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Ocular Anatomy - Exam 1 > Exam 1 - 005 Review of Orbital Nerves > Flashcards

Exam 1 - 005 Review of Orbital Nerves Flashcards

1
Q

Location of cell bodies of CN III

A 
Oculmotor nucleus (cell bodies innervating skeletal muscles)
Edinger Westphal nucleus (in midbrain, contains cell bodies of preganglionic parasympathetic neurons that innervate smooth muscles)
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2
Q

What does the superior division of CN III innervate?

A

Superior division of CN III-

  • Superior Rectus
  • Lecator Palpebrae Superioris Muscle
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3
Q

What does the inferior division of CN III innervate?

A

Inferior division of CN III

  • Medial Rectus
  • Inferior Rectus
  • Inferior Oblique
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4
Q

Damage to Right oculomotor nerve AND EW nucleus

A

+on Right Side: unresponsive, dilated pupil and no accommodation; weakness of ipsilateral SR, MR, IR, IO, no ptosis
+on Left side: weakness of contralateral SR

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5
Q

Damage to Right oculomotor nerve

A

no symptoms on left side but on right side: ptosis; unresponsive, dilated pupil and no accommodation

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6
Q

Cell body location of CN IV

A

axons emerge from neuron cell bodies in the trochlear nucleus
motor nucleus in midbrain

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7
Q

What does CN IV innervate?

A

superior oblique

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8
Q

Damage to the left trochlear NUCLEUS

A

Damage to left trochlear nucleus causes loss of function of right superior oblique muscle

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9
Q

Damage to right trochlear NERVE

A

Damage to right trochlear nerve causes loss of function of right superior oblique muscle

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10
Q

Where are the sensory neuron cell bodies of CN V located?

A

Trigeminal ganglion

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11
Q

Where are the motor neuron cell bodies of CN V located?

A

Motor Nucleus of CN V

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12
Q

What does CN V innervate?

A

Lacrimal Nerve- sensory to lacrimal nerve, innervates skin and conj of lateral ⅓ of upper eyelid and scalp

Frontal Nerve->Supraorbital Nerve (skin and conj of central part of upper eyelid, skin of forehead and scalp and frontal sinus) and ->Supratrochlear N. (conj and skin of medial ⅓ of upper lid and skin of medial part of forehead)

Nasociliary Nerve

–>Posterior ethmoidal N.

–>Anterior ethmoidal N. (skin on dorsum and tip of nose)

–>Infratrochlear N. (skin and conj of medial ⅓ of upper lid, lacrimal sac, caruncle, puncta & canaliculi)

  • ->Sensory root to ciliary ganglion (connect ciliary ganglion to nasociliary nerve)
  • ->LPCN
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13
Q

Where are the cell bodies of CN VI located?

A

axons of motor neurons in abducens nucleus (in dorsal part of lower pons)

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14
Q

What does CN VI innervate?

A

Lateral rectus

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15
Q

Damage to CN VI causes what?

A

Damage to right abducens nerve causes loss of function of right lateral rectus muscle

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16
Q

Where are the cell bodies of LPCN located?

A

branch of Nasociliary Nerve (branch of Trigeminal Nerve);

cell bodies of the sensory neurons are in the trigeminal ganglion

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17
Q

What does LPCN innervate?

A

sensory fibers from cornea, bulbar conj, iris, ciliary body

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18
Q

Where are the cell bodies of SPCN located?

A

postganglionic parasympathetic neurons’ axons exit the ciliary ganglion as SPCN and pierce back of eyeball

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19
Q

What does SPCN innervate?

A
  • sphincter pupillae muscle (pupil constriction)

- ciliary body muscle (accomodation to see near)

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20
Q

Sympathetic Innervation of Muller’s muscle and dilator pupillae muscle

A
  1. Central sympathetic neurons (cell bodies in hypothalamus; axons terminate in lateral horn gray of spinal cord levels C8, T1, T2)
  2. Preganglionic sympathetic neurons (cell bodies in lateral horn gray of spinal cord levels C8, T1, T2; axons cross lung apex and terminate in superior cervical sympathetic chain ganglion)
  3. Postganglionic sympathetic neurons ( cell bodies in superior cervical sympathetic chain ganglion; axons hitch hike on ICA and…)
    a. jump onto CN VI and then onto ophthalmic division of CN V and travel in nasociliary nerve, carried in LPCN and synapse on dilator pupillae muscle
    b. jump onto CN III and in orbit, postganglionic sympathetic fibers hitch-hike along the sup. & inf. divisions of CN III to reach Mueller’s muscles
    c. jump onto ophthalmic div CN V, onto frontal nerve and then supraorbital nerve to supply sympathetics to sweat glands on forehead above orbit
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21
Q

