neuro Test 2 Flashcards
(100 cards)
1
Q
Cauda equina
A
in subarachnoid space in lumbar and sacrum
2
Q
Naming nerve roots
A
Run over the named vertebra until C7- where nerve runs under and is called C8 nerve root
3
Q
Definition of a neurotransmitter- 4 points
A
- Synthesized by a neuron
- Accumulates in presynaptic terminals from which release occurs
- When released, produces same response as when exogenous source is applied
- Is removed from the synaptic cleft
4
Q
4 categories of neurotransmitter
A
- Acetylcholine (Ach)
- Biogenic Amines
- Amino Acids
- Peptides
5
Q
Acetylcholine (Ach)
A
major neurotransmitter of parasympathetic nervous system, both pre and post ganglionic.
also for sympathetic preganglionic neurons
used at neuromuscular junctions
in nuclei of the brain for learning, spatial and recognition memory. (Die in Alzheimers disease)
6
Q
Biogenic amines
A
contain an NH2 group. norepinephrine, serotonin and dopamine.
7
Q
Norepiniephrine
A
type of biogenic amine
neurotransmitter of postganglionic sympathetic neurons.
in CNS- localized to locus ceruleus in brain stem. function to modulate central sensory nuclei, activation of cerebral cortex, sympathetic preganglionic cell bodies in thoracic spine and paradoxical sleep
8
Q
Serotonin
A
type of biogenic amine
works with norepinephrine and others for cyclical sleep patterns
Associated with Raphe nucleus- projects to large areas of CNS- cortical activation and modulation of many brain centers
9
Q
Dopamine
A
type of biogenic amine
associated with Parkinsons (substantia nigra to the basal ganglia) and schizophrenia
associated with small nuclei in CNS that project to larger areas.- motor, cognitive, psychological well being.
10
Q
Amino acids
A
Four common transmitters: Glutamate and Aspartate are excitatory (cause depolarizations). GABA and Glycine and inhibitory (inhibit depolarizations).
associated with memory formations, long term changes, neuroplasticity
11
Q
Peptides
A
strings of amino acids linked by peptide bonds
modulatory in function. often work with other neurotransmitters- stored in synaptic vesicles with other neurotransmitters and released together.
have effects that are slower to develop, so can influence the postsynaptic cells response to next input
12
Q
Stage 1: Release of Neurontransmitters
A
cell is depolarized by Na and K+ leaving cell. this causes the inflow of Ca2+. releases neurotransmitters
13
Q
Stage 2: processing in the synaptic cleft
3 different mechanisms
A
- Neurotransmitters can be metabolized in the synaptic cleft by enzymes. Mostly Ach and peptides. Important- myasthenia gravis
- Neurotransmitters removed by an uptake protein. Mostly are amino acids and biogenic amines. Clinically- cocaine, MPTP, Parkinsons disease and dopamine, antidepressants- serotonin and norepiniephrine
- Removed by glial cells. major form for amino acids. excitatory amino acids can be toxic to the brain
14
Q
Stage 3: Effect on postsynaptic cell
A
there must be a receptor for the neurotransmitter to bind to- two major categories of receptors
- Ligand gated ion channels-has a binding site for a particular neurotransmitter, when bound the ion channel will open. Nicotinic Ach is a good example of ligand gated
- G-coupled protein receptors- have a binding site for a particular transmitter. causes a cascade in the cell which can change the polarization of the membrane. Muscarinic Ach
15
Q
Parasynaptic communication
A
neurotransmitters have to travel out of the synapse so find cells with proper receptors
do not have an immediate effect, used to enhance of attenuate other neurotransmitters
ex- enkephalin- runners high
16
Q
Steps of sensory processing
A
- Transduction- form of physical energy stimulates receptors and creates action potentials
- Propagation of action potentials to the spinal cord or brainstem.
