Pathways Flashcards
1
Q
What is the primary function of the spinothalamic tract?
A
The spinothalamic tract primarily transmits pain and temperature sensations to the brain.
2
Q
Name the two main types of sensory receptors associated with the spinothalamic tract.
A
A-delta and C
3
Q
Fill in the blank: The spinothalamic tract ascends from the spinal cord to the ________ in the thalamus.
A
ventral posterior nucleus (VP)
4
Q
What is the location of the first-order neurons in the spinothalamic tract?
A
The first-order neurons are located in the dorsal root ganglia.
5
Q
Which Rexed laminae are primarily associated with the spinothalamic tract?
A
Lamina I and Lamina II (substantia gelatinosa). (And 5)
6
Q
What is the pathway taken by second-order neurons in the spinothalamic tract?
A
Second-order neurons ascend contralaterally via the white anterior commisure
7
Q
Fill in the blank: The spinothalamic tract is part of the ________ system.
A
anterolateral
8
Q
Which part of the brain processes the sensory information carried by the spinothalamic tract?
A
Somatosensory cortex
9
Q
Where do the third-order neurons of the spinothalamic tract project to?
A
They project to the primary somatosensory cortex.
10
Q
What does DCML stand for?
A
Dorsal Column-Medial Lemniscus pathway
11
Q
Which type of sensory information does the DCML pathway primarily transmit?
A
Fine touch, vibration, and proprioception
12
Q
Name the two main fascicles involved in the DCML pathway.
A
Fasciculus cuneatus and Fasciculus gracilis
13
Q
True or False: The Fasciculus cuneatus carries sensory information from the upper body.
A
True
14
Q
True or False: The Fasciculus gracilis carries sensory information from the lower body.
A
True
15
Q
Where do the first-order neurons of the DCML pathway synapse/terminate?
A
The cuneatus and gracillis nuclei in the medulla oblongata
16
Q
Fill in the blank: The second-order neurons of the DCML pathway decussate in the _____ before ascending to the thalamus.
A
medulla oblongata
17
Q
What is the name of the fine motor tract formed by the second-order neurons after decussation?
A
Medial lemniscus
18
Q
Where do the second-order neurons of the DCML pathway relay sensory information? (Terminate)
A
Ventral posterolateral nucleus (VPL) of the thalamus
19
Q
What is the final destination of the sensory information transmitted by the DCML pathway?
A
Primary somatosensory cortex (postcentral gyrus)
20
Q
Which part of the body is primarily represented in the Fasciculus cuneatus?
A
Upper limbs and upper trunk
21
Q
Which part of the body is primarily represented in the Fasciculus gracilis?
A
Lower limbs and lower trunk
22
Q
True or False: The DCML pathway is responsible for transmitting pain and temperature sensations.
A
False
23
Q
What type of fibres are primarily involved in the DCML pathway?
A
A-alpha and A-Beta
24
Q
First order neurons of cochlear tract (ignoring the ones that go from the hair cells to the spiral ganglion)
A
Go from the spiral ganglion to the ventral and dorsal cochlear nucleus
25
What are the two types of neurons found in the cochlear nucleus?
Dorsal neurons and ventral neurons.
## Footnote
These neurons have different pathways and destinations within the auditory system.
26
What level do dorsal cochlear neurons decussate and what tract?
They decussate at the level of the pons and go up the lateral lemniscus contralaterally to the inferior conniculus.
## Footnote
Decussation refers to the crossing over of nerve fibers from one side of the brain or spinal cord to the other.
27
What is the pathway of ventral neurons in the cochlear pathway?
Ventral neurons go to the superior olivary nucleus ipsilaterally and contralaterally, then to the lateral lemniscus.
## Footnote
This pathway is important for sound localization.
28
Where do the second order neurons of the cochlear pathway go and terminate
Go from the dorsal and central cochlear nuclei to the inferior colliculus via lateral lemniscus and terminate there (ignoring the ventral pathway)
## Footnote
The inferior colliculus is a key auditory center in the brain.
29
What is the third order neuron in the cochlear pathway?
Neurons go from the inferior colliculus to the medial geniculate nucleus in the thalamus.
## Footnote
This order is critical for further processing of auditory information.
30
What is the fourth order neuron in the cochlear pathway?
Neurons go from the medial geniculate nucleus to the auditory cortex in the temporal lobe.
## Footnote
The auditory cortex is responsible for the perception of sound.
31
Fill in the blank: The cochlear pathway consists of __________ order neurons.
three
32
True or False: The cochlear pathway involves only ipsilateral connections.
False
## Footnote
The pathway includes both ipsilateral and contralateral connections.
33
What are nociceptors and their relation to Rex lamina?
Nociceptors are sensory receptors that respond to harmful stimuli and project to Rex lamina 1, 2, and 5.
