Neuro Flashcards
(326 cards)
1
Q
Give 3 functions of the cranial meninges.
A
- Protects the brain and spinal cord form injury.
- Provides a framework for cerebral and cranial vasculature.
- Provides a space for the flow of CSF.
2
Q
What are the 3 meningeal layers?
A
- Dura mater (outermost).
- Arachnoid mater.
- Pia mater (inner most).
3
Q
What are the 2 connective tissue sheets of dura mater?
A
- Endosteal layer - lines the cranium.
2. Meningeal layer.
4
Q
Where are the dural venous sinuses located?
A
Between the endosteal layer of dura and the meningeal layer.
5
Q
What vein do the dural venous sinuses drain into?
A
The internal jugular veins.
6
Q
Name 3 locations where the dura mater folds inwards as dural reflections?
A
- Falx cerebri.
- Tentorium cerebelli.
- Falx cerebelli.
7
Q
Where is the falx cerebri located?
A
It lies in the longitudinal fissure between the cerebral hemispheres.
8
Q
Where is the tentorium cerebelli located?
A
The tentorium cerebelli is a thick fibrous roof lying over the posterior cranial fossa and the cerebellum.
9
Q
Where is the falx cerebelli located?
A
Between the 2 lobes of the cerebellum.
10
Q
What lies beneath the arachnoid mater?
A
The subarachnoid space containing CSF and arteries.
11
Q
What is the function of the blood-brain barrier?
A
It protects the brain by preventing the passage of some substances from the circulation into the nervous tissue.
12
Q
Which meningeal layers are highly vascularised?
A
The dura and pia mater. The arachnoid mater is avascular.
13
Q
Name the 3 elements that make up the blood-brain barrier.
A
- Capillary endothelial cells.
- Basement membrane.
- Astrocytic end-feet.
14
Q
What are the 2 main arteries that supply blood to the brain?
A
- Vertebral arteries.
- Internal carotid
2. Internal carotid arteries.
15
Q
Which arteries supply about 80% of blood to the brain?
A
The internal carotid arteries.
16
Q
What are the vertebral arteries a branch of?
A
The subclavian arteries.
17
Q
Where do the vertebral arteries enter the skull?
A
Through the foramen magnum.
18
Q
What are the internal carotid arteries branches of?
A
The common carotids. Arise from bifurcation at the same level as the upper border of the thyroid cartilage.
19
Q
What do the vertebral arteries supply?
A
The posterior cerebrum and the
contents of the posterior cranial fossa.
20
Q
What do the internal carotid arteries supply?
A
The anterior and middle parts of the cerebrum and the diencephalon.
21
Q
Where do the internal carotid arteries enter the skull?
A
Through the carotid foramina.
22
Q
What are the terminal branches of the internal carotid arteries?
A
The middle and anterior cerebral arteries.
23
Q
What does the middle cerebral artery supply?
A
The lateral surface of the hemispheres.
24
Q
What does the anterior cerebral artery supply?
A
The medial aspect of the hemispheres and the corpus callosum.
25
What does the posterior cerebral artery supply?
The occipital lobe.
26
What artery passes through foramen spinosum?
The middle meningeal artery.
27
What do the two vertebral arteries form?
The basilar artery.
28
Where is a berry aneurysm likely to occur?
At branching points in the circle of willis, especially at the anterior communicating artery.
29
What is a berry aneurysm?
A sac-like out pouching that will progressively enlarge until it ruptures resulting in haemorrhage.
30
What are the two types of stroke?
1. Ischaemic.
| 2. Haemorrhagic (intracerebral or subarachnoid).
31
Where are dural venous sinuses located?
In between the endosteal and meningeal layers of dura.
32
Where do cerebral veins drain into?
Into dural venous sinuses.
33
What does the great cerebral vein drain?
Deep brain structures.
34
What sinus does the great cerebral vein drain into?
The straight sinus.
35
Where is the straight sinus located?
In the midline of the tentorium cerebelli.
36
What vessels lie in the cavernous sinus?
- Cn 3, 4, 5(1), 5(2) and 6.
| - Internal carotid artery.
37
Why is the cavernous sinus of clinical importance?
If this sinus is infected Cn 3, 4, 5(1), 5(2) and 6 and the internal carotid artery could be affected.
38
How do dural venous sinuses and veins outside the skull communicate?
Via emissary veins.
39
What is the clinical significance of emissary veins?
They represent a possible route for infection to spread into the cranial cavity.
40
Briefly describe the pathway of venous drainage starting at the great cerebral vein.
Great cerebral vein -> straight sinus -> transverse sinus -> sigmoid sinus -> internal jugular vein -> jugular vein -> brachiocephalic vein -> SVC.
41
What sinuses form the confluence of sinuses?
The straight sinus and the superior sagittal sinus.
42
Where is the largest aggregation of choroid plexus?
In the lateral ventricles.
43
Where is the majority of CSF produced?
In the lateral ventricles (greatest amount of choroid plexus here`).
44
What is ependyma?
A thin-epithelial like structure lining the ventricles.
