Cranial Nerves I Flashcards
(41 cards)
1
Q
Cranial Nerve Modalities: Somatomotor
A
- GSE
- Skeletal mm. of tongue and eye (extrinsic)
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
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)
4
Q
Cranial Nerve Modalities: Somatosensory
A
- GSA
- Touch, temp., pain receptors in skin, oral and nasal cavities, and pharynx
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
6
Q
Cranial Nerve Modalities: Special Sensory
A
- SSA- vision, hearing, and balance
- SVA- smell and taste
7
Q
Innervation Chart
A
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
9
Q
The Orbit
A
- Bony margin (7 bones)
- Frontal
- Ethmoid
- Lacrimal
- Maxillary
- Palatine
- Sphenoid
- Zygomatic
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
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)
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
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
14
Q
Optic nerve between
A
Chiasm and retina
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
16
Q
Optic tract
A
Between chiasm and thalamus
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
CN III: Short ciliary n.
* Parasympathetic (CN III)
* Sympathetic
* Sensory (CN V1)
26
CN III: Long ciliary n.
* Sympathetic
* Sensory (CN V1)
27
CN III: Pupillary Light Reflex
* 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
Pupillary Constriction Diagram
29
CN III: Acommodation reflex
* 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
Ptosis
* 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
CN IV
* Trochlear n.
* GSE
* Somatomotor
* Superior oblique m.
32
CN VI
* Abducens n.
* GSE
* Somatomotor
* Lateral rectus m.
33
Extra-Ocular Palsies
* 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
CN V
* Trigeminal nerve
* GSA, SVE
* Three branches
* CN V1: opthalmic n. (GSA)
* CN V2: maxillary n. (GSA)
* CN V3: mandibular n. (GSA, SVE)
35
CN V: Somatosensory (GSA)
* 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
CN V: GSA location
* cell bodies of GSA neurons found in trigeminal ganglion
* located in middle cranial fossa
* inside cavernous sinus
37
CN V: Branchiomotor
* 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
Orbital Blowout Factures
* 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
Trigeminal Neuralgia
* 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
Trigeminal neuropathy
* 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
Differential diagnoses of trigeminal neuropathies
TMJ disorders, dental infection
