Studied by 40 people
This one might bend me over
What does it mean that the auditory pathway is diffuse?
Not all of the information crosses.
You could have a stroke that affects the auditory part of the brain and still have some function.
Where does auditory information go after the spiral ganglion?
Either the dorsal cochlear nucleus (information crosses after this) or the ventral cochlear nucleus.
Both routes then lead to the inferior colliculus (midbrain) and medial geniculate (dorsal thalamus).
What is the external auditory meatus?
Area between the outside world and the tympanic membrane.
The opening that leads to the inside of the ear.
What is the middle ear?
area between the tympanic membrane and the cochlea
What is the internal ear?
cochlea
What maintains pressure in the middle ear?
the auditory tube
What is the malleus?
middle ear ossicle
what connects the malleus to the stapes?
the incus
What are the oval and round windows?
Openings in the middle ear that help move fluid in the cochlea to enable hearing
oval window receives sound
round window dampens sound.
What does the round window prevent by moving in the opposite direction of the ossicles to dissipate sound?
echo
What muscle is attached to the malleus?
tensor tympani (dampens sound when it contracts)
innervated by trigeminal nerve
What muscle is attached tp the stapes?
Stapedius (pulls stapes away from oval window)
Smallest muscle in the body
innervated by facial nerve
What cranial nerves subserve taste (gustation)
CN VII facial nerve for anterior 2/3 of tongue
CN IX glossopharyngeal nerve for posterior 1/3 of tongue
CN X vagus for epiglottis
What is the relationship between taste and smell?
Taste is amplified by smell.
Where does the taste pathway cross?
taste is a completely crossed pathway
cross from solitary nucleus to the VPM (ventroposteriomedial nucleus of the thalamus)
Ends up in the postcentral gyrus areas 3,1,2
Olfaction
primative sense that does not cross
Olfaction pathway
From bipolar cells - OF nerves - OF bulb - OF tract
From the tract it can go to medial stria to septal area (memory area)
From tract it can go to later stria to prepyriform & entorhinal cortex (where we identify smells)
What is vibratory sense part of? (what pathway)
Pacinian receptors of the discriminative touch pathway.
Where is the first information synapse in the discriminative touch pathway?
Nucleus Gracilis (information from lower body)
Nucleus Cuneatus (information from upper body)
BOTH FOUND IN THE MEDULLA
Where does discriminative touch pathway from the body cross?
Internal arcuate fibers which form the medial lemniscus.
How many neurons are in the discriminative touch pathway?
3
Where does discriminative touch from the face synapse?
Chief sensory nucleus of the trigeminal nerve.
They neurons then decussate at the ventral trigeminal thalamic tract and synapse again in the VPM.
Then on through the internal capsule to the Brodmann areas 3,1,2.
What side would lose discriminative touch in a spinal cord injury?
touch would be lost on the ipsilateral side
This pathway decussates at the medulla, so any injury below the medulla is ipsilateral damage.
What do Golgi Tendon Organs detect?
Tension
Anatomy of a muscle spindle
2-18 intrafusal fibers located in the spindle on the ends.
What do dynamic bag fibers detect?
change in muscle length and velocity
What do static bag fibers detect?
static stretch (afferent fiber)
What would happen if you only activated the gamma motor neurons?
It would cause a weak contraction of intrafusal fibers making them more susceptible to changes in muscle length.
How to initiate a monosynaptic stretch reflex?
tapping on a large tendon to activate the Ia afferent fibers to cause the muscle to stretch quickly.
How does motor unit recruitment work?
Recruit from smallest to largest motor unit.
What is a motor unit?
A motor neuron and all of the fibers it innervates
What is the cross extensor reflex?
a noxious stimuli produces flexion at the ankle, knee, and hip.
Produces extension in the opposite limb to maintain balance of the body.
What is the corticospinal system?
voluntary control system.
starts at the precentral gyrus, decussates at the pyramids and continues to the spinal cord.
