The Orbit Flashcards by Adam Purviance

What is the roof, medial wall, lateral wall, and floor of the orbit?

roof: frontal bone, lesser wing of sphenoid
medial wall: ethmoid, lacrimal, maxilla
lateral wall: zygomatic, greater wing of sphenoid
floor: mxilla, zygomatic, palatine

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The lacrimal groove is an important landmark in the orbit. What is it between and what does it hold?

between the lacrimal and maxillary bones; lacrimal sac

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The optic canal is an important landmark in the orbit. Where at in the orbit is it located and what does it transmit?

at the apex, in the lesser wing of sphenoid; transmits optic nerve and ophthalmic artery

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In regards to the composition of the eyelids, a thin palpebral part of the ___ ___ lies anterior to the tarsi and is separated from the skin by a thin layer of loose CT

orbicularis occuli

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In regards to the composition of the eyelids, a “skeleton” of the eyelids is formed by dense CT plates known as the superior and inferior ___ for the upper and lower lids respectively

tarsus

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In regards to the composition of the eyelids, the ___ glands are embedded in the tarsi, with openings in the margins of the eyelids.

tarsal

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What do the tarsal glands secrete?

an oily substance that prevents overflow of tears in normal production

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In regards to the composition of the eyelids, the ___ ___ ligament connects the tarsi to the medial margin of the orbit and is the origin for the orbicularis occuli. The ____ ____ ligament connects the tarsi to the lateral margin of the orbit

medial palpebral; lateral palpebral

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In regards to the composition of the eyelids, an orbital ____ is continuous with the periosteum and at the level of the orbital margin, extends into the eyelids and fuses with the tarsi

septum

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In regards to the composition of the eyelids, the aponeurosis of the ___ ____ ____ attaches to the superior tarsus. Smooth muscle fibers froming the ___ ___ muscle also inserts here. These muscles elevate the eyelid.

levator palpebrae superioris; superior tarsal

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The ____ lines the inner surface of the eyelids

conjunctiva

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Sebaceous and sweat glands present in the eyelids have openings by the ____

eyelashes

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Eyelashes are arranged in 2-3 rows at the free margin of the eyelid from the ___ ____ to the level of the ____ ____. Just medial to this site in the lid margin is the lacrimal ____

lateral canthus; plica semilunaris; papilla

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What is the basic structure of the eyelids?

skin, SC tissue, striated muscle, tarsus and orbital septum, smooth muscle, and conjunctiva

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The lacrimal gland is situated in the ____ part of the ____ part of the orbit

anterior; superolateral

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There are numerous ducts that drain the lacrimal gland, opening into the lateral part of the ____ ____

superior fornix

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The tear collects ____ in the lacrimal lake. The lacrimal lake contains an elevated mucosal site called the lacrimal ____ and a vertical fold of conjunctiva, the semilunar fold

medially; caruncle

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Tears then flow into the lacrimal ___ of the upper and lower eyelids via their openings, the lacrimal ___.

canaliculi; puncta

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The lacrimal puncta are on the elevations known as lacrimal ____, located just medial to the eyelashes

papillae

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The lacrimal canaliculi empty into the lacrimal ____ located in the lacrimal groove adjacent to the nose

sac

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The lacrimal sac continues inferiorly as the _____ duct that empties into the nasal cavity, guarded by a valve

nasolacrimal

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The lacrimal gland receives sensory from the ____ nerve, a branch of the ophthalmic nerve (V1)

lacrimal

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The lacrimal gland receives parasympathetic innervation by preganglionic fibers from the ____ nerve synapsing the ____ ganglion.

facial (greater petrosal nerve); pterygopalatine

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Postganglionic axons travel ____ then ___ to reach the lacrimal gland

V2; V1

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Sympathetic innervation of the lacrimal gland is via postganglionic axons from the ___ ____ ganglion -> deep petrosal nerve + great petrosal nerve = the nerve of the ___ ___ and reach the pterygopalatine ganglion in the pterygopalatine fossa

superior cervical; pterygoid canal

The outer, white, fibrous layer of the globe of the eyeball is the ____.

