Exam 3 Flashcards
cerebellum primary function
coordinating motor functions
what motor functions does the cerebellum coordinate?
balance, equilibrium, muscle tone, motor learning
where is the cerebellum located?
posterior cranial fossa
what is the vermis?
rounded, elongated central part of the cerebellum
how many lobes does the cerebellum have?
3
what are the 3 lobes in the cerebellum called?
anterior lobe, posterior lobe, flocculonodular lobe
what separates the anterior + posterior lobes of the cerebellum?
primary fissure
which lobe is considered to be the oldest + most primitive?
flocculonodular lobe
spinocerebellum functional area charateristics
ascending, afferent, sensory input, unconscious proprioception
where is the spinocerebellum functional area located?
anterior lobe, vermis, paravermis
cerebrocerebellum functional area characteristics
descending, efferent, motor output
where is the cerebrocerebellum functional area located?
posterior lobe
vestibulocerebellum functional area characteristics
ascending, afferent, sensory input, balance
where is the vestibulocerebellum functional area located?
flocculonodular lobe
anterior lobe functions
mediate unconscious proprioception through the spinocerebellar pathways
posterior lobe functions
influences initiation, planning, and coordination of movement that helps determine the strength, direction, + scope of the movement through cerebrocerebellar pathways
flocculonodular lobe functions
rec
What are the 4 cerebellar nuclei?
dentate nucleus, emboliform nucleus, globose nucleus, fastigial nucleus
dentate nucleus characteristics
lateral hemispheres. regulates fine-control of voluntary movements, cognition, language, + sensory functions
what is the interposed nucleus?
the emboliform + globose nuclei
what is the interposed nucleus responsible for?
coordinating agonist/antagonist muscle pairs
fastigial nucleus characteristics
smallest + oldest nuclei. connected with the flocculonodular lobe
vestibulocerebellar loop
coordination of balance, vestibulo-ocular reflex, output to lower motor neurons for trunk + limb stability
spinocerebellar loop
coordination + correction of trunk + limb movements
cerebrocerebellar loop
streamlining of cortical output
what are the 3 criteria of a neurotransmitter?
- substance must be present within the presynaptic neuron
- substrate must be released in response to presynaptic depolarization + the release must be Ca+ dependent
- specific receptors for the substance must be present on postsynaptic cell
what are the main excitatory neurotransmitters?
acetylcholine, glutamate, + dopamine
what are the main inhibitory neurotransmitters?
GABA + serotonin
what are the 3 layers of the cerebral cortex, superficial to deepest?
molecular layer, purkinje cell, + granular layer
what cells are in the molecular layer?
axons of granule cells, dendrites of purkinjes, stellate cells, basket cells
what cells are in the purkinje cell layer?
large neuronal purkinje cell bodies
what cells are in the granular layer?
granule cells, golgi cells, axons from mossy fibers
neuronal sharpening
repitition of an object stimulus results in faster and better recognition of this object
excitatory cells in the 3 layers in the cerebral cortex?
climbing fibers, mossy fibers, golgi cell, granule cell
inhibitory cells in the 3 layers in the cerebral cortex?
purkinje cell, stellate cells, basket cells
what might cerebellar dysfunction present with clinically?
balance problems, gait disorders/ataxia, uncoordinated movement, speech problems, visual problems, vertigo
what are dentate ligaments?
bilateral extensions of pia mater
how many spinal nerves are there?
31 pairs
how many cervical n are there?
8 pairs
how many thoracic n are there?
12
how many lumbar n are there?
5
how many sacral n are there?
5
how many coccygeal n are there?