45
Tight junctions prevent the passage of fluid into the ventricles. Why is this important?
It means that the volume and composition of CSF can be closely controlled.
46
What embryonic part of the brain is the midbrain formed from?
Mesencephalon.
47
What embryonic part of the brain is the pons formed from?
Metencephalon of Rhombencephalon.
48
What embryonic part of the brain is the medulla oblangata formed from?
Myelencephalon of Rhombencephalon.
49
What are the characteristic features of a cervical vertebra?
- Small vertebral body.
- Transverse foramen for vertebral arteries.
- Bifurcation of spinous processes (except C7).
- Triangular intervertebral foramen.
50
What region of the vertebral column has the greatest capacity for rotation?
The thoracic region.
51
What region of the vertebral column has the least capacity for flexion?
The thoracic region; this is due to the presence of the ribcage.
52
What are the 2 components of an intervertebral disc?
1. Nucleus pulposus.
| 2. Annulus fibrosus: concentric layers of collagen surrounding the nucleus pulposus.
53
What does the ligamentum flavum connect?
Connects the laminae of adjacent vertebrae.
54
Where does the spinal cord end?
a) in an adult.
b) at birth.
c) in the embryo.
a) L2.
b) L3.
c) runs the entire length of the vertebral column.
55
Where would you insert a lumbar puncture needle?
At the L3/L4 level in the sub-arachnoid space in order to take CSF.
56
Where would you insert an epidural needle?
Between the dura mater and vertebrae in order to inject anaesthesia.
57
What is the conus medullaris?
The tapered, lower end of the spinal cord.
58
What is the filum terminale?
A fibrous strand that proceeds downwards from the apex of the conus medullaris.
59
What is the cauda equina?
Spinal nerves from the lower spinal cord that hang obliquely downwards.
60
Define dermatome.
An area of skin with a sensory nerve supply from a single root of the spinal cord.
61
What is the dermatome for the thumb?
C6.
62
What is the dermatome for the knee?
L3.
63
What is the dermatome for the big toe?
L5.
64
Name 4 ascending spinal pathways.
1. DCML.
2. Spinothalamic.
3. Spinocerebellar.
4. Spinoreticular.
65
What sensations does the DCML pathway convey?
Fine touch, 2-point discrimination and proprioception.
66
What sensations does the spinothalamic pathway convey?
- Lateral spinothalamic - pain and temperature.
- Anterior spinothalmic - crude touch
| - Anterior spinothalamic - crude touch.
67
Describe the DCML pathway.
Fine sensation is detected by touch or proprioception receptors. Afferent signals are carried along 1st order neurones to the dorsal columns and up to the medulla where they synapse. 2nd order neurones decussate in the medulla and travel up to the thalamus where they synapse. 3rd order neurones then travel through the internal capsule to the somatosensory cortex.
68
Which dorsal column would an afferent signal from the lower limb use?
The gracile fasciculus (medial part of dorsal column). They then synapse at the gracile nucleus of the medulla.
69
Which dorsal column would an afferent signal from the upper limb use?
The cuneate fasciculus (lateral part of dorsal column). They then synapse at the cuneate nucleus of the medulla.
70
Describe the spinothalamic pathway.
Nociceptors or thermoreceptors detect pain, temperature or crude touch. 1st order neurones carrying these signals enter the spinal cord and ascend 2-3 spinal levels before synapsing in the dorsal horn of grey matter. 2nd order neurones decussate either through the anterior or lateral tracts and then travel up to the thalamus where they synapse. 3rd order neurones travel through the internal capsule to the primary somatosensory cortex.
71
Where is the somatosensory cortex located?
Post-central gyrus in parietal lobe.
72
What sensations is the lateral spinothalamic tract responsible for?
Pain and temperature.
73
What sensation is the anterior spinothalamic tract responsible for?
Crude touch.
74
What is the function of the spinocerebellar tracts?
They carry unconscious proprioceptive information to the ipsilateral cerebellum.
75
Do the fibres decussate in the spinocerebellar tracts?
No! They go to the ipsilateral cerebellum.
76
What sensation does the spinoreticular tract convey?
Deep/chronic pain.
77
Name 5 descending pathways.
1. Corticospinal.
2. Vestibulospinal.
3. Rubrospinal.
4. Tectospinal.
5. Reticulospinal.
78
Where in the thalamus do the DCML and spinothalamic tracts synapse?
In the ventral posterio-lateral division (VPL) of the nucleus of thalamus.
79
What descending pathways are described as pyramidal?
Corticospinal and corticobulbar tracts - responsible for voluntary control.
80
What descending pathways are described as extrapyramidal?
Vestibulospinal, rubrospinal, tectospinal, reticulospinal - responsible for involuntary and automatic control of all musculature, such as muscle tone, balance, posture and locomotion.
81
Are there any synapses within the descending pathways?
No. At the termination of the descending tracts, the neurones synapse with a lower motor neurone. (All the neurones within the descending motor system are UMNs).
82
What are the corticospinal tracts responsible for?
