practical 2 sensory pathways W2 Flashcards

1
Q

major sensory pathways and their functions?

A

dorsal columns (fasciculi gracilis and cuneatus): proprioception and discriminative touch (aka fine touch)

spinothalamic tract: pain, crude touch, temperature

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2
Q

difference between fine and crude touch?

A

fine: allows localisation of touch
crude: doesn’t allow localisation of touch

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3
Q

dorsal columns pathway?

A

->peripheral receptor
->dorsal root ganglion
->fasciculus cuneatus/gracilis
->nucleus cuneatus/gracilis (medulla)
->internal arcuate fibres (medulla)
->medial lemniscus (medulla/pons/midbrain)
->VPL thalamus
->internal capsule
->corona radiata
->post central gyrus

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4
Q

what does the dorsal root ganglion contain

A

cell bodies of sensory neurons

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5
Q

spinothalamic pathway?

A

->peripheral receptor
->DRG
->dorsal horn
->ventral white commissure
->spinothalamic tract of spinal cord
->spinal lemniscus
->VPL thalamus
->internal capsule
->corona radiata
->post central gyrus

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6
Q

caudal medulla features?

A

posterior: fasciculus gracilis lies medial to fasciculus cuneatus. deep to these lie the corresponding nuclei.

medial: internal arcuate fibres run to the medial lemniscus which lines the anterior median fissure.

anterior: pyramid

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7
Q

where is the medial lemniscus found in different cross sections of the brainstem

A

medulla: medial, stretches anterior/posterior

mid-pons: deep to pontocerebellar fibres (transverse pontine fibres). stretches medial/lateral

midbrain: lateral, in continuous line with spinal lemniscus

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8
Q

where is the location of the nucleus gracilis and nucleus cuneatus marked? where are these visable?

A

gracile and cuneate tubercles
visible on dorsal surface of medulla above fasciculus cuneatus/gracilis

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9
Q

how to identify the thalamus on half brains and coronal brain sections?

A

half brain - find 3rd ventricle, forms wall of this (visible superior)

coronal section - lateral to third ventricle, medial to internal capsule

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10
Q

where do neurons carrying sensory information for the head and neck synapse?

A

ventroposteriomedial nucleus of the thalamus (VPM nucleus)

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11
Q

where do neurons carrying sensory information from the rest of the body synapse?

A

ventroposteriolateral nucleus of the thalamus (VPL nucleus)

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12
Q

what areas of grey matter form the boundaries of the internal capsule?

A

caudate nucleus
lentiform nucleus (globus pallidus, putamen)
thalamus

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13
Q

what is the functional arrangement of fibres within the internal capsule?

A

anterior limb: fibres associated with higher functions
posterior limb: major ascending somatosensory fibres and descending motor fibres

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14
Q

where is the primary somatosensory cortex?

A

post central gyrus (gyrus immediately posterior to central sulcus)

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15
Q

what is the principle arterial blood supply to the sensory cortex receiving information from the lower limb?

A

anterior cerebral artery

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16
Q

what is the principle arterial blood supply to the cortex receiving information from the head?

A

middle cerebral artery

17
Q

where are dorsal root ganglia found?

A

dural root sleeve in the intervertebral foramen (only visible when some bone has been cut away)

18
Q

what are the large pink cells visible in a H and E stained DRG section?

A

cell bodies of first order sensory neurons.

19
Q

what are dorsal root ganglion?

A

a collection of sensory neuron cell bodies outside of the CNS

20
Q

features of the cervical spinal cord?

A

increased grey matter due to increased neuron cell bodies to provide innervation to upper limbs
large amount of white matter (increases closer to brain)

21
Q

features of thoracic spinal cord?

A

small amount of grey matter

22
Q

features of lumbar spinal cord?

A

increased grey matter due to increased neuron cell bodies to provide innervation to lower limbs
less white matter than cervical as further from brain

23
Q

sacral spinal cord features?

A

very small amount of white matter as far from brain

24
Q

what is a dermatome

A

the specific region on the surface of the body innervated by the sensory axons carried in each individual spinal nerve (and the trigeminal nerve)

25
Q

body region associated with C2/3 dermatome?

A

posterior scalp and neck

26
Q

body region associated with C6 dermatome?

A

anterior arm and thumb

27
Q

body region associated with T4 dermatome?

A

ant/post thorax at level of 6th rib (approx. nipples level)

28
Q

body region associated with T10 dermatome?

A

ant/post abdomen at level of umbilicus

29
Q

body region associated with L4 dermatome?

A

front of knee to medial aspect of ankle/foot

30
Q

what is carried in the trigeminal nerve?

A

sensory information for the head and neck

31
Q

where is the trigeminal nerve found in the brain stem

A

enters brainstem at level of the pons
visible on a cross section travelling inwards, lateral to the pontocerebellar fibres.

32
Q

sensory nuclei in brainstem where sensory neurons with cell bodies in the trigeminal ganglion synapse? what type of information is associated with each nucleus?

A

mesencephalic nucleus: proprioception

chief sensory nucleus: touch, pressure

nucleus of the spinal tract of the trigeminal: pain, temperature

33
Q

trigeminothalamic fibres decussate in the brain stem and travel to the thalamus. where in the thalamus do these fibres synapse?

A

ventroposteriomedial nucleus of thalamus

34
Q

locations of the nuclei where trigeminal ganglion nerves synapse? (brainstem)

A

mesencephalic nucleus: rostral
chief sensory nucleus: middle
nucleus of spinal tract of the trigeminal: caudal (lateral to dorsal columns, visible on isolated brainstem)

35
Q

what information does the spinocerebellar pathway carry

A

control of posture
coordination of movement

36
Q

where is the cell body of the first and second order neurons of the spinocerebellar pathway found?

A

first order: dorsal root ganglion
second order: mostly in dorsal horn of spinal cord

37
Q

2 principle tracts relating to spinocerebellar pathway? do they cross?

A

dorsal spinocerebellar tract (does not cross, ipsilateral)
ventral spinocerebellar tract (does cross, contralateral)

38
Q

where do the dorsal and and ventral spinocerebellar tracts enter the cerebellum? (describe where these are found)

A

dorsal: inferior cerebellar peduncle (medial to middle cerebellar peduncle)

ventral: superior cerebellar peduncle (diagonal ridge)

39
Q

what type of sensory information is carried in the spinocerebellar tract

A

relative stretch in muscles from muscle spindles
stretch in tendons
joint receptors
pressure on skin and superficial fascia