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126 Cards in this Set

  • Front
  • Back
Which pathway provides motor signals going down?
Corticospinal Tract
Which pathways provide sensory tracts going up?
1. Spinothalamic Tract
2. Dorsal Column
What percentage of motor fibers crossover in the decussation of the pyramids. Where do those fibers end up? Where do the fibers that do not crossover end up?
1. 80%
2. Lateral Funiculus of the Corticospinal Tract
3. Ventral Corticospinal Tract
What purpose do the fibers in the ventral corticospinal tract serve?
The innervate the axial musculature.
Why do some strokes only appear to affect the distal musculature?
They only affect the lateral corticospinal tract, leaving the ventral aspect - which controls the axial musculature - unaffected.
What does the dorsal column become?
Medial lemniscus
What modalities does the dorsal column carry?
Vibrations, proprioreception and two point touch
The cell bodies of the primary sensory neurons of the dorsal column are found where?
Dorsal root ganglion outside the spinal cord
What are the first fibers to enter the dorsal funiculus? What do they make up?
1. Leg fibers enter first
2. Facisculus graciulus
What are the second fibers to enter the dorsal funicilus? What do they make up?
1. The arm fibers enter second
2. Facisculus cuneatus
Where do fibers that file into the dorsal funiculus synapse?
The caudal medulla
How do the fibers of the dorsal funiculus crossover? What positions do they end up in? What structure are they dorsal to?
1. They twist as the crossover.
2. The arm fibers end up being dorsal while the legs end up being vateral (both of these are medial as)
3. Decussation of the pyramids
What are the fibers of the dorsal funiculus that can been seen crossing over called?
Arcuate fibers
Where do you find the fasiculus cuneatus and gracilus relative to their nuclei?
Lateral
The nuclei of the spinal tract of V has similar function as what?
The spinothalamic tract
What are the modalities of the Spinal Tract of V?
Pain and temperature sensation of the face
Where is the spinal tract of V in relation to its nucleus?
Lateral
What part of the pain and temperature homounculous does the spinal tract of V contribute to? The spinothalamic tract?
1. Spinal tract of V - Head
2. Spinothalamic tract - Arms and Legs
If there is damage to the Spinal Tract of V before the fibers cross, one sees (ipsilateral/contralateral) pain and temperature sensation loss?
Ipsilateral
What system is responsible for headaches?
The trigeminal system
In the trigeminal system, where are the primary sensory neurons located?
Outside the CNS, in the trigeminal ganglion
Where do the sensory fibers of the Spinal Tract of V synapse? What happens next?
1. Anywhere along the Spinal Nucleus of V
2. They crossover to the spinothalmic tract to provide the head of teh homonuculous
Can one see the crossover of fibers in the Spinal Tract of V? Why or why not?
No because the crossover is very gradual
If the spinothalamic tract is ever damaged, one sees (ipsilateral/contralateral) pain and temperature sensation loss.
Contralateral
Where do the Spinal Tract and Nucleus of V begin?
Mid Pons
Where does the trigeminal nerve enter?
The level of the pons
What are the four nuclei associated with the Spinal Tract of V?
1. Chief Sensory Nucleus
2. Spinal Nucleus
3. Mesencephalic Nucleus
4. Motor Nuceus
Where do the fibers of the spinothalamic tract synapse?
The dorsal horn
Where do the fibers of the spinothalamic tract crossover?
Anterior white commissure
What defect can cause a suspended sensory defect?
Syrinx
In the spinothalamic tract, which neurons enter first? Second?
1. Legs enter first
2. Arms enter second
Where do all sensory pathways end up before they make it to the cortex?
The thalamus
What are the two nuclei in the thalamus?
1. Ventral Posterior Medial
2. Ventral Posterior Lateral
In the homounculus in the thalamus, what part of the body is associated with the VPM and the VPL?
1. VPM - Head
2. VPL - Body (legs are most lateral)
What part of the spinal tract allows some of the fibers of the spinothalamic tract to move up or down BEFORE they synapse in the dorsal horn?
Lissauer's Tract
Where is Lissauer's tract located in relation to the beginning of the dorsal horn?
Dorsal and lateral
Where is the spinothalamic tract in relation to the Spinal Nucleus of V?
Ventral (just below)
Within the spinothalamic tract, where do the leg fibers run? The arm fibers?
1. Legs are lateral
2. Arms are medial
Where do you see the nucleus of CN XII?
In very center of the caudal medulla
What contributes to CN XI?
Part of the Spinal Accessory Nucleus and part of the cervical spinal cord
Where is the spinal accessory nucleus located?
Lateral to the dorsal aspect of the decussation of the pyramids.
Where do the alpha motor fibers of the spinal accessory nucelus go?
Trapezius and SCM
What is a result of a hyperactive CN XI?