- Generation of a perception
17
Q
Pacinian corpuscle
A
has a central, single nerve axon, that when deformed by pressure on the skin sends action potentials. the greater the force, the higher frequency of action potentials
18
Q
Rapid adapting
A
Pacinian corpuscle and meissner’s corpuscle
only respond when filament is applied or removed
19
Q
Slow adapting
A
Merkel cells and Ruffini endings
respong constantly to pressure
20
Q
Hair follicles
A
free nerve endings that wrap around hair cells. rapid adaptors
21
Q
Receptors responsible for 2 point discrimination
A
- Pacinian corpuscles and Ruffini endings have larger receptive fields
- Merkel and Meissners have small receptive fields
22
Q
Vibration
A
Transduced by pacinian corpuscle. rapid adapting
23
Q
Shape best by
A
Ruffini and Merkel
24
Q
Movement of object across skin
A
Pacinian and Meissners
25
Texture of an object
Merkels
26
Mechanism of position sense
Muscle spindles
27
Cells of the muscle spindle
1. Nuclear bag cells- type 1A neurons- annulospiral also innervate nuc chains. fast adapting
2. Nuclear chain cells- have 1A and II fast and slower adapting. can tell a change in muscle length and what the new muscle length is.
28
Intrafusal fibers
gamma fusimotor nerves innervate it. so that it is always taught and able to respond to stretch.
29
Joint receptor- 4 types
found in peri-Articular tissues of synovial joints. used near end range of joint
1. resemble ruffini, slow to adapt and easy to stimulate. in superficial layers of PROXIMAL joints, more active at end range
2. Resemble Pacinian corpuscle, found in deeper layers of distal joints at end range.
3. Found in ligaments of synovial joints except for spine. Hard to stimulate and slowly adapting.
30
Golgi tendon organ
transduce info about muscle tension. located at musculotendonous junctions.
innervated by type Ib nerve fibers
31
Pain receptors/free nerve endings
respond to tissue damage
use ion channels instead of deformation of a membrane around nerve
hyperalgesia- histamine and prostaglandin help in transduction process- blocked by NSAIDS
sensitization- second messenger induced phosphorylation- produces a larger response
mechanical- ENaC- sharp dull test
chemical- TRPV1-admits sodium and calcium ions in response to noxious heat, low pH, and certain chemicals ex. capsacin
thermal 5C- TRPV1,V2- ion flow in response to only heat.
32
Hot/cold receptors
1mm diameter areas on skin respond to either hot or cold.
linearly responsive to temperature but have a ceiling.
Cold- TRPM8, A1
Warm- TRVP3, 4
33
Deep tendon reflex
sensory nerves from muscle spindle are stimulated when strike to the tendon increases the length of the muscle.
type 1a nerve fibers convey action potentials to the spinal cord and synapse on motor neurons that innervate the same muscle that was tapped. both neurons involved have large diameter so happens quickly.
34
Tactile info entering spinal cord- 4 options
1. Ascend without synapse
2. Enter, synapse on dorsal horn and ascend dorsal columns
3. Enter spinal cord, synapse on motor neurons
4. Enter spinal cord, synapse on other neurons
35
Tactile sense from the body
Axons from the dorsal columns project to medulla where synapse on nucleus gracilis/cuneatus. cross in the mid medulla on internal arcuate fibers- decussation of the medial lemniscus. ascend on opposite side to ventral posterior lateral nucleus, then posterior limb of internal capsule to primary somatosensory cortex.
36
Nociceptive specific and wide range neurons- Lamina
Lamina I,V,VII,VIII
37
Pain senses from body
A delta or C fibers carrying pain info approach dorsal roots and central axons bifurcate to ascend/descend 1-3 spinal levels before entering the dorsal horn (dorsolateral fasciculus or Lisauer's tract). use excitatory amino acids(glut/asp) and peptides as co-transmitters (substance P). synapse on nociceptive specific or wide dynamic range neurons in the dorsal horn lamina I,V,VII,VIII.
also could synapse on interneurons in lamina II.
