NAP Lab - Practical 2

tract

a bundle of axons traveling together in the CNS

nerve

a bundle of axons traveling together in the PNS

nucleus

a cluster of neuron cell bodies in the cns

ganglion

a cluster of neuron cell bodies in the PNS

gray matter =

cell bodies, glia, etc.

white matter =

myelinated axons

nerve fiber

myelinated or unmyelinated axon

fascicle/fasciculus

a bundle of nerve fibers/axons

endoneurium

CT layer that surrounds a single nerve fiber

perineurium

CT layer that surrounds a fascicle

epineurium

CT layer that surrounds an entire nerve trunk

Olfactory nerve

CN1
Sensory
Sense of smell

disorder caused by damage to olfactory nerve

Anosmia (inability to smell)

Optic nerve

CNII
Sensory
Sense of vision, pupillary light reflex

disorder(s) caused by damage to optic nerve

Ipsilateral blindness
Loss of pupillary light reflex
Color blindness

Oculomotor nerve

CNIII
Motor
Moves eyes up/down/medially, elevates upper eyelid, constricts pupil, adjusts eye lens

disorder(s) caused by damage to oculomotor nerve

Ptosis (drooping eyelid)
Diplopia (double vision)

Trochlear nerve

CN IV
Motor
Moves eye medially and down

disorder(s) caused by damage to trochlear nerve

Diplopia
Difficulty reading
Visual problems during descension

Trigeminal nerve

CNV
Mixed
Blink reflex and sensation from face (sensory)
Chewing (motor)

disorder(s) caused by damage to trigeminal nerve

Trigeminal neuralgia (severe sharp pain in one or more branches of TGN)

Abducens nerve

CNVI
Motor
Moves eye laterally

disorder(s) caused by damage to abducens nerve

diplopia (double vision)

facial nerve

CNVII
Mixed
Blink reflex, facial expression, salivation and tear production (motor/glands)
Sense of taste (sensory)

disorder(s) caused by damage to facial nerve

Bell’s palsy (paralysis or paresis of ipsilateral muscles of facial expression)

vestibulocochlear nerve

CNVIII
Sensory
Sensation of head position and movement (vestibular branch), sense of hearing (cochlear branch)

disorder(s) caused by damage to vestibulocochlear nerve

Conductive deafness (transmission of vibrations prevented in outer or middle ear)
Sensorineural deafness (damage of receptor cells or cochlear nerve)

Glossopharyngeal nerve

CN IX
Mixed
Sense of taste, sensory limb of gag reflex, swallowing, salivation

which gland is responsible for salivation and which nerve controls it

parotid gland; glossopharyngeal nerve

disorder(s) caused by damage to glossopharyngeal nerve

Interruption of gag reflex and swallowing reflex
Decreased salivation

Vagus nerve

CNX
Mixed
Motor limb of gag reflex, swallowing, speech production, regulating visceral organs

disorder(s) caused by damage to vagus nerve

Interruption of gag and swallowing reflex
Difficulty swallowing
Poor digestion

spinal accessory nerve

CN XI
Motor
Elevates shoulders, turns head

disorder(s) caused by damage to spinal accessory nerve

Paralysis of ipsilateral sternocleidomastoid and trapezius

hypoglossal nerve

CNXII
Motor
Moves tongue

disorder(s) caused by damage to hypoglossal nerve

Difficulty speaking and swallowing
Atrophy of ipsilateral tongue

Label this chart

1 - epineurium
2 - nerve fascicles
3 - perineurium

Label this chart

1 - Fasciculi
2 - Endoneurium
3 - Nerve fiber
4 - Epineurium
5 - Perineurium

Label this chart

1 - Epineurium
2 - Perineurium
3 - Axon
4 - Myelin
5 - Endoneurium

How can you test olfactory nerve

Smelling something (ex: vanilla extract)

How can you test vestibulocochlear nerve

Trying to locate your phone by hiding it and having someone call you while it’s on vibrate, by seeing if you get dizzy on a swivel chair, or by using the Weber’s or Rinne’s tests

Weber’s test

Tests CN VIII
Tuning fork on top of your head and see if the sound is equal in both ears

Rinne’s test

Tuning fork on jaw and seeing if air conduction is louder or if bone conduction is louder (air conduction should be louder if nerve function is normal)

How to test optic nerve

Snellen chart or colorblind quiz

How can you test hypoglossal nerve

Stick your tongue out and see if it deviates to the side. If it does, your nerve is damaged

How to test trigeminal nerve

Eat something and see if you have difficulties chewing, drink something and see if you have trouble swallowing, or brush a cotton ball on your face and see if you can feel it on your face

How can you test glossopharyngeal nerve

Drink water and see if you have swallowing difficulties

How can you test spinal accessory nerve

Turn your head and shrug your shoulders and see if you have difficulties

How can you test oculomotor nerve

Follow a pen with your eyes or cross your eyes to look at the tip of your nose

what does the somatosensory system consist of

sensory receptors, sensory neural pathways, parts of brain involved in sensory perception

types of somatosensations

touch, pain, temperature, proprioception

stages of somatosensation

Activation of sensory receptors
Receptor responds to stimuli by conversion of a sensory signal to an electrical signal (action potential)
The electrical signal is carried to the brain and processed in specialized regions of brain for that sensation

types of somatosensory receptors

mechanoreceptors, chemoreceptors, thermoreceptors, nociceptors

mechanoreceptors

respond to mechanical deformities/forces
touch, pressure, vibration, stretch, hearing

chemoreceptors

respond to chemical changes in the cellular environment including cell death
taste, smell, blood composition

thermoreceptors

respond to changes in temp

nociceptors

respond to painful stimuli
responds when something may cause harm to tissues

What speeds up transmission of info to the cerebral cortex

Myelination, large diameters, and fewer synapses along the pathway

receptive field

size of an area of skin innervated by a single sensory neuron
tend to be smaller distally and larger proximally

why are fingertips, for example, more sensitive than backs?