The control of voluntary muscles. Anterior - axial muscles. Lateral - limb muscles.
83
Describe the corticospinal tracts.
Originate in the primary motor cortex, descends through corona radiata and internal capsule to the medullary pyramids. 90% decussates here and becomes the lateral corticospinal tract; the remaining 10% forms the anterior corticospinal tract. The anterior tract then decussates through the anterior white commissure. Both tracts terminate in the ventral horn.
84
Describe the corticobulbar tracts.
Originate in the primary motor cortex, descends through corona radiata and internal capsule to the brainstem. The fibres terminate on motor nuclei of cranial nerves. They synapse with LMN's which carry motor signals to the face and neck.
85
Where do the extrapyramidal tracts originate?
The brainstem.
86
Where do the vestibulospinal tracts originate and what are they responsible for?
1. Originate from vestibular nucleus.
2. Responsible for muscle tone and postural control.
- Remains ipsilateral.
87
Where do the reticulospinal tracts originate and what are they responsible for?
1. Originate from reticular formation.
| 2. Responsible for spinal reflexes.
88
Where do the tectospinal tracts originate and what are they responsible for?
1. Originate from tectum nuclei (superior and inferior colliculi).
2. Responsible for head turning in response to visual and auditory stimuli.
89
Where do the rubrospinal tracts originate and what are they responsible for?
1. Originate from red nucleus.
2. Responsible for assisting motor functions.
- Contralateral.
90
What tracts are known as the ventrolateral/anterolateral system?
Spinothalamic tracts.
91
Damage to the anterolateral system will present with what symptoms?
Contralateral loss of pain and temperature sensation.
92
What tracts are known as the dorsomedial system?
DCML.
93
What would be the signs of a complete spinal cord lesion?
- Weakness in all muscle groups below the lesion.
- Complete sensory loss below lesion.
- Spasticity and hyperreflexia.
94
What is Brown-Sequard syndrome?
Hemi-section of the spinal cord.
95
What would be the signs of Brown-Sequard syndrome?
- Ipsilateral weakness and loss of motor function below the lesion.
- Ipsilateral loss of proprioception, 2-point discrimination and fine touch.
- Contralateral loss of pain and temperature sensation 2-3 spinal segments below the lesion.
96
What are the 3 primary vesicles?
- Prosencephalon (forebrain).
- Mesencephalon (midbrain).
- Rhombencephalon (hindbrain).
97
What are the sub-divisions of the prosencephalon?
- Telencephalon.
| - Diencephalon.
98
What does the telencephalon form?
- The cerebral hemispheres.
99
What does the diencephalon form?
- Thalamus.
| - Hypothalamus.
100
What does the mesencehpalon form?
- Midbrain.
| - Colliculi.
101
What are the sub-divisions of the rhombencephalon?
- Metencephalon.
| - Myelencephalon.
102
What does the metencephalon form?
- Cerebellum.
| - Pons.
103
What does the myelencephalon form?
- Medulla oblangata.
104
Where are the lateral ventricles formed in the embryo?
Telencephalon.
105
Where is the 3rd ventricle formed in the embryo?
Diencephalon.
106
Where is the 4th ventricle formed in the embryo?
Rhombencephalon.
107
What are the pluripotent stem cells that lie within the neural folds?
Neural crest cells.
108
What do neural crest cells develop into?
Schwann cells, pigment cells, adrenal medulla, dorsal root ganglia, Cn 5, 7, 9 and 10.
109
How is the neural tube formed?
Notochord in mesoderm signals the ectoderm to form a thickened neural plate. Mitosis forms a neural groove. There are neural folds either side of the groove. These fuse at the midline forming the neural tube.
110
When should the neural tube fuse?
By the end of the 4th week.
111
What vitamins are needed to ensure the neural tube fuses.
B9 (folic acid) and B12.
112
Approximately how much CSF do we have?
120ml.
113
What is hydrocephalus?
An accumulation of CSF in the ventricular system. Often due to a blockage in the cerebral aqueduct.
114
Name 4 substances contained within the CSF.
1. Protein.
2. Urea.
3. Glucose.
4. Salts.
115
Define axonal transmission.
Transmitting information from A to B.
116
Define synaptic transmission.
Integration/processing of information.
117
What are the 5 fundamental processes of neurotransmission?
1. Manufacture.
2. Storage.
3. Release.
4. Interaction with post-synaptic receptor.
5. Inactivation.
118
Give 2 examples of fast neurotransmitters. Do fast neurotransmitters have short or long lasting effects?
- Ach, GABA.
| - Short lasting effects.
119
Give 3 examples of neuromodulators. Do neuromodulators have short or long lasting effects?
- Dopamine, serotonin, noradrenaline.
| - Long lasting effects.
120
What is an endorphin?
A peptide with opiate like effects. They inhibit the release of substance P.
121
How long does the refractory period last?
5-10ms.
122
What is the relative refractory period?
It follows the absolute refractory period and is a time during which a 2nd stimulus that is stronger than the first is needed to produce another AP.
