Two involuntary muscles control the size of the pupil: - system - fibers - action - speed

Sphincter pupillae - parasympathetic - circular fibers - constriction - fast Dilator pupillae - sympathetic - radial fibers - dilation - slow

Anatomy - Orbit Flashcards by Tiffany Reid

What bones form the roof and floor of the orbit?

Floor

orbital process of maxilla
palatine bone

Roof
-orbital part of frontal bone

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What bones form the walls of the orbit?

Medial walls

Orbital plate of ethmoid
Frontal process of maxilla
Lacrimal
Sphenoid

Lateral walls

frontal process of zygomatic bone (ant)
greater wing of sphenoid (post)

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The apex of the orbit is at the __

Optic canal in the lesser wing of the sphenoid

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What separates the floor of the orbit from the lateral wall?

Inferior orbital fissure

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What houses the lacrimal gland?

Fossa for the lacrimal gland in the orbital part of the frontal bone

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Fissures and foramina of the orbit

Optic canal
Superior orbital fissure
Inferior orbital fissure
Infraorbital groove
Ethmoidal foramina

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The optic canal goes through ___ and allows for passage of ___

Goes through the lesser wing of the sphenoid

Allows for passage of
Optic n. (CN II)
Ophthalmic a.

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Superior orbital fissure is located ___ and allows for passage of ___

Between the greater and lesser wings of sphenoid

Allows for passage of:
CN III
IV
VI
V1
Ophthalmic v.

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Inferior orbital fissure is located ___ and allows for passage of ___

At the right angle to the superior orbital fissure
-between greater wing of sphenoid and maxilla

Allows for passage of 
CN V2 (maxillary n.)
Infraorbital vessels

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Travel of the infraorbital groove?

What does it contain?

Begins from inferior orbital fissure
Travels anteriorly 
Becomes enclosed in bone
Forms infraorbital canal
Opens below orbital rim as the infraorbital foramen

Contains infraorbital n. and vessels

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Ethmoidal foramina allows for passage of __

Anterior and posterior ethmoidal nerves and vessels

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____ humor is irreplaceable and more dense than ___

Vitreous

Aqueous

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The aqueous humor is located in the (anterior/posterior) chamber of the eye

Which is between cornea and iris

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The posterior chamber is located between ___ and ___

Iris and lens

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3 layers of the eyeball and what they contain

Fibrous
- sclera, cornea
Vascular
- choroid, ciliary body, iris
Retinal
- optic disc, macula, ocular fundus

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Tough fibrous layer covering the posterior 80% of the eyeball.

The anterior part is visible as the white of the eye

Sclera

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Transparent part of the fibrous layer located in the anterior part of the eye.

Cornea

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The cornea is more ___ than the sclera and projects ___

Convex

Anteriorly

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Blinking and tears are elicited by touching what? and innervation of what nerve?

Cornea

Ophthalmic n. (V1)

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The ____ lines most of the sclera and contains a rich capillary bed, with the smallest vessels located next to the ___, which is avascular

Choroid

Retina

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The ____ connects the choroid with the iris. It is both ___ and ___

Ciliary body
Muscular
Vascular

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The ___ is a thin contractile diaphragm with a central aperture, the ___, for transmitting ___.

Iris
Pupil
Light

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Two involuntary muscles control the size of the pupil:

system
fibers
action
speed

Sphincter pupillae

parasympathetic
circular fibers
constriction
fast

Dilator pupillae

sympathetic
radial fibers
dilation
slow

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The optic part of the retina consists of 2 layers:

Neural layer
- light sensitive
- continuation of the CN II
Pigmented layer
- attached to choroid
- helps reduce scattering of light through absorption

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During a retinal detachment, which layer of the retina becomes dislodged?

Neural layer only

Where the Optic Nerve (CN II) enters the eyeball, the retina contains the __

Optic disc

True or false: | the optic disc has photoreceptors

False

The oval-shaped area of acute vision is called the __

Macula

The posterior part of the eyeball wig its retina is called the ____. This is where light is ___

Ocular fundus | Focused

Light traveling to the retina passes through the following structures:

``` Cornea Anterior chamber Posterior chamber Lens Vitreous humor ```

The anterior chamber is filled with ___, which is produced by ___

Aqueous humor | Ciliary body

The posterior chamber is filled with __

Aqueous humor

The lens is attached to the ciliary processes by __

The suspensory ligament

Explain accommodation

- passive stretching and thinning of the lens brings far objects into focus - sphincter like contraction of ciliary muscle relaxes the lens, bringing near objects into focus (parasympathetic)

Layers of the eyelids, anterior to posterior

1. thin skin with loose CT layer 2. Skeletal muscle fibers 3. Orbital septum 4. Tarsi (dense CT, eyelid "skeleton") 5. Conjunctiva 6. Muscles of superior eyelid

Skeletal muscle fibers on the second layer of the eyelids: Action Innervation

Palpebral part of orbucularis oculi - involuntary (orbital part is voluntary) - gently close eyelid - innervates by CN VII

What is the orbital septum? | Attachments?

- Fibrous membrane - Continuous with periosteum of the orbital rim and the tarsi - in the upper eyelid it also attaches to levator palpebrae superioris tendon

The superior and inferior tarsi are made of ___. Attachments?

Dense CT Medially: Maxilla through Medial Palpebral ligament Laterally: zygomatic bone through lateral Palpebral ligament

Tarsal glands produce ___

