Brainscape's Knowledge GenomeTM


Top Flashcards (Certified)
All Flashcards

Anatomy 2 > CN 1-6 > Flashcards

CN 1-6 Flashcards

(102 cards)

Start Studying
1
Q

Fasiculations

A

spontaneous contractions of small groups of muscle fibers that can be visible at the skin surface. Fibrillations are contractions of individual muscle fibers that can not be seen visually but are detected using electrical monitoring

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Clonus

A

rapid series of alternating muscle contractions that occur in response to the sudden stretch of a muscle.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

Corticospinal tract (CST)

A

Originates in cerebral cortex, precentral gyrus and nearby areas
Descends thru cerebral peduncle, basis pontis, medullary pyramid, decussates at spinomedullary junction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

CN 1

A

Axon type: SSA
CNS origin or termination: Olfactory bulb
Peripheral origin or termination: olfactory epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

CN 2

A

Axon type: SSA
CNS origin or termination: Lateral geniculate nucleus (in thalamus), superior colliculus, hypothalamus

Peripheral origin or termination: Lateral geniculate nucleus (in thalamus), superior colliculus, hypothalamus

Originates in eye, goes to thalamus. Relay nuclei for vision.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

CN 3

A

Axon type: GSE
CNS origin or termination: Oculomotor nucleus

Peripheral origin or termination: Superior, inferior, medial recti; inferior oblique, levator palpebrae superioris muscles

Axon type: GVE
CNS origin or termination: Edinger-Westphal nucleus (in above)

Peripheral origin or termination: Ciliary ganglion, Sphincter pupillae muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

CN 4

A

Axon type: GSE
CNS origin or termination: Trochlear nucleus

Peripheral origin or termination: Superior oblique muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

CN 6

A

Axon type: GSE
CNS origin or termination: Abducens nucleus

Peripheral origin or termination: Lateral rectus muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Olfaction

A

Taste & smell: conscious chemical sensation
Olfaction: detects volatile chemicals (odorants) drawn into nasal cavity
Humans can detect about 10,000 different odors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

Olfactory epithelium

A

Peripheral origin of olfactory system

Patch in roof of nasal cavity, bilateral

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Olfactory epithelium contains

A

3 million receptor cells,
Bowman’s gland ducts,
Sensory endings from CN V (irritants)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

Olfactory receptor

A

A small bipolar neuron
Dendrite ends in olfactory vesicle, from which 10-30 cilia spread over the surface in a layer of mucus secreted by Bowman’s glands

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Olfactory receptor stimulates

A

chemosensitive cilia

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Olfactory receptor lifespan

A

Replaced throughout life; lifespan 1-2 months

Unusual among human neurons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Axons from olfactory receptors

A

among thinnest and slowest

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

Collect into a series of bundles (only about 20) called

A

olfactory fila, pass thru holes in cribriform plate of ethmoid bone

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Olfactory fila make up

A

CN1, Synapse on 2nd order neurons in olfactory bulb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Olfactory bulb & tract

A

Develops as an outgrowth of telencephalon

Tract reaches ipsilateral hemisphere with no relay in thalamus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Olfactory fibers sort in

A

bulb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

Each type of olfactory receptor (different colors) sends an axon to one

A

glomerulus of a mitral cell even though these cells are intermingled in the olfactory epithelium

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

Olfactory tract made up of axons from

A

mitral and tufted (not shown here) cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

Olfactory bulb projections - Collaterals to

A

anterior olfactory nucleus (1)

Thought to regulate sensitivity of olfactory bulb

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

Olfactory bulb projections - Fibers project to

A 
both bulbs (red)
Cross midline in anterior commissure, which is in the brain and not on the surface as depicted here
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

Lateral olfactory stria:

A

lateral (primary) olfactory area

Medial olfactory stria Cortex over uncus, entorhinal area, limen insula, amygdala
Pyriform area: uncus, entorhinal area, limen insula

