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sp15 neuroanatomy - dr. pierson > Lecture 4 - Ascending Sensory Systems > Flashcards

Lecture 4 - Ascending Sensory Systems Flashcards

1
Q

Somatosensory receptors have a cell body in the _____ _____ _____ (DRG), a central ______ process, and a ______ process ending in skin, muscle, or joint.

A
  • dorsal root ganglion
  • CNS
  • peripheral
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2
Q

What are the 2 types of cutaneous receptors in the skin?

A
  • encapsulated

- nonencapsulated

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3
Q

Which 3 cutaneous receptors are encapsulated?

A
  • Pacinian corpuscle (vibration)
  • Meissner’s corpuscle (touch)
  • Ruffini endings (pressure)
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4
Q

Which 3 cutaneous receptors are non-encapsulated?

A
  • endings around hairs (touch)
  • Merkel endings (touch)
  • free nerve endings (pain, temperature, itch, touch)
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5
Q

3 receptors in hairy skin

A
  • endings around hairs
  • Merkel endings
  • free nerve endings
  • all non-encapsulated
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6
Q

4 receptors in hairless (glabrous) skin

A
  • Meissner’s corpuscle
  • Merkel cell
  • Pacinian corpuscle
  • Ruffini endings
  • all encapsulated except Merkel cell
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7
Q

Discriminative touch (two point discrimination) that is concentrated in finger tips is done by ______ _______. These receptors have fast conducting _____ fibers.

A
  • Meissner’s corpuscle

- Aβ

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8
Q

Discriminative touch endings inferior to Meissner’s corpuscles are called _______ endings. These receptors have fast conducting _____ fibers. Their adaptation is _____.

A
  • Merkel
  • Aβ
  • slow
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9
Q

Descriminative touch impulses are carried up the _____ ______ ______ ______ pathway. This pathway also enables _________ (spatial position) and vibration.

A
  • posterior column-medial lemniscal pathway (PCML)

- proprioception

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10
Q

The posterior column - medial lemniscal (PCML) pathway has ____ fibers. Its decussation level is at the ______, and it relays in the lateral _______ at the ventral posterolateral nucleus (VPL). Its termination is in the ______ ______ of the cerebrum.

A
  • Aβ
  • medulla
  • thalamus
  • postcentral gyrus
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11
Q

TRUE or FALSE. Spatial resolution (location) of a stimulus is more precise when there are more receptors.

A

TRUE - more receptors in the fingertips than hands allow us to feel location of stimuli in fingertips more easily

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12
Q

Detection of vibrations, especially in the fingers and palms, is done by ______ ______. They have ___ fibers.

A
  • Pacinian corpuscles

- Aβ

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13
Q

Pain, crude touch, and temperature are signaled with ____ _____ _____ in the skin.

A

free nerve endings

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14
Q

Fast pain is carried by _____ fibers, while slow pain is carried by _______ fibers.

A
  • δ (delta)

- unmyelinated

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15
Q

3 general types of pathways:

  • Long, _____ fibers going to thalamus, cerebellum, or brainstem nuclei
  • Long, _____ fibers going from cerebral cortex or brainstem nuclei to spinal cord gray matter
  • Short, _____ fibers interconnecting different spinal cord levels for reflexes
A
  • ascending
  • descending
  • propriospinal
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16
Q

TRUE or FALSE:

Fibers from different pathways often travel together, regardless of their destination in the brain.

A

FALSE - different fibers do travel together, but usually only if the destination is the same

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17
Q

Descending tracts are located primarily in _____ ______and _____ _____ (white matter).

A
  • anterior funiculi
  • lateral funiculi

*funiculi ARE white matter tracts in spinal cord

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18
Q

Ascending tracts are found in ______ ________ of the spinal cord.

A

all funiculi (anterior, lateral, and posterior)

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19
Q

Propriospinal fibers surround the spinal cord _____ ____.

A

gray matter

20
Q

The PCML conveys ______ and limb _______ information. It is an _______ tract, meaning that afferent neurons carry information towards the brain. Receptors that pick up stimuli for the PCML are mostly _________.

A
  • touch
  • position
  • ascending
  • mechanoreceptors
21
Q

The spinal afferent cell bodies of the PCML are located in the _____ _____ ______. The fibers enter the spinal cord, and divide into _______ (directly to brainstem) and _____ divisions.

A
  • dorsal root ganglion
  • medial
  • lateral
22
Q

In the PCML, most fibers caudal to T6 are added to fasciculus _______. Rostral to T6, fibers begin forming fasciculus _______. They eventually syanpse in the ______ at these nuclei.

A
  • gracilis
  • cuneatus
  • brainstem (medulla)
23
Q

In the PCML, fibers are added from most inferior to most superior spinal levels laterally in a pattern of lamination. This means that sacral fibers for PCML, all the way up the cord, are most _____, while cervical levels are most ______.

A
  • medial

- lateral

24
Q

In the PCML, 1° fibers synapse in nucleus _______ and nucleus ________. 2° fibers decussate in the _____ _____ and form the ______ ______. 3° fibers originate in the _______ (VPL nuclei), ascend through the internal capsule, and synapse in the primary somatosensory cortex of the ________ _______.

