10.17.16 Orbit I Flashcards
1
Q
What three bones make up the outer rim of the orbit?
A
- Frontal bone
- Zygomatic
- Maxilla
2
Q
What four bones make up the inside of the orbit?
A
- Lacrimal bone
- Ethmoid bone
- Sphenoid bone
- Palatine bone
3
Q
The lacrimal bone has a fossa for the ___.
A
Lacrimal sac
4
Q
The superior orbital fissure lies between what two structures?
A
The lesser and greater wings of the sphenoid bone
5
Q
The inferior orbital fissure lies between what two structures?
A
Greater wing of the sphenoid and the maxilla
6
Q
The orbit is ___ in shape and has a base, four walls, and an apex.
A
Pyramidal
7
Q
What forms the base and apex of the orbit?
A
Base: orbital margin
Apex: optic canal
8
Q
What forms the four walls of the orbit?
A
Superior (roof): frontal bone, lesser wing of sphenoid
Inferior (floor): maxilla, zygomatic, palatine
Lateral: Zygomatic, sphenoid, little bit of frontal
Medial: ethmoid, lacrimal, little bit of maxillary, frontal, and sphenoid
9
Q
“Blow-out” fractures due to a sharp blow to the eye can result in what?
A
The eye falling into the maxillary sinus below the floor of the orbit
10
Q
What is the strongest wall of the orbit?
A
Lateral wall
11
Q
What are palpebrae?
A
Eyelids
12
Q
What do the palpebrae do?
A
Protect and aid in the lubrication of the eye
13
Q
What are the layers of the palpebrae?
A
- Skin
- Subcutaneous connective tissue
- Muscular layer
- Submuscular layer
- Tarsal plate
- Tarsal glands
- Palpebral conjunctiva
14
Q
What is the space between the upper and lower lids, bounded by the upper and lower palpebral margins?
A
Palpebral fissure
15
Q
The skin of the of palpebrae contain what two types of glands?
A
Sweat glands (glands of Moll) and sebaceous/ciliary glands (glands of Zinn)
16
Q
The eyelashes are contained in the layer of the skin at the anterior border of the ___ junction.
A
Mucocutaneous
17
Q
Obstruction of the ciliary glands results in a ___.
A
Stye
18
Q
What does the subcutaneous connective tissue of the palpebrae allow?
A
Free movement of the overlying skin
19
Q
What does the muscular layer of the palpebrae contain?
A
The palpebral portion of orbicularis oculi
20
Q
What does the submuscular layer contain?
A
The nerves which supply the eyelid
21
Q
What gives form to the upper and lower eyelids?
A
Tarsal plate
22
Q
What muscle attaches to the superior aspect of the tarsal plate of the upper lid?
A
Levator palpebrae superioris
23
Q
What do secretions from the tarsal glands do?
A
Prevent the eyelids from sticking together, help form a seal between the lids when they are closed
24
Q
What condition occurs when the ducts of the tarsal glands become blocked?
A
Chalazion
25
What is the mucus membrane that helps moisten the eye itself?
Palpebral conjunctiva
26
The palpebral conjunctiva is continuous with the ___, which covers the sclera of the eye.
Orbital conjunctiva
27
What is the junction of the palpebral and orbital conjunctiva?
Fornix
28
What causes Horner's syndrome?
Lesion to the superior cervical sympathetic ganglion, which paralyzes the tarsal muscle on the affected side
29
What is the clinical manifestation of Horner's syndrome?
1. Ptosis (dropping eyelid)
2. Meiosis (small pupil)
3. Anhydrosis (lack of sweating and reddening of the skin on the affected side)
30
What are the medial and lateral acute angles of the eye?
Medial canthus and lateral
31
What is the space between the upper and lower lids known as?
Palpebral fissure
32
The larger medial angle of the eye is known as the ___.
Lacrimal lake
33
What is the fleshy elevation seen in the medial angle of the eye within the lacrimal lake?
Lacrimal caruncle
34
What is the connective tissue band found lateral to the lacrimal caruncle?
