Ascending tracts and sensation

Question 1

What does Meissner corpuscle detect?

Answer 1

Discriminative touch (rapidly adapting)

Question 2

What does Pacinian corpuscle detect?

Answer 2

Deep pressure & vibration; Mechanoreceptors (distortion). (Rapidly adapting)

Question 3

What do Ruffini endings detect?

Answer 3

Touch; Sheer stress/forces (slowly adapting)

Question 4

What do Merkel discs detect?

Answer 4

Light, sustained touch (slowly adapting)

Question 5

What do free nerve endings detect?

Answer 5

Pain (slowly adapting) & temperature (rapidly adapting)

Question 6

What do muscle spindles detect?

Answer 6

Muscle stretch receptor

Question 7

What does the primary somatosensory cortex do?

Answer 7

Receives contralateral sensory input from the body (including taste)

Question 8

What does the superior parietal lobe do?

Answer 8

Integration of sensory inputs, sensory memory, perception of contralateral self/world

Question 9

What do association fibres do?

Answer 9

Allow one area of cortex to communicate with another area of cortex on the same side of hemisphere

Question 10

What do commissural fibres do?

Answer 10

Allow communication between different hemispheres eg. corpus callosum

Question 11

What do projection fibres do?

Answer 11

Allow communication between brainstem and spinal cord

Question 12

In Dorsal column, where do 1st order neurons travel to?

Answer 12

Nuclei in the lower medulla

Question 13

In dorsal column, where do 2nd order neurons travel from and to?

Answer 13

From nuclei in lower medulla to thalamus

Question 14

What tract do 2nd order neurons ascend via?

Answer 14

A lemniscus

Question 15

Where do 3rd order neurons travel from and to?

Answer 15

From thalamus to primary sensory cortex

Question 16

What tract do 3rd order neurons ascend via?

Answer 16

Internal capsule

Question 17

Where does decussation occur?

Answer 17

In second order neurons

Question 18

What input does ventral posterior medial nucleus (VPM) receive?

Answer 18

Sensory input from face CN V

Question 19

What input does ventral posterior lateral nucleus (VPL) receive?

Answer 19

Sensory input from body

Question 20

What type of sensation does dorsal column pathway carry?

Answer 20

Discriminative touch & vibration; conscious proprioception

Question 21

What type of sensation does spinothalamic tract carry?

Answer 21

Pain & temperature; simple touch

Question 22

What type of sensation does spinocerebellar tract carry?

Answer 22

Unconscious proprioception

Question 23

What are the two fasciculi found in dorsal column pathway?

Answer 23

Fasciculus gracilis and fasciculus cuneatus

Question 24

What sensation and from where does fasciculus gracilis carry?

Answer 24

Discriminative touch & vibration; conscious proprioception from legs (below T6)

Question 25

What sensation and from where does fasciculus cuneatus carry?

Answer 25

Discriminative touch & vibration; conscious proprioception from arms (above T6)

Question 26

What are second order neurons of the dorsal column pathway from the body collectively called?

Answer 26

Medial lemniscus

Question 27

What does the fasciculus gracilis synapse onto?

Answer 27

Nucleus gracilis in the lower medulla

Question 28

What does the fasciculus cuneatus synapse onto?

Answer 28

Nucleus cuneatus in the lower medulla

Question 29

What are second order neurons of the dorsal column pathway from the face collectively called?

Answer 29

Trigeminal lemniscus

Question 30

What are the first order neurons in the dorsal column face pathway and where do they synapse?

Answer 30

Trigeminal sensory nerves enter pons and synapse in CN V nucleus

Question 31

Where do second order neurons of the dorsal column face pathway ascend to?

Answer 31

Ventral posterior medial nucleus (VPM) of the thalamus

Question 32

If the dorsal column in spinal cord is damaged? What will be lost and will it be ipsilateral or contralateral?

Answer 32

Loss of discriminative touch, vibration and conscious proprioception​ BELOW the level of the lesion​. Ipsilateral.

