1
Q
What covers the Iris?
A
• The transparent cornea.
2
Q
What is at the junction of the cornea and the white sclera?
A
• The corneo-scleral junction, otherwise known as the limbus.
3
Q
What is the bulbar conjunctiva?
A
- The conjunctiva lines the inside of the eyelids and covers the sclera (white part of the eye).
- It is a loop of epithelium that seals the space between the eyelid and the sclera that helps to prevent the entrance of microbes into the eye. (see photo later in ppt)
- The conjunctiva helps lubricate the eye by producing mucus and tears, although a smaller volume of tears than the lacrimal gland.
- It is composed of non-keratinized, stratified squamous epithelium.
4
Q
What happens when the conjuntiva becomes irritated?
A
- The conjunctiva is usually transparent
* it contains some tiny blood vessels that can become enlarged if the conjunctiva is irritated.
5
Q
What is the palebral conjunctiva?
A
• The conjunctiva continues onto the posterior side of the eyelids as the palpebral conjunctiva.
6
Q
What are the medial and lateral canthus?
A
• There is a medial and lateral canthus where the upper and lower eyelids meet.
7
Q
What are the lacrimal caruncle, papilla, and puncta?
A
• At the medial canthus there is a lacrimal caruncle along with lacrimal papilla and puncta that are the sites of drainage of tears.
8
Q
Describe the shape and angle of the orbit.
A
- anterolateral to the orientation of the head from inside out.
- The apex of the orbit is at the posteriomedial aspect of the orbit.
- The medial walls of the orbit are essentially parallel to the sagittal plane.
- The axis of the eyes is different than the axis of the orbit which has implications for muscle movements of the eyes (discussed later)
9
Q
What lines the media wall of the orbit?
A
• Ethmoid, Lacrimal, and Maxillary
10
Q
What lines the roof of the orbit?
A
• Frontal Bone
11
Q
What lines the floor of the orbit?
A
Maxillary
12
Q
What lines the lateral wall of the orbit?
A
• portions of the zygomatic bone anteriorly and the greater wing of the sphenoid posteriorly.
13
Q
What lines the apex of the orbit?
A
• the greater wing of the sphenoid, laterally and the lesser wing of the sphenoid, medially
14
Q
Where are the superior orbital fissure, optic canal, and the inferior orbital fissure within the orbit? See Netter 4
A
- The superior orbial fissure separates the greater and lesser wing between the lateral wall and the apex.
- The optic canal is in the lesser wing of the sphenoid at the back of the apex
- The inferior orbital fissure is an opening between the maxillary bone and the greater wing of the sphenoid
15
Q
All together: See netter 4 What lines the media wall of the orbit? What lines the roof of the orbit? What lines the floor of the orbit? What lines the lateral wall of the orbit? What lines the apex of the orbit?
A
- The media wall contains the Ethmoid, Lacrimal, and Maxillary
- The roof contains the Frontal Bone
- The Floor contains the Maxillary
- The lateral wall contains the portions of the zygomatic bone anteriorly and the greater wing of the sphenoid posteriorly.
- The apex contains the the greater wing of the sphenoid, Laterally and the lesser wing of the sphenoid, medially
16
Q
What is the periorbita?
A
- a loose periosteum that surrounds the orbit
* All of the contents of the orbit are contained within it
17
Q
Within the orbit the… See Netter 4
Optic canal is Where?
Superior orbital fissure is Where and open to what?
Anterior and posterior ethmoid canal is Where and open to what?
Inferior orbital fissure is Where and open to what?
Zygomatic foramen is Where and open to what?
Lacrimal canal is Where and open to what?
A
- Optic canal is in the lesser wing of sphenoid at the back of the apex
- Superior orbital fissure is between greater and lesser wing of sphenoid and open to middle cranial fossa
- Anterior and posterior ethmoid canal is between frontal & ethmoid and open to upper nasal cavity
- Inferior orbital fissure is between maxillary, sphenoid and zygomatic bone and open to pterygopalatine fossa
- Zygomatic foramen is in the Zygomatic bone and open onto face
- Lacrimal canal is between lacrimal and maxillary bone and open into inferior meatus of nose
18
Q
What nerve and artery pass through the optic canal?