123
What are the 2 components of a refractory period?
The absolute refractory period which is followed by the relative refractory period.
124
What is the neuronal resting potential?
-70mV.
125
How is the neuronal resting potential maintained?
3Na+ are pumped out of the cell for every 2K+ pumped in. This process requires ATP. There are many Na+/K+ transport pumps.
126
Define nociceptive pain.
Pain derived from actual damage to non-neural tissue, it is due to the activation of nociceptors.
127
Define neuropathic pain.
Pain caused by a primary lesion or dysfunction of the nervous system.
128
Are C fibres myelinated or unmyelinated?
Unmyelinated.
129
Describe C fibres.
- They are the smallest nerve fibres.
- Unmyelinated and so have slow conduction speeds.
- They have a high activation threshold meaning they detect selectively nociceptive stimuli.
130
Describe A delta fibres.
- Small nerve fibres but larger than C fibres.
- Thinly myelinated.
- They have a high activation threshold.
131
What type of pain are A delta fibres responsible for?
The sensation of a quick, sharp, localised pain; 'first pain'.
132
What type of pain are C fibres responsible for?
C fibres respond to high intensity stimuli. They are responsible for a slow, deep, spread-out pain; 'second pain'.
133
What is voluntary motor control?
Goal directed (conscious) or habitual (unconscious/automatic). E.g. running, walking talking etc.
134
What is involuntary motor control?
Eye movements, facial expressions, posture, diaphragm etc.
135
What neurones innervate muscle fibres.
Alpha motor neurones.
136
Define motor unit.
A single alpha motor neurone and all the muscle fibres it innervates.
137
Do the finger tips have lots of muscle fibres or few muscle fibres?
Few muscle fibres. This allows for greater movement resolution.
138
Does function of a muscle affect how many muscle fibres there are?
Yes! The finger tips have few muscle fibres because they require greater movement resolution.
139
What are spinal reflexes?
- Involuntary, physiological responses to stimuli e.g. withdrawing your hand when you touch something hot.
- Unlearned and instinctive: unconditioned responses.
140
What information do muscle spindles provide?
How much each muscle is stretched.
141
What neurones innervate muscle spindles?
Gamma motor neurones.
142
What are muscles spindles composed of?
Intrafusal fibres. (They are embedded in muscle - extrafusal fibres).
143
Withdrawal reflex: what does reciprocal innervation of antagonistic muscles explain?
It explains why the contraction of one muscle induces the relaxation of the other; this permits the execution of smooth movements.
144
What do golgi tendon organs measure?
Mechanoreceptors that measure changes in tension of a muscle.
145
What nerve fibres innervate golgi tendon organs?
Afferent type 1b sensory nerve fibres (inhibitory).
146
What is the response of golgi tendon organs if they detect a change in tension?
They inhibit alpha motor neurones to prevent muscle contraction if the force gets too great.
147
What is an UMN?
A neurone that is located entirely in the CNS. Its cell body is located in the primary motor cortex.
148
What is a LMN?
A neurone that carries signals to effectors. The cell body is located in the brain stem or spinal cord.
149
What are the signs of UMN weakness?
- Increased muscle tone.
- Hyper-reflexia.
- Spasticity.
- Minimal muscle atrophy.
150
What are the signs of LMN weakness?
- Decreased muscle tone.
- Hypo-reflexia.
- Flaccid.
- Muscle atrophy.
- Fasciculations.
151
What can cause UMN weakness?
MS, brain tumour, stroke.
152
What can cause LMN weakness?
Slipped disc, neuropathies.
153
What are the characteristic features of MS?
MS comes and goes and its symptoms are exacerbated after having a shower.
154
What is myasthenia gravis?
An autoimmune disease; antibodies destroy Ach receptors.
155
What are the signs of myasthenia gravis?
Weakness and tiredness. Actions like chewing become progressively much harder.
156
What does myasthenia gravis affect: LMN, UMN, neuromuscular junctions?
Neuromuscular junctions.
157
Where do the two optic nerves meet?
At the optic chiasm. The images from the two eyes are fused here.
158
Where do the optic tracts terminate?
Lateral geniculate body in the thalamus.
159
What is the loop of optic radiation responsible for the upper visual field called?
Meyer's loop. It travels through the temporal lobes.
160
Which lobes of the brain does the loop of optic radiation responsible for the lower visual field travel through?
Travels through the parietal lobes.
161
What is the dorsal stream?
The 'where' stream. It is thought to determine the objects spatial location. It travels through the parietal lobe.
162
What is the ventral stream?
The 'what' stream. It is thought to be involved in identification and recognition. It travels through the temporal lobe.
163
What would be the affect on the visual field if there was a complete lesion of the left optic nerve?
Total left eye blindness.
164
What would be the affect on the visual field if there was a complete lesion of the optic chiasm?
Bipolar hemianopia. (Left eye - left sided blindness, right eye - right sided blindness).
165
What would be the affect on the visual field if there was a complete lesion of the right optic tract?
Left homonymous hemianopia. (Left side blindness of both eyes).