Plica semilunaris
35
Where is the lacrimal gland located?
Superolateral aspect of the orbital
36
The ducts of the lacrimal gland drain into the ___.
Superior palpebral fornix
37
From where do tears flow?
Lacrimal gland
38
Where do tears drain?
Puncta lacrimali (at medial canthus of the eye)
39
What connects the lacrimal puncta with the lacrimal sac?
Lacrimal canaliculus
40
Are the motor fibers to the lacrimal gland sympathetic or parasympathetic in nature?
Parasympathetic
41
The specific branch of CN VII that contains the secretomotor parasympathetic fibers to the lacrimal gland is the ___.
Greater petrosal nerve
42
The greater petrosal nerve continues across the foramen lacerum, where it is met by the ___ nerve.
Deep petrosal nerve
43
Does the deep petrosal nerve contain sympathetic or parasympathetic fibers?
Sympathetic
44
What nerve do the greater and deep petrosal nerves form?
Nerve of the pterygoid canal
45
The nerve of the pterygoid canal runs through the ___. Then, it courses into the pterygopalatine fossa to the ___ ganglion.
Pterygoid canal; pterygopalatine
46
What synapses in the pterygopalatine ganglion?
ONLY the parasympathetic fibers of the nerve of the pterygoid
47
The postganglionic fibers of the nerve of the pterygoid canal join the ___ nerve and follow its zygomaticotemporal branch anteriorly.
Maxillary nerve (CN V2)
48
After joining CN V2, these fibers join the ___ and follow it to the lacrimal gland.
Lacrimal branch of CN V1
49
Parasympathetic stimulation of the lacrimal gland leads to ___. Sympathetic stimulation results in ___.
Increased lacrimal secretion (tearing); vasoconstriction and decreased tear production
50
What are the 7 extraocular muscles?
1. Superior oblique
2. Levator palpebrae superioris
3. Superior rectus
4. Medial rectus
5. Lateral rectus
6. Inferior rectus
7. Inferior oblique
51
From where do the recti muscles originate?
Anulus tendineus
52
What is the anulus tendineus?
Fibrous ring which encircles the junction of the superior and inferior orbital fissures and optic canal
53
What is the origin of inferior rectus?
Anulus tendineus
54
What is the origin of lateral rectus?
Anulus tendineus
55
What is the origin of medial rectus?
Anulus tendineus
56
What is the origin of superior rectus?
Anulus tendineus
57
What is the insertion of inferior rectus?
Inferior aspect of eyeball, posterior to corneoscleral junction
58
What is the insertion of lateral rectus?
Lateral aspect of eyeball, posterior to corneoscleral junction
59
What is the insertion of medial rectus?
Medial aspect of eyeball, posterior to corneoscleral junction
60
What is the insertion of superior rectus?
Superior aspect of eyeball, posterior to corneoscleral junction
61
What innervates inferior rectus?
Oculomotor nerve (CN III), inferior division
62
What innervates lateral rectus?
Abducent nerve (CN VI)
63
What innervates medial rectus?
Oculomotor nerve (CN III), inferior division
64
What innervates superior rectus?
Oculomotor nerve (CN III), superior division
65
What supplies inferior rectus?
Ophthalmic artery
66
What supplies lateral rectus?
Ophthalmic artery
67
What supplies medial rectus?
Ophthalmic artery
68
What supplies superior rectus?
Ophthalmic artery
69
What is the function of inferior rectus?
Depresses, adducts, laterally rotates eyeball
70
What is the function of lateral rectus?
Abducts eyeball
71
What is the function of medial rectus?
Adducts eyeball
72
What is the function of superior rectus?
Elevates, adducts, and medially rotates eyeball
73
What are the extraocular muscles that do not originate from the anulus tendineus?
1. Superior oblique
2. Inferior oblique
3. Levator palpebrae superioris
74
What is the origin of superior oblique?
Body of sphenoid (above optic foramen), medial to origin of superior rectus
75
What is the insertion of superior oblique?