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Medial olfactory stria
to medial (secondary) olfactory area Subcallosal region of medial frontal lobe surface Emotional response to smell
26
Intermediate olfactory stria
Rudimentary in humans
27
Limen insula
refers to the junction point between the cortex of the insula and the cortex of the frontal lobe
28
Olfactory information sent to….
Hypothalamus, thalamus, hippocampus, orbital cortex, amygdala Direct projections and a thalamic relay: DMN to… Olfactory association cortex: orbital surface of frontal lobe and anterior insula (near taste) Ipsilateral
29
Cornea and lens focus image on
retina
30
Focus requires
refraction of light
31
Lens accounts for about a
third of the eye’s refractive power Major role in adjusting focus for near/ far objects Most refraction is in air-water interface at corneal surface
32
Iris
Affects brightness and quality of image focused on retina
33
Pupil size controlled by 2 smooth muscles in iris
1)Pupillary sphincter: encircles pupil, stronger than dilator Smaller pupil improves ocular performance (like small aperture size improves camera lens performance) 2) Pupillary Dilator: arranged in radiating spokes from the pupil
34
Rods & Cones: Photoreceptors
Highly specialized cells with different structural regions
35
Rod and cones outer segement
contain visual protein Photons absorbed here cause receptor potential
36
Rods
rhodopsin | Low-acuity; monochromatic vision in dim-light
37
Cones
Cone pigments | High-acuity, color vision, need a lot of light
38
Retinal structure -1st synapse layer
terminate on bipolar & horizontal cells
39
Retinal structure - Bipolar cells project to 2nd synapses
horizontal cells spread laterally interconnect receptors, bipolar cells, horizontal cells
40
Bipolar cells terminate on
ganglion cells and amacrine cells; amacrine cells interconnect bipolar cells, ganglion cells and other amacrine cells
41
Ganglion cell axons in optic nerve travel to
Optic chiasm, partial decussation Enter optic tract Most travel to lateral geniculate nucleus (LGN); thalamic relay for vision Others go to superior colliculus, hypothalamus From LGN to primary visual cortex in banks of calcarine sulcus of occipital lobe
42
Fibers from nasal half of retina cross to
contralateral optic tract
43
Fibers from temporal half of retina enter
ipsilateral optic tract | So each optic tract “sees” the contralateral visual field
44
Depth perception
Need to examine comparable areas of both retinas, which is accomplished by chiasm
45
LGN: Structure
-layered, precise retinotopic arrangement Pattern is the same in each LGN layer so any given point in the visual field is represented as a 6 layered cell column in LGN Each layer gets input from one eye 1, 4 & 6 contralateral eye 2, 3 &5 ipsilateral eye
46
LGN projects to
primary visual cortex Fibers representing inferior visual fields most superior in radiations Those representing superior visual fields, most inferior in radiations
47
Superior colliculus
Optic tract fiber bypass LGN go to superior colliculus & pretectal area (junction of midbrain and diencephalon) Also primary visual cortical projections to superior colliculus
48
Hypothalamus
Suprachiasmatic nucleus, gets direct retinal input Master timer of circadian rhythm Daily body temperature changes, hormone secretion, eating, drinking
49
anopia or –anopsia
denote loss of one or more quadrants of visual field
50
Hemianopia
loss of half a visual field
51
Quadrantanopia
loss of one quarter of a visual field
52
Homonymous
similar visual field lost in each eye
53
Heteronymous
two eyes have non-overlapping visual field loss
54
Visual field deficits
Damage anterior to chiasm only affects ispilateral eye Damage at chiasm causes heteronymous deficits Damage to optic tract causes homonymous deficits
55
Superior rectus
CN 3, Elevation for eye
56
Inferior rectus
CN 3, depression
57
Medial rectus
Adduction CN3
58
Inferior oblique
``` External rotation (Extorsion CN3 ```
59
Superior oblique
CN4, Internal rotation (Intorsion) downward & lateral
60
Lateral rectus
CN4, Abduction
61
III nucleus consists of
multiple columns of neurons that supply each muscle
62
Parasympathetic input to the eyes
Pupillary constrictor muscle
63
Pupillary light reflex
Constriction of pupils in response to light involves four sets of neurons
64
Pregang. Parasym. fibers in III nerve
synapse in ciliary ganglion
65
Each pretectal nucleus is linked to
both EWN, via the posterior commissure
66
Afferent limb
retinal ganglion cells to pretectal nuclei
67
Postgang. fibers in
short ciliary nerves, enter iris, supply sphincter (constrictor) of pupillae
68
Accommodation (the near response)
