Neuroscience 3-1 Ascending Pathways Overview Amanda C. Conta Steencken Flashcards
Name the four somatosensory circuits.
- Dorsal Column-Medial Leminiscal System
- Anterolateral (spinothalamic) System
- Spinocerebellar system
- Trigeminal system
Anterolateral system carries what kind of information?
Protopathic sense from trunk and limbs
Dorsal Column-Medial Lemniscal System carries what kind of information?
Epicritic sense from trunk and limbs
What does protopathic mean?
Pain and temperature, and crude touch, nocioception
What does epicritic mean?
Mechanosensation
What does mechanosensation include?
Vibration, position, 2-point discrimination, simple touch
Where can you find the gracile and cuneate nuclei?
Medulla
Where do fibers from the dorsal column-medial lemniscal system decussate?
At the level of the medulla
What’s the pathway for vibration/light touch?
Skin –> DRG –> posterior (dorsal) columns –> primary sensory neuron –> sensory decussation in internal arcuate fibers –> Posterior (dorsal) column nuclei (cuneate/gracile) –> secondary sensory neuron (medial lemniscus) –> thalamus (ventral posterior lateral nucleus)
Where do mechanoreceptors from the lower body synapse?
The gracile nucleus in the caudal medulla
Where do mechanoreceptors from the upper body synapse?
The cuneate nucleus in the caudal medulla
Where do the mechanoreceptor neurons decussate?
In the caudal medulla, in the internal arcuate fibers, AFTER entering their respective dorsal column nuclei
Where do the anterolateral neurons decussate?
At the level of the spinal cord
What do anterolateral and dorsal column medial lemniscal systems have in common?
They both project from the thalamus to the primary somatosensory cortex.
What are the three things we are to associate with the spinocerebellar tract?
Ipsilateral
Proprioception
Cerebellum
What information does the trigeminal system carry?
All sensory information from the head and neck:
- -epicritic
- -protopathic
- -proprioceptive
The thalamus surrounds what ventricle?
3rd
Name this structure: relay center of the brain, conveying sensory and motor information to/from the cerebral cortex.
Thalamus
Sensory circuits are also known as __1__ circuits, while, motor circuits are also known as __2__ circuits.
- Ascending
2. Descending
Why are the descending tracts called the pyramidal system? Is this direct or indirect motor system?
Because the motor axons pass through the medullary pyramids, this is an example of direct cortical motor control