38
Inter neurons in dorsal horn
live in lamina II of dorsal horn.
also called substantia gelatinosa
A delta or C fibers can synapse on them, then they synapse on other neurons in the dorsal horn
help to modulate the flow of pain and temperature info through the dorsal horn
39
3 components of anterolateral system
1. Spinothalamic- perception and localization of pain
2. Spinomesencephalic/hypothalamic- affective, emotional and autonomic response to pain
3. Spinoreticular- arousing quality of pain
40
Spinothalamic
perception and localization of pain
from Lamina I and V to thalamus
crosses on anterior white commisure to ascend anterolateral system on opposite side, through posterior limb of internal capsule
Synapse on ventral posterior lateral nucleus and posterior nuclei of thalamus. then to primary somatosensory cortex
41
Spinomesencephalic/hypothalamic
affective, emotional and autonomic response to pain
ALSO from Lamina I and V to mesencephalon and hypothalamus
crosses on anterior white commisure to ascend anterolateral system on opposite side. synapse on neurons in reticular formation, parabrachial nucleus and periaquaductal gray in midbrain. and to hypothalamus.
42
Spinoreticular
arousing quality of pain
from VII and VIII to reticular formation in pons and medulla
ascend on BOTH SIDES of anterolateral system, synapse in reticular formation, send axons to central lateral and intralaminar nuclei of thalamus. then wide spread targets of cortex for arousing qualities of pain.
also activates cingulate gyrus in limbic lobe, and insular cortex- responsible for picking an appropriate response to the pain
43
Endogenous pain modulation circuits
1. Interneurons in spinal cord help to inhibit pain. Ex GABA and opiod peptide Enkephalin work in Lamina II.
2. Descending projections of neurons from periaquaductal gray in midbrain, locus ceruleus in midbrain/pons, and raphe nucleus in medulla- all inhibit pain projection neurons. Some use serotonin and norepinephrine, some activate internuerons in dorsal horn to use enkephalin
44
Transcutaneous electrical nerve stimulation
stimulate large A alpha and Beta nerves which are thought to facilitate GABAnergic and glycinergic interneurons in the dorsal horn. This is thought to inhibit the release of pain mediating neurotransmitters from A delta and C fibers
45
Crude touch from anterolateral system
if the dorsal columns are knocked out, the anterolateral system can produce perception of crude touch because of changes in temperature on skin when it is touched.
46
Brown Sequard syndrome
injury in spinal cord will produce loss in pain/temp on one side, and loss in tactile sensation from opposite side
injury above mid medulla losses will be same side
47
Tactile sense in the face
from A-alpha and Beta of the trigeminal nerve. cell bodies in the semilunar/trigeminal ganglion. enter brain stem in the rostral pons and synapse on the principle sensory nucleus of trigeminal nerve. most neurons cross and ascendas trigeminal lemniscus with medial lemniscus. synapse on VENTRAL POSTERIOR MEDIAL nucleus. through genu of internal capsule to primary sensory cortex
48
Pain and temp from face
from A-delta and C fibers of the trigeminal nerve. cell bodies in the semilunar/trigeminal ganglion. enter brain stem in the pons and immediately descend trough to the medulla on spinal trigeminal tract and nucleus. cross and ascend with anterolateral system to synapse on VENTRAL POSTERIOR MEDIAL nucleus. through genu of internal capsule to primary sensory cortex
49
Damage of medial lemniscus and anterolateral system
in spinal cord and lower level of brain stem they are farther from each other and less likely to be damaged together.
higher up- more likely to damage together
50
Allodynia
lowering of pain threshold. so light touch becomes painful
51
Hyperalgesia
abnormally robust response to what is normally a painful stimulus. a normal pain becomes extreme pain
52
Complex regional pain syndrome
constant experience of pain that is often described as burning
type 1- develops after injury to extremity that does not involve a peripheral nerve. called reflex sympathetic dystrophy.
type 2-develops after injury to extremity that does involve a peripheral nerve. called causalgia
53
Dejerine Roussy syndrome. aka Thalamic pain syndrome
numbness, parathesia(tingling), and constant burning pain usually in face.
usually due to damage of ventral posterior medial nucleus of thalamus on opposite side.
burning develops when damage spreads to ventral posterior nucleus.
can also occur in extremities- would be in ventral posterior lateral nucleus on opposite side of symptoms
54
Alpha motor nuerons
innervate skeletal muscle
| large diameter, found in ventral horn of spinal cord
55
Gama motor neurons
innervate contractile portion of muscle spindle
56
Autonomic motor neurons
innervate cardiac, smooth muscle and glands.
