Neurology Physiology Flashcards
What makes up the CNS?
Brain
Spinal Cord
What divisions are there to the nervous system?
CNS
Peripheral NS
Enteric NS
What is the peripheral nervous system divided into?
Sensory and motor
What is the motor division of the peripheral NS split into?
Somatic and autonomic
What is the autonomic division of the motor division of the peripheral NS divided into?
Sympathetic
Parasympathetic
What are the 2 types of cells present in the nervous system?
Neurons
Glial cells
How are impulses carried in a neuron?
As an AP
Are neurons excitable cells?
Yes
Are glial cells excitable?
No
Are glial cells or neurones more numerous in the NS?
Glial cells
What are glial cells?
Non-excitable supporting cells
In what direction relative to the cell body do impulses carry AP?
Away from cell body
In what direction relative to the cell body do dendrites carry AP?
Towards the cell body
Are there multiple dendrites and one axon or multiple axons and one dendrite?
Multiple dendrites and one axon
What is the cytoplasm contained in the cell body known as?
Perikaryon
What is the cytoplasm contained in the axon known as?
Axoplasm
Can neurons repair themselves?
Axons can repair but cells bodies cannot
Do neurons have a slow or high metabolic rate?
High
Do neurons divide by mitosis?
No
What is the function of the myelin sheath?
Increases conduction speed in axons
Do AP travel down the axon in a continuous manner?
no jumps from one node of ranvier to the next
What are the 2 types of neurons?
Myelinated and non-myelinated
What type of cell creates the myelin sheath in the PNS?
Schwann cells
What type of cell creates the myelin sheath in the CNS?
Oligodendrocytes
How is the myelin sheath formed?
By secretion of the cell membrane going round the axon
What classification of disease is MS?
Autoimmune
What do groups of cell bodies form?
Ganglia
What do groups of myelinated axons form?
Nerves
What makes up the brainstem?
Midbrain
Pons
Medulla
What is found below the hypothalamus?
Stalk of the pituitary gland
What are the 3 layers of the developing embryo?
Ectoderm
Mesoderm
Endoderm
Thickening of which layer forms the neural tube?
Ectoderm
How is the neural tube formed?
Thickening of the ectoderm
Invaginated to form the neural tube
What are the peripheral cells to the neural tube called?
Neural crest cells
What does the cavity of the neural tube persist as in the adult brain?
Ventricles
What fluid is contained in the ventricles of the brain?
CSF
What are the names of the ventricles?
Lateral ventricles
3rd ventricle
Cerebral aqueduct
4th ventricle
What shape is the IV ventricle?
Diamond
What are the 3 meninges?
Dura
Arachnoid
Pia
Where is CSF found in the meninges?
Subarachnoid space
What is the Filum terminale composed of?
The ending of the pia matter
Where does the cerebral aqueduct lie?
In the midbrain
What does the inter ventricular foramen connect?
The lateral ventricles to the 3rd ventricle
What are the layers of the scalp?
Skin Connective tissue Aponeurosis Loose connective tissue Pericranium
What does the falx cerebri lie between?
2 cerebral hemispheres
What does the falx cerebelli lie between?
2 cerebella hemispheres
What does the tentorium cerebelli lie between?
The cerebrum and cerebellum
Which dural fold overlies the pituitary gland?
Diaphragma sellae
What composes the white matter in the spinal cord?
Myelinated axons
What are the 2 horns of the grey matter?
Dorsal horn
Ventral horn
Where do sensory fibres synapse?
In the dorsal ganglia
Where do motor neurons have their cell bodies?
In the ventral horn
Where do motor neurons exit the spinal cord via?
Ventral roots
What is the central canal?
Hole in the middle of the centre of the spinal cord
Where do ascending pathways carry information?
towards the brain
Where do descending pathways carry information?
Away from the brain
Are ascending pathways motor or sensory?
Sensory
Are descending pathways motor or sensory?
Motor
How many neurons are there in ascending pathways?