166
What would be the affect on the visual field if there was a lesion of the meyer's (temporal) loop of the left optic radiation?
Right homonymous superior quadrantanopia. (Right upper quadrant of both eyes affected).
167
What would be the affect on the visual field if there was a lesion of the parietal loop of the left optic radiation?
Right homonymous inferior quandrantanopia. (Right lower quadrant of both eyes affected).
168
What occular muscles does the superior branch of Cn 3 innervate?
- Levator palpebrae superioris.
| - Superior rectus.
169
What occular muscles does the inferior branch of Cn 3 innervate?
- Medial rectus.
- Inferior rectus.
- Inferior oblique.
170
What occular muscle does Cn 4 innervate?
Superior oblique.
171
What occular muscle does Cn 6 innervate?
Lateral rectus.
172
What is the origin and insertion of levator palpebrae superioris?
Origin: common tendinous ring.
Insertion: Upper eyelid.
173
What is the action(s) of superior oblique on the eyeball?
- Intorsion.
- Depression.
- Abduction.
174
What is the action(s) of inferior rectus on the eyeball?
- Depression.
- Extorsion.
- Adduction.
175
What is the action(s) of medial rectus on the eyeball?
- Adduction.
176
What is the action(s) of superior rectus on the eyeball?
- Elevation.
- Intorsion.
- Adduction.
177
What is the action(s) of inferior oblique on the eyeball?
- Extorsion.
- Elevation.
- Abduction.
178
What is the action(s) of lateral rectus on the eyeball?
- Abduction.
179
What is the function of the outer ear?
It gathers sound energy and focuses it on the tympanic membrane; this vibrates the tympanic membrane. The outer ear also amplifies sound.
180
What nerve provides general sensation to the outer ear?
Cn 10.
181
What 3 bones make up the ossicular chain?
Malleus, incus and stapes.
182
What is the smallest bone in the human body?
The stapes.
183
What is the function of the ossicles?
To transmit vibrations from the tympanic membrane to the oval window.
184
What nerve provides general sensation to the middle ear?
Cn 9.
185
What muscles can change the stiffness of the ossicular chain?
Stapedius and tensor tympani.
186
What nerve innervates stapedius?
Cn 7.
187
What nerve innervates tensor tympani?
Cn 5.
188
How do stapedius and tensor tympani change the stiffness of the ossicular chain?
They control the mobility of malleus and stapes and so protect the inner ear from loud noises.
189
What is the function of the round window?
It vibrates with opposite phase to vibrations entering the inner ear through the oval window. This moves the fluid in the cochlea which means that hair cells of the basilar membrane will be stimulated and that audition will occur.
190
What is the function of the vestibular system?
Balance and spatial orientation.
191
What are the vestibular apparatus?
1. Otolithic organs: utricle and saccule.
| 2. 3 Semi-circular canals.
192
What do the semi-circular canals detect?
Angular acceleration.
193
What do the otolithic organs detect?
- Linear acceleration.
| - Changes in head position relative to gravity.
194
Where are vestibular hair cells located?
In the utricle and saccule and in 3 ampullae at the base of the semi-circular canals.
195
What is the function of the vestibular hair cells?
They detect changes in motion and position of the head by stereocilia transduction.
196
What are the 3 cavities of the cochlea?
1. Scala vestibuli.
2. Scala media.
3. Scala tympani.
197
Which of the cavities of the cochlea are filled with perilymph?
Scala vestibuli and scala tympani.
198
What is the helicotrema?
Where the scala vestibuli and scala media meet.
199
What is the scala media filled with?
Endolymph.
200
Which cavity of the cochlea houses the organ of corti?
The scala media.
201
What does the organ of corti sit on?
The basilar membrane.
202
What is the stria vascularis?
A structure involved in the active transport of K+ into the scala media.
203
What is the potential of the scala media?
+80mV.
204
What are the 3 structures that make up the organ of corti?
1. Hair cells.
2. Supporting cells.
3. Auditory nerve fibres.
205
How many rows are there of:
a) Inner hair cells?
b) Outer hair cells?
a) 1 row of IHC's.
| b) 3 rows of OHC's.
206
Which hair cells have 95% afferent nerve fibres?
Inner hair cell's (OHC's - efferent).
207
Is the base or the apex of the basilar membrane wider?
The apex.
208
Is the base or the apex of the basilar membrane more sensitive to high frequency sounds?
The base.
209
What structures are present on the IHC's and OHC's?
Stereocilia.
210
What structures connect adjacent stereocilia?
Tip links.
211
What happens to the stereocilia when the basilar membrane vibrates?
They bend. This opens the hair cells' ion channels and there is an increase in auditory nerve firing.
212
True or False; antibiotics can damage stereocilia.
True!
213
Describe the I'MAuditory pathway.
Inferior colliculi -> inferior brachium -> medial geniculate body.
- Concerned with the reflex of looking towards a loud noise.
214
What structures make up the basal ganglia?
- The striatum: putamen and caudate nucleus.
- Globus pallidus: internal and external segments.
