Neuroscience Exam 3: The Sound Of Silence

Front 1

General Sensory Pathway flow

Back 1

External Energy (thermal/electrical/mechanical/chemical/electromagnetic) -> receptors on distal ends of sensory neurons (transduction of energy) -> action potentials (electrochemical process) -> afferent sensory neurons in PNS (cranial and spinal nerves)(nociceptors, GTOs, muscle spindles, meissner corpuscles, ruffini corpuscles, pacinian corpuscles, merkel’s disks, free nerve endings, joint receptors)
(above are all 1st order sensory neurons – may also be called type I, II, III, IV fibers depending on diameter of axons and degree of myelinations)

Front 2

special senses include:

Back 2

-Olfaction (olfactory CN I)
-vision (optic CN II)
-gustation (Facial CN VII
-Glossopharyngeal CN IX)
-audition (vestibulocochlear CN VIII)
-Equilibrium (vestibulocochlear CN VIII)

Front 3

3 Spinal Cord Pathways

Back 3

-Dorsal Column (conscious proprioception, fine touch, 2-pt discrimination, steriognosis, vibration, movement sense)
-Spinothalamic Tract (pain, temp, touch)
-Ventral and Dorsal Spinocerebellar Tracts (unconscious proprioception)

Front 4

General sensations originate through

Back 4

originate through a visceral/somatic receptive field

Front 5

visceral vs somatic receptive field sensations

Back 5

Produce the same general sensations – except 2-pt discrimination, stereognosis (ability to discern objects by touch – without looking at them), and conscious body sense (strictly fx of skeletal muscle) are not produced in visceral receptive fields.

Front 6

Receptive fields definition

Back 6

a region of somatic/visceral tissue capable of recognizing sensory info and activating the receptor

Front 7

Receptive fields characteristics

Back 7

a. May be small or large – size may change – they are dynamic in nature
b. Correspond to respective myotomes (muscle pattern), dermatomes (skin pattern), scleratomes (connective tissue pattern)
c. Convergence of 1st order sensory neurons onto same dorsal horn. (Multiple can converge on same dorsal horn)

Front 8

Types of visceral receptive fields

Back 8

i. Organs
1. Thorax, abdomen, pelvis

Front 9

Types of somatic (body/soma) receptive fields

Back 9

i. Skin, muscles, joints, bone, fat

Front 10

Crude touch/light touch characteristics

Back 10

you are aware that you are being lightly touched.

SPINOTHALAMIC TRACT

Front 11

Fine touch/two-point discrimination/tactile discrimination characteristics

Back 11

finess (texture, etc); associated with stereognosis

DORSAL COLUMN SYSTEM

Front 12

Stereognosis definition

Back 12

perception of three-dimensional shapes or objects via touch only; modality responsible is fine touch.

Front 13

Vibratory sense definition

Back 13

based on cyclic frequency (tuning fork)

Front 14

Conscious proprioception characteristics

Back 14

-cortex, ability to perceive body position sense; occurs in post-central gyrus
-DORSAL COLUMN SYSTEM
1. Static: not moving - ability to sense and perceive body position (sitting still, knowing legs are crossed)
2. Dynamic/kinesthetic sense: ability to sense movement and balance

Front 15

Unconscious proprioception definition

Back 15

proprioceptive information that goes to cerebellum (coordination of muscle tone, equilibrium) for processing

Front 16

Unconscious proprioception characteristics

Back 16

1. same info that goes through dorsal column system to the post-central gyrus for conscious proprioception. It has just evolved to go directly to cerebellum to allow for faster responses/changes.
2. Can be static or dynamic.
3. Cerebellum is involved with muscle tone, gait, and coordination.
SPINOCEREBELLAR TRACT

Front 17

Noxious stimuli

Back 17

stimulus that damages or has the potential to damage tissue

Front 18

Pain definition

Back 18

response to noxious stimuli of tissue

Front 19

SpinoThalamic Tract sensations

Back 19

Crude/Light Touch
Temperature
Pain

Front 20

Dorsal Column System sensations

Back 20

Fine touch/2 pt discrimination/tactile
Conscious Proprioception

Front 21

spinocerebellar tract sensations

Back 21

Unconscious proprioception

Front 22

Nomenclature systems for identifying neuron types (1st order sensory neurons)- Fiber type system:

Back 22

i. I, II, III, or IV (Largest, fastest, myelinated are I)
ii. Criteria based on:
1. Diameter of fiber/axon
2. Conduction velocity
3. Myelinated/unmyelinated

Front 23

Nomenclature systems for identifying neuron types (1st order sensory neurons)- Greek letter system

Back 23

i. Criteria based on:
1. Diameter
2. Myelinated/unmyelinated

Front 24

Nomenclature systems for identifying neuron types (1st order sensory neurons)- Histological type system:

Back 24

i. Criteria based on:
1. Anatomy/histology of neuron
2. Proper name (i.e., pyramid shaped=pyramidal neuron)

Front 25

Type 1a neurons characteristics

Back 25

13-20 µm diameter
myelinated
80-120 m/s conduction velocity
Primary receptors of muscle spindle

Front 26

Type 1b neurons characteristics

Back 26

13-20 µm diameter
myelinated
80-120 m/s conduction velocity
Golgi Tendon organ

Front 27

Type 2 neurons characteristics

Back 27

6-12 µm diameter
myelinated
33-75 m/s conduction velocity
Secondary receptors of muscle spindle
All cutaneous mechanoreceptors

Front 28

Type 3 neurons characteristics

Back 28

1-5 µm diameter
Thin myelin
3-30 m/s conduction velocity
Free nerve endings of touch and pressure
Nociceptors of neospinothalamic tract
Cold thermoreceptors

Front 29

Type 4 neurons characteristics

Back 29

0.2-1.5 µm diameter
Not myelinated
0.5-2.0 m/s
Nociceptors of paleospinothalamic tract
Warmth receptors

Front 30

a. Adaptation definition

Back 30

response and adjustments a neuron makes to a stimulus

receptor organ makes the adjustment- remember that AP begins at first node of Ranvier

Front 31

Rapidly adapting receptors/neurons: aka phasic characteristics

Back 31

a. provides information about the change in rate and pattern;
b. filters information coming through the environment;
c. sensory neurons adapt to input (environment) so you are not overstimulated;
d. cannot isolate stimulation.
e. 2 phases: high phase and adaptive phase – which is lower

Front 32

Slowly adapting receptors/neurons: aka tonic characteristics

Back 32

a. constantly aware of receptive field that the neuron is firing from;
b. can isolate stimulation.
c. Nociceptors are an example: Ability to discriminate where noxious stimuli are coming from.

Front 33

convergence definition

Back 33

when sensory information is coming in – onto 2nd order sensory neurons (many 1st orders to single 2nd order)

Front 34

divergence definition

Back 34

after convergence to a single ganglion, signals can then diverge to multiple places

Front 35

Receptor organs characteristics

Back 35

always at the distal end of sensory neuron (the proximal end travels to the brain and spinal cord)
a. Respond to different types of external energy
b. There are 5 kinds

Front 36

i. Pain receptors definition

Back 36

free nerve endings that receive noxious information

in somatic) or somatic; respond to mechanical energy or stimulation (anything that produces force).

Front 37

ii. Thermorecpetors definition

Back 37

free nerve endings respond to changes in temperature

Front 38

iii. Chemoreceptors definition

Back 38

free nerve endings reception to chemical

Front 39

iv. Electromagnetics definition

Back 39

rods/cones in retina of the eye; respond to electromagnetic energy (light).

Front 40

v. Mechanoreceptors definition

Back 40

-specialized structures
-visceral (not as well defined/described as in somatic) or somatic
-respond to mechanical energy or stimulation (anything that produces force).

Front 41

i. Merkel’s disc definition

Back 41

mechanoreceptor

modified epithelial (epidermal/skin) cell; the distal end of a sensory neuron meets with it.

Front 42

Merkel's disc characteristics

Back 42

1. Responds to steady skin indentation and mechanically stretches skin.
2. Small receptive field
3. Tonic (slowly adapting)
4. Responds to fine touch, two-point discrimination.
5. Myelinated for fast AP.

Front 43

ii. Meissner corpuscle definition

Back 43

mechanoreceptor

encapsulated distal ends – large receptor organ

Front 44

Meissner corpuscle characteristics

Back 44

1. Responds to steady skin indentation
2. Small receptive field
3. Phasic (rapidly adapting)
4. Located in skin.
5. Responds to fine touch, two-point discrimination.
6. Myelinated for fast AP.

