Last Minute Revision CNS Flashcards
(63 cards)
1
Q
Types of intrafusal fibres
A
- Nuclear bag fibres - nuclei aggregated as bags in the central portion
- Nuclear chain fibres - nuclei are arranged in single row
2
Q
Sensory nerve supply of muscle spindle
A
- Annulospiral endings
2. Flower spray endings
3
Q
Annulospiral endings
A
- 1a afferents
- end as a ring around central portion of nuclear bag and chain fibres
- both dynamic and static response
- respond both to changes in length and velocity of change
4
Q
Flower spray endings
A
- A beta fibres
- only from nuclear chain fibres
- mainly static response
5
Q
Static response
A
When receptor portion is stretched slowly number of impulses transmitted from both primary and secondary endings increases directly proportional to degree of stretching
6
Q
Dynamic response
A
When length of receptor increases suddenly primary ending is powerfully stimulated and responds actively to rapid rate of change and spindle length but only while the length is actually increasing
7
Q
Motor nerve supply
A
- Gamma 1 efferents - NBF dynamic
2. Gamma 2 efferents - NCF static
8
Q
Mechanism of activation of muscle spindle
A
- Stretch of muscle causes stretch of spindle activating primary and secondary endings
- Activation of Gamma motor efferents
9
Q
Functions of muscle spindle
A
- Participates in stretch reflex
- Regulation of muscle tone and posture by alpha gamma co activation
- Proprioception
- Monitors length of muscle
10
Q
Alpha Gamma co activation
A
Alpha motor neurones and gamma motor neurones are stimulated simultaneously.
Causes for extrafusal and muscle spindle fibres to contract at same time.
1. Prevents activation of muscle spindle reflex
2. Maintains damping function
11
Q
Brain areas controlling gamma motor system
A
- Reticular activating system
2. Signals from cerebellum, basal ganglia, cerebral cortex
12
Q
Components of stretch reflex arc
A
- Muscle spindle
- Afferent sensory nerves
- Spinal cord
- Motor nerves
- Extrafusal fibres
13
Q
Phasic stretch reflex
A
- dynamic
- activating primary endings
- causes contraction of muscle containing muscle spindle and inhibition of antagonistic muscle
- helps bring about movement
14
Q
Tonic stretch reflex
A
- static
- activation of both primary and secondary endings
- causes steady contraction of muscle containing spindle
- for maintaining tone and posture
15
Q
Location of Golgi tendon organ
A
- junction between muscle fibres and tendon
- detect tension in muscle
16
Q
Functions of Golgi tendon organ
A
- Modulates muscle tension during movements
- Prevent muscle tear
- Inverse stretch reflex and lengthening reaction
17
Q
Spastic gait
A
Lesion in pyramidal tract
Hemiplegia
18
Q
Drunken gait
A
Cerebellar ataxia
19
Q
Festinant gait
A
Parkinsonism
Bent forward moves in rapid shuffling steps
20
Q
Stamping gait
A
Tabes dorsalis
Due to loss of sensory feedback to brain
21
Q
High stepping gait
A
Weakness of extensor muscles of feet
Common peroneal nerve palsy
22
Q
Waddling gait
A
Myopathies and muscular dystrophies
Body tilted back
23
Q
Scissors gait
A
Congenital spastic paraplegia
24
Q
Hypotonia seen in
A
- Destruction of motor fibres
- Destruction of dorsal columns
- Stimulation of inhibitory areas of brain
- Inhibition of facilitatory areas
- Sleep
- Thalamic and cerebellar lesions
- Barbiturates
25
Hypertonia seen in
1. Stimulation of facilitatory areas
2. Destruction of inhibitory areas
3. Increase Gamma motor neuron activity
4. Increase Alpha motor neurone activity
26
Spasticity
Lesion of pyramidal tract
Involves only one group of muscles
Clasp knife rigidity
Proportional to stretch
27
Rigidity
```
Lesion of basal ganglia
Involve both agonists and antagonists
Lead pipe rigidity
No auto inhibition
Resistance is present through passive movements
```
28
Cerebellar disorders
1. Drunken gait
2. Hypotonia
3. Pendular reflexes
4. Asynergia
5. Dysmetria
6. Intention tremors
7. Asthenia
8. Rebound phenomenon
9. Dysdiadochokinesia
10. Nystagmus
11. Scanning speech
SIN AAA DDD
29
Functions of semicircular canals
1. Give info about rotational movement of head
2. Help maintain equilibrium
3. visual fixation during angular rotation of head
30
Vestibulo ocular reflex
- Form stable image on retina during rapid head rotation
- producers conjugate movements of eyes in opposite direction of head rotation
- vestibular apparatus with 3rd, 4th, 6th cranial nuclear through medial longitudinal fasciculus
31
Optokinetic reflex
- Person viewing rapidly moving object from stationary position
- eyes move along stimulus till it disappears and return to original position rapidly
- superior colliculus with 3rd, 4th, 6th cranial nerves through medial longitudinal fasciculus
32
Functions of otolith organs
1. Info about static position of head
2. Respond to linear acceleration
3. Utricle detect dorsiflexion and ventriflexion
4. Maintain balance while jumping or walking down stairs
33
Main outlet for efferents of basal ganglia
Globus pallidus
34
Afferents of basal ganglia
Corticostriatal - ipsi., Frontal and parietal
| Thalamostriate - intralaminar and centromedian
35
Internuclear connections of basal ganglia
Nigrostriatal
Nigropallidal
Striatonigral
Strialopallidal
36
Efferent connections of basal ganglia
Pallidothalamic via ansa fasicularis and ansa lenticularis
| Nigrothalamic
37
Food intake hypothalamus
VMN - satiety centre
| LN - feeding centre
38
Chorea
Destruction of GABA ergic neurons in caudate n.