A
- The optic nerve and ophthalmic artery
- Note: In the apex, there is a tendinous ring that gives rise to muscles that control eye movements. This ring surrounds the optic canal with the optic nerve and ophthalmic artery.
19
Q
hat nerves and vein pass through the supraorbital fissure? See Thieme 484
A
• extraocular nerves • trochlear nerve • oculomotor nerve • abducens nerve • Ophthalmic division of the trigeminal nerve, V1, actually enters as several small branches: the lacrimal, frontal and nasociliary nerves. Ophthalmic veins (superior vein)
20
Q
As the ophthalmic division of the trigeminal nerve passes through the the supraorbital fissure it enters as three small branches. What are they?
A
• the lacrimal, frontal and nasociliary nerves
21
Q
What is the route of the V2 Zygomatic branch through the orbit and to the face?
A
• The inferior orbital fissure transmits the zygomatic branch of V2, which ascends from the pterygopalatine fossa into the orbit. In the lateral wall of the orbit, quite close to the inferior orbital fissure, there’s a small zygomatic foramen that allows the zygomatic nerve to pass through the zygomatic bone to innervate skin of the cheek.
22
Q
What is the route of the anterior and posterior ethmoid nerves and arteries?
A
• The anterior and posterior ethmoid nerves and arteries pass through the anterior and posterior ethmoid canals in the orbit and then into the ethmoid sinuses and nasal cavity.
23
Q
What is the route of the nasolacrimal duct?
A
• anteriorly there is a lacrimal canal that permits passage of the nasolacrimal duct and extends down into the inferior part of the nasal cavity
24
Q
What is the annulus tendinious?
A
• most of the extraocular muscles arise from a common tendon, the annulus tendinious.
25
Where does the levator palpebrea attach?
• The levator palpebrae muscle is most superior and attaches to the tarsal plate of the upper eyelid.
26
Where does the superior rectus muscle attach?
• attaches into the sclera of the upper eyeball
27
What is the course of the superior oblique? What is the movement that it causes?
• Extends from the annulus tendineous to loop around a connective tissue sling called the trochlea.
* Extends from the annulus tendineous to loop around a connective tissue sling called the trochlea.
* depresses, abducts, and intorts
28
Where does the inferior oblique muscle attach? What are its actions?
* This is the one extraocular muscle that doesn't arise from the apex of the orbit.
* The anterior floor of the orbit and runs posteriorward to attach to the inferior side of the eyeball.
* Elevates, adducts, and extorts
29
What is the action of the superior oblique?
| What is the action of the inferior oblique?
* Superior oblique depresses, abducts, and intorts
* Inferior oblique elevates, adducts, and extorts
• Note: the superior rectus and inferior rectus cancel each other’s intortion/extortion adduction/abduction, so that they can function together in depression or elevation.
30
Explain testing the 6 positions of gaze.
* an H-shaped pattern of movement
* adduction and abduction of the pupil are each a function of a single muscle, the medial and lateral rectus muscles, respectively.
* Elevation and depression of the adducted eye are functions of the inferior and superior oblique muscles, respectively.
* Elevation and depression of the abducted eye are the functions of the superior and inferior rectus muscles, respectively.
* Note: one eye will be abducted, the other eye will be adducted
31
Elevation and depression of the adducted eye are functions of the What muscles?
Elevation and depression of the abducted eye are the functions of the What muscles?
* inferior and superior oblique muscles, respectively.
* superior and inferior rectus muscles, respectively.
* (obliques do the opposite when adducted ie inferior elevates, superior depresses)
32
What is ptosis?
• Severe drooping of the eye caused by weakness of the levator palpebrae muscle
33
What is the Superior Tarsal Muscle? Is it innervated by para or sympathetic nerves? What happens when the said nerves are damaged?
* a small, tonicaly active smooth muscle that attaches from the levator palpebrae into the tarsal plate.
* sympathetic nerve fibers
* Damage to sympathetic fibers results in slight drooping (and constricted pupil)
34
Sever drooping (ptosis) is caused by what? What is slight drooping caused by?
* Severe drooping of the eye caused by weakness of the levator palpebrae muscle
* Slight drooping is caused by damage to sympathetic fibers that innervate the Superior Tarsal Muscle (question eyelid or eye?)
35
What are the extraocular nerves? Where do they enter the orbit?
