Sensory Pathways

0.0(0)
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/13

encourage image

There's no tags or description

Looks like no tags are added yet.

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

14 Terms

1
New cards

Sensory Pathways

  • Somatosensory

  • auditory

  • visual

2
New cards

Somatosensory pathways

  • carry sensory info to cerebral cortex

  • dorsal column pathway

  • spinothalamic tract

3
New cards

3-neuron chain pathways

First-order neurons

Second-order neurons

Third-order neurons

<p>First-order neurons </p><p>Second-order neurons </p><p>Third-order neurons</p>
4
New cards

First-order neurons

  • Start as peripheral nerve & enter spinal cord

  • Cell bodies in dorsal root ganglia

5
New cards

Second-order neurons

  • Axons cross midline before ascending to thalamus

  • Cell bodies in grey matter of brainstem/spinal cord

6
New cards

Third-order neurons

  • Start in thalamus

  • Via internal capsule

  • To primary somatosensory cortex

7
New cards

Dorsal column pathway

  • somatosensory pathway

  • Function: mechanoreception: localised touch and pressure, vibration, proprioception

  • 2nd order neuron - cross together at medulla in sensory decussation

<ul><li><p>somatosensory pathway</p></li><li><p>Function: mechanoreception: localised touch and pressure, vibration, proprioception</p></li><li><p>2nd order neuron - cross together at medulla in sensory decussation</p></li></ul><p></p>
8
New cards

Spinothalamic pathway

  • somatosensory pathway

  • Function: nociception (pain) and thermorecepetion (temp)

  • 2nd order neuron - cross immediately at different levels of the spinal cord

<ul><li><p>somatosensory pathway </p></li><li><p>Function: nociception (pain) and thermorecepetion (temp)</p></li><li><p>2nd order neuron - cross immediately at different levels of the spinal cord</p></li></ul><p></p>
9
New cards

Auditory sensory pathways

  • Auditory information travels from inner ear to brainstem via CN VIII

  • In brainstem:

  • 1 st relay

    • Cochlear nuclei

  • 2 nd relay

    • Superior Olivary Complex

  • 3 rd relay

    • Inferior colliculus

<ul><li><p>Auditory information travels from inner ear to brainstem via CN VIII</p></li><li><p>In brainstem:</p></li><li><p>1 st relay</p><ul><li><p>Cochlear nuclei</p></li></ul></li><li><p>2 nd relay</p><ul><li><p>Superior Olivary Complex</p></li></ul></li><li><p>3 rd relay</p><ul><li><p>Inferior colliculus</p><p></p><p></p></li></ul></li></ul><p></p>
10
New cards

Auditory sensory pathways cont.

  • From brainstem to medial geniculate body in thalamus

  • From thalamus to primary auditory cortex (Heschl’s gyrus)

    • Message recognised, memorised & integrated into voluntary response

  • has bilateral innervation - therefore lesions in central auditory pathway in 1 hemisphere won’t result in unilateral deafness

<ul><li><p>From brainstem to medial geniculate body in thalamus</p></li><li><p>From thalamus to primary auditory cortex (Heschl’s gyrus)</p><ul><li><p>Message recognised, memorised &amp; integrated into voluntary response</p><p></p></li></ul></li><li><p>has bilateral innervation - therefore lesions in central auditory pathway in 1 hemisphere won’t result in unilateral deafness</p></li></ul><p></p>
11
New cards

Visual Sensory Pathways

  • Retina has point-to-point representation of visual fields

  • Axons of retinal ganglion cells leave eye as optic nerve

  • Optic nerves unite in optic chiasm

  • After chiasm optic tracts go to thalamus

  • Project to primary visual cortex via optic radiations

<ul><li><p>Retina has point-to-point representation of visual fields </p></li><li><p>Axons of retinal ganglion cells leave eye as optic nerve</p></li><li><p>Optic nerves unite in optic chiasm</p></li><li><p>After chiasm optic tracts go to thalamus</p></li><li><p>Project to primary visual cortex via optic radiations</p></li></ul><p></p>
12
New cards

Visual pathways are crossed

  • R visual field processed in L occipital lobe

  • R half of visual field projects to L half of each retina

  • Axons from left half of each retina project to L hemisphere

  • Nerve fibres from inner half of retina cross midline to enter opposite tract at optic chiasm

<ul><li><p>R visual field processed in L occipital lobe </p></li><li><p>R half of visual field projects to L half of each retina </p></li><li><p>Axons from left half of each retina project to L hemisphere </p></li><li><p>Nerve fibres from inner half of retina cross midline to enter opposite tract at optic chiasm</p></li></ul><p></p>
13
New cards

Path of R visual field info

  • R visual field: area R to own midline when looking ahead

  • light from R visual field strikes L half of each retina

  • L of L retina: temporal projection to ipsilateral V1

  • L of R retina: nasal projection crosses midline at chiasm to contralateral V1

<ul><li><p>R visual field: area R to own midline when looking ahead </p></li><li><p>light from R visual field strikes L half of each retina </p></li><li><p>L of L retina: temporal projection to ipsilateral V1 </p></li><li><p>L of R retina: nasal projection crosses midline at chiasm to contralateral V1</p></li></ul><p></p>
14
New cards

Lesions in visual sensory pathways can result in

  1. Scotoma (small blind spot)

  2. Monocular blindness

  3. Bitemporal hemianopia (tunnel vision)

  4. Heteronymous left-sided field defect

  5. Left superior quadrantanopia (homonymous)

  6. Left hemianopia with macular sparing

<ol><li><p>Scotoma (small blind spot) </p></li><li><p>Monocular blindness </p></li><li><p>Bitemporal hemianopia (tunnel vision) </p></li><li><p>Heteronymous left-sided field defect </p></li><li><p>Left superior quadrantanopia (homonymous) </p></li><li><p>Left hemianopia with macular sparing</p></li></ol><p></p>

Explore top notes

Explore top flashcards