What muscles are innervated by the lateral subnuclei of CN III

A

◾ipsilateral inferior rectus
◾ipsilateral inferior oblique
◾ipsilateral medial rectus

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22
Q

What muscles are innervated by the medial subnucleus of CN III

A

◾contralateral superior rectus

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23
Q

What muscles are innervated by the central nucleus of CN III

A

both of the levator palpebrae superioris muscles

24
Q

What do the cell bodies in the Edinger Westphal nucleus innervate

A

Smooth muscles of the eye, specifically:
◾sphincter pupillae muscle (pupil constriction)
◾ciliary body muscle (for accomodation to see at near)

25
Q

Pathway of zygomatic nerve

A

•Zygomatic N. enters orbit via IOF,

  • runs along lateral wall of orbit;
  • exits through zygomatico-orbital foramen
  • divides into zygomaticofacial nerve (innervates skin overlyin bony prominence of cheek) and zygomaticotemporal nerve (innervates skin overlying pterion and onto scalp)
26
Q

Path of Infraorbital Nerve

A
  • Infraorbital N. enters orbit via IOF
  • runs forward through infraorbital groove and canal on orbital floor
  • exits through infraorbital foramen to provide sensory innervation to conj and skin of lower eyelid, skin of upper lip, soft part of cheek, lateral side of nose
27
Q

Path of motor nerves of CN III

A
  1. Enter orbit using SOF and goes through common tendinous ring
  2. Begins at oculomotor nucleus
    a. Located dorsally in midbrain at level of inferior colliculus near midline
    b. Travel to innervate EOMs
28
Q

Path of parasympathetic nerves of CN III

A
  1. Enter orbit using SOF and goes through common tendinous ring
  2. Begin at Edinger Westphal nucleus
    a. Located in midbrain at level of superior colliculus
  3. Parasympathetic fibers move inferiorly and run in the inferior division of CN III
  4. Leave inferior division and pass through the motor root of the ciliary ganglion and synapse on postganglionic parasympathetic neuron cell bodies in ciliary ganglion
  5. Postganglionic parasympathetic neurons’ axons exit ciliary ganglion as SPCN and pierce back of eyeball
  6. Innervate sphincter pupillae and ciliary body muscle
29
Q

Path of Sensory nerves of CN III

A
  1. Enter orbit using SOF and goes through common tendinous ring
  2. Begin at trigeminal ganglion
  3. Go to bulbar conjunctiva, iris, ciliary body, and cornea
    a. Via LPSNjump on nasociliary n. and then the ophthalmic division of CN V and then to trigeminal ganglion
    i. From trigeminal ganglion they go to pons where they synapse on cell bodies in sensory nucleus of CN V
    b. Via SPCNlead into ciliary ganglion (dendrites just pass through) and exit through sensory root and joins nasociliary n.
    i. Nasociliary leads to ophthalmic division of CN V which leads to trigeminal ganglion
    ii. From trigeminal ganglion the go to pons where they synapse on cell bodies in sensory nucleus of CN V
30
Q

Path of CN IV

A

i. Emerges from neuron cell bodies in Trochlear nucleus w/in midbrainpass dorsallycross in dorsal aspect of midbrainemerges from dorsal midbrain at inferior colliculus
ii. Enters orbit through SOF above common tendinous ring
iii. Passes medially above origin of levator palpebrae superioris to innervate SO

31
Q

Path of CN VI

A

i. Axons of motor neurons in abducens nucleus
ii. Emerges from pontomedullary junction nearest midline
iii. Enters orbit through SOF and through common tendinous ring
iv. Passes laterally in orbit and enters medial surface of LR

32
Q

Nerves that pass into the orbit through the common tendinous ring

A

i. Upper division of CN III
ii. Nasociliary n.
iii. Abducens n.
iv. Lower division of CN III

33
Q

signs/symptoms if Upper division of CN III is damaged

A
  1. Damage to SR and levator palpebrae superioris
34
Q

signs/symptoms if the nasociliary nerve is damaged

A
  1. Loss (or partial loss) of sensation to skin on tip of nose, ethmoid air cells, ciliary body, iris, cornea, bulbar conjunctiva, medial part of upper eyelid, punctum, canaliculi, lacrimal skin, and skin on roof of nose
35
Q

Signs/symptoms if abducens nerve is damaged

A
  1. Damaged on right side
    a. Right eye looks mediallyMR takes over
    b. During EOM testing, patient cannot look right w/ right eye
36
Q

Signs/symptoms if lower division of CN III is damaged

A
  1. Damage to MR, IR, and IO
37
Q

Nerves that pass above the common tendinous ring

A

i. Lacrimal n.
ii. Frontal n.
iii. Trochlear n.