- Subthalamic nucleus.
- Substantia nigra.
215
What is the function of the basal ganglia?
It is connected and configured to serve as a specialised action selection mechanism. It determines WHAT you do via a system of inhibition and disinhibition.
216
Name 4 disorders associated with basal ganglia dysfunction.
1. Huntington's disease.
2. Parkinson's disease.
3. ADHD.
4. OCD.
217
What is the reason behind the signs of PD?
Not enough dopamine.
218
What are the signs of parkinson's disease?
1. Tremor.
2. Bradykinesia.
3. Rigidity.
219
What is the reason behind the signs of HD?
Too much dopamine.
220
What are the signs of huntington's disease?
1. Chorea (jerky, involuntary movements).
2. Dementia.
3. Personality change.
221
Briefly describe how dopamine is produced.
Tyrosine -> L-dopa -> dopamine.
222
What is the function of the limbic system?
The limbic system is involved with emotion, behaviour, long-term memory, olfaction and motivation. It is also thought to have a role in learning.
223
What structures are contained within the limbic system?
Hippocampus, amygdala, fornix, mammillary bodies, cingulate gyrus, anterior nuclei of thalamus, hypothalamus.
224
What is the papez circuit?
A circuit that connects the main structures of the limbic system. It is involved in memory and emotions.
225
A patient is diagnosed with a lesion to Cn 3, how would the eye appear to the examiner?
'down and out' due to unopposed action of lateral rectus and superior oblique.
226
Why would ptosis (drooping of the eyelid) occur?
If there was a loss of innervation to levator palpebrae superioris.
227
Where are Cn 1 nuclei located?
Olfactory bulb.
228
Where are Cn 2 nuclei located?
Lateral geniculate body.
229
What is the function of the cerebellum?
Precise control, fine adjustment and coordination of motor activity based on continual sensory feedback. The cerebellum decides HOW you do something. It computes motor error and adjusts commands and projects it back to the motor cortex.
230
What structures lie anteriorly to the cerebellum?
The pons and medulla. The 4th ventricle lies in between these and the cerebellum.
231
What structure connects the two cerebellar hemispheres?
The vermis.
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What are the two fissures of the cerebellum called?
- The primary fissure.
| - The horizontal fissure.
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What are the lobes of the cerebellum hemispheres called?
The anterior and posterior lobes.
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How does the cerebellum control coordination, precision and timing of movements?
It compares the brain's intentions with actual actions and makes any necessary modifications.
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What are the 3 layers of the cerebellar cortex?
- Molecular (outermost).
- Purkinje.
- Granular.
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What are the 2 inputs into the cerebellum?
- Climbing fibres.
| - Mossy fibres.
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Where do the mossy fibres come from?
They come from the pons via the middle cerebellar peduncle.
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Where do the climbing fibres come from?
The come from the olivocerebellar nuclei via the inferior cerebellar peduncle.
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What do the inferior cerebellar peduncles do?
They connect the medulla and the cerebellum and convey muscle proprioception and vestibular inputs.
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What do the middle cerebellar peduncles do?
They connect the pons and the cerebellum and they 'tell' the cerebellum about voluntary motor outputs.
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What is the output from the cerebellum?
Purkinje cell axons.
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Where do the purkinje cell axons go to?
Most go to the dentate nucleus. They then pass into the superior cerebellar peduncle to decussate, and then travel to the thalamus and the red nucleus.
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What do the superior cerebellar peduncles do?
They connect the midbrain and the cerebellum and carry mostly efferent fibres.
244
Name 4 cerebellar nuclei.
1. Dentate.
2. Emboliform.
3. Globose.
4. Fastigial.
245
What is the affect on movement in cerebellar injury?
Movements are slow and uncoordinated.
246
What are some symptoms of cerebellar injury?
- Loss of coordination.
- Inability to judge distances.
- Intention tremor.
- Staggering, wide based walking.
- Weak muscles.
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What is the peripheral nervous system?
The nervous system outside the brain and spinal cord. It includes the cranial nerves (except 1 and 2) and the spinal nerves.
248
Is the CNS or the PNS protected by the blood-brain barrier?
The CNS.
249
What spinal nerves innervate the biceps reflex?
C5/6.
250
What spinal nerves innervate the ankle reflex?
S1/2.
251
A 30-year-old man presents with increased muscle tone, brisk reflexes and fasciculations. Which spinal tract is likely to be affected?
Corticospinal (UMN and LMN weakness).
252
Where does the spinothalamic tract decussate?
Within the spinal cord, 2-3 spinal segments above.
253
A patient can understand what you're saying but is unable to construct sentences in response. What part of the brain is affected?
Broca's area in the dominant frontal lobe.
254
A man is feeling very distressed as he woke up being unable to feel the right side of his face and his right arm and leg. What lobe is affected?
The parietal lobe (somatosensory cortex). Feel is the key word here.
255
A woman presents to the stroke unit being unable to move/feel her left leg/foot. Which artery has been affected?
Right anterior cerebral artery.