- involuntary jerky mvmts of limbs, orofacial muscles
Sydenhams - in children due to rheumatic fever
Huntington's - autosomal. Chorea + dememtia
39
Athethosis
Inability to fix muscles of fingers toes in one position
Destruction of GABA neurons in putamen
Appear as grasping mvmts
40
Ballism
Lesion in subthalamic body
| Flinging involuntary mvmts of extremeties on opp. Side
41
Body temperature hypothalamus
Preoptic
Ant. Hypothalamus
Post. Hypothalamus
42
Preoptic nucleus receives info by
Blood flowing through hypothalamus
| Cutaneous receptors of cerebral cortex
43
Anterior hypothalamus
```
Stimulus:
When temp. Inc.
Action:
Cutaneous vasodilation
Sweat secretion
```
44
Posterior hypothalamus
```
Stimulus:
When temp. Dec.
Action:
Cutaneous vasoconstriction
Rigors
```
45
Thirst hypothalamus
```
Preoptic
LN
Stimulus:
Inc. tonicity
Oral dryness
ECF volume Dec.
```
46
Functions of hypothalamus
1. Food intake reg.
2. Body temp. Reg.
3. Thirst reg.
4. ECF volume reg.
5. Endocrine
6. Reproduction
7. Reproductive behaviour
8. Sleep wake cycle
9. ANS control
10. Emotion reg.
11. Stress
12. Circadian rhythm
13. Reward punishment
47
Sleep wake cycle hypothalamus
Diencephalic sleep zone
Basal forebrain sleep zone
Slow wave sleep
48
Papez circuit
Ant. Thalamic nuclei -
Cingulate gyrus
Hippocampus
Mamillary bodies
49
Functions of limbic system
1. Autonomic function
2. Discriminative feeding
3. Memory and learning
4. Emotional behaviour
5. Sexual behaviour
6. Olfaction
7. Reward punishment
8. Maternal behavior
50
NREM sleep
```
Hypotonia
Slow delta waves
No rapid eye mvmts
Dreams can't be recalled
No pontogeniculooccipital spikes
Low pulse, bp
Low serotonin
Sensory threshold Inc.
Low brain activity
Low O2 consumption
```
51
REM sleep
```
Reduced muscle tone
Fast beta waves
REM saccades
Dreams recalled clearly
Teeth grinding
Pontogeniculooccipital spikes seen
Irregular bp, pulse
Noradrenaline Dec.
Sensory threshold very high
More brain activity
More O2 consumption
```
52
Significance of evoked potentials
1. Find integrity of pathway
2. Auditory evoked potential to test hearing in newborn
3. Understanding sensory connections
4. Map centres for sensation
5. Localise site of lesion
53
Focal seizures
- begin in localised region of cortex
- local to 1 hemisphere
- promote rapid neuronal discharges
- called Jacksonian March
- starts from particular area and spreads to adjacent areas
- usually by brain tumor
54
Generalized seizures
- cannot be referred to one hemisphere
55
Grand mal seizure
- sudden loss of consciousness followed by convulsions
- epileptic aura felt
- starts with tonic contractions followed by clonic
- EEG spikes
56
Petit mal seizure
- Sudden loss of consciousness
- no convulsions
- spike dome EEG
57
Parts involved in short term memory
```
Hippocampus
Mamillary bodies
Thalamus
Amygdala
Prefrontal cortex
```
58
Mechanisms of short term memory
Reverberating circuits
PTP
Presynaptic facilitation
59
Mechanism of long term memory
LTP
60
Physiological changes seen in LTP
1. Change in the expression of postsyn. Neuron
2. Inc. Synthesis and release of neurotransmitter
3. Change in receptor response
61
Structural changes in LTP
1. Formation of new connections
2. Inc. no of releasing sites and receptor sites
3. Change in neuroglial cells
62
Speech centres
Area 42, 18, 19, 39
Wernickes
Brocas
63
Functions of external ear
1. Inc. sound pressure on tympanic membrane
2. Sound collection, localisation
3. Humid environment
4. Prevents entry of foreign bodies
5. Limits frequencies reaching tympanum