Cervical dystonia
What are the main two things one should first notice in the rostral medulla?
1. Pyramids
2. Inferior olivary nucleus
Where does one see the nucleus of CN XII in a rostral section?
They are located towards the dorsal midline.
The rootlets of CN XII exit between what two structures?
Inferior olivary nucleus and the pyramids
What fibers enter the inferior olivary nucleus?
Central tegmental tract fibers
What fibers exit the inferior olivary nucleus and where do they go upon exit?
1. Olivocerebellar fibers
2. The inferior cerebellar peduncle of the opposite side
What type of stain is used for locating white matter?
Weigert stain
What nucleus looks like an eye all by itself?
Solitary Nucleus
Which nucleus is described as having a tract in the center with the actual nucleus around the tract?
Solitary nucleus
What nucleus is located medial to the solitary nucleus?
The dorsal motor nucleus of X
What is the nebulous regoin medial to the solitary nucleus and what is its function? Why is it nebulous?
1. Reticular formation
2. Control HR, BP, sympathetic pathways
3. So that some sort of insult doesn't wipe all the functions out
What are two functions of the solitary nucleus?
1. Special sensory - toxins, CO2 levels and pressure
2. Taste
What is dysautonomia?
Nerves of the reticular formation do not work correctly resulting in fluctuating vital signs.
What functions does the dorsal motor nucleus of X serve?
Sends motor signals to smooth muscle and cardiac muscle
Why does the motor nucleus of X sit next to the solitary nucleus?
So that information collected by the solitary nucleus can result in HR and BP changes.
What is responsible for gut motility?
Dorsal Motor Nucleus of X
Where are you if you see CN XII?
Medulla
Where are you if you see CN V?
Mid Pons
What does the nucelus ambiguous contain?
Apha motor neurons
Where do you find the nucleus ambiguous?
Medial to the spinothalamic tract
What muscles does the nucleus ambiguous control?
Muscles of the larynx and pharynx
Damage to what nucleus could cause a change in voice or liquids coming out of the nose upon swallowing?
Nucleus ambiguous
What sensory functions does the vagus nerve carry? Motor?
1. Pain and special sense (baroreceptor and chemoreceptor)
2. Heart, blood vessel walls, gut ect
Glossopharyngeal Nucleus fibers go into what nuclei?
1. Solitary Nucleus
2. Spinal nucleus of V
CN IX is mainly involved in what?
Taste
The motor aspect of CN IX is contributed by what nucleus? What muscle does it innervate?
1. Nucleus ambiguous
2. Stylopharyngeus
In the rostral medulla, is the Spinal Nucleus of V large or small?
Small, remember it is like a bowling pin...skinny at the top and fat at the bottom
What is the nucleus of scattered neurons that go into the midbrain?
Mesencephalic Nucleus of V
What is the nucleus of primary sensory, pseudounipolar neurons that were sucked into the brainstem and were pulled up rostrally into the midbrain?
Mesencephalic Nucleus of V
What synapses directly on the motor nucleus of V which sends motor neurons to the muscles of eating?
Mesencephalic Nucleus of V
What is responsible for the jaw-jerk reflex?
Mesencephalic Nucleus of V
The trigeminal sensory function is responsible for what modalities?
Vibration and Proprioreception
Which nucleus sends information from the inner ear to the axial musculature and eyes?
Vestibular nuclei
What are the two pathways information leaving the vestibular nuclei can take?
1. Ventral funiculus
2. Medial longitudinal fasciculus
Which two nuclei does the MLF synapse on?
Nuclei for CN III and VI
If one were to drink too much and develop nystagmus, what pathway is affected?
Vestibular nuclei pathway involving the medial longitudinal fasciculus
What is another name for the area lining the 4th ventricle? What its function?
Area postrema - the vomiting center
What area postrema close to?
1. Vestibular pathways
2. Nucleus solitarious
3. Dorsal Motor Nucleus X
Why is the area postrema the vomiting center? What does it do?
It does not have a good BBB and can sense toxins and activate the dorsal motor nuclues of X to cause vomiting.
What are the fibers in the pons that will eventually make up the pyramids in the medulla? What tract to they belong to?
1. Pyramidal fascicles
2. Corticospinal tract
What coordinates the pyramidal fascicles?
The cerebellum on the contralateral side
What nuclei and fascicles is responsible for connecting the corticospinal tract to the contralateral cerebellum?
Pontine nuclei and fascicles
What level do you find the inferior cerebellar peduncle?
Medulla
What level do you find the middle cerebellar peduncle?
Pons
What level do you find the superior cerebellar peduncle?
Cerebellum
Which cerebellar peduncle is the largest? What is it mainly composed of?
Middle - pointine fascicles
Where do the fibers from the superior cerebellar peduncle go?