3
Where do first order neurons in ascending pathways carry sensory information?
from peripheral nerves to the spinal cord or brainstem where they synapse with 2nd order neurons
What is the pyramidal like structure at the termination of the spinal cord?
Cornus medullaris
What is the horses tail of the spinal cord?
Cauda equina
Where does the pia matter terminate?
At the filum terminale
Where does the lateral spinothalmic tract decussate?
At the level of the spinal cord
What does the lateral spinothalmic tract detect?
Pain and temperature
What does the dorsal spinothalmic tract detect?
Deep touch and pressure
Where do the dorsal ascending tracts decussate?
At the medulla oblongata
Where do the 2nd neurons of ascending tracts end?
At the thalamus
Where do 3rd order neurons arise from?
The thalamus
Where does the 3rd sensory neurons carry information to?
The sensory cortex of the cerebrum
Where is the sensory cortex located?
Behind the central sulcus
Do cerebellar tracts control contralateral or ipsilateral sides of the body?
Ipsilateral
How many pairs of spinal nerves are there?
31
Where is grey matter located in the brain?
In the outer portion
Where is grey matter located in the spinal cord?
In the inner matter
Where is white matter located in the brain?
In the middle
Where is white matter located in the spinal cord?
In the outer portion
What is a depression in the brain called?
Sulci
What is an elevation in the brain called?
Gyri
Which fissure separates the 2 lobes of the cerebrum?
Mean longitudinal fissure
What is the corpus callosum?
Bridge that allows the hemispheres of the brain to communicate with one another
What are the 4 lobes of the brain?
Frontal
Parietal
Occipital
Temporal
What does the parieto-occipital sulcus separate?
Parietal and occipital lobe
Is the frontal lobe for sensory or motor functions?
Motor
Where is the visual field located?
In the occipital lobe
What is the temporal lobe functions?
Hearing and smell
What is the primary area?
Where the information first goes to
What is the association area?
Where the information is made sense
What is area 4 function?
Primary motor cortex
Somatic representation of contralateral half of body W
What is the function of area 44, 45?
Broca’s area of motor speech
Motor control of you physically speaking
What is the function of area 1,2,3?
Primary sensory area
Receives general sensation from contralateral half of body
What is the function of the superior parietal lobule.
Interprets general sensory information and conscious awareness of contralateral half of body
What is the function of area 41,42?
Primary auditory cortex
Where are auditory association areas located
Posterior to 41,42
Do we have auditory areas on one or both sides?
Both
What is Wernicke’s area?
Area located in the dominant hemisphere, crucial for understanding spoken words
Where is the primary visual cortex located?
On either side of the calcarine sulcus
Part of the occipital lobe is the primary visual cortex what is the rest of the occipital lobe?
Visual association areas
What is Broca’s area?
Motor speech area
What is Wernicke’s area?
Auditory association area necessary for recognition of the spoken word
What is aphasia?
Problem with speech due to damage to one or more speech areas in the brain
What is broca’s aphasia?
Is able to understand speech
But cannot make full sentences
But can hear and understand that they are not making sense
What is Wernicke’s aphasia?
When the person has fluent speech
but uses meaningless words and is not aware of this
motor function is working fine
However their temporal lobe and understanding has been damaged
What are the 3 types of myelinated axon fibres?
Commisural fibres
Association fibres
Projection fibres
What is the function of commisural fibres?
Connect corresponding areas of the two hemispheres
What is the function of association fibres?
Connect one part of the cerebral cortex with the other in the same hemisphere
What are projection fibres?
Fibres that run between the cerebral cortex and various subcortical centres
What types of fibres make up the internal capsule?
Projection fibres
What is the internal capsule?
Narrow area between the thalamus and caudate nucleus medially and the lentiform nucleus laterally
Where does the internal capsule derive blood supply from?
Middle cerebral a.
What is the basal ganglia with the tail?
Caudate nucleus
Which lobe deals with vision?
Occipital
Which lobe deals with hearing?
Temporal
What is area 4 of the brain?
Primary motor cortex
What is area 6 of the brain?
Motor association areas
What area is located in the inferior frontal gyrus?