* Motor nerves of the orbit
* cranial nerves 3, 4 and 6, the oculomotor, trochlear and abducens nerves.
* the superior orbital fissure.
36
What muscle does the abducens nerve innervate?
What muscle does the trochlear nerve innervate?
What muscle does the ocular motor nerve innervate?
* The lateral rectus muscle is innervated by the abducens nerve
* The superior oblique muscle is innervated by the trochlear nerve.
* All of the other muscles are innervated by the oculomotor nerve.
37
Explain this mnemonic LR6 (SO4)3
* lateral rectus innervated by the 6th cranial nerve
* the superior oblique muscle innervated by the 4th
* all the other muscles innervated by the 3rd.
38
What Cranial Nerve is the sensory nerve of the orbit? It divides into what three branches just before passing the superior orbital fissure?
* ophthalmic division of the trigeminal nerve, or V1.
* Frontal, Nasocilliary, and Lacrimal
* (Note the nasocillary has several terminal branches, and the frontal terminates into two branches)
39
Trace the course of the frontal nerve and its subsequent branches. What do they innervate?
* The frontal nerve is the most superior branch and is superior to the levator palpebrae muscle
* it divides into a large supraorbital nerve that goes onto the forehead
* and a small supratroclear nerve that innervates skin around the medial eyebrow.
40
Trace the course of the nasocilliary branch and its subsequent branches? What do they innervate? (quick version of this card is coming)
* nasocilliary branch parallels the ophthalmic artery and gives rise to a large anterior ethmoidal nerve which runs into the nasal cavity and then out onto the bridge of the nose.
* The other terminal branch is the infratrochlear nerve which supplies skin at the medial canthus of the eye.
* The long ciliary branches supply sensory innervation to the outer coverings of the eye and are important for corneal sensation
* The ciliary ganglion gives rise to short ciliary nerves that enter the eye with the optic nerve.
* These are sensory nerves but also contain autonomic nerve fibers as we will discuss in a moment.
41
Trace the course of the lacrimal nerve. What does it innervate?
• passes by the lacrimal gland, supplying some skin over the lateral part of the eyebrow.
42
The quick card for the nasocillary branches:
The Nasocilliary travels with what artery?
The Ethmoidal/External Nasal nerve innervates?
The Infratrochlear nerve innervates?
The Long Cilliary nerve innervates?
The Short Cillary nerve innervates and enters the eye with what other nerve?
* Ophthalmic
* Bridge of the nose
* Medial eye
* Cornea of eye
* Ciliary ganglion to ciliary nerves enter eye with optic nerve
43
Parasympathetic eye nerves follow what nerve into the orbit? What is their route? What is their action?
* follow the oculomotor nerve.
* branches go to the ciliary ganglion and through short ciliary nerves into the eyeball.
* constrict the pupil and also contract the ciliary muscle to focus on near objects
44
When the ciliary muscle contracts what happens to the suspensory ligaments and the lens?
* takes tension off of suspensory ligaments
| * the lens becomes more spherical adapting a closer focus
45
Trace the course of sympatheic nerve fibers to the eye.
* from the upper thoracic spinal cord through the ventral roots and white rami communicans to the sympathetic chain.
* The fibers to the eye will ascend the sympathetic chain to the superior sympathetic ganglion, where they will synapse.
* Postganglionic sympathetic fibers will follow the carotid artery to get to the orbit and eyeball.
46
What is the action of sympathetic nerves on the eye? Damage to the sympathetic nerves would do what?
* dilate the pupil and innervate the superior tarsal muscle that elevates of the upper eyelid (so you can see better)
* Damage to sympathetic causes a small pupil and slight ptosis (drooping) of the upper lid.
47
The levator palpebrae muscle attaches into the eyelid and the anterior part of the tarsal plate.
The levator palpebrae muscle attaches into the eyelid and the anterior part of the tarsal plate.
48
What are Meibomian glands?
* The tarsal plate includes dense connective tissue and meibomian glands, which secrete an oily secretion onto the edge of the eyelid and into the tears.
* This helps prevent evaporation of tears and drying of the eye.
49
What is Chalazion?
• blockage of this tear duct and swelling of the meibomian glands.
50
What is a stye (hordiolum)?
• ciliary glands attach to the eyelashes. These glands can get blocked and infected, and they produce a stye or hordiolum
51
The superior tarsal muscle attaches from the levator palpebrae to the upper part of the tarsal plate.
