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LCRS > CNS anatomy > Flashcards

CNS anatomy Flashcards

1
Q

What is the CNS briefly? What does it include? And what is its main role?

A

The CNS is the central nervous system-composed of the brain-the brain stem and the spine
Its main role is information processing-intaking from PNS afferent division and acting through PSN efferent division (autonomic and somatic)

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2
Q

How is the spinal cord organised? How many nerves are found coming out? where do they exit/enter?

A

Spinal cord sits within the spine-coming down from the brain-goes from C1 to L1/2 (shorter than vertebral column)-after that only nerves coming out/down
All the nerves come out under their named cervical (eg: T12 comes out under C12), except for C1
31 spinal nerves for average 33 vertebrae

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3
Q

From how the spinal cord is organised, where would a lumbar punction be done to take fluid?

A

Would be done after the spinal cord ends-between L2/3 or L3/4-lower in children because spinal cord takes more space

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4
Q

Describe the anatomy of the spinal cord? (in relation to horns, roots, ganglia, efferent and afferent

A

Spinal cord is made of a center of grey matter (cell bodies) and white matter (axons going up/down)
Spinal cord has 4 horns on each side (2xDorsal hrn, 2x ventral horn)
Ventral horn in connected to ventral root (motor, efferent)-connects to mixed nerve with dorsal root
Dorsal horn connected to dorsal root (afferent, sensory)-has a ganglia with cell bodies)-connects to ventral root to make mixed nerve

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5
Q

What are the functions of the spinal cord?

A 
Spinal cord is the connector between PNS/ANS and the brain (efferent and afferent go up and down from brain to periphery)
eg: intakes the snesory signals and carries motor signals-also role is sympathetic
coordinate reflexes (direct)
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6
Q

What are the 3 parts of the brain usually descibred?

A

Cerebrum (main brain)cerebral hemisphere and diecenphalon), brain stem (midbrain, pons, medulla) and cerebellum

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7
Q

Describe the rough anatomy of the brain stem, its functions and main features.

A

Brain stem is between spinal cord and cerebral hemisphere-all sensory and motor fibres pass by it and can activate stuff
Midbrain proxiam to brain-then pons and then medulla
Contain nuclei of 10/13 cranial nerves (III-XII)
Main roles-regulates vital functions like breathing, heart rate, blood pressure, swallowing (ANS)
Many defensive reflexes (cough, gag sneeze)

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8
Q

What is the diencephalon composed of? What are its main functions?

A

Diencephalon is part of cerebrum-made of thalamus and hypothalamus (thalamus is 2 lobes either side of brain stem), hypo is smaller lobe center connected to pit gland
Hypothalamus role-intrgation of singals and hormonal, ANS and other functions
Thalamus-integration centre for special senses-and projction to cortex-involved in emotional status, appropriate motor response, consciousness

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9
Q

What are the 2 parts that make up the cerebral hemispheres?

A

2 hemispheres (cortex) and basal ganlia-on top of brain stem and diecenphalon

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10
Q

Describe the 3 different parts of the basal ganglia, and their function

A

3 parts-caudate, putamen and globus pallidus-form 2 ganglia on either side
2x Putamen is lateral to the ganglia (on the outside)
2x Caudate is on top, connected by striate (drosal/superior to caudate)
Together they make Corpus striatum
Globus pallidus sits medial to the caudate-on the other side
together they form lentiform nucleus
Function-control movement-fine tuning, inhbiting innapropriate movement

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11
Q

Describe the organisation of the cerebral cortex, naming schemes for features

A

Cerberal cortex-frontal lobe , then parietal , then occipital
On either side-temporal lobes
The flods make gyrus (outgrowth) and suclus (foldings)
hemispheres are speratated by longitudinal fissure
Frontal and partietal seprates by central fissure

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12
Q

Describe the main functions of the cortical functional areas

A

Frontal cortex-has prefrontal cortex (sense of relation with world-mood personality), brocha area (left-speech), motor association area (plan a program for muscle contraction for an action (like dancing), primary motor cortex (contralateral-for movement)
Parietital cortex-primary somethetic cortex-sense
Somesthetic associatin area-interpresents sensory intepreation and coordinate very large
Ociipital-primary visual cortex and visual association area
Temporal-Wernicke area (left)-recognise language, primary gustatory (taste), aditory cortex (hear)

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13
Q

Describe the anatomy, function and main features of the cerebellum

A

attached posterially to brainstem
Outsdie grey cortex with parallel folds, deeper-white matter (nuclei)
Two hemispheres in lobes-central vermis (dip)
Connected to balance, spinal cord for posture and muscle tone, motor cortex and thalamus-helps you learn and commit to memory (specially movement)

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14
Q

How are different parts of the brain connected? What are the 3 main fibers in the cerebrum?