Front 45

Ability to discern 2-point discrimination is based on

Back 45

the number of Meissner corpuscles and Merkel’s disks located in that area.

Thus, there is a smaller concentration of Meissner and Merkel’s in the back, forearm, and calf than in the finger/thumb, lips and big toe

Front 46

iii. Pacinian corpuscle characteristics

Back 46

mechanoreceptor
1. Responds to vibration
2. Large receptive field (poorly localize perception)
3. Phasic (rapidly adapting)
4. Located in skin, muscles, connective tissue, interosseous membranes
5. Myelinated for fast AP

Front 47

iv. Ruffini endings characteristics

Back 47

mechanoreceptor
1. bundles of encapsulated endings, collagenic fibers at the distal end of sensory neurons.
2. Respond to crude touch and pressure (may also respond to vibration, but the pacinian corpuscle is the primary receptor for that.)
3. Large receptive fields
4. Tonic (slowly adapting)
5. Myelinated for fast AP.

Front 48

v. Free nerve endings definition

Back 48

mechanoreceptor

resembles telodendria; does not have specialized structures – is not encapsulated

Front 49

Free nerve endings characteristics

Back 49

mechanorecptor
1. Responds to crude touch; thermal; and noxious (painful) stimulation (mechanical, chemical, or thermal – upper/lower limits of temp)
2. May or may not be myelinated
3. Specific free nerve endings: A-delta (IV) or C (III) fibers
a. C fibers are non myelinated
b. A-delta fibers are thinly-myelinated

Front 50

Muscle spindle characteristics

Back 50

mechanoreceptor associated with skeletal muscle; begin with intrafusal and extrafusal muscle fibers.
1. Respond to conscious and unconscious proprioception, both static and dynamic.
2. Measures length and the rate of change of length in skeletal muscle cells.
3. Distal end of Type I-a fibers
4. Myelinated

Front 51

Golgi tendon organ characteristics

Back 51

mechanoreceptor
tendons of skeletal muscle
1. Respond to all proprioception, conscious and unconscious
2. Measure tension and rate of change of tension in skeletal muscle cells.
3. Distal end of Type I-b fibers
4. Myelinated

Front 52

Spinothalamic tract characteristics

Back 52

-noxious stimulation PAIN, temperature, crude touch
-receives input from UE, LE, trunk, abdomen, and pelvis
-As it ascends the spinal cord, it adds more and more 2nd order sensory neurons – so it is larger at the top than at the bottom. (3 neuron pathway)

Front 53

Spinothalamic tract 1st order characteristics

Back 53

i. Nociceptors located in spinal nerves or nerves of ANS.
ii. Somatic and visceral receptive fields
iii. Cell bodies in Dorsal root ganglia of spinal nerves
iv. Synapse with 2nd order in dorsal horn; may or may not synapse with interneurons.

Front 54

Spinothalamic tract 2nd order characteristics

Back 54

i. Decussate immediately at point of entry to contralateral side and ascend as spinothalamic tract. ( Know point of decussation!!)
ii. Name change: becomes the spinal lemniscus upon entry to the tegmentum of the medulla.
iii. Continues ascent through the tegmentum
iv. Terminates with the thalamus at the ventral posterior lateral nucleus (VPL=R nucleus)

Front 55

Spinothalamic tract 3rd order characteristics

Back 55

i. Synapse between 2nd and 3rd order in thalamus
ii. 3rd order ascends through the internal capsule to terminate in the postcentral gyrus of the parietal lobe.

Front 56

Modalities lost if spinothalamic tract is cut

Back 56

i. Lose perception (pain, temp, crude touch) of contralateral side below level of lesion, if the tract is cut once it enters the spinal cord.
ii. Lose perception of the ipsilateral side if the tract is cut at a spinal nerve.

Front 57

Dorsal column system fxns

Back 57

conscious proprioception, two-point discrimination, vibration, movement sense, fine touch and stereognosis.

Front 58

Dorsal column system 1st order characteristics

Back 58

i. Sensory neurons in spinal nerves
ii. Cell bodies in DRG
iii. Receptors found in skin, subcutaneous tissue, muscle, tendon, and joints.
iv. Enter dorsal horn but do not decussate
v. Ascend ipsilaterally in the dorsal white column to the medulla

Front 59

1. Fasciculus gracilis fxn

Back 59

1st order from LE that synapses with the nucleus gracilis in the tegmentum of the medulla. (medial aspect of dorsal column)

Front 60

2. Fasciculus cuneatus

Back 60

1st order from UE that synapses with the nucleus cuneatus in the tegmentum of the medulla. (lateral aspect of dorsal column)

Front 61

Dorsal column system 2nd order characteristics

Back 61

i. Decussate in medulla to collectively form the medial lemniscus.
ii. Ascends the tegmentum of the brainstem and terminates in the ventrobasal nuclear complex of the thalamus.

Front 62

Dorsal column system 3rd order characteristics

Back 62

i. 2nd synapses with 3rd in thalamus
ii. Passes through the internal capsule and goes to the postcentral gyrus of parietal lobe to allow conscious proprioception, two-point discrimination, vibration, movement sense, fine touch, and stereognosis.

Front 63

d. Modalities lost if dorsal column system is cut

Back 63

i. Loss on ipsilateral side if cut at or before the medulla (dorsal column of SC)
ii. Loss on contralateral side if cut after the medulla (ex if lesion is in pons)

Front 64

Spinocerebellar tract 1st order characteristics

Back 64

i. Located in spinal nerves
ii. Cell bodies in dorsal root ganglia
iii. Receptors located in skin, muscles, tendons, and joints
iv. Terminate in dorsal horn (specifically lamina VII [aka Nucleus Dorsalis or Clarke’s Nucleus]) to synapse with 2nd order

Front 65

Spinocerebellar tract 2nd order characteristics

Back 65

i. Associated with T1-L2 levels
ii. There is an anterior and posterior tract

Front 66

Posterior spinocerebellar tract characteristics

Back 66

-does not decussate (ascends on ipsilateral side)

-enters the cerebellum via the inferior cerebellar peduncle to relay information from the LE.

Front 67

Anterior spinocerebellar tract characteristics

Back 67

-decussates at the point of entry
-enters the cerebellum via the superior cerebellar peduncle (superior is primarily efferent – though the anterior spinocerebellar tract is an exception to this rule)

Front 68

Lesions of spinocerebellar tract effects

Back 68

would result in some loss of motor control – but this is more of a finesse type system – so there would be less noticeable clinical symptoms

Front 69

Olfactory Nerve 1st order location and path

Back 69

i. Located in nasal mucosa associated with the superior nasal concha and meatus.
ii. Pass through the cribriform plate of the ethmoid bone and synapse with the 2nd order sensory neurons in the olfactory bulbs.

Front 70

Olfactory Nerve 2nd order location and path

Back 70

i. Olfactory nerve splits into the medial and lateral stria to enter the rhinencephalon of the forebrain.
ii. 2nd orders in the medial stria decussate to the contralateral side via the anterior commissure. (Bilateral projection pattern. Some straight to cortex, other contralateral via anterior commissure)
iii. Terminate in various portions of the temporal lobe (amygdala and parahippocampal gyrus) *this is where you perceive smell*

Front 71

only sensory modality that does not initially process through the thalamus before going to the cortex

Back 71

olfactory

Front 72

Optic nerve 1st order characteristics

Back 72

i. Rods and cones located in the retina
ii. Synapse with 2nd order (aka bipolar cells) which are also located in the retina

Front 73

Optic nerve 2nd order characteristics

Back 73

i. Bipolar cells in the retina
ii. Synapse with 3rd order sensory neurons (ganglia cells) in the retina

Front 74

Optic nerve 3rd order characteristics

Back 74

i. Optic nerve (chiasm): 3rd order neurons from the temporal (lateral) retina stay on the same side. 3rd order neurons from the nasal (medial) retina decussate (aka partial Decussation).
ii. Nerve becomes the optic tract
iii. Project into the lateral geniculate body of the thalamus to synapse with 4th order.
-some of these go to superior colliculus and pretectal nucleus of the midbrain for their involvement with visual reflexes.

Front 75

Optic nerve 4th order characteristics

Back 75

i. Collectively form optic radiations to travel to the visual cortex (area 17) of the occipital lobe where images are perceived

Front 76

Trigeminal Nerve 1st order characteristics

Back 76

i. Form parts of the nerve (i.e., V1, V2, V3)
ii. Cell bodies in semiulunar ganglion
iii. Proprioceptors have cell bodies in the mesencephalic nucleus of midbrain and pons.
i. Mesencephalic nucleus: located in midbrain
ii. Synapse with one of three nuclei depending on the modality.
b. Where it goes depends on what type of info it brings in.