The superior tarsal muscle attaches from the levator palpebrae to the upper part of the tarsal plate.
52
What prevents infections on the face and anterior eyelid from extending directly into the orbit and vice versa?
* thick connective tissue extending from the edge of the orbit down into the eyelid.
* Similarly, blood and infection in the orbit does not extend onto the face without penetrating this connective tissue.
53
There is a thin layer of conjunctiva on the posterior aspect of the eyelid, the palpebral conjunctiva, which then becomes continuous with the conjunctiva over the eyeball.
There is a thin layer of conjunctiva on the posterior aspect of the eyelid, the palpebral conjunctiva, which then becomes continuous with the conjunctiva over the eyeball.
54
What are Pinguecula?
* Age-related (aka degenerative) thick connective tissue within the conjunctiva
* yellow-white deposit adjacent to the limbus
* Does not affect vision
55
What are Pterygium?
* growth of chronic vascular inflammatory tissue usually on the medial side of the eye
* Does not affect vision
56
Histologically, what is the lacrimal gland?
Where is it located?
What does it secrete?
Where does it drain to?
• compound tubuloalveolar gland with serous acini.
• in the superolateral orbit.
• serous fluid includes enzymes and water. (There are other secretions from the meibomian glands)
• multiple small ducts open into the conjunctival sac fluid distributes across the eye.
o tears drain into the lacrimal sac through the
o lacrimal puncta and canaliculi.
o They are then transported to the nose.
57
Where does the optic nerve attach to the eye? The optic nerve is an extension of the brain and is surrounded by dura matter, arachnoid and cerebrospinal fluid. Where does the dura attach?
* enters the orbit through the optic canal and attaches to the posteromedial aspect of the eyeball.
* The dura matter attaches to the sclera as the nerve enters the eyeball.
58
What is the course of the ophthalmic artery? What are its branches in the orbit?
* Follows the course of the nasocilliary nerve then gives the following branches
* 1) the central retinal artery (enters the optic nerve)
* 2) the supraorbital artery which only joins the supraorbital nerve
* 3) branches that follow most of the branches of the nasocilliary nerve.
59
During the physical exam where can the central retinal artery be seen?
• in the fundus of the eye with an ophthalmoscope.
60
Where do the superior and inferior ophthalmic veins drain? What do they communicate with? How does this relate to infection?
* through the superior orbital fissure into the cavernous sinus.
* these veins communicate with veins of the deep and superficial face structures.
* provides a route for spread of infection from the sinuses, pharynx, and face back into the orbit and even the cavernous sinus.
61
```
What are the actions of…
Medial Rectus
Lateral Rectus
Superior Rectus
Inferior Rectus
Superior Oblique
Inferior Oblique
```
```
MR: Adducts
LR: Abducts
SR: Elevates, Adducts, and Intorts
IR: Depresses, Adducts, and Extorts
SO: Depresses, Abducts, and Intorts
IO: Elevates, Abducts, and Extorts
```
62
What eye muscles ADDUCT?
MR, SR, IR
63
What eye muscles ABDUCT?
LR, SO, IO
64
What eye muscles Elevate?
SR and IO
SR: Elevates, Adducts, and Intorts
IO: Elevates, Abducts, and Extorts
65
What eye muscles Depress?
IR and SO
IR: Depresses, Adducts, and Extorts
SO: Depresses, Abducts, and Intorts
66
If the visual image is low, the pupil has drifted ___?
If the image is high, the pupil has drifted ___?
If the image is lateral, the pupil has drifted ___?
If the image is medial, the pupil has drifted ___?
If the image is intorted, the pupil has ____?
If the image is extorted, the pupil has ____?
The pupil operates like a pinhole camera.
```
image up : pupil down
image down : pupil up
image lateral : pupil medial
image medial : pupil lateral
image intorted : pupil extorted
image extorted : pupil intorted
```
67
What eye muscles intort?
| What eye muscles extort?
SR and SO
| IR and IO
68
What is the orbital septum (palpebral ligament)?
orbital septum (palpebral ligament) is a membranous sheet that acts as the anterior boundary of the orbit. It extends from the orbital rims to the eyelids. It forms the fibrous portion of the eyelids.
HAE Quiz 3
flashcards
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