sclera

The ___ of the eyeball is avascular and is highly sensitive to touch, while the ___ is the site of attachment to extrinsic muscles and is pierced by vessels and nerve

cornea; sclera

The middle, vascular layer of the eyeball (urea) has 3 parts. What are they?

the choroid, ciliary body, and iris

This is the largest part of the vascular layer of the eyeball. It provides the inner retinal layer with an oxygen supply and nutrients

choroid

This is the anterior continuation of the choroid, forming a ring-like thickening that contains muscles as we'll as vessels, and connects to the iris.

ciliary body

Folds of tissue project from the inner surface of the ciliary body forming ciliary processes that are attachment sites for the ___ via ___ fibers that form the suspensory ligament of the lens, and also secrete aqueous humor

lens; zonular

The ___ projects from the ciliary body as a circular aperture that lies on the anterior surface of the lens. It is the site for color of the eyes and contains muscle fibers that can either increase or decrease the pupil.

iris

Muscle fibers arranged in a circular pattern in the iris form the ___ ____ and are innervated by parasympathetic fibers. Muscle fibers arranged radially form the ____ ___ which is innervated by sympathetic fibers

sphincter pupillae; dilator pupillae

The inner layer of the eyeball is the ___ which consists of a large posterolateral optic part and a smaller anterior non-visual part. The two parts are continuous as a jagged line, the ora serrata.

retina

This part of the retina is sensitive to light and has two layers: an outer pigmented layer attached to the choroid and an inner neural layer attached to the pigmented layer only at the optic nerve and ora serrata

optic part

What occurs in the condition known as detached retina?

the inner neural layer separates from the pigment layer

The posterior part of the optic part of the retina contains the ___ ___ where the optic nerve leaves which is also the site of the branching of the ___ artery of the retina

optic disc; central

The highest visual sensitivity of the retina is at the ___ ___ with the ___ ___, located lateral to the disc

macula lutea; fovea centralis

The non-visual part of the retina covers what?

the inner surface of the ciliary body and iris

This is the space between the cornea and iris, and is filled with aqueous humor

anterior chamber

This is the space between the posterior surface of the iris and the anterior surface of the lens and also contains aqueous humor

posterior chamber

Aqueous humor is produced in the ____ chamber by the ___ ___

posterior; ciliary processes

After starting in the posterior chamber, where does aqueous humor flow?

through the pupil into the anterior chamber where it is taken up by the scleral venous sinus at the iridiocoroneal angle

Reduced uptake of aqueous humor leads to increased intraocular pressure. This condition is known as what?

glaucoma

The vetoer body (humor) is permanent and is traversed by the ____ canal, the remnant of an embryonic blood vessel that nourished the lens

hyaloids

The ___ is a transparent biconvex structure that is highly elastic

lens

Opacity of the lens is referred to as a ____

cataract

The fascial sheath of the eyeball forms a socket for the eyeball, separating it from ___ and attaching it to the ___

fat; sclera

Medial and lateral expansions of the sheath of the eyeball form medial and lateral ___ ligaments that limit abduction and adduction of the eyeball.

check

The blending of the check ligaments inferiorly with muscle coverings forms the ___ ligament of the eyeball

suspensory

The apex of the orbit points ____

posteriorly

The medial walls of the orbits are ___, lateral walls are at approximately ____ degrees

parallel; 90

____ muscles are involved with movements of the eyeball. ____ muscles control the shape of the lens and size of the pupil

extrinsic; intrinsic

What is the action, origin, insertion, and innervation of orbicular occuli?

action: palpebral portion closes eyelids gently (sleep and blinking) origin: medial palpebral ligament insertion: superior and inferior tarsus innervation: facial nerve

What is the action, origin, insertion, and innervation of levator palpebrae superioris?

action: raises upper eyelid origin: lesser wing of sphenoid insertion: superior tarsus, and skin of the upper eyelid innervation: occulomotor nerve and inferior lamella

What is the innervation of the superior tarsal muscle (smooth muscle)?

superior cervical ganglion (sympathetic)

What is the action and innervation of superior rectus?

action: elevates, adducts, intort eyeball innervation: occulomotor (sup. branch)

What is the action and innervation of inferior rectus?

action: depresses, adducts, extorts eyeball innervation: occulomotor (inf. branch)

