Ascending Tracts

Question 1

Conscious ascending tracts

Answer 1

Dorsal column-medial lemniscal
Anterolateral system

Question 2

Unconscious ascending tracts

Answer 2

Spinocerebellar tracts

Question 3

Function of dorsal column-medial lemniscal pathway

Answer 3

Carries fine touch, vibration and proprioception

Question 4

2 different pathways of dorsal column-medial lemniscal pathway first order neurons

Answer 4

Signals from upper limb (T6 and above)
Signals from lower limb (below T6)

Question 5

dorsal column-medial lemniscal pathway signals from upper limb

Answer 5

Travel in fasciculus cuneatus (lateral part of dorsal column)
Synapse in nucleus cuneatus of medulla

Question 6

dorsal column-medial lemniscal pathway signals from lower limb

Answer 6

Travel in fasciculus gracilis (medial part of dorsal column)
Synapse in nucleus gracilis of medulla

Question 7

Where do the dorsal column-medial lemniscal pathway first order neurons synapse

Answer 7

Medulla

Question 8

Where is the Fasciculus gracilis

Answer 8

Medial part of dorsal column

Question 9

Where is the Fasciculus cuneatus

Answer 9

Lateral part of dorsal column

Question 10

Where do the second order neurones of the dorsal column-medial lemniscal pathway decussate

Answer 10

Medulla

Question 11

dorsal column-medial lemniscal pathway second order neurones

Answer 11

Begin in cuneate or gracilis nucleus
Decussate and travel in the contralateral medial lemniscus
Synapse at thalamus

Question 12

Where do the 2nd order neurons meet the 3rd order neurons of the dorsal column-medial lemniscal pathway

Answer 12

Thalamsu

Question 13

What do the 2nd order neurons of the dorsal column-medial lemniscal pathway travel to the thalamus in

Answer 13

Contralateral medial lemniscus

Question 14

dorsal column-medial lemniscal pathway third order neurons

Answer 14

transmit the sensory signals from the thalamus to the ipsilateral primary sensory cortex of the brain
ascend from the ventral posterolateral nucleus of the thalamus, travel through the internal capsule and terminate at the sensory cortex.

Question 15

Where do the third order neurons of the dorsal column-medial lemniscal pathway terminate

Answer 15

Sensory cortex

Question 16

Where does the third order neurons of the dorsal column-medial lemniscal pathway travel through

Answer 16

Ventral posterolateral nucleus of thalamus
Internal capsule
To sensory cortex

Question 17

2 parts of the Anterolateral system

Answer 17

Anterior Spinothalamic tract
Lateral Spinothalamic tract

Question 18

Function of anterior Spinothalamic tract

Answer 18

Crude touch and pressure

Question 19

Function of lateral Spinothalamic tract

Answer 19

Pain and temperature

Question 20

Anterolateral system first order neurons

Answer 20

arise from the sensory receptors in the periphery.
They enter the spinal cord, ascend 1-2 vertebral levels, and synapse at the tip of the dorsal horn – an area known as the substantia gelatinosa.

Question 21

Where do the Anterolateral pathway first order neurons synapse

Answer 21

Substantia gelatinosa (tip of dorsal horn)

Question 22

Where do the second order neurons of the Anterolateral tract decussate

Answer 22

Within spinal cord to form 2 tracts

Question 23

Where do the second order neurons of the Anterolateral system synapse

Answer 23

Thalamus

Question 24

Anterolateral system third order neurons

Answer 24

Thalamus to ipsilateral primary sensory cortex
Ascend from ventral posterolateral nucleus of thalamus, through internal capsule

Question 25

Function of posterior Spinocerebellar tract

Answer 25

Carries proprioceptive information form the lower limbs to ipsilateral cerebellum

Question 26

4 individual pathways of Spinocerebellar tract

Answer 26

Posterior Spinocerebellar tract Cuneocerebellar tract Anterior Spinocerebellar tract Rostral Spinocerebellar tract

Question 27

Function of Cuneocerebellar tract

Answer 27

Proprioceptive information from upper limbs to ipsilateral cerebellum

Question 28

Function of anterior Spinocerebellar tract

Answer 28

Proprioceptive information from lower limbs Decussate twice so terminate in ipsilateral cerebellum

Question 29

Function of rostral Spinocerebellar tract

Answer 29

proprioceptive information from the upper limbs to the ipsilateral cerebellum.