Front 77

Spinal nucleus of V characteristics

Back 77

1st order (pain, temp, touch) synapses with 2nd order; located in tegmentum of the medulla

Front 78

Spinal nucleus of V 2nd order characteristics

Back 78

1. Decussate to contralateral side in medulla to become the trigeminal lemniscus.
2. Ascends to the thalamus.

Front 79

Spinal nucleus of V 3rd order characteristics

Back 79

1. Project via the internal capsule to the post-central gyrus of the parietal lobe.

Front 80

c. Main (chief) sensory nucleus of V characteristics

Back 80

-1st order (two-point discrimination, vibratory sense, and fine touch) synapses with 2nd order

-located in the tegmentum of the pons.

Front 81

Main (chief) sensory nucleus of V 2nd order decussation location

Back 81

1. Decussate in the pons and become part of the trigeminal lemniscus.

Front 82

Main (chief) sensory nucleus of V 3rd order project where

Back 82

1. Project via the internal capsule to the post-central gyrus of the parietal lobe

Front 83

Mesencephalic nucleus characteristics

Back 83

1st order (proprioception) synapses with 2nd order

located in the midbrain

Front 84

Mesencephalic nucleus 2nd order decussates where

Back 84

1. Decussate in the midbrain to become part of the trigeminal lemniscus.

Front 85

Mesencephalic nucleus 3rd order projects where

Back 85

1. Project via the internal capsule to the post-central gyrus of the parietal lobe

Front 86

G. Facial Nerve sensory characteristics

Back 86

innervates the anterior 2/3 of the tongue for taste (special sense) responds to chemical input CN VII. 3 neuron pathway

Front 87

Facial nerve 1st order characteristics

Back 87

i. Originate with the anterior 2/3 of the tongue.
ii. Cell bodies located in the geniculate ganglia.
iii. Synapse with 2nd order in the solitary nucleus
ii. May also synapse with 2nd order in the spinal nucleus of V.

Front 88

Solitary nucleus for facial nerve characteristics

Back 88

located in the tegmentum of the medulla

shared with CN IX and X. (VII, IX, and X share the solitary nucleus)

Front 89

spinal nucleus for facial nerve characteristics

Back 89

located in the tegmentum of the medulla.

This portion innervates the skin of a small portion of the external ear

Front 90

Facial nerve 2nd order decussation and ascension

Back 90

i. Decussate in the medulla to the contralateral side
ii. Ascend to the thalamus as the trigeminal lemniscus. (joins the trigeminal lemniscus – shared with trigeminal nerve)

Front 91

Facial nerve 3rd order picked up where

Back 91

i. Picked up in the thalamus where it projects through the internal capsule to the parietal lobe.

Front 92

Vestibular nerve 1st order characteristics

Back 92

1. Receptors located in the utricle, saccule, and semicircular canals.
2. Cell bodies in the vestibular ganglia.
3. Synapse with 2nd order in the vestibular nuclei.
a. Vestibular nuclei: 2 sets of 4 located in the tegmentum of the pons

Front 93

Vestibular nerve 2nd order project where

Back 93

1. Project to several important areas:
a. Cerebellar cortex (via thalamus)
b. Contralateral cerebral cortex (via the thalamus)
c. Spinal cord
d. Motor nuclei of CN III, IV, VI.
e. Reticular formation
f. Contralateral vestibular nuclei

Front 94

b. Cochlear nerve fxn

Back 94

transmitting sound waves

Front 95

coclear nerve 1st order characteristics

Back 95

1. Receptors located in the organ of corti and the cochlea of the inner ear.
2. Cell bodies in the spiral ganglia.
3. Synapse with 2nd order in the dorsal and ventral cochlear nuclei (located in the tegmentum of the pons)
4. Decussate in the pons (at the trapezoid body).

Front 96

cochlear nerve 2nd order pathway

Back 96

1. Ascend as the lateral lemniscus which projects to the inferior colliculus of the tectum of the midbrain.

Front 97

cochlear nerve 3rd order projects where

Back 97

1. Project to the medial geniculate body of the thalamus

Front 98

cochlear nerve 4th order projects where

Back 98

1. Project to auditory cortex (superior temporal gyrus) in the temporal lobe via the internal capsule.

Front 99

double decussation of cochlear nerve occurs where

Back 99

-double decussation occurs in the trapezoid body

-Decreases the amount of auditory loss if cochlear nerve is damanged

Front 100

Auditory pathway (descending order)

Back 100

cochlea
ventral cochlear nucleus
dorsal cochlear nucleus
superior olivary nucleus
via lateral leminiscus
inferior colliculus
medial geniculate body
auditory cortex (temporal lobe)

Front 101

glossopharyngeal nerve sensory/taste fxn

Back 101

innervates the posterior 1/3 of the tongue for taste

Front 102

Glossopharyngeal nerve sensory/taste 1st order characteristics

Back 102

a. Taste receptors located on the posterior 1/3 of the tongue
b. Cell bodies in the inferior glossopharyngeal ganglia
c. Synapse with 2nd order in the solitary nucleus
i. Solitary nucleus: located in the tegmentum of the medulla; shared with CN VII, X.

Front 103

Glossopharyngeal nerve sensory/taste 2nd order decussation and path

Back 103

a. Decussate in the pons/medulla
b. Become part of the trigeminal lemniscus, which ascends to the thalamus.

Front 104

Glossopharyngeal nerve sensory/taste 3rd order project to

Back 104

a. Project to the post-central gyrus of the parietal lobe via the internal capsule.

Front 105

Glossopharyngeal nerve sensory/general sensation fxn

Back 105

innervates the pharynx, soft palate, and posterior 1/3 of the tongue – for general sensation.

Gag reflex

Front 106

Glossopharyngeal nerve sensory/general sensation 1st order characteristics

Back 106

a. Receptors located in the pharynx, soft palate, and posterior 1/3 of the tongue.
b. Cell bodies located in the inferior or superior glossopharyngeal ganglia.

Front 107

Glossopharyngeal nerve sensory/general sensation 2nd order characteristics

Back 107

a. Synapse with the 1st order in the spinal nucleus of V in the medulla and pons.
b. Decussate to the contralateral side and become part of the trigeminal lemniscus

Front 108

Glossopharyngeal nerve sensory/general sensation 3rd order project to

Back 108

a. Project to the post-central gyrus of the parietal lobe via the internal capsule.

Front 109

Taste pathway descending order

Back 109

Tongue
CN VII, IX, X
Medulla/pons
solitary nucleus
thalamus
Gustatory cortex (insula, frontal operculum, Posterior post central gyrus)

Front 110

Vagus nerve sensory fxns

Back 110

innervates the epiglottis (soft palate) for taste.

Front 111

vagus nerve 1st order characteristics

Back 111

a. Receptors in epiglottic region
b. Cell bodies in the inferior vagal ganglia
c. Synapse with 2nd order in the solitary nucleus in the tegmentum of the medulla.

Front 112

vagus nerve 2nd order decussation and ascension

Back 112

a. Decussate in the medulla to become part of the trigeminal lemniscus.
b. Ascend the tegmentum of the medulla, pons, and midbrain on the way to the thalamus.

Front 113

vagus nerve 3rd order synapse location and path

Back 113

a. Synapse with 2nd order in the thalamus
b. Pass through the internal capsule and terminate in the post-central gyrus of the parietal lobe

Front 114

vagus nerve general sensations fxn

Back 114

innervates the external ear, pharynx, and thoracic, abdominal, and pelvic visceral structures

Front 115

1. Thoracic, abdominal, and pelvic viscera: (visceral receptive fields) vagus nerve 1st order characteristics

Back 115

i. Begin in visceral structures
ii. Follow vagus nerve back to brain stem
iii. Cell bodies in the superior and inferior vagal ganglia in the neck.

Front 116

1. Thoracic, abdominal, and pelvic viscera: (visceral receptive fields) vagus nerve 2nd order characteristics

Back 116

i. Synapse with 1st order in the solitary nucleus in the medulla.
1. Solitary nucleus is taste and all visceral sensory info from vagus nerve.
ii. Become part of the trigeminal lemniscus.