Area 44,45,
In what areas of the brain does the primary sensory area lie?
Area 1,2,3
What is the function of the primary sensory area?
Receive general sensations from contralateral half of the body
In what area does the primary visual cortex lie?
Area 17
What is the function of area 18,19?
Visual association cortex
Concerned with the interpretation of visual images
Where do basal ganglia lie?
Deep within the cerebral hemispheres
Where doe the substantia nigra lie?
In the midbrain
Which basal ganglia is functionally part of the other basal ganglia but not anatomically?
Substantia nigra
Which basal ganglia make up the striatum?
Caudate nucleus
Putamen
Which basal ganglia runs immediately laterally to the lateral ventricles?
Caudate nucleus
Which are the input regions of the basal ganglia?
Caudate nucleus and putamen
Which basal ganglia compose the output regions?
Globus pallidus
Substantia nigra
What is the major function of the basal ganglia?
Help regulate and terminate movements
Why are the basal ganglia often referred to as the extrapyramidal system?
Because they play a role in controlling the motor systems
Where do the output regions of the basal ganglia output to?
The thalamus
Which basal ganglia make up the lentiform nucleus?
Globus pallidus
Putamen
what are the 2 descending lateral pathways?
Corticospinal tract
Rubrospinal tract
Which is longest descending tract?
Corticospinal tract
From which area does 2/3 of the CST originate?
From area 4 and 6
Where does the other 1/3 of the CST originate?
Somatosensory
where do the corticospinal and rubrospinal tracts decussate?
At the medulla (pyramids)
Which side of the body does the right motor cortex control?
Left
Which side of the body does the left motor cortex control?
Right
Where does corticospinal tracts synapse on the spinal cord?
On the ventral horns
Where do rubrospinal tracts originate from the brain?
Magnocellular red nucleus of the midbrain
If the CST is lesions how can normal function almost be restored?
The RST can take over and restore function
the RST can assume almost all the duties of the CST when the CST is lesioned
What are the 2 ventromedial pathways ?
Vestibulospinal and tectospinal tracts
What does the Vestibulospinal tract do?
Stabilises the head and neck
Where do pyramidal tracts originate?
In the cortex
Where do extrapyramidal tract originate from?
midbrain
Are pyramidal tracts responsible for voluntary or involuntary motor movement?
Voluntary
Where does the TST begin?
In the superior colliculus
Where does the VST begin?
In the vestibular nucleus
How many neurons are there in descending pathways?
2
What is the function of the tectospinal tract?
to ensure eye movement remain stable with movement of the body
Does the CTS decussate?
Yes to control contralateral side
Does the rubrospinal tract decussate?
Yes to control the contralateral side
What are the two lateral descending pathways?
Corticospinal tract
Rubrospinal tract
What are the four ventromedial descending pathways?
Tectospinal tract
Vestibulospinal tract
Pontine Reticulospinal tract
Medullary Reticulospinal tract
Where do upper motor neurons target?
Lower motor neurons in the spinal cord
What is meant by somatotopic?
An specific area codes for another specific area
What muscles do medial LMN control?
Proximal muscles
What muscles do lateral LMN control?
Distal muscles
What is located in the precentral gyrus?
Primary motor cortex
What is located rostrally to the precentral gyrus?
Pre-motor areas
Association areas
What is area 6?
Pre-motor area
What does the central sulcus separate?
Primary motor
and primary sensory areas
How many somatotopic maps does area 6 have?
2
How many somatotopic maps does area 4 have?
1
Are somatotopic maps proportionate?
No very disproportionate
Does one cell in the motor cortex stimulate one certain muscle?
No
By stimulating a certain area of the motor cortex this will lead to an overall action
What is the function of the junction where axons converge in area 6?
Where signals encoding what actions are desired are converted into how the actions will be carried out
When you only think about doing a movement but do not carry this movement out which area is activated?
Area 6 in the cortex
When you are actually doing the movement but the CST or RST which cortex area is stimulated?
Area 4 of the cortex
When a specific area of the brain is stimulated what is show on PET?