What is the action and innervation of medial rectus?

action: adduction of eyeball innervation: occulomotor (inf. branch)

What is the action and innervation of lateral rectus?

action: abducts eyeball innervation: abducens nerve

The superior oblique arises from the sphenoid and reaches the ____

trochlea (attached to frontal bone)

What is the action and innervation of superior oblique?

action: intorsion, depress, and abduct eyeball innervation: trochlear nerve note: SOLID = Supeior Oblique Lateral movement (abduction) Intorsion Depression

The inferior oblique is the only extrinsic eye muscle that does not arise from the ___ part of the orbit.

posterior note: its origin is from the medial side of the floor of the orbit, the orbital surface of the maxilla just lateral to the nasolacrimal groove. It inserts just inferior to the lateral rectus

What is the action and insertion of the inferior oblique?

action: extorsion, elevates, abducts eyeball inervaiton: occulomotor (inf. branch)

For each of the following nerves, give the movements or actions that indicate a clinical issue occulomotor trochlear abducens

occulomotor: down and out, ptosis, pupil dilation trochlear: down and in abducens: inability to abduct the eye

The ophthalmic artery is a branch of the ___ that enters the orbit though the optic canal.

ICA

This branch of the ophthalmic artery travels with the optic nerve to the retina

central artery of the retina

This branch of the ophthalmic artery supplies the lacrimal gland, lateral sides of the eyelids, and zygomatic branches

lacrimal

This branch of the ophthalmic artery travels through the supraorbital notch to the forehead and scalp to vertex

supraorbital

This branch of the ophthalmic artery supplies ethmoidal air cells and superior nasal cavity

posterior ethmoidal

This branch of the ophthalmic artery gives off anterior meningeal; then supplies nasal cavity including nasal septum and lateral wall. It ends as the lateral nasal artery.

anterior ethmoidal

This branch of the ophthalmic artery supplies the forehead and is one of two terminal branches

supratrochlear

This branch of the ophthalmic artery supplies the upper surface of the nose and is one of the two terminal branches

dorsal nasal

This branch of the ophthalmic artery becomes the anterior ciliary artery

muscular to intrinsic muscles

This branch of the ophthalmic artery supplies the medial area of the upper and lower eyelid including the nasolacrimal duct

medial palpebral

The superior and inferior ophthalmic veins drain into the ___ sinus

cavernous

The superior ophthalmic vein communicates with ____ and ___ veins (triangle of danger)

supraorbital; angular

The inferior ophthalmic vein communicates with the ____ plexus of veins, ____ ___ vein and the ___ sinus

pterygoid; superior ophthalmic; cavernous

The bulb of the eyeball is drained by 4 ___ veins which empty into the ophthalmic veins

vorticose

An increase in CSF pressure surrounding the optic nerve will cause what?

bulging of the optic disc

This nerve is the smallest of the cranial nerves but has the greatest intracranial length.

trochlear

The nucleus of the trochlear nerve is found where?

caudal midbrain

The trochlear nerve exits the dorsal surface of the brainstem and winds anteriorly to enter the lateral wall of the ____ sinus

cavernous

Injury of the trochlear nerve causes weakness of ____ eye movement and ___

downward (vertical diplopia); torsion (response to tilting head sideways)

The abducens nerve nucleus is located in the ___ on the floor of the ___ ventricle

pons; 4th

Aneurysms of the ICA can damage what nerve?

abducens

Abducens nerve dysfunction induces ____, a convergent squint on a distant object

esotorpia note: patient may turn face towards side of the affected eye

The oculomotor nerve originates form the oculomotor nucleus at the level of the midbrain and form the _____-___ nucleus.

Edinger-Westphal

The oculomotor nerve carries what two types of fibers?

somatic motor and visceromotor

A branch to the ciliary ganglion carries preganglionic ____ fibers from Edinger-Westphal nucleus to the ciliary ganglion.

parasympathetic

The ciliary ganglion is located between the ____ nerve and the ____ ___ muscle

optic; lateral rectus

Horner's syndrome is damage to the superior cervical ganglion causing a triad of problems. Name them.

ptosis - drooping of eyelid miosis - consrticted pupil anhydrosis - loss of hemifacial sweating