Don’t forget Make sure you contact your personal tutor - even if only by , 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 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 The descending fibres cross in the medulla en route to the spinal cord This picture of an homunculus drawn over the surface of the cortex has been removed to avoid breaking copyright.

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

Tap tendon just below patella stretch muscle activate receptors extensor contractsextensor  mn Renshaw cellinhibitory interneurones flexor relaxesflexor  mn Monosynaptic Reflex

Simple withdrawal reflex

More fully…

Full crossed extensor reflex

Simple scheme Plan Execute Cortical association areas MovementIdea Premotor and motor cortex

Overview of control Plan Execute Basal ganglia Cortical association areas Lateral cerebellum intermediate cerebellum MovementIdea Premotor and motor cortex