Lecture 9 The Spinal Cord and the Periphery Flashcards
Where does the axons of the sensory fibres enter in the spinal cord
Dorsal root into the dorsal horn
Where does the axons of the motor fibres exit the spinal cord
Ventral root from the ventral horn
What are the 3 columns of the white matter
Posterior
Lateral
Anterior
Ascending pathways are___
Sensory
Descending pathways are___
Motor
Name 3 important tracts
Corticospinal/Pyramidal Tract
Posterior/dorsal column
Lateral spinothalmic tracts
What is the purpose of Corticospinal/Pyramidal Tract
Carries motor impulses from motor cortex to skeletal muscle
What is the purpose of the posterior/dorsal column
carries touch, tactile localisation, vibration sense, proprioception
What is the purpose of the lateral spirothalmic tract
Pain and temperature
Where does the corticospinal/pyramidal tract pathway Strat from
Primary motor cortex (area 4)
Define Corticobulbar fibres
Cross before the medulla
Define corticospinal fibres
Cross at decussation of pyramids at medulla
How many neurons are between the peripheral receptor and the cortes of the posterior/dorsal column
3
Where does the 1st neuron of the posterior/dorsal column synapse
With cell body of 2nd neuron at lower part of medulla
Where does the 2nd order neuron of the posterior/dorsal column decussate
Medulla to become medial lemniscus and passes through the medulla, pons and midbrain to the thalamus
Where does the 3rd neuron in the posterior/dorsal column head through
Starts from thalamus and axons pass through IC and radiate to post central gyrus
What area does the posterior/dorsal column end up in, in the cortex
Area 1,2,3
Where does the first order neuron of the spinothalamic tract begin and end
Enters into grey matter and ends at the same level
What is the path of the second order neuron in the spinothalamic tract
Cross over to reach the lateral area and becomes the lateral spinothalimic tract
Where does the 2nd order neuron end in the spinothalamic
Thalamus
Where does the 3rd order neuron end in the spinothalamic tract
Begins at thalamus and ends at IC radiation to reach post-central gyrus
What is the purpose of the stretch reflex
Important in control of muscle tone and posture (e.g. buckling and almost falling)
What is the purpose of the flexor relfex
Prevent injury
Why is Inhibitory neuron activated
In stretch reflex joints are controlled by two opposing sets of muscles, extensors and flexors, which must work in synchrony. Thus, when a muscle spindle is stretched and the stretch reflex is activated, the opposing muscle group must be inhibited to prevent it from working against the resulting contraction of the homonymous muscle
