Neuroanatomy Flashcards Preview

Neurology > Neuroanatomy > Flashcards

Flashcards in Neuroanatomy Deck (116):

what is the CNS composed of?

the brain and spinal cord


what is the PNS composed of?

12 pairs of cranial nerves 

31 pairs of spinal nerves (& branches)


what are the first 3 swellings of the neural tube called during development - around week 4?




*these are primary vesicles


the prosencephalon and rhombencephalon divide into two further parts at around 6-8 weeks - what are these secondary vesicles called?

prosencephalon = telencephalon and diencephalon 

rhombencephalon = metencephalon and myelencephalon 



what do each of the secondary vesicles give rise to in a mature brain?

telencephalon = cerebral hemispheres 

diencephalon = thalamus and hypothalamus 

mesencephalon = midrain 

metencephalon = pons and cerebellum 

myelencephalon = medulla oblongata 


what three structures make up the brain stem?



medulla oblongata 


what are the two main types of cells found in CNS and what is their functions?

neurones = communicate via electrical impulses 

glial cells = "glue" the CNS together as there is no connective tissue for support


what are the 2 main types of neuron and what type of signals usually flow through each?

multipolar - many dendrites and one axon extending into PNS (motor efferents travel along these)

pseudo-unipolar = cell body in PNS (sensory afferents travel along these)


what are the four main types of glial cells found in CNS and what is their role?

astrocytes = supportive, maintain BBB and homeostasis

oligodendrocytes = myelination in CNS (not PNS)

microglia = immune monitoring and antigen presentation (similar to macrophages)

ependymal cells = ciliated columnar epithelium lining ventricles 


describe how oligodendrocytes myelinate nerve fibres in order to speed up the rate of electrical conduction?

myelinate sections - leaving small gaps (called nodes of ranvier)

electrical signals must jump over this gap which speeds up signal conduction


how do microglia appear in their resting phase compared to a phase where they encounter an insult of infection?

resting = short, spiny cell processes 

when activated by infection = rounder and more similar to macrophage 


ependymal cells form a barrier between the CSF and the brain tissue - true or false?

false - CSF can still move outwith ventricles regardless of this layer of epithelium 


what are the 2 types of astrocytes and which is found in grey and white matter?

grey matter = protoplasmic astrocyte 

white matter = fibrous astrocyte 


what are gyri, sulci and fissures?

gyri = bulges of cerebral hemispheres 

sulci = indentations (or sunken in parts)

fissures = deep sulci 


what is the difference in the make up of grey matter and white matter?

grey = cell bodies of neurones, synapses and support cells

white = axons of neurones and support cells (no cell bodies)


describe the distribution of grey and white matter in the spinal cord?

grey matter - H shaped (has 2 anterior horns and 2 posterior horns) 

white matter = surrounds grey H 



what is the function of the central sulcus?

differentiates regions with different functionalities (ie primary sensory and motor cortexts)



where is the primary somatosensory cortex located?

post-central gyrus 


where is the primary somatomotor cortex located?

pre-central gyrus 


what is the corpus callosum?

large area of white matter carrying material between the right and left hemispheres of the brain 


what is the relevance of the calcarine sulcus?

marks the location of primary visual cortex 



what is contained in the fornix of the brain and what is its function?

limbic system found here

plays a role in memory making 


what are the four traditional lobes of the brain?






what seperates the frontal and parietal lobes?

central sulcus 


what seperates the frontal and parietal lobe from the temporal lobe?

lateral sulcus 


what seperates the parietal and occipital lobes?

parieto-occipital sulcus 

*this is defined more medially than it is on lateral brain 


what non-traditional lobe of the brain is found concealed in the cerebral hemispheres, and what is its function?

insular lobe (insula)

plays a role in patients experience of pain 


what 3 layers make up the meninges (superficial to deep)?

dura mater 

arachnoid mater

*subarachnoid space containing CSF*

pia mater 


why is it difficult to remove the dura mater from the inner surface of cranium?

it acts as periosteum for the inner part of the skull


describe how the layout of the arachnoid and pia mater create the subarachnoid space?

arachnoid mater = stretched layer over brain 

whereas pia mater = only 1-2 cells thick, so falls into all the sulci and tightly covers gyri 

space between these 2 layers create CSF


why are the lateral ventricles shapes the way they are?

to extend CSF into all traditional lobes of the brain 


what could potentially cause a blockage in the ventricular system?

a tumour pressing on cerebral aqueduct 

*this could cause hydrocephalus


what other nervous system is often forgotten about in the body?