Front 117

1. Thoracic, abdominal, and pelvic viscera: (visceral receptive fields) vagus nerve 3rd order characteristics

Back 117

i. Synapse with 2nd order in the thalamus.
ii. Terminate in the post-central gyrus of the parietal lobe.

Front 118

vagus nerve external ear 1st order characteristics

Back 118

i. Small peripheral nerves from the external ear.
ii. Cell bodies located in superior and inferior vagal ganglia.

Front 119

vagus nerve external ear 2nd order characteristics

Back 119

i. Synapse with 1st order in the spinal nucleus of the medulla.
ii. Associate with the trigeminal lemniscus.

Front 120

vagus nerve external ear 3rd order characteristics

Back 120

i. Synapse with 2nd order in the thalamus.
ii. Terminate in the post-central gyrus of the parietal lobe.

Front 121

A. Reticular formation characteristics

Back 121

-collection of small nuclei of the tegmentum of the brainstem

-Primary integrating area of the brainstem relating to consciousness

Front 122

tegmentum definition

Back 122

elongated gray mass that extends between the medulla and the midbrain.

Primary global integration area of the brainstem

Front 123

Reticular formation- Median (closest to midline) characteristics

Back 123

1. Pain modulation, inhibition of pain perception.
2. Raphe nuclei
a. Uses serotonin as primary neurotransmitter
3. Projects to spinal cord to modulate pain transmission to conscious centers.
4. NOT IMPORTANT IN ARAS (Ascending Reticular Activating System).

Front 124

Reticular formation- Medial (middle part): primarily in medulla and pons characteristics

Back 124

1. Makes sense of input
2. Efferent component of the reticular formation: influences the basic activities of the body
a. Sleep cycle, drowsiness, alertness, awareness.
3. Contains nuclei that project to (next slide)
4. Rubrospinal and reticulospinal tracts terminate with LMN.
5. Efferent component of ARAS.

Front 125

Reticular formation- Medial (middle part): primarily in medulla and pons contain nuclei that project to:

Back 125

a. Hypothalamus
b. Thalamus
c. Spinal cord
d. Other tegmental nuclei
e. Cranial nerve nuclei

Front 126

Reticular formation- lateral column characteristics

Back 126

1. Primary afferent component.
2. Receives input from collaterals, neurons associated with major ascending pathways.
3. IMPORTANT PART OF ARAS.

Front 127

Ascending Reticular Activating System (ARAS) controls

Back 127

controls the various states of arousal

Front 128

Ascending Reticular Activating System (ARAS) made up of

Back 128

ii. Made of medial and lateral zones/columns.

Front 129

functional system of the reticular formation?

Back 129

Ascending Reticular Activating System (ARAS)

Front 130

Ascending Reticular Activating System (ARAS) receives sensory input from

Back 130

1. Cranial nerves and CNS
2. Ascending sensory systems from spinal nerves
3. Cerebral areas of cortex
4. Cerebellum

Front 131

Ascending Reticular Activating System (ARAS) fxn

Back 131

if the ARAS is not working right, then the cortex is not getting information.
1. Sleep cycle
2. Drowsiness (as a result of not enough sensory input)
3. Awareness
4. Alertness

Front 132

Ascending Reticular Activating System (ARAS) clinical significance

Back 132

anesthesia acts by hyperpolarizing the neurons in the ARAS to decrease output, thus deactivating nuclei in the reticular formation by competing for binding sites.

Front 133

ARAS path starting with afferent input

Back 133

Afferent Input --- lateral column of reticular formation (afferent component) ---- medial column of reticular formation (efferent component) ---- outcomes of ARAS ----- sleep cycle/drowsiness/alertness/awareness

Front 134

Consciousness definition

Back 134

a. Conscious experience means that you are aware of feelings, ideas, dreams, and thoughts.

Front 135

Normal consciousness- level 1 characteristics

Back 135

1. Spontaneous (voluntary) speech at a normal rate.
2. Normal voluntary and reflex somatic motor activity.
3. Eyes open
4. Normal oculomotor activity.

Front 136

lethargy level 2 characteristics

Back 136

a. Spontaneous sentences, spoken slowly.
b. Decreased speed of voluntary motor activity.
c. Eyes open.
d. Decreased oculomotor activity.

Front 137

lethargy level 3 characteristics

Back 137

a. Spontaneous words, spoken infrequently.
b. Decreased speed and coordination of voluntary motor activity.
c. Eyes open or closed.
d. Decreased oculomotor activity.

Front 138

stupor level 4 characteristics

Back 138

i. Vocalization only to stimuli that cause pain.
ii. Marked decrease in spontaneous motor activity.
iii. Eyes generally closed, some spontaneous eye movement.

Front 139

stupor level 5 characteristics

Back 139

i. No vocalization.
ii. Appropriate defensive movements (generally flexor) to movements that cause pain.
iii. Eyes generally closed.

Front 140

stupor level 6 characteristics

Back 140

i. No vocalization
ii. Mass movements to stimuli that cause pain.
iii. Eyes closed, decreased spontaneous conjugate eye movement.

Front 141

coma level 7 characteristics

Back 141

i. No vocalization.
ii. Decerebrate posturing (postural change that occurs in some comatose pts consisting of episodes of axial rigidity, rigid extension of the limbs, internal rotation of the UEs, and marked PF of feet) to stimuli that causes pain, or no response.
iii. Eyes closed, absent spontaneous eye movements.

Front 142

Coma usually involves disfunction of

Back 142

Cerebral cortex, reticular formation of midbrain and upper pons, and thalamus

Front 143

damage from coma caused by

Back 143

1. General sensation does not get to the cortex because of damage to it.
2. Nuclei of reticular formation is damaged, not the ascending pathway.
3. Information goes up to the thalamus, but collaterals are not synapsing with the nuclei of the reticular formation, so there is no information in the brainstem.

Front 144

toxic coma definition

Back 144

may be caused by medications, drugs.

Front 145

liver failure relationship to coma

Back 145

may also cause coma – build up high levels of toxins which are toxic to the neurons. Renal failure can do the same thing.

Front 146

glasgow coma score characteristics

Back 146

1. 3-15 – high is good; low is bad
2. Criteria:
a. Best eye movement (4 pts)
b. Best verbal response (5 pts)
c. Best motor response (6 pts)

Front 147

cardinal signs of cerebral death

Back 147

coma, absence of brain stem reflexes, cephalic reflexes, EEG silence, apnea

Front 148

criteria for cerebral death

Back 148

1. Prerequisite: all appropriate diagnostic and therapeutic procedures have been performed.
2. Criteria to be present for 30 minutes at least 6 hours after the onset of coma and apnea.

Front 149

i. Cerebral unresponsivity definition

Back 149

state in which the pt does not respond purposefully to externally applied stimuli, obeys no commands, and does not utter sounds spontaneously or in response to a painful stimulus.

Front 150

c. Apnea definition

Back 150

absence of spontaneous respiration, manifested by the need for controlled ventilation for at least 15 minutes

Front 151

cephalic reflexes

Back 151

papillary, corneal, oculoauditory, oculovestibular, oculocephalic, ciliospinal, snout, pharyngeal, cough, and swallowing.

Front 152

EEG silence characterstics

Back 152

EEG with absence of electrical potentials of cerebral origin.
i. EEG measures electrical activity of some post-synaptic potentials
ii. Normal frequency: 2-20
iii. Rhythm seems to reside in the thalamus

Front 153

a. Alert wakefulness characteristics

Back 153

awake, alert, eyes open
i. Beta rhythm, > 13 Hz/sec

Front 154

b. Relaxed wakefulness characteristics

Back 154

awake, relaxed (not alert), and eyes open
i. Alpha rhythm, 8-13 Hz/sec

Front 155

c. Relaxed drowsiness characteristics

Back 155

fatigued, tired, eyelids may narrow/close, head may droop, lapses of alertness and attention, and still awake but not asleep.
i. Decrease in alpha wave amplitude and some decrease in frequency – closer to the 8 Hz.

Front 156

Sleep-Wake cycle characteristics

Back 156

natural endogenous cycle/rhythm of the body
i. Cyclic: the natural physiologic processes (HR, BP) that vary throughout the day.
ii. Tuned to the day and night circadian cycle

Front 157

i. Suprachiasmatic nucleus characteristics

Back 157

contains retinal cells sensitive to light.
1. Located in the hypothalamus, above the optic chiasm.
2. Maintains circadian rhythm and biological clock.
3. Primary biological clock allows the body to stay within cycle.
4. Sleep is influenced by, but NOT controlled by, the suprachiasmatic nucleus

Front 158

Sleep center characteristics

Back 158

1. Located within the reticular formation of the pons.
2. Inhibitory in nature, puts us in a sleep state.
3. Interacts with ARAS (excitatory) as a feedback loop. (As long as ARAS is overriding sleep center, you are awake)
4. Involves a slow accumulation and dissipation of transmitter substances (NT/NM)

Front 159

Sleep is a ( ) process

Back 159

e. Active process: sleep is not the absence of wakefulness; the brain is not inactive.