higher receptor density and smaller receptive fields

what are the three types of somatosensory pathways that bring sensory info to the brain

conscious relay pathways (DC/ML: discriminative touch/conscious proprioception; ALS: discriminative pain and temperature), divergent pathways (single sensory signal can take different neural pathways w/ different responses), and unconscious relay pathways (proprioception from muscle spindles, tendon tension/stretch, position info)

DC/ML pathway

1st ON (psuedounipolar) enters the spinal cord, ascends ipsilaterally until reaching the medulla, where it synapses with second order neuron in the gracilis (midline; carries sensations from lower body) or cuneatus (lateral; upper body) nucleus.
2nd ON (interneuron) axon crosses the midline of medulla and ascends until synapsing with ventral posterolateral nucleus of the thalamus.
3rd ON axon ascends from the thalamus thru internal capsule to cerebral cortex

where is the somatosensory cortex

in the postcentral gyrus of the anterior parietal lobe

Anterolateral/spinothalamic pathway

1st ON (pseudounipolar) synapses with 2nd ON right after entering spinal cord. 2nd ON (interneuron) axon crosses the midline of the spinal cord, ascends contralaterally and synapses with the VPL of thalamus. 3rd ON axon ascends from thalamus through internal capsule to cerebral somatosensory cortex

precentral gyrus processes what

motor info

somatosensory homonculus

shows how much of the somatosensory cortex is devoted to a specific part of the body

electrodiagnostic studies

sensory nerve function can be examined by recording its electrical activity using either SEPs or nerve conduction studies

Somatosensory Evoked potentials (SEPs)

a type of electrodiagnostic study that evaluates peripheral nerves and CNS pathways and measures speed of impulses from sensory neuron to brain

Nerve conduction studies (NSCs)

A type of electrodiagnostic study to evaluate the function of a peripheral nerve; can determine damage to a nerve; measures how fast an electrical impulse moves along the nerve.
3 measurements are compared to normative values for the strength and speed of a nerve signal

what are the 3 measurements for the strength and speed of a nerve signal used in NSCs? describe them

distal latency (time required for depolarization to reach distal recording site—msec), amplitude (strength of a signal in uV; indicates the number of axons conducting), and conduction velocity (m/s)

gryi

rounded elevations/ridges on the surface of cerebrum

sulci

grooves/depressions on the surface of the cerebrum

fissures

deep groove/sulcus that divides an organ into lobes or parts

Label this

1 - longitudinal fissure
2 - precentral gyrus
3 - sulcus
4 - postcentral gyrus

Label this

1 - precentral gyrus
2 - central sulcus
3 - postcentral gyrus
4 - parieto-occipital sulcus
5 - transverse cerebral fissure
6 - cerebellum
7 - superior temporal gyrus
8 - lateral fissure

ataxia

Improper reporting of somatosensory info; interruption of proprioceptive information
Feedback issues cause lack of muscle control and inability to coordinate volutnary movements
Balance problems, trouble walking, slurring words
Sensory ataxia (proprioception problem; only a problem when eyes are shut) or cerebellar ataxia (gait problems, lack of coordinated movements)

primary hyperalgesia

Increased or excessive response to painful stimulus above normal pain
Often caused by nerve damage

secondary hyperalgesia

painful stimulus spreads to other parts of your body beyond where the pain stimulus originates

allodynia

Pain caused by a stimulus that does not normally cause pain

paresthesia

Sensations of tingling, burning, itching, or numbness, mostly in arms or legs
Not typically painful
Can be temporary or chronic

Analgesia

Inability to feel pain; interruption of the pain pathways

Label this

A - optic chiasm
X - olfactory nerve
R - olfactory bulb

Label this

A - optic
Y - optic nerve

Label this

C - trigeminal nerve
D - medulla
P - spinal accessory

Label this

Q - oculomotor nerve
B - abducens
Z - pons
D - medulla

Label this

1 - Olfactory tract
2 - Optic nerve
3 - Oculomotor
4 - Trigeminal
5 - Abducens
6 - Vestibulocochlear
7 - Glossopharyngeal
8 - Vagus
9 - Accessory
10 - Hypoglossal
11 - Trochlear
12 - Facial

What is this a picture of

Anterolateral system/Discriminative Pain and Temperature pathway

What is this a picture of?

DC/ML pathway (Discriminative touch and conscious proprioception)

which cranial nerves are found on the lateral pons

trigeminal

which cranial nerves are associated with the ability to shrug your shoulders

spinal accessory

which cranial nerves help you wrinkle your forehead and raise your eyebrows

facial

which cranial nerves are associated with the gag reflex

glossopharyngeal and vagus

which cranial nerves are found medially at the junction of the pons and medulla

abducens

which cranial nerves are the largest

trigeminal

which cranial nerves extend on the underside of the frontal lobe to synapse in the temporal lobe

olfactory

which cranial nerves send signals from the inner ear

vestibulocochlear

which cranial nerve has a branch receiving sensations from the maxilla (upper lip)

trigeminal

which cranial nerve innervates the sternocleidomastoid muscle and allows turning your head from side to side

spinal accessory

which cranial nerves are associated with eye movements

oculomotor, trochlear, abducens

which 2 cranial nerves are responsible for taste sensations

glossopharyngeal (posterior 1/3) and facial (anterior 2/3)