Passes through trochlea, attaches to superior sclera between superior and lateral recti
76
What innervates superior oblique?
Trochlear nerve (CN IV)
77
What supplies superior oblique?
Ophthalmic artery
78
What is the function of superior oblique?
Abducts, depresses, and medially rotates eyeball
79
What is the origin of inferior oblique?
Anterior floor of orbit lateral to nasolacrimal canal
80
What is the insertion of inferior oblique?
Lateral sclera deep to lateral rectus
81
What innervates inferior oblique?
Oculomotor nerve (CN III), inferior division
82
What supplies inferior oblique?
Ophthalmic artery
83
What is the function of inferior oblique?
Abducts, elevates, and laterally rotates eyeball
84
What is the origin of levator palpebrae superioris?
Lesser wing of sphenoid, anterior to optic canal
85
What is the insertion of levator palpebrae superioris?
Superior tarsal plate
86
What innervates levator palpebrae superioris?
Oculomotor nerve (CN III), superior division
87
What supplies levator palpebrae superioris?
Ophthalmic artery
88
What is the function of levator palpebrae superioris?
Raises upper eyelid
89
Which of the 6 eye muscles elevates the eye?
Superior rectus and inferior oblique
90
Which of the 6 eye muscles depresses the eye?
Inferior rectus and superior oblique
91
Which of the 6 eye muscles adducts the eye?
Superior rectus, inferior rectus, medial rectus
92
Which of the 6 eye muscles abducts the eye?
Superior oblique, inferior oblique, lateral rectus
93
Which of the 6 eye muscles rotates the eye medially?
Superior rectus and superior oblique
94
Which of the 6 eye muscles rotates the eye laterally?
Inferior rectus and inferior oblique
95
What three nerves innervate the extraocular muscles?
1. Oculomotor nerve (CN III)
2. Trochlear nerve (CN IV)
3. Abudcent nerve (CN VI)
96
Through what foramen or fissure do the nerves that innervate the extraocular muscles enter?
Superior orbital fissure
97
What nerves innervate which extraocular muscles?
1. Lateral rectus - CN VI
2. Superior oblique - CN IV
3. All others - CN III
LR6, SO4, AO3
98
The optic nerve (CN II) enters the orbit via the ___ canal with the ___ artery.
Optic; ophthalmic
99
What does the optic nerve do in the eye?
Conveys sensory information (vision) from the retina to the CNS
100
What is the largest nerve in the orbit?
Optic nerve (CN II)
101
What supplies sensory innervation to the orbit and external eye?
Ophthalmic division of the trigeminal nerve (V1)
102
The ophthalmic division of the trigeminal nerve (CN V1 enters the orbit through the ___.
Superior orbital fissure
103
What are the three primary branches of the ophthalmic nerve (CN V1)?
1. Lacrimal nerve
2. Frontal nerve
3. Nasociliary nerve
104
What does the lacrimal nerve do?
Provides sensory innervation to the lacrimal gland and the lateral aspect of the eye and upper and lower palpebrae
105
The postganglionic parasympathetics that run to the lacrimal gland join the ___ nerve after running with the zygomaticotemporal branch of CN V2.
Lacrimal
106
What nerve runs on top of levator palpebrae superioris?
Frontal nerve
107
What are the 2 divisions of the frontal nerve?
1. Supratrochlear nerve
| 2. Supraorbital nerve
108
Which division of the frontal nerve is more medial? More lateral?
Medial: supratrochlear
Lateral: supraorbital
109
What does the supratrochlear nerve do?
Supplies sensory innervation to the skin above the medial canthus and a portion of the scalp
110
What does the supraorbital nerve do?
Supplies the superior palpebra and the scalp above
111
The ___ nerve is the direct continuation of the frontal nerve and exits the orbit via the ___.
Supraorbital; supraorbital foramen (notch)
112
What are the 5 branches of the nasociliary nerve?
