ANATOMY- the ascending tracts (teach me anatomy)

Question 1

what are the ascending tracts?

Answer 1

-they refer to the neural pathway which sensory information from the peripheral nerves is transmitted to the cerebral cortex

AKA somatosensory pathway

Question 2

what tracts can the ascending tracts be split into?

Answer 2

CONSCIOUS TRACT= comprised of the dorsal column- medial meniscal pathway (DCML) and the anterolateral system

UNCONSCIOUS TRACT= comprised of the spinocerebellar tracts

Question 3

what is the conscious tract of the ascending tract comprised of?

Answer 3

-dorsal column medial lemniscal pathway (DCML)

-anterolateral system

Question 4

what information does the dorsal column-medial lemniscal pathway (DCML) carry?

Answer 4

it carries sensory modalities of:
- fine touch (tactile sensation)
-vibrations
-proprioception

Question 5

what major structures in the spinal cord and brainstem allow information to be transmitted in the DCML pathway?

Answer 5

-in the spinal cord, information travels via the dorsal (posterior) columns

-in the brainstem, information is transmitted through the medial lemniscus

Question 6

what groups of neurones are involved in the DCML pathway?

Answer 6

first, second and third order neurones

Question 7

what is the role of the first order neurones in the DCML?

Answer 7

-first order neurones carry sensory information regarding touch, proprioception or vibration from the peripheral nerves to the medulla oblangata

they have 2 different pathways they may take:

• signals from the upper limb (T6 and above) travel in the fasciculus cuneatus (the lateral of the dorsal column) and then synapse in the nucleus cutaneatus of the medulla oblangata
• signals from the lower limb (below T6) travel in the medial part of the dorsal column. They then synapse in the nucleus gracilis of the medulla oblangata

Question 8

what are the 2 pathways the first order neurones may take once they carry the transmissions to the medulla oblangata

Answer 8

Signals from the upper limb (T6 and above)- travel in the fasciculus cuneatus (the lateral part of the dorsal column). They then synapse in the nucleus cunatus of the medulla oblangata

Signals from the lower limb (below T6)- travel in fasciculus gracilis (the medial part of the dorsal column). They then synapse in the nucleus gracilis of the medulla oblangata

Question 9

what two tracts does the anterolateral system comprise of?

Answer 9

-anterior spinothalamic tract
-lateral spinothlamic tract

Question 10

what sensory modalities does the anterior spinothalamic tract carry?

Answer 10

sensory modalities of crude touch (lightly stroking skin or wisps of hair) and pressure

Question 11

what sensory modalities does the lateral spinothalamic tract carry?

Answer 11

pain and temperature

sPinoThalamic= Pain + Temperature

Question 12

explain the spinothlamic tract

Answer 12

-peripheral sensory receptors sense pain, temperature, crude touch or pressure and this information is carried to the first order neurons
-first order neurons synapse at the substantia gelatinosa and info is passed to second order neurones
-2nd order neurons dessucate at the spinal cord and then form 2 distinct tracts (Anterior and lateral spinothalamic tracts)
-information regarding crude touch and pressure travels to the anterior spinothalamic tract
-information regarding pain and temperature travels though the lateral spinothalamic tract
-anterior + lateral spinothalamic tracts travel superiorly in the spinal cord and synapse at the thalamus (passing info onto third order neurones)
-third order neurons carry info from the thalamus (ventral posterolateral nucleus) through the internal capsule and terminate at the sensory cortex