Neuro revision Flashcards
cerebrospinal fluid circuits in which space?
the subarachnoid space
- the extradural space normally consists of nothing- can fill with blood in an extradural haemorrhage
- subdural space normally consists of nothing apart from bridging veins
the superior colliculus is part of which structure?
midbrain
- colliculi sit on the dorsal aspect of the midbrain
a region of white matter is identified in the cord which contains both ascending and descending axons. what is the correct term for this?
funiculus
- tract contains axons travelling in a single direction only (either ascending or descending)
- fasciculus is a subdivision of a tract
the thalamus, an important structure in the sensory system, is fond in which division of the CNS?
Diencephalon
one complication of subarachnoid haemorrhage is blockage of arachnoid granulations. what might the effect of this be?
raised intracranial pressure
the CNS shares an embryological origin with which other tissue?
the skin
- CNS is derived from ectoderm- as is skin
- gut derives from endoderm and muscle from mesoderm
pure sensory loss in a single dermatome with no associated weakness suggests damage to which structure?
dorsal root
- would affect multiple dermatomes with associated weakness if the spinal cord was damaged.
- ventral root affected= weakness with no sensory loss
which region of cortex sits anterior to the central sulcus?
primary motor cortex
- primary sensory cortex sits posterior to the central sulcus
- premotor area sits anterior to primary motor cortex
which subdivision of the CNS contains cell bodies and dendrites?
grey matter
which cranial nerve emerges ventrally from the ponto-medullary junction?
abducens nerve
- trigeminal nerve emerges from the lateral aspect of the pons
- facial nerve emerges laterally from the ponto-medulary junction
considering the motor homunculus, which region of the body is represented most laterally in the primary motor cortex?
the face
- lower limbs represented medially
- hands sit in an intermediate position
a meningomyelocoele contains what?
spinal cord and CSF
- meningo= meninges (hence CSF)
- myelo= cord
which type of neurone brings information into the CNS
afferent neurones
- efferent neurones carry impulses away from the CNS
- interneurones connect afferents and efferents
the hippocampus is found in which lobe of the brain?
temporal lobe
- sits infers-medially in the temporal lobe
a tumour at the level of the interventricular foramen might lead to dilation of which structures?
lateral ventricles
- lateral ventricles drain into the interventricular foramen before entering the third ventricle
the Raphe nuclei produce which NT?
5-HT (serotonin)
an important source of dopamine for the motor system can be found in which structure?
substantia nigra
- resides in the midbrain
in which regions would NA be produced?
locus coeruleus
which cell type can assume a macrophage- like appearance when activated?
microglia
- immune- type cells
in the midbrain, which large white matter structures connect the cerebral hemispheres to the brainstem?
crus cerebri / cerebral peduncles
- attach the cerebellum to the brainstem
- the superior colliculi are features of the dorsal midbrain and deal with relax actions to visual stimuli
which cell type is primarily responsible for maintenance of the BBB?
astrocytes
the fall cerebra is composed of which meningeal layer?
meningeal dura
- in the midline (sagittal plane) the meningeal dura separates from the periosteal layer and dips down between the hemispheres to form the falx
- periosteal dura is adhered directly to the inner table of the skull
- arachnoid sits deep to the meningeal dura
the third ventricle drains directly into which structure?
the cerebral aqueduct
- from the aqueduct the CSF goes to the fourth ventricle
- the central canal of the cord emanates from the 4th ventricle and contains an insignificant amount of CSF
which part of the bringer lies at the level of the tentorium cerebelli?
midbrain
- the midbrain sits in the ‘tentorial notch’ and can be compressed if the uncut of the temporal lobe herniates into the posterior fossa
give an example of an excitatory NT
glutamate
So-called ‘bridging veins’ transverse which space?
subdural space
- extradural space contains branches of the middle meningeal artery
what is a modality?
- ‘unit’ of sensation, relying on a distinct receptor type
what are the modalities of the spinothalamic system?
(important for survival)
- pain
- temperature
- crude touch
what are the modalities of the dorsal column system?
- vibration
- 2 point discrimination
- proprioception
- fine touch
what are primary sensory neurones responsible for?
- the initial encoding of sensory information
- each primary neurone receives input from a single receptor type
- have their cell body in the dorsal root ganglion, and collect information from a single dermatome alone their peripheral axon
- project into the spinal cord alone their central axon
what are rapid vs slow adapting receptors?
eg mechanoreceptors
- respond best to changes in strength of stimulation
- frequency of firing diminishes rapidly after the initial stimulation
- slow adapting receptors change their frequency of firing very little after the initial stimulus - how pain is persistent
what is a receptive field?
region of skin that a given sensory neurone supplies
describe the somatosensory system order
first order sensory neurones
- cell body in DRG (sensory ganglion)
- communicate with a receptor
- central axon projects ipsilateral to the cell body of a 2nd order neurone
second order sensory neurones
- cell body in spinal cord dorsal horn or medulla
- decussate onto 3rd order neurones
third order sensory neurones
- cell body in the thalamus
- project to primary sensory cortex (post central gyrus) via internal capsule
through what do first order neurones of the DCML system ascend through above and below T7?
lower body (T7 and below) - ascend through the gracile fasciculus to the gracile nucleus in the medulla
upper body (T6 and above) - ascend through the cuneate fasciculus to the cuneate nucleus in the medulla
what is the pathway of second order neurones of the DCML pathway?
neurones project to contralateral thalamus in the medial lemniscus
what is the pathway of third order neurones of the DCML pathway?
- thalamic neurones receiving information from the lower half of the body project to medial part of primary sensory cortex
- thalamic neurones receiving information from upper half of body project to lateral part of primary sensory cortex
what is the topographical organisation of the dorsal columns?
- axons from the lower parts of the body run most medially
- axons from progressively superior body segments are added laterally to the dorsal columns