Lecture: Ascending Sensory Pathways I

Question 1

What is the Spinothalamic pathway responsible for?

Answer 1

Pain
Temperature
some touch

Question 2

What is the dorsal column pathway responsible for?

Answer 2

Touch
Vibration
joint position (proprioception)
discriminative touch

Question 3

Describe the type of fibres in the spinothalamic pathway

Answer 3

Thin
Poorly myelinated or unmyelinated
conduction slow

Question 4

Describe the type of fibres in the dorsal column pathway

Answer 4

large diameter
heavily myelinated
fast conduction

Question 5

Are the dorsal column pathway and spinothalamic pathway ipsilateral, or contralateral?

Answer 5

Dorsal Column - Ipsilateral, then crosses at closed medulla

Spinothalamic - contralateral, crosses at point of entry

Question 6

To which part of the thalamus does the information carried in these pathways project?

Answer 6

Ventroposterolateral thalamus

Question 7

Where does the primary neuron synapse?

Answer 7

With the secondary neuron in the dorsal grey horn on the same side that it enters.
Just at different levels depending on STT or DCP

Question 8

To which part of the thalamus do sensory fibres from the face ascend?

Answer 8

Ventroposteromedial

Question 9

Describe briefly how the post-central gyrus is somatotopically mapped

Answer 9

From lateral to medial:

Pharynx-tongue-mouth-face (ascending)-thumb-hand-along arm-trunk-down body-legs-toes-genitals

Question 10

What is the spinothalamic pathway renamed as it enters the medulla?

Answer 10

The Spinal Lemniscus

Question 11

How are the dorsal column pathways organised?

Answer 11

Into two pathways, the Gracile Fasciculus and the Cuneate Fasciculus
Terminate at the Gracile and Cuneate Tubercles respectively

Question 12

Describe the Gracile Fasciculus

Answer 12

More medial to midline
runs whole length of the spinal cord
receives information from lower limbs and trunk

Question 13

Describe the Cuneate Fascicle

Answer 13

More lateral
exist above T6 only
receives info from the arms

Question 14

Where do the primary neurons of the Dorsal Column Pathway synapse?

Answer 14

In the gracile/cuneate nuclei, located in the tubercles on the dorsal brainstem

Question 15

Describe the course of the secondary neurons in the DCP

Answer 15

Cross at the closed medulla
Referred to as Internal Arcuate Fibres
Pass to the Medial Lemniscus where they ascend to VPL thalamus

Question 16

is the medial lemniscus somatotopically mapped?

Answer 16

Yes, divisions for Arm, Trunk and Leg

Question 17

How do fibres travel from the thalamus to the Post central gyrus?

Answer 17

Via the Internal Capsule