Increased blood flow and firing of AP
What is refraction (eye)?
Bending of light waves to fall on the retina
What 3 things make up accommodation?
Lens change shape
Pupil constricts
Eyes converge
Describe the event of lens thickening in accommodation
Ciliary muscles contract making the ciliary body bulge Space in middle decreases Suspensory ligaments become lax Lens is no longer under stretch Lens becomes thicker
Does parasympathetic or sympathetic innervation make the pupils constrict?
Parasympathetic
Which muscles cause the eyes to converge?
Medial rectus
Which cranial nerve controls the medial rectus?
CN III
What is myopia?
Short signtedness
What is hyperopia?
Long sigghtedness
What causes astigmatism?
Non-spherical curvature of the cornea
What is presbyopia?
Long sightedness of the elderly
What causes myopia?
Often too long an eyeball
Meaning rays bend before they reach the retina
What are symptoms of myopia?
Headache
Complaining of not being able to see far away
Younger children and toddlers have loss of interest
Infants - divergent squint
What is the treatment for myopia?
Spectacles
Contact lenses
Laser eye surgery
What causes hyperopia?
Eye ball too short
Rays bend and from image behind the retina
How does the person accommodate for hyperopia?
Uses accommodative power to make the lens thicker
Why does accommodation not work eventually in hyperopia?
Eventually all accommodative power is used up
What type of lenses are required for astigmatism?
Toric lenses
What causes presbyopia?
Age
Less able to contract ciliary muscle causing decrease in accommodative power
Which retina sees the left visual field?
Right
Which retina sees the right visual field?
Left
What is the point where fibres from each optic nerve cross?
Optic chiasma
Which fibres cross over at the optic chiasma?
Nasal fibres
Which retina sees the left visual field?
Right
Which retina sees the right visual field?
Left
What is the point where fibres from each optic nerve cross?
Optic chiasma
Which fibres cross over at the optic chiasma?
Nasal fibres
Where do optic fibres synapse?
At lateral Geniculate Body
Which lobe of the brain processes visual information?
Occipital lobe
What is area 17?
Primary Visual Cortex
On which side of the retina is the right visual field seen?
Left
Which side of the brain processes information from the right visual field?
Left
What damage would you expect if the right optic nerve was damaged?
Blindness in the right eye
What damage would you expect if the optic chiasma was affected?
Visual loss from peripheral visual fields
Bi- temporal hemianopia
What damage would you expect if the right optic tract was damaged?
Loss of left visual field
Contralateral homonymous hemianopia
What are the two groups of eye muscles?
Intrinsic
Extrinsic
What are the 4 recti muscles of the eye?
- medial rectus
- lateral rectus
- inferior rectus
- superior rectus
What are the 2 oblique muscles of the eye?
Superior oblique
Inferior oblique
Which is the only eye muscle to arise anteriorly?
IO
Which eye muscle lies directly above SO?
LPS
Levator Palpebrae Superioris
Which cranial nerve innervates all eye muscles except SO, LR?
CN III
Which cranial nerve innervates SO muscle?
CN IV
Which cranial nerve innervates LR muscle?
CN VI
What is the action of the medial recuts?
Adduction
What is the action of the lateral recti?
Abduction
What is the primary action of Superior rectus?
Elevation
What is the primary action of the IR?
Depression
What is the primary action of the SO?
Intorsion
What is the primary action of the IO?
Extorsion
What is esotropia?
Convergent squint of the eye
What is exotropia?
Divergent squint of the eye
What are the intrinsic muscles of the eye/
Ciliaris muscle
Constrictor papillae
Dilator pupillae
What is the action of contraction of the ciliaris muscle?
Accommodation
Thickening of the lens
Due to lax on the suspensory ligaments
What is the action of the constrictor pupillae?
Works to constrict the pupil under parasympathetic innervation
What is the action of the dilator pupillae?
Works to dilate the pupil under sympathetic innervation
What muscle runs radially in the iris?
Dilator Pupillae
What is the normal reaction of the pupils toincreased illumination?
Both pupils constrict
What is the normal reaction of the pupils to decreased illumination?
