Lecture 6 Flashcards
What are the three sensory tracts?
•Dorsal Columns-Medial Lemniscal Tract
•Spinothalamic (Anterolateral Tract)
•Spinocerebellar and Cuneocerebellar Tracts
What is the motor tract?
Corticospinal
What are the two pathways in the Dorsal Columns-Medial Lemniscal Tract?
•Gracile Tract
•Cuneate Tract
What does the Gracile Tract sense?
Discriminative touch and conscious proprioception for on the contralateral side for lower limbs
What does the Cuneate Tract sense?
Discriminative touch and conscious proprioception for on the contralateral side for upper limbs
What is the difference between the Gracile Tract and the Cuneate Tract?
Gracile tract senses lower limbs and the Cuneate tract senses upper limbs
How many neurons are in the Gracile Tract pathway?
Three
How many neurons are in the Cuneate Tract pathway?
Three
What pathway are the Gracile and Cuneate tracts both apart of?
The Dorsal Column-Medial Lemniscus pathway
Where do the Gracile and Cuneate tracts synapse?
At the medulla and the VPL nucleus of the thalamus
Do the gracile and cuneate tracts switch sides and if so where?
Yes they do when they synapse at the medulla
What is Conscious Proprioception?
The ability to sense the position of your body in space and to feel where your natural range of movement should take you
What are the steps in the Gracile pathway?
- Sensory information is sensed in lower limbs by the PNS and carried in the CNS by the Gracile Tract
- The Gracile Tract synapses at the medulla and switches sides
- Information is then carried up the Medial Lemniscus pathway to the VPL nucleus of the Thalamus
- It synapses at the thalamus and then information is carried to the corresponding section of the primary somatosensory cortex
What are the steps in the Cuneate pathway? (DCML)
- Sensory information is sensed in upper limbs by the PNS and carried in the CNS by the Cuneate Tract
- The Cuneate Tract synapses at the medulla and switches sides
- Information is then carried up the Medial Lemniscus pathway to the VPL nucleus of the Thalamus
- It synapses at the thalamus and then information is carried to the corresponding section of the primary somatosensory cortex
Where do the Gracile and Cuneate pathway synapse?
At the Medulla and the VPL nucleus of the thalamus
How many neurons are in the Gracile and Cuneate pathways?
Three neurons
Where do the Gracile and Cuneate pathways crossover?
At the first synapse at the medulla
What is the organization of neurons from the PNS in the Gracile and Cuneate tracts?
Neuron 1 - From PNS to Medulla
Neuron 2 - Medulla to VPL nucleus in the thalamus
Neuron 3 - VPL nucleus in the thalamus to corresponding area of primary somatosensory cortex
What side of the brain is something processed in the Dorsal Column-Medial Lemniscal Pathway sensed?
The contralateral side
What side of the brain is something processed in the Cuneate Pathway sensed?
The contralateral side
What side of the brain is something processed in the Gracile pathway sensed?
The contralateral side
Of the Gracile and Cuneate tract which one is more medial and which one is more lateral?
•Gracile is medial
•Cuneate is lateral
What would a lesion to any of the Dorsal Column-Medial Lemniscus pathways cause?
Contralateral inability to have conscious proprioception and discriminative touch
What would cause contralateral inability to have conscious proprioception and discriminative touch?
A lesion to any of the Dorsal Column-Medial Lemniscus pathway
What would a lesion to Cuneate pathways cause?
Contralateral inability to have conscious proprioception and discriminative touch in upper limbs
What would a lesion to Gracile pathways cause?
Contralateral inability to have conscious proprioception and discriminative touch in lower limbs
What would a lesion to the Spinothalamic-Anterolateral pathways cause?
Contralateral Analgesia
What would cause Contralateral Analgesia?
A lesion to the Spinothalamic-Anterolateral Pathway
What does the Spinothalamic-Anterolateral pathway sense?
Somatic Pain
How many neurons are in the Spinothalamic-Anterolateral pathway?
Three
What are the differences between the Spinothalamic and the Dorsal Column-Medial Lemniscal pathway?
The Dorsal Column-Medial Lemniscal synapses at the medulla while the Spinothalamic-Anterolateral synapses at the spinal cord.
The Dorsal Column-Medial Lemniscal switches sides at the Medulla while the Spinothalamic-Anterolateral switches sides as soon as it synapses and reaches the spinal cord.
What is the Pathway of the Spinothalamic-Anterolateral tract?
- Pain is sensed from the PNS and carried into the spinal cord
- It synapses in the spinal cord and switches sides onto the spinothalamic tract
- It is carried to the thalamus where it synapses at the VPL nucleus
- From the VPL nucleus it goes to the corresponding portion of the primary somatosensory cortex
Where does the Spinothalamic-Anterolateral tract synapse
It synapses when it reaches the spinal cord and the VPL nucleus of the thalamus
What is the order of neurons in the Spinothalamic-Anterolateral Tract
- PNS to spinal cord
- Spinal cord to VPL nucleus in thalamus
- VPL nucleus in the primary somatosensory cortex
Does the Spinothalamic-Anterolateral tract switch sides and if so where?
It switches sides when it synapses at the spinal cord
Which tracts switch sides?
So far the Dorsal Column-Medial Lemniscus pathway switches at the medulla. The Spinothalamic-Anterolateral pathway switches at the spinal cord