Lens flat at rest due to tension on its capsule exerted by the suspensory ligament To view an object close up: ciliary muscle contracts, which relaxes lens suspensory ligaments and lens bulges (thickens) Sphincter pupillae contracts Decrease light coming though lens periphery (which is thinner)
69
Convergence - accommodation
visual axis of both eyes converge due to increased tone in medial rectus muscles
70
Sympathetic input to the eyes - Central fibers from hypothalamus
cross midline in midbrain join ipsilateral descending fibers in pons and medulla
71
Preganglionic fibers emerge in first | -sympathetic input to eyes
thoracic ventral nerve root and ascend sympathetic chain to SCG
72
Postganglionic fibers run along | -sympathetic input to eyes
external and internal carotid arteries and their branches | Fibers leave IC, join Vi in cavernous sinus, then to ciliary nerves
73
Results of III injury
The affected eye is “down and out” Eye ipsilateral to lesion deviates laterally Medial rectus is weak and lateral rectus is unopposed, lateral strabismus Patient cannot move the eye medially, weak medial rectus Vertical movement impaired, weak superior and inferior recti and inferior oblique ipsilaterally Diplopia: double vision Ipsilateral levator palpebrae superioris weak: ptosis
74
Mydriasis
pupil on affected side is dilated Pupillary dilator is unopposed as pupillary sphincter and ciliary muscle are dysfunctional Pupil does not constrict in response to light Lens cannot be focused for near vision
75
Trochlear nerve (IV) - axons
leave the nucleus and course dorsally, decussate and exit brainstem on dorsal surface- only cranial nerve to do so
76
Results of IV injury
Superior oblique moves eye downwards and laterally
77
IV deficits much less noticeable than III deficits
Affected eye points up a bit, head tilts away from lesion e.g. A right palsy results in a head tilt to the left this lines up the normal eye with the extorted affected eye Patients report diplopia when going downstairs or reading
78
CN IV
Innervates ipsilateral lateral rectus, which abducts eye
79
CN IV in
floor of 4th ventricle, caudal pons
80
Medial to VI nucleus are the
MLF and motor fibers of VII
81
Internal genu of VII nerve:
site where fibers wrap around and turn to exit
82
VI nucleus and internal genu
facial colliculus
83
IV nerve injury
medial strabismus (affected eye deviated medially)
84
Both eyes work together during gaze
Look laterally to one side requires ipsilateral rectus and the contralateral medial rectus to contract simultaneously
85
Medial longitudinal fasciculus (MLF)
allows coordination of head and eye movement
86
MLF interconnects
III, IV & VI nuclei to allow this
87
III, IV & VI nuclei contain motor neurons and
internuclear neurons that ascend in MLF
88
MLF injury results in…
Internuclear ophthalmoplegia | “paralysis of the eye due to damage between the nuclei”
89
MLF damage removes
excitatory input to ipsilateral III nucleus
90
Eye ipsilateral to lesion fails to
move past midposition during horizontal gaze
91
Both VI nuclei are intact so
lateral movements of both eyes are intact
92
Control of eye movements -3 main movements
Scanning, tracking, compensation
93
Scanning
Scanning: eyes move from one visual target to another in high-speed movement know as saccades
94
Tracking
a.k.a, smooth pursuit, eyes follow area of interest across visual field
95
Compensation
gaze held on object of interest during head movement, known as vestibulo-ocular reflex (vestibular system also at work)
96
Gaze centers
in brainstem reticular formation
97
Horizontal saccades
paramedian pontine reticular formation (PPRF), each pulls eye to its own side
98
Upward saccades
midbrain, rostral interstitial nuclei of the MLF (riMLF)
99
Downward saccades
in midbrain next to upward center
100
Pathways involved in voluntary saccade to the left.
1. Projection from right frontal eye field activates left paramedian pontine reticular formation (PPRF). 2. Some PPRF neurons activate adjacent abducens neurons 3. Other PPRF neurons send heavily myelinated (fast) internuclear fibers along the medial longitudinal bundle to activate oculomotor neurons serving medial rectus.
101
Simultaneous contraction of the respective rectus muscles
yields a saccade to the left.
102
78 year old male who had a stroke He is weak on the right side of his body and needs assistance to get into the dental chair The left eye is deviated inward and he cannot move that eye outward Where is this patient’s lesion?
Left corticospinal tract lesion in pons. Abducens nerve issue, not an abducens nucleus (interneurons and would affect gaze). Also, that would be a massive lesion.

Anatomy 2 (15 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions