Neuroanatomy Flashcards
(147 cards)
1
Q
Which autonomic neurones use ACh?
A
preganglionic in both the sympathatic and parasympathetic
postganglionic in parasympathetic
2
Q
Where do glutamate and GABA have their effect? what do they do?
A
In the CNS
Glutamate - excitatory neurotransmitter
GABA - inhibitory
3
Q
Where does glycine have its effect? What does it do?
A
Mainly in the spinal cord
It is an inhibitory neurotransmitter
4
Q
What types of molecules are glutamate/GABA/glycine?
A
Amino acids
5
Q
On what part of the nervous system does noradrenaline have its effect?
A
Post ganglionic sympathetic neurones in the PNS and some sites in the CNS
6
Q
Dopamine and serotonin act in the brain/spinal cord/both
A
Dopamine and serotonin work in both.
7
Q
What type of molecule are noradrenaline/dopamine/serotonin?
A
Monoamines
8
Q
the majority of neurones utilising the monoamines have cell bodies located in which part of the brain?
A
The brainstem
9
Q
Where in the brainstem are noradrenaline - using cell bodies found?
A
The locus coerucleus
10
Q
Where in the brainstem are dopamine - using cell bodies found?
A
the substantia nigra
11
Q
Where in the brainstem are serotonin - using cell bodies found?
A
the raphé nucleus
12
Q
What is the other name for serotonin?
A
5-hydroxytryptamine (5HT)
13
Q
Give examples of fast and slow neurotransmitters
A
Dopamine - slow
Glutamate/glycine/GABA/ACh - fast
14
Q
What is the different between a fast and slow neurotransmitter?
A
Fast - works directly on the post-synaptic membrane to bring about rapid changes in ion permeability
Slow - works through an intermediary messenger to bring about slower changes in permeability
15
Q
How is neurotransmitter signalling terminated?
A
Destruction of the transmitter
Reuptake into nerve cells or glial cells
16
Q
Cholinergic systems tend to be terminated by reuptake - true/false
A
false - tend to be terminated by destruction
17
Q
Mono-amines and amino acid transmitters tend be terminated by reuptake - true/false
A
True
18
Q
Neuroglia are far outnumbered by nerve cells in the nervous system - true/false
A
false - they are the predominant cells of the nervous system
19
Q
What are astrocytes?
A
Star cell - they form the perivascular end feet of the capillary walls and so contribute largely to the blood brain barrier.
20
Q
Why is the blood brain barrier both beneficial and troublesome?
A
It prevents uptake of harmful substances into the brain (benefit) and prevents entry of some therapeutics (troublesome).
21
Q
What is an oligodendrocyte?
A
A cell which produces myelin to surround the axons of neurones
22
Q
What is the difference(s) between an oligodendrocyte and a Schwann cell?
A
Oligodendrocytes - CNS; one cell surrounds many axons
Schwann Cells - PNS; many cells surround one axon
23
Q
What is the name of the gaps between myelin?
A
The Nodes of Ranvier
24
Q
Why is conduction faster in myelinated axons?
A
The charge can only move across the cells at the nodes. therefore it “jumps” from one node to the other (saltatory conduction).
25
What is the function of a microglial cell in the healthy person?
It has little function in the healthy individual; normally dormant
26
What is the function of a microglial cell in the person with CNS damage?
Proliferates and migrates to site of injury; phagocytic function to remove debris. The macrophage of the brain!
27
What are ependymal cells?
Epithelium which line the ventricles and choroid plexus
28
Ependymal cells are ciliated - true/false
true
29
Why are ependymal cells ciliated?
this is believed to aid the circulation of CSF.
30
What are the usual causes of brain tumours?
Glial cells - astrocytomas or oligodendrogliomas
31
Why are neurones not able to give you tumours?
they are (normally!) incapable of replication
32
Why are microglial tumours not classed as brain tumours?
they are immune cells; if they become neoplastic, they are lymphomas.
33
Define efferent and afferent nerves
Efferent -> towards the periphery
| Afferent -> towards the centre
34
Muscles are innervated by sensory/motor/both type of neurones
both
35
Individual muscle cells run parallel/perpendicular to the axis of contraction
Parallel
36
The two main functional groups of muscle fibres are ______ & ______. Explain the difference
Extrafusal - contractile fibres
| Intrafusal - sensory stretch and tension receptors
37
Extrafusal fibres are much more/less numerous than intrafusal fibres
more
38
What is motor unit?
One alpha motor neurone + all the muscle fibres that one neurone (and subsequent branches) innervate
39
where do the cell bodies of the alpha motor neurone lie?
Ventral horn of the spinal grey matter
| Motor nuclei of the cranial nerves in the brainstem
40
Small motor units provide precision/power. Large motor units provide precision/power (delete as appropriate).
Small - precise
| Large - powerful
41
what is contained in a muscle spindle?
Intrafusal fibres
42
Sensory endings in intrafusal fibres enter the dorsal/ventral horn of the grey matter
Dorsal
43
What supplies motor innervation to modulate the sensitivity of the intrafusal fibres?
Gamma motor neurones
44
What are the three broad types of stimuli?
Mechanical
Thermal
Chemical
45
if an afferent AP reaches the consciousness it is referred to as _______
sensory
46
What do efferent nerve endings innervate?
muscle or secretory gland to bring about contraction or secretions
47
Unencapsulated nerve endings are less common than encapsulated ones - true/false
false - much more common
48
What is an unencapsulated nerve ending?
One in which its terminal endings lie freely in the tissues
49
What modalities do unencapsulated sensory nerve endings carry?
pain and temperature in the skin
50
What type of fibres are unencapsulated sensory nerve endings made up of?
A-delta and C fibres
51
Describe A-delta and C-fibres
Thin diameter, very little myelination - A-delta
Thin diameter - no myelination - C
Both as slow conducting fibres
52
Where are merkel endings (discs) found? What do they do?
Near the epidermal border
| Detect touch and pressure
53
Describe merkel disc fibres
relatively large, myelinated axons.
54
Meissner's Corpuscles are encapsulated/unencapsulated
| Where are they found?
Encapsulated
| Dermal papillae
55
Meissners corpuscles are found in large numbers in ______ and responsible for ______ & ________. they are ______ adapting
The fingertips
fine touch and discriminatory touch
Fast adapting
56
Which two receptor cells are responsible for two point discrimination?
Meissner's corpuscles
| Merkel's discs.
57
What is the difference in the distribution of meissner's corpuscles and merkel's discs?
meissners - not in hairy areas
| merkel's present in hairy areas.
58
Where are pacinian corpuscles located?
Skin and deep tissues such as joints and mesentry
59
What type of fibres are pacinian corpuscles associated with? what do they respond to? they are _____ adapting
A-alpha fibres
Mechanical distortion but especially vibration
Rapidly adapting
60
What are ruffini endings?
Slowly adapting mechanoreceptors in the dermis
61
What is the transmitter in all striated muscle at the neuromuscular junction?
Acetylcholine
62
When a peripheral nerve is transected or otherwise seriously damage the portion proximal/distal to the damage degenerates and dies
Distal to the damage
63
At first the proximal part of a peripheral nerve that has been damaged will start to degenerate but may regenerate if _____
the damage is far enough from the cell body.
64
What bounds the anterior cranial fossa?
anteriorly and laterally - frontal bone
Posteriorly and laterally - lesser wing of sphenoid
Inferiorly - ethmoid, frontal and anterior part of the body and lesser wing of sphenoid
65
What is contained within the anterior cranial fossa?
The left and right frontal lobes
66
Which bone forms the roof of the orbit?
the frontal bone
67
What forms the crista galli?
| What does the crista galli do?
A sharp midline ridge in the ethmoid bone
| Point of attachment for the fall cerebri
68
What is the falx cerebri?
Sheet of dura which separates the left and right cerebral hemispheres.
69
Where do the cribriform plates lie?
lateral to the crista galli
70
What bound the middle cranial fossa?
Anteriorly and laterally - lesser wing of sphenoid
Posteriorly and laterally - superior border of the petrous part of the temporal bone
Posteriorly and medially - dorsum sellae of the sphenoid bone
Floor - body and greater wing of sphenoid, squamous and petrous temporal bone
71
What is contained in the middle cranial fossa?
Pituitary (in pit. fossa)
| left and right Temporal lobes
72
Name the entry/exit points in the middle cranial fossa
```
Optic canal (CNII and ophthal artery)
Sup. orbital fis. (CNIII, IV, VI and V1)
Foramen rotundum (CNV2)
Foramen ovale (CNV3)
Foramen spinousum (middle meningeal artery)
```
73
What bounds the posterior cranial fossa?
Anteriorly/medially - dorsum sellae of sphenoid
Anteriorly/laterally - superior border of petrous part of the temporal bone
Posteriorly - internal surface of the squamous part of the occipital bone
Floor - mastoid part of temporal bone and squamous, condylar and basilar parts of the occipital bone.
74
What is contained in the posterior cranial fossa?
The brainstem
75
What foramen does the medulla pass through?
the foramen magnum - to become continuous with the spinal cord.
76
What passes through the foramen magnum?
The medulla/vertebral arteries/spinal root of the accessory nerve
77
Where is the hypoglossal canal?
In the lateral wall of the foramen magnum
78
Where does the jugular foramen lie?
Between the occipital bone and petrous temporal bone
79
What passes through the jugular foramen?
Jugular veins, CNIX-XI.
80
Where does the internal auditory meatus lie?
In the vertical wall of the petrous temporal bone
81
What passes through the internal acoustic meatus?
CNVII and CNVIII.
82
Where does the cerebellum lie?
In the floor of the posterior cranial fossa.
83
What is the medial longitudinal fissure (great longitudinal fissure?)
The fissure which divides the left and right cerebral hemispheres.
84
What dural structure passes into the medial longitudinal fissure?
the falx cerebri
85
Posteriorly the falx cerebri becomes continuous with what structure?
the tentorium cerebelli
86
Where does the tentorium cerebelli lie?
In the transverse cerebral fissure.
87
What forms the dural venous sinuses?
the two layers of dura separating to form blood containing spaces.
88
Describe the arachnoid mater
Translucent, soft membrane; loosely envelops the brain. Separated from the dura by subdural space.
89
What is present in the subdural space?
Veins on their way to the dural venous sinuses
90
Describe the pia mater
Microscopically thin, delicate membrane which is highly vascular and adheres very closely to the brain.
91
What lies between the pia and arachnoid mater?
Subarachnoid space
92
What lies in the subarachnoid space?
Connective tissues
Numerous arteries and veins
Cerebrospinal fluid
93
What structure in the spinal cord does CSF flow through?
The central canal (vestigial)
94
Where does the central canal enter the brain?
It enters the brain at the rostral medulla
95
What chamber is the central canal continuous with in the rostral medulla?
The fourth ventricle
96
Where does the fourth ventricle lie?
On the dorsal brainstem beneath the cerebellum
97
What runs on each side of the fourth ventricle?
Lateral recesses which extend toward the lateral margin of the brainstem. Continuous with the SA space via the foramen of luschka at the cerebellopontine angle
98
What forms the roof of the fourth ventricle?
Cerebellum
| Caudally by pia and ependyma
99
What is the foramen of magendie?
A central defect in the caudal roof of the fourth which drains CSF into the SA space via the cisterna magna.
100
Where does the fourth ventricle terminate rostrally? What does it become continuous with?
The pontomesencephalic junction
| The cerebral aqueduct
101
Where does the cerebral aqueduct run? Where does it terminate?
the length of the midbrain. terminates at the rostral margin of the midbrain
102
What forms the third ventricle?
Hypothalamus/thalamus - laterally
| Pia-ependyma - roof
103
What provides communication between the third and the lateral ventricles?
foramen of munro (interventricular foramen)
104
Describe the lateral ventricle
C-shaped
| Frontal, occipital and temporal horns and a body.
105
What forms the walls and roof of the lateral ventricles
Lateral wall - head of caudate nucleus
Roof - corpus callosum
Medial wall - septum pellucidum
Body floor - thalamus/tail of caudate nucleus
Floor of temporal horn - hippocampus
Roof of temporal horn - tail of caudate nucleus
106
Where is CSF located?
the ventricular system
Cranial SA space
Spinal SA space
107
Where is CSF produced?
Choroid plexus of the lateral, 3rd and 4th ventricles.
108
Describe CSF
Colourless
little protein
little cells
109
How much CSF should a person have at any one time?
150mls approximately.
110
Where is most CSF produced?
Choroid plexus of the lateral ventricles
111
Describe the flow of CSF
lateral ventricles -> foramen of munro -> 3rd ventricle -> aqueduct -> 4th ventricle -> Foraminae of luschka/magendie -> SA space
112
Where does most CSF flow once in the SA space?
Around the cerebral hemispheres
113
CSF is reabsorbed by which structures?