Front 160

neuronal activity etc. during sleep

Back 160

1. There is not an overall massive inhibition of neuronal activity.
2. Neurons continue to fire and some areas of the brain are more active than others.
3. Blood flow and oxygen demand do not decrease.

Front 161

Purpose of sleep

Back 161

1. “Catch-up time”: represents a period of rest for specific elements, during which time they can replenish substrates important for the generation of AP (upregulation and downregulation of genes)
2. Important in long-term chemical and structural change that the brain must undergo to make learning and memory possible.
3. Purposes of adaptation of organisms

Front 162

EEG Frequencies (rhythms) (BAT-D)

Back 162

- Beta Rhythm: 13 Hz and up
- Alpha Rhythm: 13-8 Hz
- Theta Rhythm: 8-4 Hz
- Delta Rhythm: 2 Hz

Front 163

E. Slow wave sleep definition

Back 163

non-REM sleep

enter slow wave from one of the stages of wakefulness

Front 164

Slow wave sleep characteristics

Back 164

i. There are no complex dreams.
ii. Primarily used for rest.
iii. Muscle tension is reduced but not eliminated.
iv. Movement is minimal but possible (i.e., no paralysis).
b. There are 4 stages; takes 30-45 minutes to go through all 4 stages, then reverse.
c. Each stage is repeatable and has an EEG pattern characterized by slower frequency and higher amplitude than the previous stage.

Front 165

Stage I sleep characteristics

Back 165

1. Light sleep, easily aroused by moderate stimuli.
2. Alpha-rhythm reduced to partial theta-rhythm (84 Hz/sec)

Front 166

Stage II sleep characteristics

Back 166

1. Further lack of sensitivity to activation and arousal.
2. Primarily theta-rhythm (8-4 Hz/sec)

Front 167

Stage III sleep characteristics

Back 167

1. Deep sleep, activation and arousal requires vigorous stimulation.
2. Theta wave (4-8 Hz) activity, as well as delta wave (~2 Hz/sec)

Front 168

Stage IV sleep characteristics

Back 168

1. True/deep sleep; arousal requires vigorous stimulation.
2. Predominantly delta rhythm (2 Hz)

Front 169

When does REM sleep occur and for how long?

Back 169

-occurs after one cycle of slow wave sleep, but can occur at every stage of sleep
-Occurs every 90 minutes and lasts for ~20 minutes {at 13+Hz/sec}.

Front 170

REM sleep characteristics

Back 170

-Involves burst eye movement activity superimposed over slow, rolling eye movement.
-Deepest state of sleep based on the criteria for external arousability (immense external stimuli to wake up)
-Lightest state of sleep based on the criteria for internal arousability (little internal stimuli to wake up)
-Profound loss of muscle tone (hypotonia/flaccidity/paralysis) throughout the body except:
i. Muscles of respiration
ii. Muscles of eye movement
iii. Muscles of the inner ear (stapedius mm)
f. Dreams common in REM.
g. Penile and clitoral erection common during REM.

Front 171

Problems of sleep

Back 171

a. Nightmares
b. Narcolepsy
c. REM sleep behavior disorder
d. Sleepwalking
e. Night terrors: wake up screaming (Stage IV)
f. Bed wetting (may occur at any stage)
g. Snoring: any stage
h. Insomnia
i. Bruxism (grinding of teeth)
j. Obstructive sleep apnea
k. Sleep deprivation: intentional absence of sleep.

Front 172

b. Narcolepsy characteristics

Back 172

manifest REM

unintentional sleep episode with REM sx.
i. Rx: amphetamines.

Front 173

c. REM sleep behavior disorder characteristics

Back 173

excessive, vivid dreams with movement

Front 174

d. Sleepwalking characteristics

Back 174

usually occurs during stage IV of non-REM sleep – body wakes up before mind does – not usually during REM sleep

Front 175

g. Snoring generally occurs with

Back 175

; generally occurs with obesity because the oropharynx has lost space

Front 176

insomnia due to

Back 176

defect of ARAS; often age-related (As you get older, ARAS isn’t as effective as previously)

Front 177

j. Obstructive sleep apnea characteristics

Back 177

blockage of airway; common in obese
i. Stop breathing for 20-30 seconds, and then take a deep breath.
ii. Can’t die because respiratory reflex will take over.
iii. Really never reach Stage IV, so people are always tired.

Front 178

a. Vestibular system information comes from

Back 178

i. Detects changes in motion and position of the head (respect to gravity and horizon).
ii. Information comes from the equilibrium triad

Front 179

when do equilibrium problems occur?

Back 179

when equilibrium triad is not in sync

Front 180

Equilibrium triad components

Back 180

i. Vision (CN II: Optic Nerve)
ii. Proprioception (Dorsal column)
iii. Vestibular system (CN VIII: Vestibulochochlear Nerve)

Front 181

i. Vision (CN II: Optic Nerve) equilibrium triad characteristics

Back 181

1. Dominant sensation in humans.
2. Constant, coordinated eye gaze; must be able to maintain.
3. Plane of vision determines head position (adjust head to coordinate gaze)
4. VOR: vestibulo-ocular reflex; keeps your eyes pointed in a particular direction despite body movement.

Front 182

ii. Proprioception (Dorsal column) equilibrium triad fxn

Back 182

1. Body position sense in context to gravity
2. Influences the muscle tone of the neck to maintain the plane of vision.

Front 183

iii. Vestibular system (CN VIII: Vestibulochochlear Nerve) equilibrium triad fxn

Back 183

1. Inner ear; detects motion and position changes of the head.

Front 184

a. Bony labyrinth location and parts

Back 184

located in lat. portion of petrous portion of temporal bone
1. cochlea
2. vestibule
3. Semicircular canals/ducts

Front 185

bony labyrinth- cochlea fxn

Back 185

the part that hears

Front 186

bony labyrinth- vestibule characteristics

Back 186

small oval chamber composed of utricle & saccule

1. Utricle & saccule detect linear acceleration.

Front 187

bony labyrinth- semicircular canals/ducts fxn

Back 187

1. Detect angular acceleration

Front 188

bony labyrinth- semicircular canals/ducts structure

Back 188

2. Anterior, posterior, & lateral
3. Set at right angles to occupy 3 planes of space.
4. form 2/3 of a circle
5. Lie posterior to vestibule
6. About 1.5 mm in diameter, except at their ends where they are dilated & referred to as ampulla

Front 189

ampulla characteristics

Back 189

bulge along the semicircular canals that contain the hair cells of the semicircular canals.
a. Face the vestibule

Front 190

perilymph definition

Back 190

fluid w/in the bony labyrinth

Front 191

Membranous labyrinth location

Back 191

inside the bony labyrinth

Front 192

b. Membranous labyrinth characteristics

Back 192

i. System of sacs & ducts that communicate w/& are suspended w/in the bony labyrinth.
ii. Contains endolymph: fluid w/in the membranous labyrinth.
1. Characteristics are identical to perilymph

Front 193

3 parts of membranous labyrinth

Back 193

1. Utricle & saccule
2. 3 Semicircular ducts
3. Cochlear duct

Front 194

1. Utricle & saccule characteristics

Back 194

a. Found in vestibule of bony labryrinth
b. Part of vestibular system
c. Communicate w/each other

Front 195

2. 3 Semicircular ducts characteristics

Back 195

a. Found in semicircular canals
b. Each duct has enlarged end referred to as ampulla
i. W/in ampulla there is a sensory area = crista ampullaris
1. Crista ampullaris: sheet of hair cells of the semicircular canals.

Front 196

3. Cochlear duct characteristics

Back 196

a. Sits in cochlea (part of bony labyrinth)
i. Deals w/sound

Front 197

functional area of semicircular canals

Back 197

Crista ampullaris

Front 198

cupula definition

Back 198

gel that spans the lumen of the canal within the ampulla; cilia project into cupula.

1. Cilia make up sensitized hair cells (~75-100 stereocilia/microvilli).

Front 199

2. Kinocilium definition

Back 199

one tall cilium per each hair cell that detects the direction in which the hair cells bend as a result of head movement

Front 200

Movement of the head causes what to happen?