A

White matter in brain describes the axons (opposite of spine)
between hemispheres, commisural fibers (corpus collosum)
Within hemispheres -association fibers
to spine and rest of body-projection fibers

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15
Q

Look up image of cranium bones

A

But remember roughtly-frontal (frontl), sphenoid, temporal, occipital
Ethmpid between frontal
Temproral on the side

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16
Q

Describe the organisation of the meninges

A

Under skin, bone-dura mater (two layers, exterior periosteal, interior meningeal)
Then arachnoid mater, then pia mater-these continue all around the cortex (not following bone but even within folds)
This is where blood vessels (capilaries and veins sit)
cortex sperated by subarachnoid space (vessels)

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17
Q

Describe the anatomy of the CSF ventricular system?

A

Large latral ventricules (2x) like horns sourround basal ganglia and diecephalon-connected to3rd ventricule-sit right between hypothalamus (little hole to allow connection) 1x
connected by aqueduct to 4th venticule (loacted near pons of brainstem)-then goes into spine and brain from there

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18
Q

What is CSF mostly made of? What is its function?

A

Similar to blood plasma BUT lower glucose, lower prots, lwoer ca, K, higher Cl, Mg, and slightly lower pH
Function-cushioning, bringing nutrition, removing waste and immune cell
used for diagnosis (lumbar punction)-if meningitis (bacterial ahs lower gluc and higher prots)

19
Q

Describe the pathway of CSF flow

A

Blood-taken by lateral, 4th and 3rd ventricule and converted to CSF (filtering)
All then goes to fourth venticule-where though lateral and medial apertures goes to subarachnoid space
At arachnoid vili of dural veins-collects into venous blood and goes back to the heart

20
Q

What does the PNS consist of?

A

ANything that inst CNS-all the nerves as soon as they exist the spine and cranial nerves

21
Q

Where do (unipolar) sensory come from in regards to embyology

A

When the neural plate form, the extriot (neural plate border) form the top of the neural tube after envagination
These cells will then split of and mirgate from spinal crest-these from sensory neurons after (cell body that go in ganglia

22
Q

What is the anatomy of sensory neurons? What are the 3 types of fibers?

A

Dendrites sit in sensory receptors in the skin-then connect to cell body in dorsal ganglia-from there axon connects back to spinal cord-sends signal back up
3 fibres are A fibres (myelianted somatic), B fibers (myelinated viscleral) and C fibers (myelinated or unmyelinated, pain)

23
Q

What does the somatic nervous system consists of?

A

part of the motor division-but conscious decisions (voluntary) or reflexes
Efferent nerves that come from upper motor neurons in cerbral cortex-then either connect down to rbrain stem or down in spinal cord
From there, lower motor neurons connected to skeletal muscle-can have more than one nerve per muscle, but only 1 per terminal per fiber

24
Q

Where do motor neurons come from in regards to embyology

A

The top cells from neural cresit form sensory (dorsal root), while ventral (basal plate) migrate as motor neurons-cell bodies stay in spin

25
Q

How do sensory and motor neurons come out of the spine?

A

2 roots-from dorsal horns-dorsal root is sensory, afferent-with cell bodies in ganglia outside
From ventral horn-ventral root-motor neuron/efferent-cell bodies in the spine then connecting to effector
The 2 quickly merge into spinal nerve-comes out under vertebrae through intervertebral foramen ‘(except c1)

26
Q

How many cranial nerves and spinal nerves do we have?

A

12 cranial nerves

31 spinal nerves C1-8, T1-12, L1-5, S1-5, coccygeal nerve (Co1)

27
Q

What does the autonomic nervous system consist of?

A

part of motor divison-2 categories-sympathetic and parasympathetic
opposite effects usually-SNS is fight, PSNS is rest
Start in the hypothalamus-1st neuron connects to brain stem nuclei or spinal cord (SNS)
From there-preganglionic (called presynaptic for vagal and sacral PSNS) neuron that connects to ganglia (near spine for SNS or in target organ for PSNS)
3rd neuron-post ganglionic/synaptic that connect to visceral efferctors

28
Q

Where do Autonomic nervous system neurons come from in regards to embyology

A

Top of basal plate (motor neurons) axons dont extend out but up-make preganglionic sympathetic (T1-L2) SNS and pre synatpic scaral neurons (s2-s4) in PSNS
Mutlipolar, Myelianted B fibres
Post ganglionic and post synaptic neuron-cell bodies move out to make ganglias (from basal plate)-multipolar unmyelinated C fibres

29
Q

What is myelin? How is in organisedd/made in the SNS?

A

Myelin sheath are mostly the protein rich cytoplasm of swchann cell-they wrap around them selves and their cytoplasm forms loops around axon-up too 100 layers in A fibrers
Small gaps between cells-nodes of ranvier where Na/k exchange can happen and increase AP
Main role in speed of propagation

30
Q

How is the speed of the impulse propagation changed in different fibres of the SNS?

