Nervous System - Spinal Cord Tracts & Brainstem Flashcards
What is the General Organization of Sensory Tracts? Does a Sensory Tract Ascend or Descend?
(From most peripheral to most central)
- First Order Neuron
- Second-Order Neuron
- Third Order Neuron
- Ascending (towards the brain)
What does the First Order Neuron do in a Sensory Tract? Where is it always located?
Function - Brings sensory information to the CNS (spinal cord) - Synapses with the 2nd Order Neuron Location - The Dorsal Root Ganglion (DRG)
What does the Second Order Neuron do?
- Relays information from the 1st Order Neuron to the 3rd Order Neuron
- Deccusates (crosses the midline) to the contralateral side
What does the Third Order Neuron do?
- Travels from the Thalamus to somatosensory (and other regions) of the Cortex
- Relays information to the Cortex from the 2nd Order Neuron
What is the exception to the 3 Neuron Rule?
- The Dorsal Spinocerebellar Tract
What is the Function of the Dorsal Column-Medial Lemniscus (DCML) Tract? is it ascending or descending?
- Conveys information about Discriminative Touch (except head region) and Conscious Proprioception (except TMJ)
- Ascending
How many Neurons does the Dorsal Column-Medial Lemniscus (DCML) tract go through?
- 3
Where is the 1st Order Neuron of the Dorsal Column-Medial Lemniscus (DCML) Tract located? What does it do?
Location
- Cell body within the Dorsal Root Ganglia
Function
- Brings information into the spinal cord via the Dorsal Horn
- Travels up the spinal cord to the 2nd Order Neuron in the Medulla
Where are the axons of the 1st order neuron of the Dorsal Column-Medial Lemniscus (DCML) Tract?
- Travel on the same side as the 1st order neuron entry point of the dorsal column
What is the difference between the information of the Upper Limb and Lower Limb regarding the Dorsal Column-Medial Lemniscus (DCML) Tract?
Upper Limb
- Travels within Fasciculus Cuneatus (more lateral)
Lower Limb
- Travels within the Gracile Fasciculus (more medial)
Where does the 1st Order Neuron synapse onto the 2nd Order Neuron in the Dorsal Column-Medial Lemniscus (DCML) tract?
- Nucleus Cuneatus of Medulla
- Gracile Nucleus of Medulla
Where does the Dorsal Column-Medial Lemniscus (DCML) tract go after the 1st Order Neuron synapses with the 2nd Order Neuron?
- Deccusates (crosses the midline), contralaterally to the point of entry
- Ascends through the brainstem as the Medial Lemniscus towards the Thalamus to the 3rd Order Neuron
Where does the 2nd Order Neuron in the Dorsal Column-Medial Lemniscus (DCML) Tract synapse with the 3rd Order Neuron?
- In the Thalamus
Where does the 3rd Order Neuron of the Dorsal Column-Medial Lemniscus (DCML) tract go? What does it do?
Pathway
- Projects from the Thalamus to the sensory area of the cerebral cortex
Function
- Relays information about Conscious Sensation
What is the Function of the Lateral Spinothalamic Tract? Is it sensory or motor? How many Neurons does it have?
Function - Conveys information about Pain and Temperature from all over the body (except the head region) Type - Sensory (ascending) # of Neurons - 3
Where is the 1st Order Neuron of the Lateral Spinothalamic Tract?
- Dorsal Root Ganglion (DRG)
Where does the 1st Order Neuron of the Lateral Spinothalamic Tract synapse with the 2nd Order Neuron?
- In the Dorsal Horn of the Spinal Cord
Describe the Pathway of the 2nd Order Neuron of the Lateral Spinothalamic Tract? (5)
- Synapsed by the 1st Order Neuron in the Dorsal Horn of the Spine
- Decussates (crosses midline) to the contralateral side
- Ascends through the lateral column of the spinal cord
- Axons of 2nd Order Neuron travel to the Thalamus
- Synapses with the 3rd Order Neuron at the Thalamus
Where does the 3rd Order Neuron of the Lateral Spinothalamic Tract project Sensory Information? What kind of information is it?
Location
- The sensory areas of the cortex
Information
- Pain and Temperature
What is the function of the Anterior Spinothalamic Tract? Is it Sensory or Motor? How many Neurons Does it have?
Function - Conveys Information about non-discriminative (crude) touch Type - Sensory # of Neurons - 3
Where is the 1st Order Neuron of the Anterior Spinothalamic Tract Located?
- The Dorsal Root Ganglion (DRG)
Where does the 1st Order Neuron of the Anterior Spinothalamic Tract synapse with the 2nd Order Neuron?
- Dorsal Horn of the Spinal Cord
Describe the Pathway of the 2nd Order Neuron of the Anterior Spinothalamic Tract (5)
- 1st Order Neuron synapses with it at the Dorsal Horn
- It Decussates to the contralateral side
- Travels up the Spinal Cord within the anterolateral column
- Axon of 2nd Order Neuron travel up to the Thalamus
- Synapses with the 3rd Order Neuron in the Thalamus
Where will the 3rd Order Neurons of the Anterior Spinothalamic Tract project information? What information does it send?
Location
- Sensory Area of the cortex
Type
- Non-Discriminative (crude) Touch
What is the Function of the Dorsal Spinocerebellar Tract? sensory or motor? How many Neurons?
Function
- Convey information about unconscious proprioception from joint and muscles of the lower limb and trunk
Type
- Sensory
Neurons
- 2 (exception to the 3 neuron rule of sensory tracts)
Where is the 1st Order Neuron of the Dorsal Spinocerebellar Tract?
- Dorsal Root Ganglion