North to the spinocerebllar tract
How do pyramidal fascicles run in the brainstem?
Longitudinally
Describe the pathway a signal coming down the sorticospinal tract takes.
1. Travels down the pyramidal fascicles
2. Synapses on the pontine nucleus
3. Pontine fascicles send the information to the contralateral cerebellum
4. Pontine cerebellum send information back to the corticospinal tract through the superior cerebellar peduncle
The motor nucleus of CN VII is found in the same place as you would find what in the rostral medulla?
Nucleus ambiguous
The alpha motor neurons cross over the nucleus of what CN in what location before exiting medial to what CN?
1. CN VI
2. The floor of the 4th ventricle
3. CN VIII
Alpha neurons innervate...
Muscle
Gamm neurons innervate...
muscle spindles
CN VIII is lateral to what CN?
CN VII
The cochlear nucleus is lateral to what? What is it shaped like?
1. CN VIII nucleus
2. Kidney bean
How is the cochlear nucleus arranged? What does this mean?
1. Tonotopically
2. Higher pitch signals go to the inner curve while lower pitch signals go to the outer curve
Describe the pathway for hearing
1. Cochlear nucleus outputs go bilaterally via the trapezoid body to...
2. The superior olivary nuclei to the...
3. Inferior colliculus via the lateral lemniscal pathway through...
4. The branchium of the inferior colliculus to the...
5. Medial geniculate body of the thalamus to...
6. Heschls gyrus
What is the superior olivary nucleus responsible for?
Sound localization in 3D space
Can damage outside the brainstem wipe out all hearing on one side?
Yes
When you see the flocculi, where are you?
Caudal pons
What nucleus replaces the nucleus of CN XII in the floor of the 4th ventricle?
Nucleus of CN VI
At what point does CN VI exit?
At the midline of the PMJ
What is the projection of CN VI into the floor of the 4th ventricle called?
Facial colliculus
What are the upper motor neurons to the cranial nerves called? How do these usually synapse? What is the exception?
1. Corticobulbar fibers
2. Bilaterally
3. The facial nucleus below the eye
What puts the head on the sensory homunculus of the medial lemniscus? What are its modalities?
Sensory nucleus of V - proprioreception and vibration
What separates the senory and motor nuclei of V?
Sulcus limitans
What marks the second highest level of the pons?
No cranial nerves
What produces seratonin?
Raphe nucleus
What flanks the beginning of the cerebral aqueduct? What is produced there?
Locus ceruleus - norepi
Describe the lemniscal boomerang
1. The lateral lemniscus - carries audio input and has nuclei in it

2. Medial lemniscus - head from V is medial, legs are lateral with arms inbewteen

3. STT is at the curve of the boomerang between the later and medial lemniscus
What is the most rostral part of the pons identified by?
Decussation of the superior cerebellar pyramids.
Describe each level of the pons.
1. Medulla/Pons Jnx - CN 8 & 7 w nuclei fusion of pyramidal fascicles
2. CN 7 & 6 - facial colliculus & nucleus, superior olivary nuc & trapazoid body
3. Mid Pons - Trigeminal nerve with main motor and sensory nuclei
4. Start of SCP, raphe and LC, no CNs
5. Decussations of both SCP and CN IV
What CN decussates on the dorsal surface of the rostral-most pons? Why? Where exactly does it decussate?
1. CN IV
2. So they control the contralateral eye
3. Roof of the cerebral aqueduct
What is the grey matter around the cerebral aqueduct called? What does it mediate? What type of NT do you find there? What else do you find there?
1. Periaqueductal grey matter
2. Pain control
3. Enkephalin
4. Raphe nucleus
What neurons are scattered in the periaqueductal grey matter?
Mesencephalic nucleus of V
When the two trigeminal heads of the STT and ML are superimposed together it is called what? Where does it go?
1. Trigeminal Thalamic Tract
2. VPM Nucleus
Where do you find the nucleus of CN IV (level and actually in cross-section)?
1. Caudal Midbrain
2. Dorsal to the MLF and ventral to the cerebral aqueduct. Also lateral to the raphe nucleus
What enters the inferior colliculus at the level of the caudal midbrain?
Lateral lemniscus
CN III leaves where?
Interpeduncular fossa
What level do you see the red nucleus?
The rostral midbrain
What do you no longer see in the rostral midbrain?
The lateral lemniscus
What carries audio input from the inferior colliculus to the thalamus?
Branchium of the inferior nucleus
What level do you find the nucleus of CN III? Where in cross-section?
1. The rostral midbrain
2. Ventral to the periaqueductal grey matter
Whatnucleus is medial and dorsal to CN III? What does it control?
1. Edinger-Westphal nucleus
2. Parasympathetic control to the eyelids and iris