256
A man presents to the stroke unit being unable to move/feel his right arm, right sided facial drooping and slurred speech. Which artery has been affected?
Left middle cerebral artery.
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A woman presents to the stroke unit with complete right sided visual field loss. Which artery has been affected?
Left posterior cerebral artery.
258
A 40-year-old removal man felt immediate back pain and a popping sensation after lifting a heavy box. The next day he noticed he was tripping over his right foot as it was dragging along the floor. What is affected?
Lower motor neurones (he has a slipped disc. The LMN nerve roots coming out of the spinal cord have been damaged).
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An elderly patient presents with a stiff flexed arm, and a stiff extended leg (both on the left) which the patient finds difficult to bend. What is affected?
Upper motor neurone – this patient has had a stroke and so the UMN’s are affected.
260
A 42-year-old female has presented with weakness in her left leg. She has been seen previously in your clinic two years ago for visual disturbance and sensory loss over the left forearm. These symptoms persisted for several weeks but then gradually resolved. Her symptoms are exacerbated following a shower. What is the problem?
Multiple Sclerosis (characterised by the fact it comes and goes. Exacerbated after a shower is also a key feature of this disease).
261
A 30-year-old woman noticed that her face had become progressively droopier whilst putting her make-up on in the mornings. Weeks later she began to experience double vision, and found it progressively more tiring and difficult to chew all the food in her mouth when eating. What is the problem?
Myasthenia Gravis (characterised by progressive weakness and tiredness. Actions like chewing become much harder. It is a neuromuscular junction disease where the Ach receptors are blocked).
262
A man has presented with a history of weakness in both of his hands, he is now unable to open jars. Both of his hands show wasting in the Thenar eminence. He has developed slurred speech and difficultly swallowing over the past 3 weeks. His tongue appears spastic and he is unable to protrude it. What is the disease?
Motor neurone disease - both UMN and LMN are affected.
263
What is the only cranial nerve to emerge from the dorsal aspect of the brainstem?
Trochlear Cn 4.
264
You are carrying out an eye examination on a patient who is looking at the tip of your nose. Behind you, on your left hand side, is a tall medical student. What would be the patients’ retinal representation of the image of this students’ face?
The retinal image is converted from right to left and reversed. The students face is now in left lower corner.
(Medical student is stood on your left but that is the patients right).
265
What are the functions of cones in the eye?
Cones are important for visual acuity and colour vision.
266
What are the functions of rods in the eye?
Rods are important for peripheral vision.
267
Define pain.
An unpleasant sensory and emotional experience associated with actual tissue damage.
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Briefly describe the pathway of afferent pain transmission.
Nociceptors, A delta and C fibres, synapse with secondary afferent neurones in the dorsal horn of the grey matter. Substance P is released. Interaction amongst afferent neurones and interneurones determines the activity of secondary neurones. The signal is carried via the spinothalamic tract to the thalamus. Third order neurones then ascend to the somatosensory cortex.
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Where is the insula located?
Deep in the lateral sulcus.
270
What is the role of the insula in pain recognition?
The insula contributes to the subjective perception of pain. It is where the degree of pain is judged.
271
What is the role of the cingulate gyrus in pain recognition?
It provides an emotional response to pain.
272
What is the Melzack Wall pain gate?
The idea that non-painful input can close the 'gate' to painful input and so prevent it from reaching the CNS. Non-noxious stimuli can prevent pain as the large fibres can override the small pain fibres. It is a physiological explanation for why 'rubbing it better' can help.
273
What is the effect of stimulating opioid receptors?
It can reduce neuronal sensitivty and so reduce the pain sensation.
274
How can opioids be used as analgesia?
They bind to inhibitory G-protein coupled receptors in the brain/spinal cord.
275
What is a neuromuscular junction?
A chemical synapse formed by the contact between a motor neurone and a muscle fibre.
276
What is the stretch reflex?
A very simple, monosynaptic reflex. If a muscle is stretched it responds by contracting.
277
Briefly describe the stretch reflex.
The muscle is stretched and intrafusal muscle fibres are stimulated -> sends afferent impulses along 1a neurones -> alpha motor neurone -> efferent impulses to extrafusal muscle fibres -> contraction.
278
Briefly describe the withdrawal reflex.
The limb is withdrawn from noxious stimuli. Afferent fibres synapse on motor neurones in spinal cord. The response is ipsilateral flexion (same side as noxious stimuli) and contralateral extension.
279
What would be the affect of damage to the cerebellar vermis?
Balance problems due to loss of postural control. Difficulty in sitting and standing up.
280
What would be the affect of damage to the cerebellar hemispheres?
Ipsilateral impaired limb coordination.
281
What do the middle cerebellar peduncles convey?
They send information from the primary motor cortex about the motor plan to the cerebellum - corticopontocerebellar tract.
282
What do the inferior cerebellar peduncles convey?
Ipsilateral muscle proprioception, balance and vestibular inputs - vestibulocerebellar tract and dorsal spinocerebellar tract. Also fibres from inferior olivocerebellar tract.
283
What afferent signals do the superior cerebellar peduncles convey?
