1.6 Somatosensory Pathways

Question 1

What are the three types of sensory receptors?

Answer 1

Interoreceptors, exteroreceptors and proprioception

Question 2

Name the three ascending sensory pathways?

Answer 2

Anterolateral system, dorsal column and spinocerebellar

Question 3

What does the antero-lateral system relay?

Answer 3

Relays pain, temp, crude touch, pressure, and proprioception sensation

Question 4

Which tracts are part of the antero-lateral system?

Answer 4

Spinohypothalamic, spinoreticular, spinotectal, spinothalamic and spinomesencephalic

Question 5

What does the dorsal column relay?

Answer 5

Fine touch and conscious proprioception

Question 6

What are the dorsal columns called?

Answer 6

Fasciculus cuneatus and gracillis

Question 7

Which senses are ipsilateral and which tract do the ascend?

Answer 7

Fine touch and proprioception - dorsal column

Question 8

Which senses are contralateral and which tract do they ascend?

Answer 8

Pain, temp and crude touch - anterolateral spinothalamic tract

Question 9

What is found in the lateral horn of a thoracic spinal vertebrae

Answer 9

nerves to the muscles of the limb, sensory relay neurone and preganglionic cell bodies of the ANS

Question 10

Where do the fine touch nerves cross?

Answer 10

Cross over in the lower medulla - at dorsal column nuclei - then go through medial lemniscus

Question 11

What causes sensory ataxia?

Answer 11

Demyelination of diseases of the dorsal column - such as MS

Question 12

What is the gait like for someone suffering sensory ataxia?

Answer 12

Broad stamping action

Question 13

What is Rhomberg’s sign?

Answer 13

Stand with feet together, arms out and eyes closed - sway - can also be a vestibule problem

Question 14

What other symptoms are there?

Answer 14

Another symptoms is the loss at two point touch discrimination

Question 15

What determines whether fibers travel in cuneate or gracilis dorsal column?

Answer 15

Gracillis - below the waste - below T6

Cuneate - above the waste

Question 16

Where are the nuclei of the fasciculus gracilis and cuneate?

Answer 16

Lower medulla

Question 17

Where do third order sensory neurons arise from?

Answer 17

Thalamus

Question 18

What travels up the lateral spinothalamic tract? Is it contralateral or ipsilateral?

Answer 18

Pain and temperature - contralateral side

Question 19

Where do the second order neurons of the lateral spinothalamic tract arise?

Answer 19

Dorsal horn synapse - substantia gelatinosa

Question 20

Where do these decussate?

Answer 20

Anterior white commissure

Question 21

What travels up the anterior spinothalamic tract? Is it contralateral or ipsilateral?

Answer 21

Crude touch and pressure

Question 22

Explain the spinocerebellar pathway

Answer 22

Dorsal - ipsilateral - inferior peduncle

Ventral - contralateral - superior peduncle

Question 23

Where the first order peripheral sensory cell bodies of the face found?

Answer 23

Trigeminal ganglion

Question 24

Where do they decussate and synapse?

Answer 24

Synapse - principle nucleus of trigeminal - cross over at the pons

Question 25

Where are first order sensory cell bodies of the touch components of CN VII, IX & X situated and what is their pathway?

Answer 25

Their associated ganglion - main sensory nucleus of trigeminal - follow the trigeminothalamic pathway

Question 26

Where does fine touch from face go through?

Answer 26

Mesencephalic nucleus of trigeminal