Transcript Nervous circuits - University of Liverpool

Don’t forget
Make sure you contact your personal
tutor - even if only by email, before
you go home for Christmas – and again
to meet them when you come back in
the New Year
Complete your PPD things on LUSID
Nervous Circuits
Reverend Dr David C.M. Taylor
School of Medical Education
[email protected]
www.liv.ac.uk/~dcmt
http://www.liv.ac.uk/~dcmt/local_html/neuro/
All images in this slideshow are © University of Liverpool, and David Taylor, 2006
Our objectives in this plenary
To use our understanding of the case to
Be able to distinguish between upper and
lower motor neuron lesions
To gain an understanding of the spinal
reflexes
To start to understand the control of
movement
Mrs Webster
Experienced weakness in her left arm
and face
In principle the problem could lie in the
periphery (spinal motor neurones etc.,)
Or it could lie centrally (with the motor
neurones or pathways that control the
spinal motor neurones)
So?
We need to distinguish between upper
and lower motor neurones.
Upper motor neurones are in the motor
cortex
Lower motor neurones are in the spinal
cord - think about the knee jerk reflex
Upper motor neurones
This picture of an homunculus
drawn over the surface of the
cortex has been removed
to avoid breaking copyright.
The descending fibres cross in the medulla en
route to the spinal cord
Pathway
This picture of the descending
motor pathways has been
removed to avoid breaching
copyright
Knee jerk reflex
stretch receptor
in muscle
contraction
of muscle
spinal motor
neurone
Monosynaptic Reflex
Tap tendon just below patella
stretch muscle
extensor contracts
activate receptors
extensor a mn
Renshaw cell
flexor relaxes
flexor a mn
inhibitory
interneurones
Simple withdrawal reflex
More fully…
Full crossed extensor reflex
Simple scheme
Plan
Idea
Cortical
association
areas
Execute
Premotor and
motor cortex
Movement
Overview of control
Plan
Execute
Basal ganglia
Idea
Cortical
association
areas
Lateral
cerebellum
Premotor and
motor cortex
Movement
intermediate
cerebellum