1
are spinal nerves sensory fibers, motor fibers, or both?
both
where do the cervical nerves exit from?
c1-c7 exit above the corresponding vertebrae
where do the rest of the spinal nerves exit from? (all except cervical)
below the corresponding vertebrae
where is the gray matter in the spinal cord?
in the middle “h” or butterfly shaped area
what are the gray matter columns?
dorsal horn, lateral horn/intermediate column, + ventral horn
dorsal horn characteristics
somatosensory. found at all levels of spinal cord
lateral horn/intermediate column characteristics
autonomic neurons that innervate visceral + pelvic organs. found in T1-L2
ventral horn characteristics
motor neurons that innervate skeletal muscle
what are the nuclei of the spinal cord?
marginal zone, substanstia gelatinosa, nucleus proprius, dorsal nucleus of clarke, interomediolateral nucleus, lateral motor neurons/medial motor neurons
marginal zone (MZ) location
the tip of the dorsal horn
marginal zone nuclei function
relays pain + temperature
substantia gelatinosa (SG) location
at the top of the dorsal horn, below marginal zone
substantia gelatinosa function
relay pain, temperature + light touch
nucleus proprius (NP) location
the neck of the dorsal horn
nucleus proprius function
relay mechanical + temperature sensation
dorsal nucleus of clarke (DNC) location
the most dorso-medial nuclei
dorsal nucleus of clarke function
UNCONSCIOUS proprioceptive info to the brain
interomediolateral nucleus (IMN) location
intermediate column + lateral horn
interomediolateral nucleus function
sensory info from viscera to brain. autonomic signals from brain to viscera
motor neurons (MN) location
ventral horns
motor neurons function
supply skeletal muscle of the limbs
what type of neurons can be in rexed lamina?
motor neurons, sensory/tract neurons, inter-neurons, propriospinal neurons
motor neurons characteristics
innervate effector tissues
sensory/tract neurons characteristics
ascend in white matter
inter-neurons characteristics
short processes
propriospinal neurons characteristics
communicate info over all distance types within the spinal cord
lamina I location
in + a little posterior to the marginal zone
lamina II location
in the substantia gelatinosa
lamina III, IV, V location
in and around the nucleus proprius
lamina VII location
intermediate gray matter, dorsal nucleus of clarke, intermediomedial column
lamina IX location
anterior horn
lamina X location
gray commissure right around spinal cord
what is another name for lamina I?
lamina marginalis or layer of waldeyer
what is the function of lamina I?
respond to noxious stimuli
lamina II associated function?
sensation of noxious/non-noxious stimuli + pain interpretation
what specific nuclei is associated with lamina II?
substantia gelatinosa
what are lamina III + IV referred to as together?
nucleus proprius
what is the main type of fibers carried by lamina III + IV?
position + light touch sense
what stimuli does lamina V respond to?
noxious + visceral afferent stimuli
what does lamina VI convey?
proprioception + spinal reflexes
what lamina corresponds with the deepest layer of the dorsal horn?
lamina VI
what pathways does lamina VI use to convey signals?
spinocerebellar
where is lamina VI absent in the spinal cord?
cervical + lumbosacral enlargements
what lamina occupies the largest region?
lamina VII
what is the location of lamina VII?
ventral + intermediate zone
lamina VII functions?
receives input from lamina II-VI + viscera. relays motor info to viscera
where is the nucleus dorsalis of clarke?
medial + ventral to dorsal horn in C8-L3
what lamina is dorsal nucleus of clarke associated with?
lamina VII
what is the function of dorsal nucleus of clarke?
form spinocerebellar tract
where are the intermediolateral cell columns located?
lateral portion of the intermediate zone
what is the function of the intermediolateral cell column?
formation of the lateral horn
where is the lateral horn of the gray matter found?
T1-L2 ONLY
where is the sacral autonomic nucleus located?
lateral part of lamina VII in S2-S4 segments
what can be found in the sacral autonomic nucleus?
preganglionic parasympathetic neurons
where is lamina VIII found?
medial aspects of the ventral horns
what regions is lamina VIII most prominent?
cervical (BP) + lumbar (lumbo-sacral plexus) enlargements
what do the cells in lamina VIII help modulate?
motor output to skeletal muscles
what descending tracts terminate in lamina VIII?
vestibulospinal + reticulospinal tracts
lamina IX locations?
small out-pockets in the dorsal lateral aspects of the ventral horns
what are lower motor neurons?