Back 200

-endolymph to move and bend the hair cells
-cell membrane stretches (when the hair cell moves toward the kinocilium), opening K+ channels and causing depolarization that results in the opening of voltage-gated Ca2+ cannels.

Front 201

2. Hair cell movement determines action potential AWAY/TOWARD characteristics

Back 201

a. AWAY from kinocilium = hyperpolarization (inhibits the cell-no AP)
b. TOWARD kinocilium = depolarization (excitatory receptor potential)
3. Depolarization will cause the membrane to release neurotransmitter.

Front 202

Hair cells- depolarization order of events

Back 202

i. Microvilia bent toward kincocilium -> protein molecules stretched -> mechanical energy -> Opens K channels (K in) -> depolarize cell membrane

Front 203

Depolarization of hair cells causes what to happen

Back 203

opens voltage gated calcium channels -> Influx of calcium -> Influences exocytosis -> Release of neurotransmitter -> Influences distal end 1st order sensory neuron (CN VIII) -example of generator potential which is a type of graded potential

Front 204

Hair cell bodies located where

Back 204

located in the vestibular ganglia

Front 205

crista ampullaris responds to what

Back 205

responds to angular acceleration and deceleration, but not constant movement.

Front 206

Otoliths fxn

Back 206

tiny crystals of calcium carbonate that move in the endolymph; function to add energy dissipation and amplify the message for movement.

Front 207

Utricle fxn

Back 207

lateral bending of head/neck; positioned horizontally - horizontal movement.

Front 208

saccule fxn

Back 208

flexion/extension of head/neck; positioned vertically - vertical movement

Front 209

5. Utricle and saccule detect

Back 209

detect linear acceleration/decelleration

Front 210

a. Nystagmus definition

Back 210

i. Movement of the eyes beginning with a slow movement to one side then a rapid movement in the opposite direction.
ii. Slow > fast in opposite directions

Front 211

2 stages of nystagmus

Back 211

1. Saccades: rapid phase
2. Slow component: slow phase

Front 212

nystagmus naming characteristics

Back 212

iv. Name nystagmus according to the rapid phase – either right or left..

Front 213

nystagmus diagnostic tests

Back 213

Nystagmus is sx of malfunctioning vestibular system:
1. Problems with:
a. Inner ear
b. CN VIII
c. Vestibular ganglia
d. Vestibular nuclei in pons
e. Cerebellum

Front 214

Caloric (temperature) nystagmus: Conduction of the endolymph- way to test for it

Back 214

1. Use cold or warm water in a syringe
2. Water causes the endolymph to move within the semicircular canal more than the saccule and more than the utricle.
3. As the endolymph moves, the hair cells move and result in nystagmus.
a. Cold water in R ear = nystagmus of L (Contralateral)
b. Warm water in R ear = nystagmus of R (Ipsilateral)
ii. If there is no nystagmus with this test, there is a possible neurological issue going on.

Front 215

Rotational nystagmus- you are moving test

Back 215

1. As the head and body pivot and circle, the eyes attempt to fix on an object in space (Slow component)
2. As the head and body continue to circle, the eye snap quickly in the direct in which the head is circling (Saccade/Fast component)
3. Action is similar to what happens when watching telephone poles from a moving train. The saccade is in the direction of the moving train.

Front 216

Rotational nystagmus- Visual field is moving

Back 216

1. If you are stationary watching a train pass in front of you, the fast component is in the opposite direction in which the train is moving

Front 217

Noxious stimulation definition

Back 217

neurons must be stimulated for pain perception; there is a potential for damage to cells/tissue.

Front 218

innocuous stimulation definition

Back 218

there is no potential to damage cells/tissue

Front 219

characteristics of nociceptors

Back 219

a. Specialized neurons which respond to noxious stimulation.
b. Have free nerve endings.

Front 220

nociceptors- A-delta fibers characteristics

Back 220

i. Type III
ii. Thinly myelinated
iii. Conduction velocity between 6-30 m/sec (FAST)
iv. Transmits acute pain, sharp and prickling pain sensations
v. Well localized as to source of stimulation
vi. Less emotional overtone (affective behavior) than C fibers

Front 221

nociceptors- C-fibers neurons

Back 221

i. Type IV
ii. Non-myelinated
iii. Conduction velocity between 0.5-2.0 m/sec (SLOW)
iv. Transmits chronic pain, burning, and aching pain
v. Pain is often of long duration and diffuse
vi. Seems to be involved with affective behavior (emotional overtone) – ie. more grumpy due to chronic pain

Front 222

How does noxious stimulation transmitted via A-delta and C fibers reach the CNS?

Back 222

i. 31 pairs of spinal nerves
ii. 4 pairs of cranial nerves
1. CN V, VII, IX, X
2. Share the spinal nucleus of V to transmit general sensation
iii. Nerves of the ANS
1. Splanchnic and sympathetic nerves of sympathetic system
2. Pelvic nerves of parasympathetic system

Front 223

How does noxious stimulation reach the brain via the CNS?

Back 223

-Spinothalamic tract: divided into lateral and medial tracts
-Found in anterolateral white column of spinal cord, bilateral

Front 224

spinothalamic tract- Lateral: neospinothalamic fxn

Back 224

transmits acute pain

Somatic and visceral pain

Front 225

spinothalamic tract- Medial: paleospinothalamic fxn

Back 225

conveys chronic pain

Somatic and visceral pain

Front 226

spinothalamic tract- Lateral: neospinothalamic characteristics

Back 226

1. 3 neuron pathway
2. Receives input from A-delta neurons
a. Type III neurons (sharp, acute pain nocioceptor)
b. Synapse with 2nd order in lamina I of dorsal horn through brainstem (become lateral meniscus) to VPL (ventral posterior lateral nucleus of thalamus)
c. 3rd order to post central gyrus
3. Allows for localization of pain source specifically (sensory discriminate aspect of pain)

Front 227

spinothalamic tract- Medial: paleospinothalamic characteristics

Back 227

1. Receives input from C fiber neurons
a. Type IV neurons (dull diffuse noxious info)
b. Synapse with 2nd order in lamina V of dorsal horn
c. Synapse w 3rd order in medial nucleus of thalamus to post central gyrus
3. As 2nd order ascend, they project collaterals to the reticular formation.
a. This interaction with the reticular formation is responsible for the association with the limbic system.
b. Therefore, it is related to motivational and affective aspects of pain.

Front 228

Trigeminal tract: characteristics

Back 228

i. CN V, VII, IX, and X share the spinal nucleus of V for general sensation
ii. Transmit pain from head and neck
iii. Receive input from either A-delta or C fibers which end in spinal nucleus of medulla
iv. Second orders synapse in thalamus and third order go to postcentral gyrus

Front 229

how does CNS respond to noxious stimulation?

Back 229

Reflexively using a protective avoidance reflex

Front 230

Protective avoidance reflex may go where?

Back 230

i. Input from A-delta or C fibers does not have to go to the brain for perception and action.
ii. May go straight to spinal cord and then to skeletal muscle for reaction
iii. May go to the brainstem
iv. Splinting/guarding: - protective avoidance reflex dealing with visceral structures

Front 231

protective avoidance reflex to brainstem characteristics

Back 231

1. Reflex arc similar to spinal cord
2. Still send off a pathway to the brain

Front 232

protective avoidance reflex- splinting/guarding characteristics

Back 232

1. Noxious stimulation of visceral organs
2. Guarding - Skeletal muscles that overlie a visceral structure that receives noxious stimulation may contract.
3. The resultant increase in muscle tone protects the underlying visceral structures.

Front 233

Modulatory mechanisms fxn

Back 233

the intensity of pain sensation is modified (generally decreased) despite the continued presence of noxious stimuli

Front 234

Descending Supraspinal inhibitory mechanism fxn

Back 234

modulates how much information ascends the spinothalamic tract

Front 235

Descending Supraspinal inhibitory mechanism characteristics

Back 235

1. Supraspinal influence comes from different areas (hypothalamus, thalamus, limbic system, frontal lobe)
2. The influence synapses with the periaqueductal gray area and projects to the nucleus raphe magnus (part of the reticular formation).
3. The descending reticulospinal tract synapses with the 2nd order sensory neuron to release an inhibitory neurotransmitter to decrease the amount of pain being sent to the post-central gyrus.

Front 236

Descending Supraspinal inhibitory mechanism activation characteristics

Back 236

1. Can happen automatically because we don’t like to be in pain.
2. Patients can be taught biofeedback mechanisms (can learn to do this)
3. Placebo effect, spiritual beliefs, TENS units, dorsal column stimulators.