synapse on a ganglion first- use Ach
preganglionic sympathetic neurons from intermediate horn of thoracic and upper lumbar spinal cord
preganglionic sympathetic from vagus and intermediate region of sacral spinal cord
57
Distal motor nuclei
found in cervical and lumbar regions
58
Axial motor nuclei
found throughout spinal cord
59
Axial group of Cranial nerves
1. Occulomotor N- 3
2. Trochlear N- 4
3. Abducens N - 6
4. Hypoglossal N - 12
60
Distal group of Cranial Nerves
1. Trigeminal N- 5 mastication
2. Facial N- 7
3. Nucleus Ambiguous- 10 pharynx/larynx
4. Acessory N - 11
61
Autonomic/Visceral group (parasympathetic)
1. Edinger-Westfall
2. Dorsal motor nucleus of vagus
3. Salivatory- runs with glossopharyngeal
62
1a inhibitory neuron
live in skeletal muscle. highlighted during a stretch reflex- deep tendon reflex.
NEEDED FOR smooth agonist/antagonist activation
63
Renshaw cells
Inhibitory in nature. receive stimulation from motor neurons and feeback to the same neuron.
stabilizes synergistic firing rates smooth agonist/antagonist activation
produce asynchronous firing so whole muscle doesn't contract at once
64
Ib inhibitory neuron
controls through convergent input appropriate muscle tension.
combines intended motion with cutaneous, joint receptors and GTO to regulate how much tension is needed in the muscle
65
Flexion reflex
flexion in response to pain, ex stepping on a nail. injured leg will flex to avoid pain and opposite leg will extend to bear weight of the body.
neurons span several levels of spinal cord on both sides
treatment in teaching people to walk- descending control- central pattern generators
66
Components of descending motor system
1. Descending projections
2. Cerebellum- refine motor commands but do not have any descending projections and cannot issue motor commands
3. Basal ganglia- same as cerebellum
4. Lower motor neurons- alpha and gamma motor neurons, and their supportive cells ex 1a inhibitory
67
Pathways that project to distal motor nuclei
1. Lateral corticospinal tract
| 2. Rubrospinal tract
68
Origins of Lateral corticospinal tract
1. Pirmary motor cortex
2. Premotor cortex
3. Supplementary motor cortex
69
Afferents of Lateral corticospinal tract
Origins receive afferent info from:
1. Basal Ganglia
2. Cerebellum
3. Primary somatosenory cortex
4. Somatosensory association cortex
70
Descending fibers of lateral corticospinal tract
organized by projections
upper extremity- rostral part of posterior limb of internal capsule,
lower extremity more caudal.
in midbrain- axons innervating upper extremity are more medial in cerebral peduncle, LE are lateral. continues through spinal cord
71
Destination and function of lateral corticospinal
terminate in cervical and lumbar enlargements.
| innervate fine motor control of opposite side distal extremity
72
Origins of rubrospinal pathway
1. Red nucleus at rostral midbrain
73
Afferents to rubrospinal
1. Cerebellum
| 2. Primary motor cortex
74
Descending fibers of rubrospinal
neurons cross from red nucleus immediately in rostral midbrain. Descend and enter spinal cord next to lateral corticospinal tract. will terminate in distal motor nuclei of upper and lower extremities
75
Function of rubrospinal
assist in production of fine motor control of distal extremities.