neurons that innervate skeletal muscle
alpha motor neurons
extrafusal fibers of striated skeletal muscle
what are characteristics of alpha motor neurons?
muscle contraction
gamma motor neurons
intrafusal fibers of neuromuscular spindles
what are characteristics of alpha motor neurons?
help maintain tone
what do the medial areas in lamina IX innervate?
axial musculature
what do the lateral areas of lamina IX innervate?
the muscles of the limbs
what lamina is the phrenic nucleus located in?
lamina IX
where is the phrenic nucleus located?
ventromedial area of the ventral horn in segments C2-C5
what is the function of the phrenic nucleus?
innervation of the diaphragm
what lamina is the spinal accessory nucleus associated with?
lamina IX
where is the spinal accessory nucleus located?
lateral area of the ventral horn, segments C1-C5
what can the spinal accessory nucleus also be referred to as?
CN XI
what is the spinal accessory nucleus responsible for?
innervation of the trapezius + sternocleidomastoid muscles
what lamina is the nucleus of onuf associated with?
lamina IX
where is the nucleus of onuf located?
ventrolaterrally in S1-S2 segments
what does the nucleus of onuf supply/innervate?
striated voluntary muscles of the pelvic floor
where is lamina X located?
surrounding the central canal
what is included in lamina X?
the ventral gray commissure, small neurons, neuroglia, + decussating axons
somatosensory spinal tract pathways generalization of modality
touch, pain, temperature, kinesthesia, proprioception
somatosensory spinal tract pathways generalization of the amount of receptors
usually 3
where is the primary neuron in somatosensory pathways?
dorsal root ganglion (spinal ganglion)
where is the secondary neuron in somatosensory pathways?
spinal cord or brain stem
where is the tertiary neuron in somatosensory pathways?
thalamus ( ventrobasal nuclear complex)
anterolateral system pathways
ventral/lateral spinothalamic, spinoreticular, + spinomesencephalic
Marginal zone location
Tip of the dorsal horn
Marginal zone function
Relays pain, temperature, + sensation
Substantial gelatinosa location
Top of the dorsal horn
Substantial gelatinosa function
Relays pain, temperature, + light touch
Nucleus proprius location
Neck of the dorsal horn
Nucleus proprius function
Relays mechanical + temperature sensation
Dorsal nucleus of Clarke location
Most dorsal-medial nuclei
Dorsal nucleus of Clarke function
Unconscious proprioceptive info to the brain
Interomediolateral nucleus location
Intermediate column + lateral horn
Interomediolateral nucleus function
Sensory info from visceral to the brain. Autonomic signals from brain to viscera
Motor neurons location
Ventral horn
Motor neurons function
Innervation viscera + skeletal muscles
Lamina I location
Very tip of dorsal horn
Lamina I function
Corresponds to the marginal zone (layer of waldeyer). Noxious/thermal stimuli
Lamina I tract pathway
Larger neurons contribute to contralateral spinothalamic tract
Lamina II location
Dorsal horn, reticular formation medulla
Lamina II function
Sensation of noxious + non-noxious stimuli + pain interpretation
Lamina VII location
Ventral + intermediate zone
Lamina VII function
Gives rise to cells involved in autonomic system. Relays motor info to viscera. Receives input from lamina II + VI + viscera
Lamina VII primary tract
Dorsal spinocerebellar tract ipsilaterally
Lamina VIII location
Medial aspect of ventral horn
Lamina VIII function
Modulate motor + skeletal muscle
Lamina VIII primary tract
Vestibulospinal + reticulospinal tracts
Lamina IX location
Very tip of the ventral horn
Lamina IX function
Innervates skeletal muscles
Where does dorsal column medial lemniscus tract start?
Dorsal column of spine
Where does the dorsal column medial lemniscus end?
VPL thalamus + somatosensory cortex
Does the dorsal column medial lemniscus decussate? If so, where?
Yes; medulla
How many neurons are in the dorsal column medial lemniscus?