Most important voluntary control tract.
synonymous with the pyramids
What happens with a lower motor neuron lesion?
alpha motor neuron is damaged
flaccid paralysis from efferent limb damage
no tendon reflexes
muscle atrophy
What happens with an upper motor neuron lesion?
damage to all other motor systems that are not the alpha motor neurons.
spastic paralysis
hyper-tendon touch reflexes
positive babinski (during a plantar reflex test, the big toe lifts and the other toes abduct) can be a sign of a neurological condition.
How do receptors act as transducers?
They convert mechanical, chemical or light energy into electrical energy.
Why do we need sensory reception?
to gain information about the outside world.
What pathway includes nociceptors and free nerve endings?
Pain and temperature
What do nociceptors detect?
tissue damage and pain
what do free nerve endings detect?
Noxious stimuli and changes in temperature and pain.
A-delta fibers detect sharp pain, cold and tickling reception.
C fibers detect aching pain, warm and itch reception.
Which are the largest nerve fibers?
A-alpha fibers and Primary afferent (sensory) fibers
1b fibers (GTO)
All myelinated so they send information very fast.
Which are the smallest nerve fibers?
type C IV fibers (unmyelinated and carry information for pain and temp)
What kind of fibers do Gamma neurons innervate?
intrafusal fibers (muscle spindles)
What kind of fibers do alpha neurons innervate?
Extrafusal fibers
What are Brodmann’s areas 3,1,2?
synonymous with the primary sensory cortex in the post central Gyrus.
end location for many of the pathways.
location for the fibers from the dorsal thalamus to synapse.
Pain and temperature pathway for the face
Starts with nociceptors or free nerve endings detecting pain.
Signals travel through CN V, VII, IX, X
Descends to descending nucleus of V to synapse.
2nd order neurons decussate in medulla and travel up the VTTT.
Signals reach VPM in the thalamus
Through the internal capsule to the brodmann’s areas.
Spinal cord pathway for light touch.
begins with free nerve endings detecting touch.
synapse in DRG
First order neurons enter spinal cord and synapse in nucleus proprious.
second order neurons decussate at anterior white commissure.
Ascend via the anterior spinothalamic tract to the VPL
Third order neurons travel through internal capsule to Broddman’s areas.
What is nociceptive pain vs neuropathic pain?
nociceptive pain is from tissue damage or inflammatory mediators like histamine and bradykinin.
neuropathic pain is from nerve injury or damage. (burning, shooting, electrical quality pain)
What is allodynia?
Usually happens within the nerve regeneration process after an injury.
Non- painful nerve fibers make connections with pain pathway neurons in the spinal cord and non-painful stimuli become painful.
Where are the pre-ganglionic sympathetic cell bodies for dilation of the pupil located?
in the spinal cord
where are the pre-ganglionic parasympathetic cell bodies for constriction of the pupil located?
Edinger-Westphal Nucleus.
what is the afferent pathway for light reflex?
optic nerve
optic chiasm
optic tract
centre is the pretectal nucleus before it gets sent to the efferent pathway.
If the left optic nerve is cut, can you still get a consensual light reflex in the left eye?
yes, but no direct light reflex.
Left optic nerve cut results in what kind of deficit?
Left Anopsia
Cut at the optic chiasm results in what kind of deficit?
Bitemporal heteronymous hemianopsia
Cut at the left optic tract results in what kind of deficit?
Right homonymous hemianopsia
Cut at the lateral geniculate results in what kind of deficit?
right homonymous hemianopsia
What is Aqueous humor?
liquid found in the anterior and posterior chambers
we make it ourselves and absorb it.
Made in the ciliary body.
What is an argyll robertson pupil?
a condition when the pupils do not constrict in response to bright light, but they do restrict when focused on a nearby object.
What is the dorsolateral tract of Lissauer?
A part of the pain and temperature pathway where first order neurons come to either ascend or descend to transmit pain on adjacent spinal levels.
What are alpha motor neurons?
lower motor neurons that innervate extrafusal fibers which are responsible for muscle contraction.
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