Question 33

How is the decussation of 2nd order neurons different between the dorsal column pathway and the spinothalamic tract?

Answer 33

In dorsal column pathway, 2nd order neurons decussate in the medulla. In STT, 2nd order neurons decussate across the anterior white commissure, 1-2 levels above it's 1st order neuron entry into the spinal cord.

Question 34

Along which tract do 1st order neurons travel along in the spinothalamic tract?

Answer 34

Tract of Lissauer

Question 35

What does the trigeminal lemniscus do?

Answer 35

Carries pain, temperature & simple touch (in STT) and discriminative touch, vibration & conscious proprioception (in dorsal column pathway) to the VPM nucleus of the thalamus

Question 36

In the brainstem, the Anterior (ASTT) and Lateral (LSTT) spinothalamic tracts merge & are collectively knowns as?

Answer 36

Spinal lemniscus

Question 37

What is syringomyelia and what does it damage?

Answer 37

Cavitation/expansion of central canal in cervical region. Damages only decussating neurons of the STT but not the spinothalamic tract itself Pain, temp and simple touch lost in shaded areas

Question 38

What tracts can the spinocerebellar tract be divided into?

Answer 38

Dorsal (Muscle spindles) and Ventral (Golgi tendon reflexes) Tracts

Question 39

What sensation is carried in dorsal spinocerebellar tract (DSCT)?

Answer 39

Muscle spindles - monitors muscle length, speed of contraction and tension

Question 40

Where does decussation happen in dorsal spinocerebellar tract (DSCT)?

Answer 40

No decussation. Uncrossed, ipsilateral 2-neuron pathway

Question 41

What do the 1st order neurons of lower limb synapse onto in the Dorsal Spinocerebellar Tract (DSCT)?

Answer 41

Clarke's Dorsal Nucleus

Question 42

What vertebral levels have Clarke's Dorsal Nucleus?

Answer 42

C8 - L3

Question 43

What is affected in Freidrich's ataxia?

Answer 43

Clarke's Dorsal Nucleus. Difficulty walking, loss of sensation in arms and legs and impaired speech that worsens over time

Question 44

Where do the 1st order neurons of the upper limb synapse onto in the Dorsal Spinocerebellar Tract (DSCT)?

Answer 44

In the pons

Question 45

Where does the Dorsal Spinocerebellar Tract (DSCT) travel to?

Answer 45

Cerebellum

Question 46

What tract do the 2nd order neurons of the Dorsal Spinocerebellar Tract (DSCT) travel along?

Answer 46

Cuneocerebellar tract

Question 47

Will a cerebellar lesion result in ipsilateral or contralateral symptoms?

Answer 47

Ipsilateral

Question 48

What tract carries upper limb sensation in the Ventral Spinocerebellar Tract (VSCT)?

Answer 48

Rostral Spinocerebellar tract

Question 49

Where does decussation occur in upper limb tract of VSCT?

Answer 49

No decussation

Question 50

Where does decussation occur in lower limb of VSCT?

Answer 50

2nd order neuron crosses in the spinal cord and then recrosses in the cerebellum

Question 51

What happens when there is damage to the spinocerebellar tract?

Answer 51

Damage to the spinocerebellar tract is rarely seen in isolation. Symptoms normally masked by other motor weakness/paralysis​ ​Pure lesions could cause: ​ - Ataxia / malcoordination of motor action​ - Wide-based gait

Question 52

What can cause dorsal column damage?

Answer 52

``` B12 deficiency Infarction Infection Compression of cord Tertiary Syphilis ```

Question 53

What are the signs/symptoms of dorsal column damage?

Answer 53

Pseudoathetosis – writhing of digits, hands and feet | Sensory ataxia – leads to positive Romberg sign & stamping gait

Question 54

How can a ventral grey matter tumour affect the STT neurons?

Answer 54

Knock out the contralateral, pain/temp but can be SACRAL sparing - due to its somatotopic organisation