38
Q

Signs/symptoms if the lacrimal nerve is damaged

A
  1. loss (or partial loss) of sensation to lateral part of upper lid and lacrimal gland
39
Q

Signs/symptoms if the frontal nerve is damaged

A
  1. loss (or partial loss) of sensation to medial part of upper lid, skin of lower forehead near midline, frontal sinus, skin on upper/central lid, forehead, and scalp
40
Q

signs/symptoms if the trochlear nerve is damaged

A
  1. Damage to right
    a. Affects right CN IV and left trochlear nucleus
    b. When looking straight, eye is slightly elevated hyper/vertical deviation
    c. Vertical diplopia
    d. Cannot look down and left during EOM testing w/ right eye
41
Q

What muscles lie adjacent to the roof of the orbit?

A

i. SOmedial

ii. Levator palpebrae superioris

42
Q

What nerves lie adjacent to the roof of the orbit?

A

i. Trochlear n. (medial)
1. Lies on top of SO
ii. Frontal n. (posterior)
1. Lies above levator palpebrae superioris
iii. Supratrochlear n. (anterior)
iv. Supraorbital n. (anterior)
v. Lacrimal n. (lateral)

43
Q

What are the other structures that lie adjacent to the roof of the orbit

A

i. Pulley for SO muscle tendon (atnero-medial)
ii. Lacrimal gland (antero-lateral)
iii. Meninges for frontal bones

44
Q

What muscles lie adjacent to the lateral wall of the orbit?

A

lateral rectus

45
Q

what nerves lie adjacent to the lateral wall of the orbit

A

i. Lacrimal n.
1. Above LR
ii. Zygomatic n.
iii. Postganglionic parasympathetics to lacrimal gland (hitch-hiking fibers)

46
Q

What other structures lie adjacent to the lateral wall of the orbit?

A

i. Lacrimal gland (at junction of roof and lateral wall)

47
Q

What muscles lie adjacent to the medial wall of the orbit?

A

i. SO (superior)

ii. MR (inferior)

48
Q

What nerves lie adjacent to the medial wall of the orbit?

A

i. Nasociliary n. (between SO and MR)
ii. Ethmoidal n.
iii. Infratrochlear n.

49
Q

What other structures lies adjacent to the medial wall of the orbit?

A

i. Lacrimal sac (anterior)
ii. Pulley for SO tendon (anterior-superior)
iii. Ethmoid air cells (medial)
iv. Sphenoid sinus (medially)

50
Q

What muscles lie adjacent to the floor of the orbit?

A

i. IO (by eyeball)

ii. IR (behind eyeball)

51
Q

What nerves lie adjacent to the floor of the orbit?

A

infraorbital nerve

52
Q

What other structures lie adjacent to the floor of the orbit?

A

i. Opening for nasolacrimal canal (antero-laterlly)

ii. Maxillary sinus (below)

53
Q

Oculomotor nucleus

A

cell bodies of neurons that innervate skeletal muscles: levator, SR, IR, IO & MR

54
Q

Edinger Westphal Nucleus

A

cell bodies of preganglionic parasympathetic neurons that innervate smooth muscles in the eye: sphincter pupillae muscle & ciliary body muscle

55
Q

Preganglionic Parasympathetic fibers of CN III

A
  • CN III travels through orbit and parasympathetic fibers slowly move inferiorly to inferior medial position at the orbit
  • preganglionic parasympathetics first run in inferior division, then with the branch that innervates inferior oblique muscle
  • …then they leave that branch and pass through motor root of the ciliary ganglion & synapse on postganglionic parasympathetic neuron cell bodies in the ciliary ganglion
56
Q

Postganglionic sympathetic fibers of CN III

A
  • neurons’ axons exit ciliary ganglion as the short posterior ciliary nerves
  • pierce the back of the eyeball and pass forward inside eye to innervate: sphincter pupillae of iris & ciliary body muscle
  • SPCN also carry sensory fibers from cornea, iris, ciliary body & bulbar conj (helping LPCN)
57
Q

Path of sensory fibers from cornea, iris, ciliary body and bulbar conj

A

cell bodies lie in trigeminal ganglion; dendrites lie in the structure (cornea…etc.); travel back by 1 of 2 routes:
i. via LPCN: LPCN → nasociliary n. → ophthalmic division of CN V → trigeminal ganglion [cell body location] =
axons → pons where they will synapse on neuron cell bodies in sensory nucleus of CN V
ii. via SPCN: SPCN → ciliary ganglion [dendrites pass through, no synapsing] → exit via “sensory root” of ciliary ganglion → nasociliary n. → ophthalmic division of CN V → trigeminal ganglion [cell body location] = axons → pons [synapse!]

Ocular Anatomy - Exam 1 (5 decks)

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