Spinal Cord and Periphery Flashcards
Where is grey matter found in the spinal cord?
Centre
Where is white matter found in the spinal cord?
Around the periphery
What composes white matter?
Myelinated axons
What are the 2 horns contained in the grey matter?
Dorsal
Ventral
Where do the axons of sensory fibres enter?
Through the dorsal route into the dorsal horn of the grey matter
Where do sensory fibres synapse?
Dorsal ganglia
Where is dorsal ganglia located?
Just outside the dorsal horn
Where do motor neurons have their cell bodies?
In the ventral horn
Where do motor neurons exit the spinal cord?
Through the ventral route
What is the central canal?
Hole in the centre of the spinal cord
What is located in the central canal?
CSF
What do ascending pathways carry?
Sensory information towards the brain
What do descending pathways carry?
Motor information away from the brain
What 3 columns are tracts arranged as?
Posterior, lateral and anterior
How many neurons are there between the peripheral receptor and cortex in ascending pathways?
3
What are the 3 neurons in ascending pathways?
1st
2nd
3rd order neuron
What do 1st neurons carry in AP?
Sensory information regarding touch, proprioception or vibration from peripheral nerves to the spinal cord or brainstem
Where do ascending pathways first synapse?
Either at the level of the spinal cord
Or at the medulla
Where do 1st order neuron cell bodies bode in AP?
In dorsal root ganglion
What happens to neurons in ascending pathways at the medulla in AP ?
Decussate to travel in the contralateral side
Where do 2nd and 3rd neurons synapse in AP?
At the thalamus
Where do 3rd order neurons finally end in AP?
At the contralateral parietal cortex
What is the function of 3rd order neurons in AP?
Transmit sensory signals from the thalamus to the contralateral primary sensory cortex of the brain
Where is the sensory cortex found?
Post central gyrus in the parietal lobe
What do lateral spinothalmic tracts detect?
Pain and temperature
What do anterior spinthalmic tracts detect?
Light touch and pressure
What do dorsal column tracts detect?
Deep touch and pressure
From the opposite side of the body
Where does the posterior spinothalmic tract decussate?
At the level of the medullae
What is the function of lateral spinothalmic tracts?
Carries information about pain and temperature to the contralateral side
Where does the lateral spinothalmic tract decussate?
At the level of the spinal cord
Where do motor tracts of the spinal cord originate?
In the cerebral cortex and brainstem
How many neurons are in descending pathways?
2
Where do descending pathways decussate?
In the brainstem
Pyramidal of the medulla
Where do 1st order neurons in DP originate?
Primary motor cortex
Does all sensory information need to be sent to the brain to make decisions?
No
What is a reflex?
An involuntary stereotypes pattern of response brought about by a sensory stimulus
Where are many reflexes mediated?
At the level of the spinal cord
What are the sequence of events in the knee jerk?
1.) Tendon is stretches
2.) Muscle fibres are stimulatesd
3.) Sensory neuron is activated
4.) Monosynaptic reflex arc (not going anywhere up the tracts to the cerebral hemispheres)
5.) Polysynaptic reflex arc to inhibitory interneuron
6.) Reciprocal innervation
7.) Muscle contraction
Flexion of the hit muscle
Extension of the contralateral muscle
Is UMN or LMN involved with reflexes?
LMN
If there is a UMN lesion are reflexes damaged?
No because UMN is not involved in them
What happens to reflexes if there is a UMN lesion?
They become exaggerated
What are the 2 divisions of the PNS?
Somatic motor
Autonomic motor
What are the 3 types of muscle in the body?
Smooth
Cardiac
Skeletal