3
Dorsal column medial lemniscus function
Vibration, fine touch, conscious proprioception
Where does lateral spinothalamic tract start
Dorsal root ganglion (drg)
Where does lateral spinothalamic tract end?
VPL of thalamus + somatosensory cortex
Does lateral spinothalamic tract decussate? If so, where?
Yes; spinal level of entrance
How many neurons are in lateral spinothalamic tract?
3
Lateral spinothalamic function
Sharp pain + temperature
Where does ventral spinothalamic tract start?
Dorsal root ganglia (DRG)
Where does ventral spinothalamic tract end?
VPL of thalamus + somatosensory cortex
Does ventral spinothalamic tract decussate? If so, where?
Yes, spinal level of entrance
How many neurons does ventral spinothalamic tract have?
3
Ventral spinothalamic function
Light touch + pressure
Where does spinoreticular tract start?
Dorsal root ganglia (DRG)
Where does 85% of spinoreticular tract end?
Medullary reticular formation
Where does 15% of spinoreticular tract end?
Interlaminar thalamic nuclei
does spinoreticular tract decussate? If so, where?
Yes, spinal level of entrance
How many neurons does the spinoreticular tract have?
3
Spinoreticular tract function
Level of consciousness/alertness in response to pain + chronic/deep pain
Where does the spinotectal tract start?
Dorsal root ganglia (DRG)
Where does spinotectal tract end?
Periaquaductal gray matter + superior colliculi
Does spinotectal tract decussate? If so, where?
Yes, spinal level at entrance
How many neurons does spinotectal tract have?
3
Spinotectal tract function
Enables us to orient eyes + head. Plays a role in pain modulation
what is another name for the spinotectal tract?
spinomesencephalic tract
Where does dorsal spinocerebellar tract start?
Clarke nucleus
Where does dorsal spinocerebellar tract end?
Cerebellum via inferior cerebellar peduncles
Does dorsal spinocerebellar tract decussate? If so, where?
No
How many neurons does dorsal spinocerebellar tract have?
2
Dorsal spinocerebellar tract function
Unconscious proprioception of trunk/lower limbs
Where does ventral spinocerebellar tract start?
Dorsal horn
Where does ventral spinocerebellar tract end?
Cerebellum via superior cerebellar peduncles
Does ventral spinocerebellar tract decussate? If so, where?
Yes, twice. Once in ventral column + once in cerebellum
How many neurons does ventral spinocerebellar tract have?
2
Ventral spinocerebellar tract function
Unconsciousness proprioception of lower limbs
Where does the cuneo-cerebellar tract start?
Dorsal root ganglia (DRG)
Where does the cuneo-cerebellar tract end?
Cerebellum via inferior cerebellar peduncles
Does the cuneo-cerebellar tract decussate? If so, where?
No
How many neurons are in cuneo-cerebellar tract?
2
cuneo-cerebellar tract function
Unconscious proprioception from upper limbs
cuneo-cerebellar tract function
Unconscious proprioception from upper limbs
Where does the rostral spinocerebellar tract start?
Dorsal root ganglia (DRG)
Where does the rostral spinocerebellar tract end?
Cerebellum via inferior + superior cerebellar peduncles
Does the rostral spinocerebellar tract decussate? If so, where?
No
How many neurons are in rostral spinocerebellar tract?
2
rostral spinocerebellar tract function
Conveys muscle tension from upper limbs
Where does the spino-olivary tract start?
Dorsal root ganglia (DRG)
Where does the spino-olivary tract end?
Cerebellum directly via inferior cerebellar peduncles
Does the spino-olivary tract decussate?
Yes
How many neurons are in the spine-olivary tract?
3
spino-olivary tract function
Unconscious proprioception + cutaneous impulses
Where does the lateral corticospinal tract start?
Pyramidal motor neurons in primary motor cortex
Where does the lateral corticospinal tract end?
Distal limb musculature
Does the lateral corticospinal tract decussate? If so, where?
Yes, distal pyramids of the medulla
How many neurons does the lateral corticospinal tract have?