Both pupils dilate
Where do fibres destined to activate the pupillary reflex go?
To the midbrain where CN III is situated
Where is CN III situated?
In the midbrain
Does the sympathetic or parasympathetic nervous system have thoracolumbar outflow?
Sympathetic
Where do ganglia lie in the sympathetic system?
Close to the spinal cord
Where do ganglia in the parasympathetic system lie?
Close to the organ
What is the autonomic NS a division of?
Efferent nervous system
Which division of the autonomic NS has long pre-ganglionic and short post ganglionic fibres?
Parasympathetic
Which division of the NS has craniosacral outflow?
Parasympathetic
What type of synapses are there between the pre and post ganglionic cells in the sympathetic system?
Cholinergic and nicotinic
In the parasympathetic system the synapses between pre- and post-ganglionic cells are …
Cholinergic and nicotinic
In the parasympathetic system the synapses between post-ganglionic cells and their targets are …..
Cholinergic and muscarinic
Post-ganglionic cells in the adrenal medulla …..
Release adrenaline
Have no axons
Are part of the sympathetic system
Contribute to mass acitvation
Which receptors does noradrenaline work on?
Alpha
Beta
Adrenergic
In the eye activation of the sympathetic system causes…..
Constriction of the radial muscle of the iris
Causing dilation of the pupil
Where do motor neurons have their cell bodies?
In the ventral horn of the spinal cord
What is contained in the central canal of the spinal cord?
CSF
What do ascending pathways carry?
Carry information towards the brain
What do descending pathways carry?
Motor information - carry information away from the brain
How many neurons are there in ascending pathways?
3
Where do 1st order neurons bode?
In the dorsal ganglion
Where do 2nd order neurons synapse with 3rd order neurons?
In the thalamus
Where do 3rd order neurons carry information?
From the thalamus to primary sensory area
Which order neuron decussates at the medulla?
2nd
What information do ascending lateral pathways carry?
Pain and temperatue
What do ascending dorsal column tract carry/
Deep touch and pressure
Where does the ascending dorsal column decussate?
At the medulla
Where does the lateral ascending tract decussate?
At the level of the spinal cord
Does the lateral ascending tract supply the contralateral or ipsilateral side?
Contralateral
Does the dorsal ascending tact supply the contralateral or ipsilateral side?
contralateral
Where do descending pathways orginate?
Cerebral cortex - primary motor area
How many neurons do descending pathways have?
2
Where does the 1st order neurons decussate in descending pathways?
At the pyramids in the medulla
Where does the 1st order neuron synapse with the 2nd order neuron in descending pathways?
Ventral horn of the spinal cord
What 4 systems control movement?
Descending control pathways
Basal Ganglia
Cerebellum
Local spinal cord and brain stem circuits
Which level is the biceps jerk at?
C6
Which level is the triceps jerk at?
C7
What level is the patellar reflex at?
L4
What level is the Achilles tendon reflex at?
S1
What is pain?
Pain is an unpleasant sensory and emotional experience
Not a stimulus
Final product of complex information processing network
What is nociception?
The detection of tissue damage by specialised transducers connected to A-dela and C fibres
What is meant by the term noxious?
Means the pain has reached the threshold
Where do pain neurons synapse and cross over?
At the level of the spinal cord
Which nerve fibres conduct pain?
A delta and C fibres
Which fibres conduct fast pain?
A delta fibres
Which fibres would transmit a sharp pinching pain?
A delta fibres
Which fibres conduct dull pain?
C fibres
Where do primary nociceptive afferent impulses primarily end?
Dorsal horn
Where do 2nd order neurons of ascending pathways go from?
Spinal cord to thalamus
Whee does pain perception occur?
In the somatosensory cortex
What is allodynia?
Pain due to stimulus that does not normally cause pain
What is hyperalgesia?
Exagerated response to normal pain stimuli
Spontaneous Pain
Spontaneous activity in nerve fibres
When does pain become chronic?
After 3-6 months
What is a distinguishing feature of C pain fibres?
They are unmyelinated