Front 237

Gating mechanism definition

Back 237

peripheral afferents interact with and modulate noxious information to other parts of the CNS

Front 238

key of gating mechanisms

Back 238

Peripheral afferents interact and modulate transmission of noxious info to other parts of nervous system*

Front 239

gating mechanisms characteristics

Back 239

i. Gate control theory of pain
ii. There is a convergence of noxious (type III and IV fibers) and non-noxious (type I and II) information to transmission cell (T cell) in the dorsal horn.
iii. The noxious pathway is competing with incoming innocuous stimulation (rubbing, shaking, etc.)
iv. This competition causes a decrease in the frequency of pain activity (i.e., 10-50-40 Hz)
v. As a result of rubbing or shaking the affected area, you feel less pain.

Front 240

Referral of pain due to convergence of afferent input definition

Back 240

pain originating in a visceral structure is perceived as coming from a somatic structure (i.e., referred from true source to a false source
-referred pain

Front 241

Convergence projection theory of Ruch definition

Back 241

input from nociceptors of somatic and visceral structures converge upon neurons at some point in the pain pathway

Front 242

Convergence projection theory of Ruch characteristics

Back 242

1. Pain from day one is used to receive pain from somatic structures
2. Visceral structures also have a-delta and c-fibers to transfer pain but the aren’t used often so brain is conditioned to perceive somatic pain
3. Brain assumes visceral pain is coming from somatic structure
4. There is some research to suggest that somatic and visceral nociceptive information converges on the same dorsal horn.
5. Under normal conditions, pain pathways are usually associated with a somatic nociceptor, rarely a visceral one.
6. When the noxious stimuli does originate from a visceral structure and activates the same neurons (that would otherwise be activated by a somatic nociceptor), the brain perceives the information as somatic based on previous experience.

Front 243

Viscerosomatic convergence characteristics

Back 243

most common; example is angina

pain in the upper extremity associated with MI or low back pain associated with kidney infection.

Front 244

Visceroviscerosomatic convergence characteristics

Back 244

-2 different visceral structures and a somatic structure. -clinical correlation results in the mimicking of heart pain as originating from the upper extremity. -Perception of pain is the same from all three structures – brain doesn’t know where it is really coming from

Front 245

Somatosomatic convergence characteristics

Back 245

little research because somatic pain is rarely life threatening (one sore MM vs. another sore MM)

Front 246

Acute pain fibers

Back 246

A delta fibers

Front 247

chronic pain fibers

Back 247

C fibers

Front 248

Allodynia definition

Back 248

pain due to a stimulus that does not usually provoke pain (ie. Gentle touch normally v gentle touch when you have a sunburn)

Front 249

hyperalgesia definition

Back 249

increased response to a stimulus that is normally painful (i.e., more painful than you would expect)

Front 250

Causalgia definition

Back 250

syndrome of sustained, burning pain and allodynia after a traumatic nerve lesion; often combined with vasomotor dysfunction and later trophic changes to tissue (i.e., RSD)

Front 251

neuropathic definition

Back 251

any pain syndrome in which the predominating mechanism is a site of aberrant (abnormal) somatosensory processing in the CNS or PNS

Front 252

Nociceptive pain definition

Back 252

reflects the degree of activation of peripheral nociceptors (A delta and C fibers) in direct response to tissue damage

Front 253

idiopathic pain definition

Back 253

occurs in the absence of an identifiable organic cause

Front 254

neuralgia definition

Back 254

pain in the distribution of a nerve/nerves (i.e., sciatica, shingles).

Front 255

pychogenic pain

Back 255

pain may be due to hypersensitization of the CNS; pt still has pain after the inflammatory process has ended, despite negative tests and measures

Front 256

Peripherally mediated hypersensitivity definition

Back 256

a common physiologic substrate that underlies hypersensitivity of PNS structures.

Front 257

Peripherally mediated hypersensitivity mechanism

Back 257

i. The resting membrane potential is reset at a lower value (less negative – easier to fire)
ii. This takes the cell closer to threshold of activation (hyperpolarized)
iii. Thus, it is easier to fire with less stimulation

Front 258

Anatomical sites of peripheral sensitization

Back 258

1. Receptor organs
2. DRG
3. Distal cellular processes
4. Proximal cellular processes

Front 259

Hypersensitivity chemicals

Back 259

1. Ligands: hyperpolarize the PNS threshold.
2. Kinins: bradykinin, kallidin
3. Interleukins: produced by WBCs; can hypersensitize tissue
4. Nerve growth factor
5. Prostaglandins: histamine, adenosine
6. Tumor necrosis factor
7. Epinephrine, formalin, capsasin

Front 260

Centrally mediated hypersensitivity caused by

Back 260

1. Loss of afferent input (deafferentation) to CNS
2. There are adjustments in the quantity of receptors on post-synaptic cell membranes (Up and down regulation of genes)
3. The neurons in the pain pathway and integrative areas are easier to fire (Leads to: Hypersensitization – allodynia – hyperalgesia)

Front 261

Centrally mediated hypersensitivity mechanism

Back 261

Increased quantities of neuromodulators (substance P, C-Fos, CGRP, others) are produced by nociceptors (A-delta and C fibers) influence the characteristics of the post synaptic membranes of the CNS (first order sensory neurons are releasing more NM)
-neurons in the pain pathway respond to other types of stimuli (Type I and II fibers) that would not normally be noxious, but feel that way because of the lessened activation threshold of the membrane due to the neuromodulators that have been released from the A-Delta and C fibers (i.e., innocuous input from mechanoreceptors).

Front 262

Centrally mediated hypersensitivity- anatomical sites

Back 262

1. Dorsal horn
2. Brain stem (reticular formation)
3. Thalamus
4. Somatosensation and its association cortices

Front 263

iv. If a pt. has experienced a major inflammatory or pathological event and still complains of pain following neg. hematologic, blood chemistry, histological, radiographic and physical examinations, the pain may be due to ....

Back 263

to hypersensitization of the CNS. This then may be the basis of psychogenic pain.

Front 264

phantom limb definition

Back 264

-perception of a missing body part, which is no longer present
-Most amputees experience a phantom limb

Front 265

Phantom pain definition

Back 265

perception of chronic pain in an absent body part; usually manifests itself after surgical amputation.

Front 266

phantom pain most common in

Back 266

most common in LE

Front 267

theories of phantom pain

Back 267

i. Neuroplasticity: some abnormalities may occur in set up
ii. Hypersentization due to loss of afferent input

Front 268

description of phantom pain

Back 268

i. May be continuous, intermittent, or random.
ii. Quite severe
iii. ~25% of patients c/o: burning, cramping, aching, crushing, stabbing, or shooting pain.
iv. Similar to sx of causalgia or peripheral nerve damage.

Front 269

Treatment for phantom pain

Back 269

i. Pharm: meds/analgesia
ii. Physical: TENS, DCS
iii. Physiological: biofeedback

Front 270

How does the CNS internally modulate pain?

Back 270

Under certain pain or stress, there are neurons that release opioid peptide chemicals that activate endogenous analgesic (pain reducing) mechanisms

Front 271

opioid peptide chemicals that activate endogenous analgesic (pain reducing) mechanisms released where?

Back 271

1. Brain
a. Amygdala
b. Hypothalamus
c. Medulla
d. Periaqueductal gray region (PAG)
2. Spinal cord
a. Dorsal horn

Front 272

iii. In order to release opioid mediated analgesia system:

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1. Pain must be prolonged
2. Could be due to psychological stress

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b. How does the opioid mediated analgesia system work?

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i. Cell membranes of the 2nd order spinothalamic tract contain opioid receptors.
ii. The opioid binds to the receptor on the 2nd order neurons.
iii. This binding causes the 2nd order neurons to become hyperpolarized (harder to fire an AP), so less noxious stimuli is transmitted.

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Opioids are all ( ) mediated analgesias and ( )

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centrally

They are all neuropeptides

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3 major chemical families of endogenous opioids

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1. Endorphins: concentrated in brainstem (raphe nucleus) (CNS)
2. Dynorphins: concentrated in the hypothalamus and limbic system
3. Enkephalins: concentrated in the dorsal horns

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Reflex sympathetic dystrophy precipitated by

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i. Precipitated by accidental or surgical trauma and various diseases.

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Reflex sympathetic dystrophy common symptoms

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1. Varying degrees of pain, vasomotor, and trophic changes.
2. Involves abnormal sustained autonomic reflexes.