enteric (digestive) nervous system 

has own set of nerve plxuses in gut walls 

influenced by ANS 


by which 2 directions is blood supplied to the brain?

from vertebral arteries and internal carotids 


what arteries connect the blood supply from vertebral and internal carotid arteries?

posterior communicating arteries 


roughly where do each of thr 3 major cerebral arteries supply?

anterior = medial brain and most of frontal lobe 

middle = lateral brain 

posterior = posterior brain 


how is the majority of blood drained from brain?

dural venous sinuses - these then drain into internal jugular vein 


why are there enlargements in the cervical and lumbar regions of the spinal cord?

increased spinal tissue required to innervate and deal with the limbs 


at what vertebral level does the spinal cord end, and what is this structure called?

L2 - conus medullaris 


what continues after the conus medullaris in order to connect to the coccyx?

thin connective tissue cord - filum terminale 

*this forms part of the cauda equina


the meninges in the spinal cord are continuous with those in brain - true or false?


however, the dura mater in spinal cord does not act as periosteum for the vertebrae, they are seperated by a fat pad known as the epidural space


what arteries help to supply blood to the spinal cord?

3 major longitudinal arteries - 2 posterior and 1 anterior (originate from vertebral arteries)

segmental arteries eg intercostal, lumbar 

radicular arteries that travel long dorsal and ventral roots 


embolic occlusion of any of the arteries supplying the spinal cord can lead to areas of infarction - true or false?



how is blood drained from the spinal cord?

anterior and posterior venous plexuses 



how do sensory signals travel up to the primary somatosensory cortex using the dorsal column/medial leminiscus system?

3 neuron process up the ascending tracts in CNS:

1st neuron ascends in dorsal column (blue)

synapse at medulla 

2nd order neuron crosses midline moving from medulla to thalamus then 

synapses (green)

3rd neurone stretches from thalamus to corresponding part of post-central gyrus (red)


why is the dorsal column split with a fissure on either side?

to differentiate sensory info coming from lower limb (medial) and upper limb (lateral)


what two main tracts are used for sensory signals ascending the spinal cord and which signals does each carry?

dorsal column / medial leminiscus system = fine touch and conscious proprioception 

spinothalamic tract = pain, temperature, deep pressure 


what is the difference between the crossing of fibres in dorsal column tract vs spinothalamic tract?

dorsal column = crosses at medulla 

spinothalamic = cross segmentally 

*spinothalamic synapses immediately in spinal cord then travels up to the thalamus rather than waiting until the medulla to synapase 


how do most somatomotor signals from the pre-central gyrus descend the spinal cord?

via the lateral or ventral/anterior corticospinal tracts 

*corticospinal tracts control fine, precise movement particularly of distal limb muscles

*corticospinal tracts also known as pyramidal tract


describe how motor signals reach the spinal cord from the brain?

1st neuron extends all the way from pre-central gyrus to the level of effect 

*may cross side at medulla (85% - lateral corticospinal tract) or may continue on same side until desired level (15% - ventral corticospinal tract)*

synapse at desired level


what is the internal capsule and what symptom would be experienced after a stroke in this area?

white matter pathway (especially for corticospinal tract)

spastic paralysis with hyperflexion of upper limbs - decorticate posturing 


there are a number of motor systems outside of the pyramidal tract - what are these often referred to?

extrapyramidal system 


what is the function of the tectospinal tract and what part of the brain does it involve?

input from cervical segments 

from tectum in posterior midbrain, down to spinal cord

mediates redlex head and neck movement in response to visual stimuli 


what is the reticulospinal tract and what movements can it facilitate?

tract between reticular formation (centre of brainstem) to spinal cord 

fibres in pons = facilitate extensor movements and inhibit flexor movements 

fibres in medulla = facilitate flexor movements and inhibit extensor 


what is the vestibulospinal tract responsible for and where does it span from?

from vestibular nuclei in pons and medulla

excites anti-gravity extensor muscles for impulse response (ie after being pushed by someone) 


what are the symptoms of brown-sequard syndrome caused by lateral hemisection of the cord?

ipsilateral paralysis 

ipsilateral hyperreflexia and extensor plantar reflex 

ipsilateral loss of vibratory sense and proprioception 

contralateral loss of pain and temperature sense 


what are the functions of the cerebellum and basal ganglia in motor movement?

feedback to motor cortex via the thalamus 

helps to improve and adapt movement the body is making 


what are the 3 lobes of the cerebellum?

anterior, posterior (largest) and flocculonodular lobe 




the cerebellum is known as a sub-tentorial organ - what does this mean?

it sits under the tentorium cerebelli (extension of dura mater which covers cerebellum)



how is the cerebellum attached to the brainstem?

