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Anatomy 2 > Neuro 5 > Flashcards

Neuro 5 Flashcards

1
Q 
Posterior column- medial lemniscus pathway
Spinothalamic tract (anterolateral pathway)
A

terminate in cortex – we have consciousness of them.

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2
Q

Posterior spinocerebellar tract
Cuneocerebellar tract
Anterior spinocerebellar tract

A

they terminate in cerebellum – we have no consciousness of them

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3
Q

Ascending and Descending Pathways

A

Consists of three general types:
Long, ascending fibers going to thalamus, cerebellum or various brainstem nuclei
Long, descending fibers going from cerebral cortex or various brainstem nuclei to spinal cord gray matter
Short, propriospinal fibers interconnecting different spinal cord levels
These fibers help coordinate flexor reflexes

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4
Q

Fibers with similar connections (destinations) tend to

A

travel together and form tracts in the spinal cord

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5
Q

Ascending tracts found in

A

all three funiculi (AF, LF, PF)

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6
Q

Descending tracts primarily located in

A

anterior (AF) & lateral (LF) funiculi

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7
Q

Propriospinal fibers

A

surround the spinal cord gray matter (propriospinal tract)

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8
Q

Somatosensory Receptors

A

Detect mechanical, chemical or thermal changes
All are pseudounipolar neurons with:
Cell body in DRG or cranial nerve ganglion
A central CNS process (spinal cord or brainstem)
Peripheral process with an ending in skin, muscle, or a joint

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9
Q

free nerve endings

A

touch = simple crude touch (brushing up against your arm).

pain, temp

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10
Q

Merkel endings

A

discriminative touch (texture, very fine) (two point discrimination)

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11
Q

Ending around hairs

A

touch

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12
Q

Ruffini ending

A

pressure

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13
Q

meisner corpuscle

A

descriminitve touch (two point descrimination)

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14
Q

Pacinian corpuscle

A

vibration

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15
Q

Obex

A

apex of fourth ventricle where it narrows to the central canal

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16
Q

Pyramidal decussation

A

interrupts anterior median fissure, at junction of brainstem and spinal cord. Contains corticospinal tract, motor fibers from cerebral cortex on their way to the spinal cord. Note pyramid bounded by anterolateral sulcus.

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17
Q

Fasciculus cuneatus

A

extends to cuneate tubercle, marking site of the nucleus cuneatus. Fasciculus gracilus extends to the gracile tubercle which is at the site of nucleus gracilus.

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18
Q

Posterior columns ascend to

A

medulla

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19
Q

Caudal (closed) Medulla

A

Caudal to the 4th ventricle
Spinothalamic tract (STT)
Nucleus and fasciculus gracilis (NG, FG)
Nucleus and fasciculus cuneatus (NC, FC)

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20
Q

Rostral (open) Medulla

A 
Medial lemniscus (ML)
Spinothalamic tract (STT)
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21
Q

Medial lemniscus

A

ascends to thalamus

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22
Q

Posterior column- medial lemniscus pathway

A

Discriminative touch; Mostly ascending large myelinated primary afferents from various mechanoreceptors
Two point discrimination & conscious proprioception
Vibratory sense
Synapses in medulla and then decussates forming the medial lemniscus
Relays in the lateral thalamus
Ventral posterolateral nucleus (VPL)
Terminates in the postcentral gyrus

23
Q

Posterior column- medial lemniscus pathway

A

Spinal afferents have their cell bodies in ipsilateral DRGs
As DRG rootlets enter cord, fibers divide into two divisions:
Medial- heavily myelinated, large diameter fibers; enter posterior column and ascend to brainstem
Lateral- finely myelinated and unmyelinated, small diameter fibers

24
Q

Rostral to T6 few fibers are added to

medial lemniscus pathway

A

fasiculus gracilis, and fasiculus cuneatus starts to form

25
Q

Fibers entering posterior columns are added

A

laterally to those already present, so a pattern of lamination develops

MLP

26
Q

Sacral levels most

A

medial, and cervical levels most lateral

MLP

27
Q

Fibers reach the brainstem and synapse in

A

nucleus gracilis and cuneatus (posterior column nuclei)

MLP

28
Q

Second order fibers cross the midline in

A

caudal medulla and form the medial lemniscus

MLP

29
Q

Third order fibers originate in

A

thalamus (ventral posterolateral nucleus) ascend thru internal capsule and synapse in primary somatosensory cortex in postcentral gyrus