``` Oily secretions Keep eyelids from sticking together Modified sebaceous glands Increase viscosity of tears Decrease evaporation ```

Mucous membrane that lines the eyelids internally and reflects into the sclera superiorly and inferiorly

Conjunctiva

The upper and lower pockets formed by the reflections of the conjunctiva onto the sclera are called:

Superior and inferior fornices

Muscles of superior eyelid elevation

Levator Palpebrae Superioris | Superior Tarsal Muscle

Origin, insertion, and innervation of levator Palpebrae superioris

Posterior part of Orbital roof Superior tarsus CN III

Origin, insertion, and innervation of superior tarsal muscle

Levator Palpebrae Superioris Superior Tarsus Sympathetic postganglionic fibers from the superior cervical ganglion

The lacrimal gland is located ___ in the ___ corner of the orbit

Anteriorly | Superolateral

Excretory ducts carry the lacrimal fluid to the ___ of the conjunctiva

Superior fornix

Lacrimal fluid that accumulates in the medial corner of the eye is drained via __

Superior and inferior lacrimal canaliculi

The openings of the canaliculi are the ___, located on the ___ surface of the eyelid

Puncta | Posteromedial

Innervation of the lacrimal gland

Production of fluid = parasympathetic through CN VII sympathetic fibers re vasoconstrictive

All recti muscles originate from the __ and insert on the __ part of the eyeball

Common tendinous ring around the Optic Nerve (annulus of Zinn) Anterior

Oblique muscles originate from the ___ and attach to the __ part of the eyeball

Orbital walls | Posterior

Actions and innervation of: | Lateral rectus

Abduction CN VI (abducens)

Actions and innervation of: | Medial rectus

Adduction | CN III

Actions and innervation of: | Superior rectus

Elevation Slight adduction CN III

Actions and innervation of: | Inferior rectus

Depression Slight adduction CN III

Actions and innervation of: | Superior oblique

When the eye is abducted: Abduction and intortion When the eye is adducted: Depression CN IV

Origin and insertion of superior oblique

Sphenoid | Goes to trochlea (pulley) and bends to insert on the superior and posterior eyeball

Actions and innervation of: | Inferior oblique

When the eye is abducted: Abduction and extortion When the eye is adducted: Elevation CN III

The only extraocular muscle that originates from the anterior part of the orbit (near the lacrimal fossa) is the __

Inferior oblique

The ___ is a large sensory nerve partially ensheathed with the cranial meninges

Optic N. (CN II)

The optic n. passes into the orbit via the ___ and collects sensory info from the ___. It projects to the ___ geniculate nucleus of the ___

Optic canal Retina Lateral Thalamus

The oculomotor n. (CN III) nuclei are in the ___. The nerve exits the brain between the __ and the ___. It passes into the orbit via the ____.

Midbrain Midbrain and pons Superior orbital fissure

The superior branch of CN III innervates the __ and ___

Levator Palpebrae Superioris | Superior Rectus

The inferior branch of CN III innervates the ___, ____, and ____.

Medial rectus Inferior rectus Inferior oblique

The _____ gives off a branch carrying preganglionic parasympathetic fibers to the ___ ganglion, which continue as ____ nerves to the sphincter pupillae muscle

Inferior branch of CN III ciliary Short ciliary

The nucleus of CN IV is located in the ___. CN IV enters the orbit via the ___. It innervates the __

Midbrain Superior orbital fissure Superior oblique

The nucleus of CN VI is in the ___. It enters the orbit through the ___ and innervates the ___

Pons Superior orbital fissure Lateral rectus

CN V1 is pure ___. It divides into what 3 nerves that pass through what opening into the orbit?

``` Sensory Superior orbital fissure 1. Nasociliary 2. Lacrimal 3. Frontal ```

Which branch off of V1 is typically first? What does it supply?

Nasociliary n. | Ciliary ganglion, eyeball, medial eyelids, nose, anterior cranial fossa

What structures does the lacrimal n. supply? Frontal n.?

Lacrimal: Lacrimal gland Conjunctiva Lateral part of upper eyelid ``` Frontal: Eyelids Conjunctiva Forehead Scalp ```

What artery supplies most of the orbit? It follows the ___ n. to enter the orbit through the ___

Ophthalmic Optic Optic canal

As the ophthalmic a. is passing along the lateral side of the optic n. it gives off the ___, which supplies the ___

Lacrimal a. | Lacrimal gland

Position of the ophthalmic a. relative to the optic n.

Inferolateral but | Upon entering the orbit it crosses superior and medial

Branches of the ophthalmic a.

1. Lacrimal 2. Central retinal 3. Posterior ciliary (6 short and 2 long) 4. Muscular branches (anterior ciliary) 5. Supraorbital 6. Ethmoidal 7. Supratrochlear

The floor of the orbit also receives blood supply from the ___, which passes into the orbit via the ___ and is a branch of the ___

Infraorbital a. Infraorbital foramen ECA

Venous drainage of the orbit is through the ___ and the ___, which pass through the ___ and enter the __ sinus.

Superior and inferior ophthalmic veins Superior orbital fissure Cavernous

The superior ophthalmic v. is formed by the joining of the ___ and the ___.

Supraorbital v. | Angular v.

____ veins from the vascular layer of the eyeball drain into the inferior ophthalmic v.

Vortical