3 penducles of white matter - superior, middle (largest) and inferior 


the small bulges on the cerebellum are not called gyri like those in the brain, what are they instead referred to as?



describe the distribution of grey and white matter seen when the cerebellum is cut?

grey matter towards the outside 

white matter in "tree" shape in centre

deep grey matter visible inside the white matter centre



what are the 3 layers of the cerebellar cortex?

molecular layer (outer)

purkinje cell layer (middle)

granule cell layer (inner)



what is contained in the granular cell layer that is easily seen on histology?

lots of neurones which recieve important afferent signals from spinal cord, cerebral cortex (relayed via pons) and vestibular apparatus 


why does the pons swell anteriorly?

it is receiving / giving a lot of information from / to the cerebellum posteriorly 


what is the only point of output in the cerebellum?

purkinje cells from all three lobes

mainly synapse on neurones of deep cerebellar nuclei 


what is the function of the flocculonodular lobe?

recieves vestibular info which is feeds back to brainstem 


if one side of the cerebellum is affected by disease, is it the ipsilateral or contralateral side of body that is affected?



what does the central vermis in the cerebellum control?

autonomic movements that we do not think about 


describe the difference in effect a lesion may have depending on where in the cerebellum it is found?

midline = affects posture control (despite preserved limb co-ordination)

unilateral = ipsilateral affect on body (disturbance of co-ordination - intention tremor and unsteady gait in absence of weakness or sensory loss)

bilateral = slowed, slurred speech (dysarthria), bilateral incoordination of arms and a staggering, wide based gait (cerebellar ataxia)


acute alcohol exposure typically results with which type of cerebellar dysfunction?

bilateral cerebellar hemisphere dysfunction 

presents with cerebellar ataxia 


what are the main functions of the basal ganglia when providing the motor cortex with feedback?

facilitate purposeful movement 

inhibit any unwanted movement 

role in posture and muscle tone 


what 5 components make up the basal ganglia?

caudate nucleus 


globus pallidus 

subthalamic nucleus 

substantia nigra 


how does the substantia nigra appear in the midbrain?

looks like a black line 


in which condition would the substantia nigra potentially not be present?


substania nigra is only present when dopamine is being produced - the black colour comes from a by-product of this reaction 


how does the basal ganglia signal to the motor cortex to enhance useful movement?

direct pathway - enhances outflow of thalamus, enhancing the desired movement 


how does the basal ganglia signal to the motor cortex to inhibit a certain movement?

indirect pathway - inhibits outflow of thalamus 


lesions in the basal ganglia cause what type of symptoms?

contralateral symptoms 

do not cause paralysis, sensory loss, loss of power or ataxia 

DOES cause change in muscle tone and dyskinesias inclusing tremor (sinusoidal movements), chorea (rapid, asymmetrical movements usually affecting distal limb musculature) and myoclonus (muscle jerks)


what 2 disorders are associated with basal ganglia and how do they present differently?

parkinsons = akinesia, rigidity and resting tremor (degeneration of dopaminergic neurones of substantia nigra)

huntingtons = chorea and progressive dementia (progressive degeneration of the basal ganglia and cerebral cortex)


why is the optic nerve considered more like the CNS?

it is myelinated by oligodendrocytes rather than schwann cells 

extends to the back of eye with meninges covering like in the brain 


CN I has no motor function - true or false?

true - only sensory 

vesicles on end of neurone pick up smell in olfactory mucosa 


where is the nuclei for CN III found?

in the centre of the midbrain (centre deals with motor) 



why does CN IV exit the brain posteriorly after having crossed the midline?

it curves round the cerebral aqueduct before exiting the contralateral part of posterior brain 


where is the CN IV nucleus found?

lower midbrain 



where is the CN VI abducens nucleus located?

caudal pons - at base of the midbrain, behind the 4th ventricle 



where is the CN XII nuclei found?

in the medulla 



why do CN III, IV, VI and XII all exit the brain medially?

this is where their nuclei are in the brainstem 

they all have motor portions - due to development they are found medially in brainstem


what are the 3 main parts of the trigeminal sensory nucleus?

spiral nucleus = extends towards (pain/temp)

principle nucleus / pontine nucleus = in middle at entry (touch/vibration)

mesencephalic = upwards (chewing proprioception)


what does the trigeminal motor nucleus control and where is it located?

some muscles of mastication eg tensor veli palatini 

located behind principle nucleus 


what are the 3 components of the facial nerve and what nucleus is used to facilitate each?