focus more on upper extremities than lower and focus more on FLEXION
76
Pathways that project to axial motor nuclei
1. Anterior corticospinal tract
2. Reticulospinal tract
3. Vestibulospinal tract
4. Tectospinal tract
77
Origin of anterior corticospinal
1. Primary motor cortex
2. Supplementary motor cortex
3. Premotor cortex
78
Afferents of anterior corticospinal
1. Cerebellum
2. Basal Ganglia
3. Primary somatosensory cortex
4. Somatosensory association cortex
79
Destination and function of anterior corticospinal
Destination- bilateral axial motor nuclei
| Function- control of bilateral axial and proximal extremity musculature
80
Descending fibers of anterior corticospinal path
between UE and LE in posterior limb of internal capsule. central in cerebral peduncle, do not cross at the decussation of the pyramids, continues on the same side in the anterior portion of spinal cord white matter. terminates bilaterally
81
Two types of reticulospinal pathway (origins)
From reticular formations in:
1. Pontine - caudal pons
2. Medullary - rostral medulla
82
Afferents of reticulospinal
1. Cerebellum
| 2. Premotor cortex
83
Descending fibers of reticulospinal
descend brain stem and spinal cord in a ventral position. to bilateral axial motor nuclei
84
Functions of different reticulospinal pathways
1. Pontine- bilateral trunk and proximal extremity EXTENSORS, while inhibiting flexors
2. Medullary- inhibits bilateral trunk and proximal extremity extensors
afferent from premotor- gets trunk ready for complex multi-joint movements
85
Origins of 2 Vestibulospinal tracts
From the vestibular nucleus
1. Vestibular nucleus in caudal Pons- More LATERAL
2. Vestibular nuc in rostral medulla- MEDIAL
86
Afferents of Vestibulospinal tracts
1. Cerebellum
| 2. Vestibular apparatus
87
Destination and function of 2 Vestibulospinal tracts
1. LATERAL/pons- bilaterally influences axial nuclei. for extensor muscles in trunk and proximal extremities. (important for keeping upright against gravity)
2. MEDIAL/medulla- terminates bilaterally in the cervical and upper thoracic regions. helps to orient head and neck in response to vestibular information
88
Origin of tectospinal tract
Superior colliculus in rostral midbrain
89
Afferents of tectospinal
1. Basal ganglia
| 2. Vision
90
Descending fibers of tectospinal
cross and descend through brain stem before taking up residence in ventral spinal cord. terminate in cervical and upper thoracic region
91
Function of tectospinal
help with coordination of upper trunk, neck and head and eye movement toward a visual target.
92
Decorticate rigidity
```
from broad damage to cortex, removes input to descending systems. rubrospinal system is still intact and causes upper extremities to flex
pontine reticulospinal(meddulary needs cortex to stimulate) and vestibulospinal systems cause extension in rest of body
```
93
Decerebrate rigidity
when damage extends to red nucleus in rostral midbrain. extension everywhere except for wrist and hand.
if transition from decorticate to decerebrate is observed it means that midbrain is shutting down- need immediate assistance
94
Lower motor neuron lesions
When motor nucleus and the axons within it are damaged
1. Fasciculations- visible muscle twitches that is no longer innervated
2. Hypoactive Deep tendon reflexes.- from death of motor neurons
3. Muscle weakness/atrophy/paralysis- from lack of innervation from an alpha motor neuron
95
Upper motor neuron lesion
When portions of nervous system that generate motor commands are damaged. (any descending motor command giving system or basal ganglia and cerebellum)
1. Pyramidal- damage to origins of pyramids and any part along pathway
- Flaccid paralysis
- Hyperactive deep tendon reflexes, spasticity and clonus replace paralysis after 3-6 weeks
- Positive babinski- dorsiflexion of big toe, fanning toes and flexion at knee/hip
2. Extra-pyramidal- damage to other descending motor giving system ex basal ganglia or cerebellum
96
Corneal reflex
normal response- bilateral eye closing
Pain sensed on trigeminal nerve- pons- spinal trigeminal tract which has nuerons that project to facial motor nucleus in caudal pons.
tests cranial nerve 5 -trigeminal
cranial nerve 7- facial
97
Jaw reflex
tendon reflex of muscles of mastication- 1a afferent neurons to trigeminal motor nuclei in rostral pons
tests both sensory and motor of trigeminal nerve CN-5
98
Gag reflex
Sensory by glossopharyngeal- CN-9, synapse in medulla and fibers are passed to nucleus ambiguous. CN 10 Vagus nerve. muscles of pharynx and larynx.
both cranial nerves and nuclei are located in medulla
99
Pupillary reflex
Light into eye- optic nerve CN-2, projects to midbrain at the edinger westfall nucleus to occulomotor nucleus CN-3. stimulates pupillary constriction.
examines optic and occulomotor
100
Finger to nose
| heel to shin
test cerebellar function