A

propagation speed is dependent of largness of axon (larger-faster) and the myelination
Therefroe A fiber-large and lyelinated-fastest
B-in between
C thin and unmyelianted-slow

31
Q

In the SNS, what are rootlets, roots, rami and ganglia?

A

rootlets are the numerous neron bundles exiting ventral/dorsal horn before connecting into ventral/dorsal root
They then connect into 1 spinal nerve-but that splits up into: Dorsal ramus of spinal nerve-goes to innervate back of spine) and ventral ramus of nerve (eg:intercostal nerve) that innervate the front of spine
(also connecting remi branch off the nerve into the ganglions of the ANS (communaicting remi)

32
Q

How are PSNS cranial nerves oragnised in the skull?

A

Nerve will come up as bundle of axon and then split off numerous times (eg vagus nerve), innervating

33
Q

How are paravertebral and collateral of the SNS organised?

A

nerves (preganglionic) start (soma) in the spinal cord-then borrow same route of efferent nerves (motors), but split of by communicating remi to sympathetic ganglia (they are stacked on top of one another either side of the spine)-or some collateral ganglia (for visceral organs, ganglia ouside the stack)
from there, nerves connect to other soma, and these go back to spinal nerve (sweat glands, piloecrector msucles, iris, salivary glangs, etcc

34
Q

What are nerve plexuses (plexi)

A

Several spinal nerves (ventral remi) connect to the same area-form plexuses before organ-network of sucesciss ventral remi that EXCHANGE fibers are redistributed
Mostly for muscles
Thoraci ventral remi dont form plexuses

35
Q

What are dermatomes? And reffered pain?

A

Each spinal nerve (efferent) comes into a specific part of the spine, and come from a specific part of the body-therefore can map out which nerve managed which parts
These parts-when sensory (area of skin MAINLY supplied by single sensory spinal nerve root)-dermatome -therefore damage in 1 nerve makes you lose sensation in that specific dermatome. eg: S2 and S3 do penis dermatome
Some area are innevrated through pelxuses-some sensory areas come from more than one spinal root
Furthermore-roots split and go to different organs, and can have other neurons in them (such as visceral afferents, or pain neurons)-actiavte nerve of a dermatome on the way back to brain-eg: visceral sensory nerve of heart joins back the same nerve as that then goes to T2,3,4 dermatomes-heart pain is felt there-REFFERED PAIN

36
Q

What are mytomes?

A

Muscle areas that are mainly innervated by a single spinal nerve (eg C1/2 do neck extension), C3 do neck laterally, etc

37
Q

What does peripheral neuropathies mean? What do the terms mono and poly neuropathy means?

A

Damage of disease of PNS nerve-can impair sensation, movement, gland or organ
Sensory nerve-cause tingling, pain, numbness, motor nerve-cause weakness hand and feet
Autonimic nerves-changes in heart rate and stuff
Can have many causes-metabolic, toxic, inflamatory, traumatic, genetic-and 30% are idiopathic (unknown origin)
Mono: single nerve affected
Poly-several nerves affected

38
Q

Describe how PNS nerves are envelopped

A

Endoneurium around individual axons/neuron-loose collager
Perineurum-around a bundle of neuron axons (tensile strnth)
Epineurum-around entire nevre-dense, has blood vessels and fatty tissue

39
Q

What do the 3 PNS nerve injurt classification (neuropraxia, axonotmesis and neutotmesis) describeN

A

Neuropraxia-reversible-selectinve demyelination,-endoneurium and axon still intact -eg: nerve compression
Axonotmesis-demyelination and axon loss but epi and perinerium intact (still continuity between nerve). Degenration distal to injury (from cell body)-walleraian degeneration
Neurotmesis-complete nerve divison (lose all 3 layers)-no nerve regrowth

40
Q

Describe the main steps of axon regeneration (after axonotmesis)

A

Distal to site of injury-wallerian degenaration makes everything degrade and clear
Then axon proximal end regenrate in tube of schann cells-grow until target is found and connect-then remyelin and works
Can go wrong and reconect wrong

41
Q

What is Electromyography?

A

Needle EMG measures the AP in target (eg:in thumb) after patient is asked to contract it
Norrmal-nothing at rest, contracts more and more as signal increases
Denervated-fibrilate at rest-very large unit for mild activation and not much more at maximal signal
Myopathy-fibrilate, then with signal smal polyphasic units, and full interference at max

42
Q

What is nerve conduction study?

A

have two electrodes along nerve trying to be studies-send a signal from the first measured by second-passing by the nerve
Can measure connection, amplitude response AND velocity

43
Q

What is somatosensroy evoked potential?

A

Mix of EMG and NCS-evaluate lesions in pathways/latecy
small stiumulus given somewhere and then measured way down pathway
need averaging because very small nerve responses

LCRS (14 decks)

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