1. motor (muscle facial expression) = facial motor nucleus 

2. parasympathetics = spinal trigeminal nucleus / salivatory 

3. taste = solitary nucleus 


what are the 4 components of CN IX glossopharyngeal and what nucleus is used to facilitate each?

taste = solitary 

small region of somatosensation in ear = spiral trigeminal nucleus 

parasympathetic = salivatory 

innervation of pharyngeal muscles = nucleus ambiguus 


what are the 4 components of the vagus nerve and what nuclei are used for these?

parasympathetic = dorsal (motor) nucleus 

taste = solitary, commissural = visceral information

sensation around ear = spinal trigeminal nucleus 

motor to some pharyngeal muscles = nucleus ambiguus 


what shape is adopted by the solitary nucleus to provide space for many different cranial nerves associated with it?

V from upper to lower medulla 


what are the three tubes which form the spiralling cochlea?

scala vestibuli 

scala media 

scala tympani 


how many turns does the cochlea make in the ear?



which organ inside the cochlea is important for sounds interpretation?

organ of corti 


what does the organ of corti sit on top of and how does this help us to hear sound?

sits on top of basilar membrane (hair cells poke up from here)

basilar membrane varies in length and stiffness throughout cochlea - makes tip of cochlea more specific for low pitch and the base more specific to high pitch 


what other membrane brushes against hair cells to turn vibrations into electrical impulses?

tectorial membrane


what carries electrical impulses from the stimulated hair cells in organ of corti to the cochlear nerve?

spiral ganglion 


describe how input from the spiral ganglion makes its way up to the primary auditory cortex?

1st neuron goes from the spiral ganglion to ventral and dorsal cochlear nuclei (at inferior cerebellar peduncle of brainstem)


2nd neuron ascends bilaterally to superior olivary nucleus 

some synapse but not all 

2nd / 3rd neurones travel up to inferior colliculus where all synapse 

these signals progress up to the medial geniculate nucleus of the thalamus 

and finally to primary auditory cortex 


identify the auditory areas within the brain?

anterolateral part of auditory cortex = low frequency 

posteromedial part of auditory cortex = high frequency 


what two structures that are passed through in the auditory pathway of the brainstem help to localise sound?

lateral leminiscus (white matter between nuclei) 

superior olivary nucleus 

*they help us tell what time sound arrived at each ear to orientate what side the sound originated from 


the vestibular pathway has more nuclei in the brainstem than in cochlea pathway - true or false?



damage to which specific named areas of the brain can cause aphasia ie inability to use language?

brocas area = difficulty producing language, saying most important word in sentence, no difficulty comprehending language 

wernickes area = difficulty comprehending language, speak words out of order / use meaningless words 


where does the vestibular nuclei connect to?

thalamus - for conscious movement 

CNs III, IV and VI - for eyes to adapt to movement 


lateral vestibular nucleus connects straight to spinal cord 


where in the brain is the primary vestibular cortex located?

there is no primary vestibular cortex 

areas upon which vestibular info has been found to converge is: area of parietal cortex just posterior to postcentral gyrus that represents hand and mouth, an area just rostral to primary auditory cortex and the posterior insular cortex


why does the fovea have more acute vision than rest of retina?

layers are thinner - light easily hits photoreceptor cells


where does the optic tract extend back to in the thalamus?

lateral geniculate nucleus (for sight)

*remember the medical geniculate nucleus is for auditory info



does the primary visual cortex have a large or small association area?



how is the visual cortex arranged at the calcarine sulcus in reference to our visual field?

lower portion of our visual field is processed in the gyrus above the calcarine sulcus 

upper portion of visual field = gyrus below 

central vision = posterior part of these gyri 

peripheral vision = anterior part of these gyri 


signals from the upper visual field have to loop around what structure embedded in cerebral hemisphere?

lateral ventricle - meyers loop 


what two areas of the brain control eye movement?

viual cortex and frontal eye field (motor area in frontal lobe) 


what type of eye movement is controlled by frontal eye field?

command movements (eg telling someone to look in particular direction = jumpy / quick movements)


what type of eye movement is controlled by the visual cortex?

smooth "tracking" movement 


what nucleus is reponsible for the bilateral response in pupillary light reflex?

edinger-westphal nucleus 


what are the 3 different types of fibres in the white matter of the cerebral hemispheres?

association fibres = connect cortical sites lying in the same hemisphere

commissural fibres = connect one hemisphere to the other, usually connecting areas with similar function 

projection fibres = connect hemispheres to deeper structures including thalamus, corpus striatum, brain stem and spinal cord