2
lateral corticospinal tract function
Voluntary muscle contraction of distal limb musculature
Where does the ventral corticospinal tract start?
Pyramidal neurons in the primary motor cortex
Where does the ventral corticospinal tract end?
Axial musculature
Does the ventral corticospinal tract decussate? If so, where?
No
How many neurons does the ventral corticospinal tract have?
2
ventral corticospinal tract function
Voluntary muscle contraction of axial musculature
Where does the lateral vestibulospinal tract start?
Lateral portion of the vestibular nuclei in brainstem deiter’s nucleus
Where does the lateral vestibulospinal tract end?
Anti-gravity muscles
does the lateral vestibulospinal tract decussate? If so, where?
No
How many neurons does the lateral vestibulospinal tract have?
2
lateral vestibulospinal tract functions
Maintains balance + upright posture by compensating for unknown movements made by the body. Aka anti-gravity muscles
Where does the medial vestibulospinal tract start?
Medial portion of the vestibular nuclei in the brainstem
Where does the medial vestibulospinal tract end?
Head + neck muscles
does the medial vestibulospinal tract decussate? If so, where?
No
How many neurons does the medial vestibulospinal tract have?
2
medial vestibulospinal tract function
Stabilizes head position in relation to eye movements w/vestibular stimuli. Communication w/CNs for eye movements (LR6SO4/3)
Where does the reticulospinal tract start?
Reticular formation in the pons
Where does the reticulospinal tract end?
Interneurons that project to both sides of the spinal cord
does the reticulospinal tract decussate? If so, where?
May or may not decussate
How many neurons does the reticulospinal tract have?
2
reticulospinal tract function
Locomotion + postural control by influences of alpha + gamma motor neurons through interneurons
Where does the tectospinal tract start?
Nucleus in superior colliculus
Where does the tectospinal tract end?
Motor neurons in cervical cord
does the tectospinal tract decussate? If so, where?
Yes, IMMEDIATELY
How many motor neurons does the tectospinal tract have?
2
tectospinal tract function
Mediates head + neck movement in response to environment stimuli
Where does the rubrospinal tract start?
Red nucleus in tegmentum of midbrain
Where does the rubrospinal tract end?
Motor neuron in anterior horn
does the rubrospinal tract decussate? If so, where?
Yes
How many neurons does the rubrospinal tract have?
2
rubrospinal tract function
Assists in fine motor control (mostly flexors of the upper limb)
is the DCML tract ascending or descending?
ascending
is the lateral spinothalamic tract ascending or descending?
ascending
is the ventral spinothalamic tract ascending or descending?
ascending
is the spinoreticular tract ascending or descending?
ascending
is the spinomesencephalic tract ascending or descending?
ascending
is the dorsal spinocerebellar tract ascending or descending?
ascending
is the ventral spinocerebellar tract ascending or descending?
ascending
is the cuneo-cerebellar tract ascending or descending?
ascending
is the rostral spinocerebellar tract ascending or descending?
ascending
is the spino-olivary tract ascending or descending?
ascending
is the lateral corticospinal tract ascending or descending?
descending
is the ventral corticospinal tract ascending or descending?
descending
is the lateral vestibulospinal tract ascending or descending?
descending
is the medial vestibulospinal tract ascending or descending?
descending
is the reticulospinal tract ascending or descending?
descending
is the tectospinal tract ascending or descending?
descending
is the rubrospinal tract ascending or descending?
descending
Which spinal levels are associated with sympathetic function and lateral horns?
T1-L2
what is the function of the dorsal horn?
a. somatosensory info
b. autonomic info of abdominal + pelvic viscera
c. motor neurons
somatosensory info
what is the function of the lateral horn?
a. somatosensory info
b. autonomic info of abdominal + pelvic viscera
c. motor neurons
autonomic info of abdominal + pelvic viscera
what is the function of the ventral horn?
a. somatosensory info
b. autonomic info of abdominal + pelvic viscera
c. motor neurons
motor neurons
