Neurology 2 Flashcards
What is meant by mechanosensory circuity?
Relating to the sensing or function of mechanical stimuli.
Mechanical stimuli are resulting from physical movements within the receptor, includes tough, vibration, sound, pressure (pain) and body movements.
Give a basic description of the DCML pathway for touch.
Touch is detected by mechanoreceptors, sensory neurons within their cell bodies in the DRG.
In a reflex arc the axon synapses with a relay neurone within the vertebrae.
In other conditions, the axon extends up the spinal cord in the dorsal columns and synapses on the dorsal column nuclei in the medulla.
A secondary neuron axon then projects to the thalamocortical nuerons
A tertiary neuron axon then extends to the primary sensory cortex.
Give a detailed description of the DCML pathway for touch.
An action potential is generated in a mechonreceptor, this is propagated along a primary sensory neurone (DRG cell body), this may then synapse with a relay neurone to form a relfex arc. Alternativly the primary nerve axon continues up the dorsal column to synapse in the dorsal column nuclei in the medulla. The secondary nerve axon travels across in medial leminiscus and continues up to synapse in the contralateral side of the body in the thalamocortical nuclei.
This tertiary neurone continues to synapse in the primary samatosensory cortex
What structures make up the dorsal column?
What are their different functions?
The fasiculus cuneatous laterally - carriers sensory information for the upper limbs
The fasiculus gracilis medially - carriers sensory information for the lower limbs
What is conscious proprioception?
The minds ability to sense where the body is located in space and hypothesise where your movements will take you
How is sensory information from proprioceptors communicated to the brain?
Proprioceptors in intrafusal muscle fibres and the golgi tendon organs are stimulated.
The action potential travels up the primary sensory neurone (DRG cell body), this may then synapse with a relay neurone to form a relfex arc. Alternativly the primary nerve axon continues up the dorsal column to synapse in the dorsal column nuclei in the medulla. The secondary nerve axon travels across in medial leminiscus and continues up to synapse in the contralateral side of the body in the thalamocortical nuclei.
This tertiary neurone continues to synapse in the primary samatosensory cortex
What is the difference between a faniculi and a fasiculus?
A faniculi is a common area of white matter, that contains a large number of axons.
A fasiculus is a specific bundle of axons within a faniculi that have a common destination or functional properties
What is important to remember when looking at images of the CNS?
White matter appears darker
Grey matter appears lighter
What is the dorsal column also known as?
The dorsal white faniculus.
Where is the dorsal column located?
What is the green label?
The central canal
What are the orange labels?
The dorsal grey horn
The ventral grey horn
What is the purple label?
Intermediate zone of grey matter
What is the black label?
Lateral white funiculus
Ventral white funiculus
What is the red label?
Dorsolateral tract of Lissauer
What is the black label?
Note structures are bilateral
The lateral corticospinal tract
What is the orange label?
Note structures are bilateral
The anterior corticospinal tract
What is the purple structure?
The dorsal column
Lateral is cuneate fasiculus
Medial is Gracile fasiculus
What is meant by M1 and S1 being a topographic map?
The density of neurons in the region correlates to the level of neuronal control over that region of the body, that the neurons travel to
What is somatosensation?
General sensation: touch, pain and proprioception.
The primary somatosensory cortex recieves afferent fibres or incoming information.
What are the different dorsal column nuclei?
The gracilis nucleus (medially)
The cuneate nucleus (laterally)
Note are bilateral structures
In the DCML pathway what is the region of the medulla where the axons cross to the contralateral region of the brain called?
Termed internal arcuate fibres
What structure allows the passage of fibres between the cerebral cortex and the brainstem?
The cerebral peduncles