  • card layout to collectively remember important points
A
  • gracilis
  • cuneatus
  • caudal medulla
  • medial lemniscus
  • thalamus
  • postcentral gyrus
  • # ° = neurons in the pathway; after each synapse, the number increases. Thus there are 3 neurons and 2 synapses in the PCML.
  • decussate = cross the midline
25
Q

Injury of the PCML results in impaired ________ and _______ tactile functions. PCML damage is tested by having a patient identify ______ of movement drawn on their skin. If PCML damage is extensive, ______ results in uncoordinated movement.

A
  • proprioception
  • discriminative
  • patterns
  • ataxia
26
Q

TRUE or FALSE:

Damage of a single pathway in the PCML often leads to heavy loss of function.

A

FALSE. There are multiple alternate paths that can circumnavigate this.

27
Q

TRUE or FALSE:

If the PCML is injured, recovery is possible to some degree. However, interpretation of complex (fine) stimuli will likely remain impaired.

A

TRUE

28
Q

The pathway that conveys pain and temperature to the brain, having a final synapse in the VPL nuclei of the thalamus is the _________ pathway. Combined with other pain pathways, all of the pain paths are collectively know as the ________ pathway. Generally, this pathway has slower conduction velocity due to the use of unmyelinated ____ fibers.

A
  • spinothalamic
    • anterolateral
  • C
  • resides in ANTERIOR half of LATERAL funiculus (white matter of spinal cord)
29
Q

In the anterolateral pathway (ALP), 1° fibers immediately synapse in the ______ _______ of the dorsal horn. 2° fibers then decussate in the ______ ______ gray matter, and travel towards the ________ portion of the spinal cord where they begin their ascent to the ________ (VPL nuclei), where they synapse again. The 3° fibers travel to many regions of the _______.

A
  • substantia gelatinosa
  • spinal cord (anterior commissure)
  • anterolateral
  • thalamus
  • cerebrum (not just the somatosensory cortex)
30
Q

Organization laterally for caudal parts to medial for rostral parts is called ________ organization.

A

somatotopic

31
Q

TRUE or FALSE:

The ALP is diverse, going to many different regions of the brain.

A

TRUE

32
Q

Spinothalamic fibers start in laminae __ and __ and project to the VPL nuclei of the thalamus.

A
  • I

- V

33
Q

Polysnaptic projections project to the spinoreticular fibers in the _____ ______ of the brainstem. They modulate _____ to level of pain. Polysnaptic projections work in tandem with ______________ fibers from laminae I & V.

A
  • reticular formation
  • attention
  • spinomesencephalic
34
Q

The autonomic response to pain is mediated by __________ fibers.

A

spinohypothalamic

35
Q

Damage to the ALP causes loss of sensation to ____, ______, and _______ sensations.

A
  • pain
  • temperature
  • itch/tickle
36
Q

TRUE or FALSE:

Some tactile/pressure info is carried by the ALP, but an injury to the ALP will not affect tactile/pressure perception because most is sensed by the PCML.

A

TRUE

37
Q

TRUE or FALSE:

A unilateral injury to the ALP will alter bowel/bladder pressure or sexual sensations.

A

FALSE.

These sensations are bilateral, so a unilateral injury to the ALP will not harm their perception.

38
Q

Somatotopic organization stresses a point-for-point correspondence of the somatosensory cortex of the cerebrum with a given body part. The illustration of this is shown by the ______ _______.

A

sensory homunculus

39
Q

A procedure that intentionally destroys a portion of the lateral funiculus to cut off contralateral pain sensation through the ALP is called a _______.

A

cordotomy

40
Q

DIRECT information from the spinal cord to the cerebellum utilizes the ________ tracts.

A

spinocerebellar

41
Q

INDIRECT information from the spinal cord to the cerebellum utilizes ______ ______ nuclei.

A

brainstem relay

42
Q

Proprioceptive information is conveyed from the spinal cord to the cerebellum is done in the _____ ______ pathway. The first synapse is in _____’s nucleus. Fibers ascend ipsilaterally through the ______ ______, then enter the cerebellum at the ______ _______ peduncle. This pathway is responsible for ______ proprioception.

A
  • posterior spinocerebellar
  • Clarke’s
  • lateral fasciculus
  • inferior cerebellar
  • leg
43
Q

The spinocerebellar tract responsible for proprioception of the arm is the ___________ tract. This tract [does/does not] synapse at Clarke’s nucleus. Arm afferents ascend to the medulla in the ______ ______. Axons from the lateral cuneate nucleus of the medulla then enter the cerebellum via the _____ ______ peduncle.

A
  • cuneocerebellar
  • does not
  • fasciculus cuneatus
  • inferior cerebellar
44
Q

Information from the spinal cord to the cerebellum regarding the legs and COMPLEX coordinated movement is carried in the _______ ________ tract (differs from coarse posterior spinocerebellar). This tract crosses the midline ______, so it remains ipsilateral to its starting point.

A
  • anterior spinocerebellar

- twice

45
Q

TRUE or FALSE:

The anterior and posterior spinocerebellar tracts are directly anterior/posterior to the ALP tract in the caudal medulla.

A

TRUE

46
Q

TRUE or FALSE:

The spinocerebellar tracts are associated primarily with nociceptors.

A

FALSE. They’re associated with mechanoreceptors.

47
Q

The somatosensory cortex is located in the ______ ____ of the ______ lobe.

A
  • postcentral gyrus

- parietal

sp15 neuroanatomy - dr. pierson (10 decks)

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