Medwiki

L14 Nervous System Motor Systems 1 _ 2

L15 Nervous System Motor Systems 3 _ 4

Lecture 1 is Lower motor neurons Lecture 2 is Upper motor neurons Lecture 3 is Basal Ganglia Lecture 4 is Cerebellum

Total objectives

  1. Understand that a lower motor neuron is an α motor neuron

  2. Understand the effects of LMN disorders on muscle tone, stretch reflex and muscle bulk

  3. Be aware of spinal cord functions, including:

    1. Spinal reflexes
    2. Role of spinal cord in processing voluntary motor commands

  4. Define the physiological/anatomical basis of the clinical concept of upper motor neuron

  5. List the main brainstem structures incolced in motor control and the pathways by which they ingluence the spinal cord and summarise their roles

  6. Outline the main features of motor cortical organisation icluding the roles of primary and secondary motor areas

  7. Describe the main signs of upper motor neuron damage and contrast these with LMN signs

  8. Identify major components of basal ganglia and the main circuit through the basal ganglia

  9. Describe the likely functions of the basal ganglia circuits

  10. Summarise the signs pathology and main treatment modes of parkinsons and huntingtons diseases

  11. identify major parts of cerebellum and the mahot circuit nomponents of the cerebellar cortex

  12. describe in general terms the likely functions of the cerebellum

  13. Summarise the main signs seen with cerebellar damage

These lectures broadly talks about motor systems.

It talks about the division of upper and lower motor neurons and the specific clinical consequences of each pathway.

there is the motor cortex

and the muscle

the motor cortex sends the signalling to the inter neuron netwoeks in the spinal cord and brainstem where the alpha neurons relay this to the muscle

the receptors in the muscle then lead back and synapse with the brain stem, thalamus, and interneuron networks in the spinal cord

the basal ganglia dont directly synapse with the muscle it instead talks back to the thalamus and the basal ganglia.

the thalamus is where all the signalling meets before heading to the motor cortex together

LMN lecture

  • understand that the α-motor neuron is the lower motor neuron
  • understand the effects of LMN disorders on muscel tone, stretch reflex and muscle bulk
  • Be aware of spinal cord functions including reflexes and role in processing voluntary motor commands

What i remember

The alpha motor neuron innervates normal muscle. within the muscle there are muscel spindles which are tensed seperately by gamma motor neurons. these maintain higher resting tension than the muscle surrounding it. There are sensory dendrite terminals which sense amount of stretch in the muscle which enable tendon (stretch) reflex.

conversely the tendon stretch neurons sense when the tendon is under too much tension and inhibits muscle firing

the spinal reflexes are generally under a degee of inhibition form the UMNs

LMN lesions means no spinal reflexes and muscle wasting along with general lack of muscle activation. examples:

  • motor neuron disease (amyotrophic lateral sclerosis)
  • polio
  • Guillain-Barré syndrome

really LMN lesions lead to loss of muscle activity and through that atrophy

UMN lesions leads to lack of voluntary force with spinal reflexes being disinhibites and spastic reflexes

UMN

Describes the spinal cord as a minibrain of interneuronal networks. this enables complex reflexes, rhythmic motor patterns, and

withdrawl reflex: ipsilateral side gets flexors activated and extensors relaxed. contralateral. had exstensors active and flexors relaxes

rhythmic movements like walking is harder due to lack of UMN regulation

as well as voluntary movement.

UMN Objectives to be able to

  1. Define the physiological/anatomical basis of the clinical concept of upper motor neuron
  2. List the main brainstem structures incolced in motor control and the pathways by which they ingluence the spinal cord and summarise their roles
  3. Outline the main features of motor cortical organisation icluding the roles of primary and secondary motor areas
  4. Describe the main signs of upper motor neuron damage and contrast these with LMN signs

most lateral CST acons syncapse on spinal interneurons rather than a-motor neurons

brainstem nuclei sophisticate movement and bind things together.

tectospinal tract is from superior colliculi and directs rapid orientation to moving obhects

reticular formation has pontine part which does antigravity reflexes and medullary part which suppresses reflexes

Cytoarchitectonics generally columns for particular function and layers for different inputs?

1at motor cortex has lots of little calls and a low threshold for electrucally evoked movement. (and also somatotopic body representation)

secondary motor cortex and supplementary motor area have higher threshold formovement and is more with deciding what happens. and also has higher order fucntions

Signs of UMN lower voluntary power tendon relfexes speed up muscle tone is higher less muscle atrophy babinski reflex is present i think

in summary

he honestly jsut fucking talks about UMN and LMN lesions

for 2 hours

Graph View

Backlinks