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Head And Neck Anatomy > Cranial Nerves I > Flashcards

Cranial Nerves I Flashcards

1
Q

Cranial Nerve Modalities: Somatomotor

A
  • GSE
  • Skeletal mm. of tongue and eye (extrinsic)
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2
Q

Cranial Nerve Modalities: Visceromotor

A
  • GVE
  • Only parasympathetic travel with CN to smooth and cardiac mm.
  • Visceral glands, salivary and lacrimal glands, mucus glands and membranes
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3
Q

Cranial Nerve Modalities: Branchiomotor

A
  • SVE
  • Skeletal mm. of the branchial arches
    • e.g.- mm of mastication, facial expression, pharynx (swallowing), larynx (speech)
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4
Q

Cranial Nerve Modalities: Somatosensory

A
  • GSA
  • Touch, temp., pain receptors in skin, oral and nasal cavities, and pharynx
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5
Q

Cranial Nerve Modalities: Viscerosensory

A
  • GVA
  • Stretch receptors of the gut
  • Baroreceptors of the carotid and aortic bodies
  • Chemoreceptors of gut and carotid body
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6
Q

Cranial Nerve Modalities: Special Sensory

A
  • SSA- vision, hearing, and balance
  • SVA- smell and taste
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7
Q

Innervation Chart

A
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8
Q

CN I

A
  • Olfactory N.
  • SVA
  • Sensation of olfaction (smell)
  • Not a true nerve, but a nerve tract (composed of 2o sensory neurons in olfactory bulb)
  • 1o neurons are receptor cells in epithelial lining nasal cavity, axons pierce cribriform plate of ethmoid bone
  • CN I is outgrowth of cerebrum
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9
Q

The Orbit

A
  • Bony margin (7 bones)
    • Frontal
    • Ethmoid
    • Lacrimal
    • Maxillary
    • Palatine
    • Sphenoid
    • Zygomatic
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10
Q

The Orbit: Contents

A
  • Eyeball
  • Extraoccular muscles
  • Nerves
    • CN II, III, IV, V1, V2, and VI
    • Sympathetic nerves in ciliary nerves
  • Vasculature: opthalmic artery, retinal artery, superior and inferior opthalmic veins
  • Lacrimal gland
  • Extraoccular fat
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11
Q

Innervation of the Orbit

A
  • Special sensory (SSA): (CN II) retina
  • Somatosensory (GSA): (CN V1) eyeball
  • Somatomotor (GSE): (CN III, IV, VI) 6 extra-ocular muscles (4 rectus, 2 oblique), and levator palpebrae superioris
  • Visceromotor (GVE): (CN III, VII) 3 intrinsic muscles (sphincter pupillae, dilator pupillae, ciliary muscles, CN III), superior tarsal muscles (sympathetic), lacrimal gland (CN VII)
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12
Q

The Eyeball

A
  • cornea: transparent covering to anterior eye
  • iris: controls pupillary diameter, determines eye color
  • pupil: a hole in the center of the iris that allows light in
  • lens: refracts light to focus image on retina
  • ciliary body: controls the shape of the lens
  • sclera: connective tissue covering to eye
  • retina: detects images through photoreceptors, sends signal to CN II
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13
Q

CN II

A
  • Optic N.
  • SSA
  • Not a true nerve, but a nerve tract (composed of axons of 2o sensory neurons)
  • 1o neurons are receptor cells (photoreceptors=rods and cones) in retina
  • Outgrowth of diencephalon
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14
Q

Optic nerve between

A

Chiasm and retina

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15
Q

Optic chiasm

A

Where optic n. fibers from the nasal side of the retina (lateral visual field) cross over to the contralateral side of the brain

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16
Q

Optic tract

A

Between chiasm and thalamus

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17
Q

Anopsia

A

loss of total visual field in one eye due to lesion of optic nerve

18
Q

Heteronymous hemianopsia

A
  • loss of 1/2 visual field on different side of the eyes
    • temporal hemianopsia: optic chiasm lesion
19
Q

Homonymous hemianopsia

A

loss of 1/2 visual field on same side of the eyes due to optic tract lesion

20
Q

CN III

A
  • Oculomotor N.
  • GSE
    • Somatomotor
    • Superior, medial, and inferior rectus mm.
    • Inferior oblique m.
    • Levator palpebrae superioris m.
  • GVE
    • Visceromotor
    • CN III carries pre-ganglionic parasympathetic fibers from the brain to the ciliary ganglion
    • Post-ganglionic parasympathetics travel via the short ciliary n. to the eyeball
    • Constrictor pupillae m., ciliary m.
21
Q

CN III: Oculomotor N.: Somatomotor function (GSE)

A
  • Superior rectus m.
  • Medial rectus m.
  • Inferior rectus m.
  • Inferior oblique m.
22
Q

Upper eyelid

A
  • CN V1- opthalmic n.
    • Somatosensory (GSA)
  • CN III- oculomotor n.
    • Somatomotor (GSE)
    • Levator palpebrae superioris m.
  • Sympathetic nervous system
    • Visceromotor (GVE)
    • Superior tarsal muscle
23
Q

CN III: Oculomotor n.: Visceromotor (GVE) Component

A
  • Pupillary light reflex
    • Pupil contraction
  • Accomodation reflex
    • Changing focus between near and far objects
24
Q

CN III: Ciliary ganglion

A
  • parasympathetic
25
Q

CN III: Short ciliary n.