## Footnote
Rex lamina refers to specific layers in the spinal cord where sensory information is processed.
34
Which substances are involved in the transmission of pain signals?
Glutamate, Substance P and CGRP (Calcitonin Gene-Related Peptide).
## Footnote
These neuropeptides are crucial for pain signaling in the nervous system.
35
What is the pathway for pain signal transmission?
Pain signals decussate via the anterior commissure and ascend through the spinothalamic tract.
## Footnote
Decussation refers to the crossing of nerve fibers from one side of the central nervous system to the other.
36
What is the role of the third-order neuron in pain pathways?
The third-order neuron projects to the somatosensory cortex, specifically from the VP of thalamus.
## Footnote
This pathway is essential for the perception of pain in the brain.
37
What type of touch does the pathway involving axons Aβ deal with?
Fine touch.
## Footnote
Aβ fibers are responsible for transmitting fine touch and proprioception signals to the central nervous system.
38
Where do Aβ fibers ascend in the spinal cord?
They ascend ipsilaterally up the dorsal column.
## Footnote
Ipsilateral ascending means that the fibers remain on the same side of the body as they travel up the spinal cord.
39
What are the two main fasciculi in the dorsal column?
* Fasciculus cuneatus
* Fasciculus gracilis
## Footnote
These fasciculi carry sensory information from the upper and lower parts of the body, respectively.
40
What happens to the fibers in the medial lemniscus?
They decussate at the medulla.
## Footnote
The medial lemniscus is a major sensory pathway that carries touch and proprioceptive information.
41
What is the second to last destination of the sensory signals in the DCML pathway?
The thalamus, specifically the ventral posterior nucleus (VP).
## Footnote
DCML stands for Dorsal Column-Medial Lemniscus pathway, which is essential for transmitting fine touch and proprioception.
42
Fill in the blank: The pathway responsible for transmitting fine touch and proprioception is called the _______.
DCML.
## Footnote
DCML stands for Dorsal Column-Medial Lemniscus pathway.
43
True or False: The dorsal column-medial lemniscus pathway carries pain signals.
False.
## Footnote
The DCML pathway is primarily responsible for fine touch and proprioception, while pain signals are carried by the spinothalamic tract.
44
What is the role of the right semicircular canals (SSC) during right sided head movement?
They get activated when the head turns to the right.
## Footnote
This activation occurs due to movement towards the kinocilium.
45
What happens when the head is turned to the left?
The left semicircular canals (SSC) get activated, while the right SSC does the opposite.
## Footnote
This is part of the vestibular system's response to head movement.
46
Where do the action potentials from the vestibular ganglion go?
They go to the vestibular nuclei.
## Footnote
This pathway is essential for processing balance and spatial orientation.
47
After you turn ur head to the right what happens to right-sided signals going to the vestibular nuclei and what does it lead to
Some decussate and goes to the contralateral abducens nuclei and tells left lateral rectus to contract, the rest goes to ipsilateral oculomotor nuclei and tell right medial rectus to contract so u end up looking to the left (where your gaze was originally)
## Footnote
This crossing over is important for coordinated responses.
48
What cranial nerves are involved in the vestibulooccular reflex
Cranial nerves III (oculomotor) and VI (abducens).
## Footnote
These nerves control eye movements in response to head movements.
49
Which muscle does the left abducens nerve innervate?
The left lateral rectus muscle.
## Footnote
This muscle is responsible for moving the eye laterally.
50
Which muscle does the right oculomotor nerve innervate?
The medial rectus muscle in the right eye.
## Footnote
This muscle is responsible for moving the eye medially.
51
When the head is turned, how do the eyes respond?
The eyes move in the opposite direction of the head turn.
## Footnote
This reflex helps maintain visual stability.
52
Tell me the first part of transduction cascade for rod cells
Light hits rhodopsin in rod cell which causes retinal it it to change from 11-cis retinal to all-trans retinal, this process releases opsin which goes and activated transducin, transducin activates a phosphdiasterase which breaks cGMP which deactivates sodium channels and leads to hyperpolarisation, reducing the action potential to bipolar cells
53
3 types of photoopsin and what wavelength they respond to
S-photopsin (blue) (short wavelength)
M-photopsin (green) (medium wavelength)
L-photopsin (red) (long wavelength)
54
Tell me next part of phototransduction cascade starting from bipolar cells
Bipolar cells receive decreased glutamate which actually activates the bipolar cells and send a *receptor* potential to the ganglion cells which gets activated and an action potential is sent down the optic nerve
55
What do horizontal and amacrine cells release and why
GABA which modulates the action potentials down the optic nerve
56
Second order neurons for optic nerve
From the visual ganglia down the left and right optic nerve, some go through chiasm and decussate some stay ipsilateral but then they form the optic tract, optic tract goes to lateral geniculate nucleus where they terminate
57
Where do the ipsilateral and contralateral fibres go to in the lateral geniculate nucleus
6 parts, ipsilateral fibres go to 2,3 and 5.