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ANS Motor and sensory components

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a. Visceral Afferent System: sensory
b. Efferent Output system
i. Sympathetic nervous system: motor
ii. Parasympathetic nervous system: motor

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B. ANS (Efferent portion) innervates:

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a. Smooth muscle (vasculature)
b. Myocardium (cardiac MM)
c. Glands

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ANS (Efferent portion) innervatation- physiological results

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a. Smooth muscles are in arteries = change BP
b. Myocardium = change HR
c. Variation of peristalsis of gastrointestinal tract (can speed up or slow down)
i. Pathological instances: spasms, hyper/hypomotility, reverse peristalsis.
d. Variation in secretions of glands
e. Release of adrenaline from adrenal medulla (also speeds up physiologic processes)
f. Dilate the iris of the eye - miosis

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efferent output sytem- parasympathetic and sympathetic systems in general fxn to

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In general – sympathetic speeds up (except digestion*), parasympathetic slows down

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Sympathetic outflow from where?

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thoracolumbar outflow system (T1 to L2 levels)

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Parasympathetic outflow from where?

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cranial-sacral outflow system (CN III, VII, IX, X and sacral spinal nerves)

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parasympathetic vs. sympathetic system

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b. 2 systems constantly at odds with other
c. symp/para tone – if you need to change the balance, then one system has to be more forceful over the other

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true visceral pain characteristics

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originates from visceral pleura, pericardium, peritoneum, or visceral organs themselves.
i. Comes from A-delta and C fibers in the nerves of the ANS
ii. Visceral afferent system is involved.

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false visceral pain characteristics

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parietal pleura, peritoneum, or pericardium is noxiously stimulated
i. Pleura, etc., is innervated by A-delta and C fibers that are located in the intercostals nerves (spinal nerves)
ii. Somatic afferent system

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Sympathetic system characteristics

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speeds up physiological processes so that the -person can meet either psychological or physiological demands. (Fight or flight)

-Two neuron pathway system (preganglionic, postganglionic); motor neurons

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sympathetic Preganglionic cell bodies of 1st order location

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are located in the lateral gray horn of the spinal cord between T1-L3

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sympathetic system- axons path

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c. Axons leave the spinal cord via the ventral horns and enter the ventral root through ventral rootlets. They then enter the sympathetic trunk through the white ramus.
i. Sympathetic trunk: made up of sympathetic ganglia and collections of axons, which are found on each side of the vertebral column in the pelvis, abdomen, thorax, and neck.
1. AKA sympathetic chain and paravertebral chain ganglia

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preganglionic sympathetic neurons characteristics

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-first in two neuron system, myelinated

-White ramus: area in which preganglionic neurons leave the spinal nerve to join the sympathetic chain.

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postganglionic sympathetic neurons characteristics

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-second in two neuron system, unmyelinated.

-Those that originate in the sympathetic chain rejoin spinal nerves via the gray ramus.

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T1 preganglionic sympathetic neurons go where?

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-to the head
-sympathetic nerves ascend sympathetic chain and synapse in ganglia in head/neck
-Postgang leaves ganglia and wraps around vessels to “piggyback its way”

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T1-T5 preganglionic sympathetic neurons go where?

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visceral structures in the thorax; sympathetic nerves
1. Leaves spinal nerve and entered sympathetic chain via white ramus
2. Synapse in sympathetic ganglia w/ postgang sympathetic nerves.
3. Post leaves the chain and forms small nerves to innervate structures

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T6 through T12 preganglionic sympathetic neurons go where?

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visceral structures in the abdomen; splanchnic sympathetic nerves
1. Axons of preganglionic neurons exit the spinal cord and do not synapse with postganglionic neurons.
2. Instead, they collectively form splanchnic nerves (distinct sympathetic nerves) upon exiting the sympathetic chain
3. Splanchnics terminate by synapsing with the postganglionic fibers in selected ganglia of the abdomen (superior and inferior mesenteric and celiac ganglia).
4. The preganglionic fibers that do not travel to become splanchnics go to the adrenal medulla to secrete adrenaline.

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L1 through L3 preganglionic sympathetic neurons go where?

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kidneys and visceral structures of the pelvis; sympathetic nerves
1. Axons of preganglionic neurons exit the spinal cord, pass through sympathetic chain, and exit as specific spinal nerves (i.e., pelvic nerves).
2. Terminate in ganglia to synapse with postganglionic neurons.
3. They then travel to respective target organs.

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White and Grey communicans characteristics

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1. White: pregang are myelinated
2. Grey: Postgang sympathetic neurons can re-enter spinal nerves via grey communicans. All postgang are non myelinated. These nerves are responsible for innervating vessels.

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Parasympathetic system characteristics

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opposite function from the sympathetic system; physiologic processes decrease with the exception of digestion (rest and digest).
a. 90% of its function is due to the vagus nerve
b. Two neuron pathway (preganglionic and postganglionic)
c. Four cranial nerves (CN III, VII, IX, and X) and the sacral portion of the spinal cord. (craniosacral output system)

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parasympathetic system cranial nerves cell bodies characteristics

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located in the motor nuclei (in the brain stem) associated with CN III, VII, IX, and X
1. Exit the brainstem and pass to specific parasympathetic ganglia where they synapse with postganglionic neurons to innervate a target structure

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parasympathetic sytem sacral nerves S2-S4 cell bodies characteristics

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1. Leave the spinal nerves collectively as parasympathetic nerves (pelvic nerves) to synapse with postganglionic neurons in parasympathetic ganglia of the pelvis which then innervate target structures.

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Oculomotor (CN III) parasympathetic fxns

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a. Causes the Ciliary body to constrict, causing accommodation (lens changes shape).
b. Causes the sphincter papillae muscle to constrict on the iris of the eye (pupil smaller), miosis.

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Oculomotor (CN III) parasympathetic preganglionic neurons path

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originate from the Edinger Westphal nucleus in the midbrain and leave with the cranial nerve.
3. Synapse with postganglionic in the Ciliary ganglion located posterior to the eyeball.

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3 parasympathetic facial nerve innervations

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a. Two of the three sets of sublingual and submandibular salivary glands.
b. Lacrimal glands
c. Numerous mucous glands associated with mucosal tissue of the mouth, nose, and paranasal sinuses.

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parasympathetic facial nerve preganglionic neurons origins

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2. Preganglionic neurons originate in the superior and inferior salivatory nuclei in the medulla.

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parasympathetic facial nerve preganglionic neurons synapse with postganglionic neurons in what two places?

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a. Submandibular ganglion: innervates the submandibular, lingual, and mucous glands.
b. Pterygopalatine ganglion: innervate the lacrimal glands and various mucous glands.

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Glossopharyngeal nerve (CN IX) parasympathetic innervation

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Third set of salivary glands (parotid)

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Glossopharyngeal nerve (CN IX) parasympathetic preganglionic neurons path

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originate in the inferior salivatory nuclei located in the medulla.
3. Axons leave with the cranial nerve and synapse with the postganglionic neuron in the otic ganglia located just inferior to the foramen ovale.
4. Terminate in the parotid glands.

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Vagus nerve parasympathetic innervations

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1. Innervates ALL visceral structures of the thorax, abdomen, and pelvis.

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Vagus nerve parasympathetic preganglionic neurons path

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2. Preganglionic neurons originate in the dorsal motor nucleus of the medulla.
3. Exit with the cranial nerve and synapse with postganglionic neurons in ganglia close to the structures being innervated.
4. Postganglionic fibers are short.

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parasympathetic innervation of the blood vessels and skin of the lower and upper extremities and trunk characteristics

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-Trick question
-There is no parasympathetic innervation of the blood vessels and skin of the lower and upper extremities and trunk
-(No parasympathetic anatomy to make it happen)

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how is sympathetic tone of blood vessels and skin of lower and upper extremities and trunk countered?

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-In order to counter the sympathetic tone (in terms of vasoconstriction and glandular secretion), the Hypothalamus instructs that the sympathetic tone decreases
-Theory: there may be some parasympathetic pathways to the blood vessels of the head, neck, and face using the facial and vagus nerves.

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ANS sympathetic nervous system neurotransmitters

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i. Preganglionic use ACh
ii. Postganglionic use norepinephrine
iii. Called the adrenergic system (utilizes adrenaline)

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ANS parasympathetic nervous system neurotransmitters

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i. Both pre and post use ACh
ii. Called the cholinergic system (utilizes acetylcholine)