Ipsilateral information on proprioception and balance from the ventral spinocerebellar tract.
284
What efferent signals do the superior cerebellar peduncles convey?
Efferent signals from the dentate nucleus that go to the red nucleus and thalamus.
285
Give 4 treatments for pain.
1. Analgesics.
2. Acupuncture.
3. Exercise.
4. Hypnotherapy.
286
In huntington's disease what area of the basal ganglia and what neurotransmitter are affected?
- Striatum (caudate nucleus).
| - GABA.
287
What site does brain stimulation affect?
Sub-thalamic nucleus.
288
What neurotransmitter is in deficit in huntington's disease?
GABA.
289
Give 4 features of pain.
1. Pain is always subjective.
2. It is a sensation.
3. It is always unpleasant.
4. It is an emotional experience.
290
How do men and women differ in their response to pain?
Women report pain more readily but can tolerate more pain than men.
291
Where do sympathetic nerves come from?
T1 -> L2 spinal nerves.
292
Where do parasympathetic nerves come from?
Cn 3, 7, 9 and 10, S2 -> 4.
293
What neurotransmitter do sympathetic and parasympathetic nerves both use at ganglia?
Ach.
294
What neurotransmitter do parasympathetic nerves use at organs?
Ach.
295
What neurotransmitter do sympathetic nerves use at organs?
Noradrenaline.
296
What week does the neural tube fuse?
Week 4.
297
What is spina bifida?
Failure of the neural tube to close in the spinal cord region.
298
What is the visual pigment in the eye?
Rhodopsin.
299
What is the function of hair cells?
Through transduction they convert mechanical stimuli into electrochemical activity and they also have a role in amplification.
300
What is the somatic nervous system?
A part of the peripheral nervous system that handles voluntary control of body movements.
301
What are the anatomical divisions of the nervous system?
The CNS (brain and spinal cord) and the PNS (cranial nerves and spinal nerves).
302
What are the functional divisions of the nervous system?
Somatic (voluntary control) and autonomic (involuntary control, further subdivided into sympathetic and parasympathetic).
303
Describe how the brain maintains its blood flow in response to hypovolemia.
Cerebral autoregulation. Hypovolemia leads to a decrease in BP and so the cerebral arterioles dilate more so as to maintain blood flow.
304
What nerve provides sensory innervation to the oropharynx?
Glossopharyngeal - Cn 9.
305
What nerve provides sensory innervation to the laryngopharynx?
Vagus - Cn 10.
306
What nerve provides sensory innervation to the nasopharynx?
Maxillary branch of the trigeminal - Cn 5(b).
307
Which part of the brain is activated in acupuncture?
Cingulate gyrus.
308
Which part of the brain has a role in addiction?
The insular cortex.
309
Stimulation of which part of the brain can result in profound analgesia?
PAG.
310
Give 3 types of glial cells in the CNS.
1. Astrocytes.
2. Oligodendrocytes.
3. Microglia.
311
What is the function of microglia?
They are the immune cells of the CNS - phagocytic and immune surveillance.
312
What is the function of myelin?
Insulates and allows rapid conduction of action potentials along an axon.
313
Neurones communicate via 2 types of synapses. What are they?
1. Chemical - majority.
| 2. Electrical.
314
What structures makes up the lentiform nucleus?
1. Putamen.
| 2. Globus pallidus.
315
How do somatic motor neurones differ from autonomic motor neurones?
Somatic motor neurone leaves the spinal cord and synapses straight onto the effector. Autonomic motor neurones have a pre-ganglionic and post-ganglionic component and so synapse at the ganglia and then at the effector.
316
Mutation of what protein can result in duchenne?
Dystrophin.
317
What is the function of dystrophin?
It provides structural stability to muscle cell membranes.
318
Which cranial nerve can be tested in the unconscious patient by observing pupillary constriction in response to light?
Optic - CN2.
319
What would pouring ice cold water in the external auditory meatus cause?
Convection currents in the semi-circular canals which results in nystagmus.
320
What is the entry/exit foramina for the ophthalmic artery?
Optic canal.
321
What is the entry/exit foramina for the superior ophthalmic vein?
Superior orbital fissure.
322
What is the entry/exit foramina for the labyrinthine artery?
Internal acoustic meatus.
323
What are the two types of deafness?
1. Conductive - sound is blocked from getting through.
| 2. Sensory neural - the problems are with the nerves.
324
Where does the substantial nigra project to?
The striatum.
325
What is the direct pathway of the basal ganglia?
The direct pathway is for when we want to make movement. The motor cortex excites the striatum which inhibits the globus pallidus internal meaning the thalamus is no longer inhibited and can send excitatory signals to the motor cortex = MOVEMENT!
326
What is the indirect pathway of the basal ganglia?
The indirect pathway is for when we want to inhibit movement. The motor cortex excites the striatum which inhibits the globus pallidus external meaning the subthalamic nucleus is no longer inhibited. The globus pallidus internal is therefore excited and the thalamus inhibited = reduced movement!