Contralateral fibres go to 1,4 and 6
58
What pathway is the medial geniculate nucleus part of?
Auditory
59
What pathway is lateral geniculate nucleus part of
Visual
60
First order neurons of optic nerve
The bipolar cells in retina synapsing with the ganglion cells which then form the optic nerve
61
Third order neurons of optic pathway
From the lateral geniculate nucleus some fibres go to the superior coniculus, some go to the pretectal nucleus (for light reflex) but what we’re interested in go from the LGN and split it into two optic radiations, one superior that goes through parietal lobe (Baums loop) and one inferior that goes through temporal lobe (Meyers loop) which all go and synapse at the primary visual cortex (Striate cortex)
62
What artery supplies the macula of the eye
Middle cerebral artery (can lead to macular sparing)
63
What is the 3rd type of light-sensitive pigment and where is it located
Melanopsin - located in the ganglion cell of the retina
64
What does melanopsin do
When light it shined into the eye it is activated and sends signals to active the pupillary light reflex also reacts to blue light and helps regulate circadian rhythm
65
Describe the pupillary light reflex when light is shined into the right eye
When melanopsin is activated it sends signals down the right and left optic nerve, after it passes to the lateral geniculate nucleus some fibres go to the pretectal nucleus (bilaterally) fibres then go to the Edinger-Westphal nucleus also bilaterally. The EWN parasympathetic fibres travels with the oculomotor nerve, go to ciliary ganglia, go to the eye, pierces the sclera and supplies sphicter pupillae muscle in the iris, sphicter pupillae is the circular muscles that causes the iris to contract = less light enters pupil
66
What is the response for the right and left eye when light is shined into the right eye
Right eye = direct response
Left eye = consensual response
67
The accommodation reflex for looking at close objects is caused by contraction of what muscle and what pathway/reflex does it mirror
Contraction of cilliaris muscle and mirror the pupillary light reflect
68
What type of fibres causes contraction of ciliaris and sphincter pupillae
Parasympathetic fibres coming from edinger-westphal nucleus
69
Where do the short ciliary nerve come from
Edinger-Westphal nucleus
70
How does accommodation for far objects happen
From dorsal horn of spinal cord sympathetic fibres go to the superior cervical ganglion, wraps around internal carotid artery becomes part of the long ciliary nerve and causes ciliaris to relax and causes dilator pupillae to contract (radial muscles) (pulls iris apart from middle)
71
Mesolimbic pathway
From ventral tegmental area (VTA) in the midbrain to the nucleus accumbens
72
Mesocortical pathway
From Ventral tegmental area (VTA) to the cerebral cortex
73
Two parts of Substantia Niagra and what they do
SB pars compacta (releases dopamine) SB pars reticulata (with the GB interus)
74
Acronym for direct pathway and the order of pathway in terms of structure
Every insomnia institution excels
Cortex —> striatum —> globus pallidus internus and SN pars reticulata —> thalamus —> cortex
75
Acronym for indirect pathway and structures it passes through
Every insomnia institution excels in Egypt
Cortex —> striatum —> globus pallidus externus—> subthalmic nucleus
—> Globus pallidus internus and SN pars reticulata —> thalamus —> cortex
76
Where does the Tuberoinfundibular pathway go from and to
From hypothalamus to the pituitary gland
77
Relationship between dopamine, prolactin and FSH
Decreased dopamine increases prolactin which decreases FSH leading to Amenorrhea
78
Describe the pathway of corticobulbar tract and their type of innervation/input for cranial nerve 3, 4 and 5 and 6
Go from the primary motor cortex, descend through the corona radiata and converge into and through the posterior limb of internal capsule alongside the corticospinal tract and bilaterally innervate cranial nerves 3, 4, 5 (motor/mandibular branch that supplies muscles of mastication) and 6
79
How does the corticobulbar tract supply cranial nerve 7
Cranial nerve 7 (facial nerve) is located in the pons and has an upper and lower part of it nucleus, the upper part innervates the forehead and is innervated bilaterally while the lower part innervates the lower face and is innervated contralaterally
80
What happens to the face if there is an left upper motor lesion
Since the upper motor neurons bilaterally innervates the upper face and only contralaterally innervates the lower face if there is a lesion in the left UPN the right UPM will keep the forehead innervated so you’ll only lose motor control over right lower face
81
What happens to the face if there is a left lower motor lesion
LMN lesion means it comes after the synapse to the facial nuclei meaning after the decussation so it would cause ipsilateral facial motor loss in both the upper and lower face
82
Describe the innervation of nucleus ambiguus and what cranial nerves it has where it’s located and what it innervates and cranial nerve 11
Nucleus ambiguus contains motor neurons that supply skeletal muscles of pharynx, larynx and soft palate through CN 9, 10 and 11, it is innervated bilaterally by the corticobulbar tract and is located into the medulla.