MLP

30
Q

Injury leads to impaired

A

proprioception and discriminative tactile functions, especially complex tactile discrimination

MLP

31
Q

Tested clinically by placing a

A

vibrating tuning fork on body surface or have patient identify a pattern drawn on them

MLP

32
Q

Spinothalamic tract (STT)/ Anterolateral pathway

A

One of multiple pathways that convey pain and temperature info
Involved in awareness and localization of painful stimuli
Ultimately ends in VPL of thalamus and some nearby thalamic nuclei
Other fibers in this pathway end in reticular formation of limbic system to mediate other pain responses
These fibers travel with the spinothalamic tract so some prefer the term anterolateral pathway (in anterior half of lateral funiculus)

33
Q

Spinothalamic tract/ Anterolateral pathway

A

Pain, temperature and some mechanoreceptor fibers enter cord via lateral division of dorsal root, project branches to posterior horn many synapse in substantia gelatinosa

34
Q

Neurons in posterior horn are

A

2nd order neurons, axons cross midline with rostral inclination, collect and form anterolateral pathway

STT

35
Q

New fibers join at

A

anteromedial edge

STT

36
Q

Somatotopic organization: STT

A

3Caudal body parts in posterolateral portion, rostral parts in anteromedial portion

37
Q

Spinothalamic fibers

A

start in posterior horn project to VPL

Medial lemniscus also uses VPL

38
Q

Other spinothalamic fibers project to

A

intralaminar nuclei and other thalamic nuclei

STT

39
Q

Spinoreticular fibers projection to

A

brainstem reticular formation
Likely important for changes in the level of attention of pain response

STT

40
Q

Spinomesencephalic fibers are important in

A

pain control mechanisms

STT

41
Q

Spinohypothalamic fibers mediate

A

autonomic response to pain

42
Q

STT

A

fibers travel in anterolateral pathway

43
Q

STT Damage causes loss of:

A

Pain and temperature sensations

Itch and tickle sensations

44
Q

Bowel and bladder pressure, sexual sensations

A

ascending bilaterally so unilateral injury does not leave a deficit

45
Q

Cordotomy

A

Destroy spinothalamic tract to produce contralateral analgesia in patients with intractable pain
Cut lateral funiculus from dentate ligament to ventral root rostral to highest dermatomal pain level
Analgesia lasts several months

Cut highest – they have rostral ascension. So if you have to cut lower to get the same effect.

46
Q

Sensory Homunculus

A

Pathways are somatopically organized

47
Q

Spinal cord information to cerebellum

A

Information from spinal cord used by the cerebellum to coordinate movement
Direct: Spinocerebellar tracts, three are well characterized
Indirect: Via brainstem relay nuclei

48
Q

Posterior Spinocerebellar Tract (PSCT)

A

Convey proprioceptive info

Ipsilateral leg proprioception

49
Q

Collaterals from posterior columns convey

A

tactile, pressure and proprioceptive info (spindles & GTO) synapse in Clarke’s nucleus

PSCT

50
Q

Axons ascend ipsilateral

A

lateral funiculus forming PSCT on cord surface

PSCT

51
Q

Fibers enter cerebellum (vermis and adjacent hemispheres) via

A

inferior cerebellar peduncle

PSCT

52
Q

Cuneocerebellar tract

A

Most spinocerebellar-like fibers that enter in cervical and upper thoracic segments (arm) do not project to Clarke’s nucleus
Arm afferents ascend in fasciculus cuneatus to lateral cuneate nucleus in the medulla
Axons from lateral cuneate nucleus collect and form cuneocerebellar tract, enters inferior cerebellar peduncle to synapse in vermis and nearby cerebellar hemispheres

53
Q

Anterior Spinocerebellar Tract (ASCT)

A

Conveys more complex information to cerebellum

Origin: lateral surface of anterior horn at lumbar levels (spinal border cells)
Primarily concerned with leg but differs from PSCT

Inputs more complex (cutaneous receptors, interneurons and from fibers in descending tracts)
So ASCT activity more related to attempted movement and not simple sensory signals
Note: crosses midline twice, so ultimately fibers end ipsilateral to their source

Anatomy 2 (15 decks)

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