrae superioris
- Lateral rectus* (CN 6)
- Medial rectus
- Superior rectus
- Inferior rectus
- Superior oblique* (CN 4)
- Inferior oblique
The (X) acts as a pulley for which extra-ocular muscle?
X = trochlea
Superior oblique
(X) is common tendinous ring in (base/apex) of eye to which (Y) muscles attach.
X = annulus of Zinn
Apex;
Y = the 4 recti muscles
Which extra-ocular muscles contribute to intorsion of eye?
Superior rectus and superior oblique
Superior oblique originates toward (lateral/medial) part of orbit. Inferior oblique originates toward (lateral/medial) part of orbit.
Both medial
T/F: Both extra-ocular oblique muscles insert on posterior part of sclera.
True
Which extra-ocular muscles contribute to extorsion of eye?
Inferior rectus and inferior oblique
Eyeball in neutral position. Which muscle(s) responsible for elevation of eyeball?
Superior rectus and inferior oblique
Eyeball is abducted. Which muscle(s) responsible for elevation of eyeball?
Superior rectus
Eyeball is adducted. Which muscle(s) responsible for elevation of eyeball?
Inferior oblique
List the actions of eye that are controlled by autonomic NS. Specify if it’s parasympathetic/sympathetic.
- Focusing/accommodation (parasympathetic)
- Constriction (para) and dilation (symp)
- Involuntary eyelid elevation (symp)
Focusing/accommodation of eye involves innervation from (X) to (smooth/skeletal) muscle within (Y).
X = CN III
Smooth;
Y = ciliary body
In focusing/accommodation of eye, the shape of (X) is changing.
X = lens
Constriction of pupil involves (para/symp) innervation to (X) muscle.
Parasympathetic;
X = constrictor (sphincter) pupillae
Dilation of pupil involves (para/symp) innervation to (X) muscle.
Sympathetic;
X = dilator pupillae
T/F: Sympathetic fibers travel through long ciliary nerve, but not short ciliary nerve.
False - but mostly through long ciliary
Sphincter pupillae innervated by:
CN III
Formal term for max constriction.
Miosis
Formal term for max dilation.
Mydriasis
Morphine can cause (miosis/mydriasis).
Miosis
Migraine can cause (miosis/mydriasis).
Mydriasis
Neurovascular structures that pass through superior orbital fissure.
- CN 3, 4, 5 (V1), 6
2. Superior opthalmic vein
Neurovascular structures that pass through supraorbital foramen.
Supraorbital artery and nerve (V1)
Neurovascular structures that pass through supratrochlear foramen.
Supratrochlear artery and nerve (V1)
Neurovascular structures that pass through anterior and posterior ethmoidal foramina.
Anterior and posterior ethmoidal arteries, veins, and nerves (V1)
Neurovascular structures that pass through nasolacrimal canal.
Nasolacrimal duct
Neurovascular structures that pass through infraorbital canal.
- Zygomatic and infraorbital nerves (V2)
- Infraorbital artery and vein
- Inferior opthalmic vein
Neurovascular structures that pass through inferior orbital fissure.
Infraorbital artery, vein, and nerve (V2)
Which bones make up superior wall of orbit?
Frontal (primarily)
Superior wall of orbit is also the floor of:
Anterior cranial fossa
Which bones make up medial wall of orbit?
Ethmoid and lacrimal bones
The paper-thin lamina papyracea separates which spaces?
Orbit and ethmoid air cells
Which bones make up lateral wall of orbit?
Zygomatic and greater wing of sphenoid
Which bones make up floor of orbit?
Maxilla (and small portion from palatine)
Branches of ophthalmic artery correspond to branches of (X) nerve.
X = ophthalmic (V1)
Ethmoidal, supraorbital, suprateochlear, lacrimal
Anastomoses between (X) veins may result in spread of infection from eye/nose to cavernous sinus.
X = angular (to facial vein) and ophthalmic veins (to cavernous sinus)
List structures passing through optic canal.
- Sympathetics
- Optic nerve
- Ophthalmic artery
- Central artery of retina (within nerve)