A
  • Parasympathetic (CN III)
  • Sympathetic
  • Sensory (CN V1)
26
Q

CN III: Long ciliary n.

A
  • Sympathetic
  • Sensory (CN V1)
27
Q

CN III: Pupillary Light Reflex

A
  • optic n. (CN II) senses light
  • oculomotor n. (CN III) constricts pupils
    • short ciliary nn.
    • constrictor pupillae mm.
    • direct (ipsilateral) and consensual (contralateral) responses
  • Sympathetic nerves dilate pupils
    • short and long ciliary nn.
    • dilator pupillae mm.
28
Q

Pupillary Constriction Diagram

29
Q

CN III: Acommodation reflex

A
  • Changing focus between near and far objects
  • Works via change in lens shape and pupil size
    • Contraction of ciliary m. puts slack on the suspensory ligametns, rounds the lens, and causes the eye to focus on near objects
30
Q

Ptosis

A
  • drooping eyelid
  • Horner’s syndrome
    • Sympathetic nerve damage
    • Ptosis + miosis (constricted pupil)
    • Loss of superior tarsal m.
    • Unopposed constrictor pupillae m.
  • Oculomotor Palsy
    • Motor and parasympathetic nerve damage
    • Ptosis and mydriasis (dilated pupil)
    • Loss of levator palpebrae superioris m.
    • Unopposed dilator pupillae m.
31
Q

CN IV

A
  • Trochlear n.
  • GSE
  • Somatomotor
    • Superior oblique m.
32
Q

CN VI

A
  • Abducens n.
  • GSE
  • Somatomotor
    • Lateral rectus m.
33
Q

Extra-Ocular Palsies

A
  • CN III Palsy: eye rotated “down and out”, due to unopposed superior oblique (CN IV)
  • CN IV Palsy: eye rotated up and in due to unopposed superior rectus (CN III) patient presents with “head tilt” to force even gaze
  • CN VI Palsy: eye adducted due to unopposed medial rectus (CN III)
34
Q

CN V

A
  • Trigeminal nerve
  • GSA, SVE
  • Three branches
    • CN V1: opthalmic n. (GSA)
    • CN V2: maxillary n. (GSA)
    • CN V3: mandibular n. (GSA, SVE)
35
Q

CN V: Somatosensory (GSA)

A
  • All branches: skin of face and meninges
  • V1: opthalmic
    • conjunctiva of eye
    • bridge of nose
    • nasal cavity
  • V2: maxillary
    • upper teeth, oral cavity
    • nasal mucosa
  • V3: mandibular
    • lower teeth
    • tongue
36
Q

CN V: GSA location

A
  • cell bodies of GSA neurons found in trigeminal ganglion
  • located in middle cranial fossa
  • inside cavernous sinus
37
Q

CN V: Branchiomotor

A
  • SVE
  • CN V3 (mandibular n.)
  • mm. of mastication: temporalis, messeter, medial and lateral pterygoids
  • tensor veli palatini m.
  • mylohyoid m.
  • anterior belly of digastruc m.
  • tensor tympani m.
38
Q

Orbital Blowout Factures

A
  • Fracture to the floor of the orbit
    • maxilla and zygoma
    • lateral walls sometimes involved
  • Signs:
    • Enopthalmos (sunken eye)
    • restricted eye movements
    • subconjunctival hemorrhage (from opthalmic a.)
    • loss of sensation around orbit and zygoma (CN V2)
  • Inferior rectus m. entrapment
    • limited upward gaze in affected eye
    • interior rectus m. herniates into maxillary sinus
    • tension placed on eyeball limits motion of superior rectus m.
39
Q

Trigeminal Neuralgia

A
  • TNA, “typical TN”
  • neuropathic pain in one side of the face
  • may be in one or more trigeminal regions
  • TNA caused by neurovascular compression of the trigeminal ganglion inside the cranial cavity
  • compression-induces myelin loss causes pain
40
Q

Trigeminal neuropathy

A
  • TNO, “atypical TN”
  • Peripheral damage due to trauma, usually to a single branch of CN V
  • Myelin loss causes pain
  • Axonal damage causes loss of sensation and/or motor function
41
Q

Differential diagnoses of trigeminal neuropathies

A

TMJ disorders, dental infection

Head And Neck Anatomy (20 decks)

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