1. Communicating branch to the ciliary ganglion/short ciliary nerve
2. Long ciliary nerves
3. Posterior ethmoidal nerve
4. Anterior ethmoidal nerve
5. Infratrochlear nerve
113
What does the communicating branch to the ciliary ganglion do?
Contributes sensory fibers to the inferior portion of the ey
114
Does the communicating branch of the ciliary ganglion synapse in the ganglion?
No
115
How does the communicating branch to the ciliary ganglion reach the eye?
Running through the short ciliary nerves
116
What do the long ciliary nerves do?
Provide sensory innervation to the eye
117
What does the posterior ethmoidal nerve do?
Runs to the posterior and middle ethmoidal air cells on the medial wall of the orbit
118
What does the anterior ethmoidal nerve do?
Runs to the middle and anterior ethmoidal air cells
119
What does the anterior ethmoidal nerve end as?
External nasal nerve
120
What does the infratrochlear nerve do?
Supplies the medial canthus, lower eyelid, and surrounding region of the orbit
121
What are the only fibers which synapse in the ciliary ganglion?
Parasympathetic fibers from the oculomotor nerve (CN III)
122
What connects the ciliary ganglion to the posterior aspect of the eye?
Short ciliary nerves
123
Where is the ciliary ganglion located?
Between the optic nerve and the lateral rectus muscle
124
What do the parasympathetic fibers of the eye do?
Cause constriction of the pupil (sphincter pupillae muscle) and allow the eye to focus on near objects (contraction of the ciliary muscle)
125
What is the path of the parasympathetic fibers to the eye?
Parasympathetic fibers of the oculomotor nerve (CN III) travel to the inferior division of CN III (specifically the branch to the inferior oblique muscles). They then run to the ciliary ganglion where they synapse. The postganglionics then course to the eye through the short ciliary nerves.
126
Contraction of the ciliary muscle changes the shape of the ___.
Lens
127
Contraction of the sphincter pupillae muscle constricts the ___.
Pupil
128
What is accommodation and what does it allow?
Combination of constriction of the pupil, changing the shape of the lens, and ocular convergence; allows one to focus on a near object after looking at a distant one
129
What is the path of sympathetic fibers to the eye?
Postganglionic sympathetic fibers originate in the superior cervical ganglion. They participate in the internal carotid plexus and then "hitch a ride" with the ophthalmic division of trigeminal (CN V1). These fibers pass through the ciliary ganglion (WITHOUT synapsing) and enter the eye via the short ciliary nerves. The fibers also reach the eye via long ciliary nerves.
130
What do the sympathetic fibers to the eye innervate?
Dilator pupillae muscle
131
What does the dilator pupillae muscle do?
Widens (enlarges) the pupil
132
The long ciliary nerves provide both ___ and ___ innervation to the eye.
Sensory; sympathetic
133
How does the ophthalmic artery enter the orbit?
Optic canal
134
What are the branches of the ophthalmic artery?
1. Meningeal
2. Lacrimal
3. Central retinal
4. Long and short ciliary (choroidal)
5. Supraorbital
6. Anterior ethmoidal
7. Posterior ethmoidal
8. Supratrochlear
9. Medial and lateral palpebral
10. Dorsal nasal
135
What do the meningeal branches of the ophthalmic artery supply
Anterior meninges
136
What does the lacrimal artery supply?
Lacrimal gland
137
What does the central retinal artery supply?
Internal retina
138
What do the long and short ciliary arteries supply?
Choroid layer of the eye
139
What does the supraorbital artery supply?
Forehead
140
What do the anterior and posterior ethmoidal arteries supply?
Paranasal sinus
141
What does the supratrochlear artery supply?
Superiomedial forehead
142
What do the medial and lateral palpebral arteries supply?
Eyelids
143
What does the dorsal nasal artery supply?
Bridge of nose
144
Venous drainage o the orbit occurs through which veins?
Superior and inferior ophthalmic veins
145
The superior and inferior ophthalmic veins pass through the ___ fissure and enter the ___.
Superior orbital; cavernous sinus
146
The eye itself is drained by the ___.
Central vein of the retina