Cranial nerve 11 is also bilaterally innervated by corticobulbar tract and supplies the SCM and Trapezius
83
Explain the innervation of corticobulbar tract of cranial nerve 12 and its effects in an left upper motor lesion
Corticobulbar tract contralaterally innervates the hypoglossal nuclei so if there is an left UML the right side of the tongue would not work, and only the left which would deviate the tongue towards the right (if left upper motor lesion tongue deviates away from affected side) (try moving ur tongue with only right side and see what happens)
84
Explain what happens in a right lower motor lesion for cranial nerve 12
Lower motor lesion innervates ipsilateral side of tongue so if there is a right RML right side of tongue doesn’t work so tongue deviates to the right (side of LML)
85
Describe the pathway of the corticospinal tract
Behind in the primary motor cortex, goes thorough corona radiata, through the posterior limb of internal capsule alongside corticobulbar tract, goes down to the midbrain via the cerebral peduncles until it reaches the pyramids in the medulla. At the pyramidal decussation 90% of the fibres decussate to form the lateral corticospinal tract while the remaining 10-20% stay on the same side and form the anterior corticospinal tract which may decussate at the level of the spinal tract they leave at. Both the lateral and anterior corticospinal tracts synapse with the lower motor neurons in the anterior horn of the spinal cord which then leave the spinal cord and innervate their respective muscles
86
Upper motor neuron lesion (corticospinal tract)
Increased muscle tone (spasticity), hyperreflexia, contralateral paresis (weakness) babinski’s sign present
87
Lower motor neuron lesion (corticospinal tract)
Decreased muscle tone (flaccidity), hyporeflexia or areflexia, ipsilateral paresis or plegia
88
Tell me how the stretch reflex works
When a muscle is abnormally stretched (like when you tap a tendon) muscle spindles are activated causing type 1a and type 2 afferent fibres (sensory fibres going *towards* spinal cord) to go from the muscle spindle to the spinal cord and directly synapse with an alpha motor neuron (efferent fibre) which sends signals to the same muscle and causes it to contract, the type 1a and 2 fibres also send a signal to an inhibitory interneuron in the spinal cord to prevent the alpha motor fibres to the antagonistic muscle to contract which is to help prevent injury (this is called reciprocal innervation)
89
What does CN 1 pass through
Cribriform plate
90
What does CN 2 pass through
Optic canal
91
What does CN 3 pass through
Superior orbital fissure
92
What does CN 4 pass through
Superior orbital fissure
93
What does CN 5 pass through
V1 - opthalmic branch - superior orbital fissure
V2 - maxillary branch - foramen rotundum
V3 - mandibular branch - foramen ovale
94
What does CN 6 pass through
Superior orbital fissure
95
What does CN 7 pass through
Internal acoustic meatus
96
What does CN 8 pass through
Internal acoustic meatus
97
What does CN 9 pass through
Jugular foramen
98
What does CN 10 pass through
Jugular foramen
99
What does CN 11 pass through
Jugular foramen
100
What does CN 12 pass through
Hypoglossal canal
101
What does the chart for the cranial nerve modalities look like and instructions on how u do it
- SAVE VA SAVE VASE
- Phone number 251-5303 (the 2 and 1 in the first 3 digits make 3 and u keep the 5 and then it’s just 03 so it’s 251-5303)
- add CN 8 for SSA, 11 to SVE and the motor only CNs to the GSE
102
Pathway of light hitting layers of retina
Ganglion cell layer then inner plexiform layer then inner nuclear layer then outer plexiform layer then outer nuclear layer then photoreceptors then pigment layer
Amacrine cells are more superficial and horizontal cells are deeper in
103
Where will uvula deviate if there is left vagus nerve lesion
Vagus nerve innervates the soft palate, and supples the soft palate ipsilaterally so if there is a lesion on the left vagus nerve the left soft palate won’t contract and will dip moving the uvula to the right
104
Good way to remember tongue deviation
UMN of hypoglossal provides contralateral innervation so tongue will move contralaterally so upper left lesion tongue deviates to right, if it’s LMN innervation is ipsilateral so tongue will move ipsilateral so lower left lesion will deviate tongue to the left
105
What supplies tongue
Anterior 2/3rd taste is supplied by facial never (via chordo tympani branch)
Anterior 2/3rd general sensation
produced by mandibular branch of trigeminal
Anterior 1/3rd taste and touch is by glossopharngeal nerve
Motor supplied by hypoglossal nerve