Question 30

Which 2 tracts carry proprioceptive information from upper limbs by the Spinocerebellar tracts

Answer 30

Cuneocerebellar tracts Rostral Spinocerebellar tracts

Question 31

Which 2 tracts carry proprioceptive information from lower limbs by Spinocerebellar tracts

Answer 31

Posterior Spinocerebellar tracts Anterior Spinocerebellar tracts

Question 32

Lesions of Spinocerebellar tracts

Answer 32

ipsilateral loss of muscle co-ordination. However, the spinocerebellar pathways are unlikely to be damaged in isolation – there is likely to be additional injury to the descending motor tracts. This will cause muscle weakness or paralysis, and usually masks the loss of muscle co-ordination.

Question 33

Lesion of DCML

Answer 33

loss of proprioception and fine touch. However, a small number of tactile fibres travel within the anterolateral system, and so the patient is still able to perform tasks requiring tactile information processing. If the lesion occurs in the spinal cord (which is most common), the sensory loss will be ipsilateral – decussation occurs in the medulla oblongata. DCML lesions can be seen in vitamin B12 deficiency and tabes dorsalis (a complication of syphilis).

Question 34

Lesions of Anterolateral system

Answer 34

impairment of pain and temperature sensation. In contrast to DCML lesions, this sensory loss will be contralateral (the spinothalamic tracts decussate within the spinal cord). Brown-Séquard syndrome refers to a hemisection (one sided lesion) of the spinal cord. This is most often due to traumatic injury, and involves both the anterolateral system and the DCML pathway: DCML pathway – ipsilateral loss of touch, vibration and proprioception. Anterolateral system – contralateral loss of pain and temperature sensation. It will also involve the descending motor tracts, causing an ipsilateral hemiparesis.

Question 35

Brown - Séquard syndrome

Answer 35

hemisection (one sided lesion) of the spinal cord. This is most often due to traumatic injury, and involves both the anterolateral system and the DCML pathway: DCML pathway – ipsilateral loss of touch, vibration and proprioception. Anterolateral system – contralateral loss of pain and temperature sensation. It will also involve the descending motor tracts, causing an ipsilateral hemiparesis.

Question 36

Sensory modalities

Answer 36

Nociceptors Mechanoreceptors Thermoreceptors

Question 37

Nociceptors

Answer 37

receptors which respond to noxious stimuli (stimuli would result in tissue injury if it were to persist) • activation results in sensation of pain • Receptors are free nerve endings on ends of type A-delta fibres and C fibres • Can be categorised into mechanical, thermal, chemical or Polymodal

Question 38

Mechanoreceptors

Answer 38

respond to deformation by means of pressure, touch, vibration or stretch • located in joint capsules, ligaments, tendons, muscle and skin

Question 39

Types of Mechanoreceptors

Answer 39

Merkel’s disc Meissner’s corpuscles Pacinian corpuscles Ruffini corpuscles Muscle spindles and Golgi tendon organs

Question 40

Merkel’s disc

Answer 40

tonic receptors in skin that respond to pressure. Key role in differentiating textures

Question 41

Meissner’s corpuscles

Answer 41

phasic receptors in skin, namely in palms of hands, soles of feet, lips and tongue. Detect initial contact or slipping of contact

Question 42

Pacinian corpuscles

Answer 42

phasic receptors in dermis, hypodermis, ligaments and external genitalia. Respond to high-frequency vibrations

Question 43

Ruffini corpuscles

Answer 43

tonic receptors in dermis, ligaments and tendons. Respond to stretch and signal position and movement of fingers

Question 44

Muscle spindles and Golgi tendon organs

Answer 44

found in skeletal muscle and detect stretch as well as involved in proprioception. Transmitted by dorsal column-medial lemniscus pathway

Question 45

Thermoreceptors

Answer 45

respond to changes in temperature • found in skin, liver, skeletal muscle and hypothalamus • Warm temperatures = C fibres • Cold temperatures = C and A-delta fibres • Transmitted via lateral Spinothalamic tract

Question 46

Type of fibres that transmit warm temperatures

Answer 46

C fibres

Question 47

Type of fibres that transmit cold temperatures

Answer 47

C fibres and A-delta fibres

Question 48

Spinothalamic tract conveys Nociceptive information to….thalamus

Answer 48

Contralateral

Question 49

Where in the spinal cord is the spinothalamic tract found

Answer 49

Anterolateral white matter

Question 50

A 78-year-old lady presents to her GP surgery with an intensely itchy vesicular rash in two separate horizontal lines at the level of the nipple and umbilicus respectively. Which dermatomal distribution is this affecting?

Answer 50

T4 and T10