Arachnoid villi/granulations
114
Where are arachnoid villi/granulations located?
On the surface of the dural venous sinuses
115
What is the purpose of CSF?
Cushion
116
Where do the arteries supplying the brain come from?
Internal carotid
| Vertebral arteries
117
Where does the internal carotid enter the cranial cavity?
Middle cranial fossa through the carotid canal
118
Describe the passage of the internal carotid in the cranial cavity
Forward into the cavernous sinus and upwards to reach the surface of the brain lateral to the optic chiasm.
119
what pre terminal branches does the internal carotid give off?
Hypophyseal
Ophthalmic artery
Anterior choroidal artery - optic tract/choroid of lateral ventricles/hippocampus/globus pallidus and internal capsule
Posterior communicating artery - joins posterior cerebral artery to form circle of Willis.
120
Where does the internal carotid branch into its terminal branches? Name them
Lateral to the optic chiasm
| Middle and anterior cerebral arteries
121
Where does the anterior cerebral artery pass into?
Medial longitudinal fissure
122
What joins with the anterior cerebral artery in the medial longitudinal fissure?
Anterior communicating artery
123
What does the anterior cerebral anterior supply?
The sensory and motor cortices of the lower limbs
124
Where does the middle cerebral artery branch? What does it supply?
Lateral fissure
Entirety of the lateral aspects of the frontal, parietal and temporal lobes - the primary motor and sensory cortices for everywhere but the lower limbs + the auditory cortex
125
Where do the vertebral arteries arise?
Subclavian arteries
126
Where do the vertebral arteries enter the cranial cavity?
Jugular foramen.
127
Name 3 branches of the vertebral arteries. What do they supply?
Anterior and posterior spinal arteries - spinal cord and medulla
posterior inferior cerebellar artery - supply the inferior surface of the cerebellum.
128
Where do the vertebral arteries terminate?
The ponto-medullary junction.
| They merge to form the basilar artery
129
Where does the basilar artery run?
The length of the pons - to supply it with multiple small pontine arteries.
130
The basilar artery gives rise to two named arteries - name them and give their function.
Anterior inferior cerebellar arteries - supplies the inferior and anterior cerebellum
The labyrinth artery - exits through acoustic meatus to supply the ear.
131
the basilar artery bifurcates to give two names arteries - what are they? Where does this happen?
The superior cerebellar artery
the posterior cerebellar artery
Midbrain-pons junction.
132
The superior cerebellar artery supplies what?
The superior portion of the cerebellum.
133
Describe the course of the posterior cerebral artery
Curves around the midbrain to supply the visual cortex of the occipital lobe and the inferomedial portion of the temporal lobe
134
What joins the internal carotid and vertebral - basilar systems? Name this anastomoses
The posterior communicating arteries
| Circle of willis
135
The circle of willis encircles which structures?
The optic chiasm, the floor of the hypothalamus and midbrain
136
There is a very important capability bestowed on the brain by the circle of willis. Explain this.
If there is obstruction in the proximal cerebral arteries, this may be compensated by the shunting of blood through the posterior communicating arteries.
137
What are the three components of venous drainage in the brain?
Deep cerebral veins
Superficial cerebral veins
Venous sinuses
138
Explain the difference between cerebral and peripheral venous drainage systems
No valves present in the cerebral venous drainage
139
What area do deep cerebral veins drain?
The forebrain including the basal ganglia, internal capsule, choroid plexus and internal capsule via the thalamostriate and choroidal veins.
140
What do the deep veins merge to become?
In each hemisphere they merge to become the internal cerebral veins.
141
Both internal cerebral veins join to become a structure. name it.
The great cerebral vein.
142
What is the great cerebral vein continuous with?
The straight sinus in the midline of the tentorium cerebelli.
143
Where do the superficial veins lie?
the SA Space
144
What do the superficial veins drain
the superior cerebral vein - lateral surface of the hemispheres.
Middle cerebral vein line of the lateral fissure
145
Where do the superficial veins drain into?
Superior cerebral vein - the sagittal sinus
| Middle cerebral vein - the cavernous sinus.
146
Describe the location of the cavernous sinuses
Lateral to the body of the sphenoid. Drains into the internal jugular vein
147
What connects the cavernous sinuses?
Two intercavernous sinuses, anterior and posterior to the pituitary, forming a ring around it.
