Motor Axis Body movement

• Voluntary movement • Pyramidal tract = corcospinal tr. + corcobulbar tr. • Involuntary movement • Control of movement

Necessary elements: 1. Cerebral cortex 2. Basal ganglia 3. 4. Recular formaon 5. Control of movement

Necessary elements: 1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Recular formaon 5. Spinal cord ”The left side of your brain controls the right side of your body” Corticospinal tracts

• First order : UMN • Upper Second order neuron: LMN motor neuron Lateral corcospinal tract: • Movement of limbs • Decussates at medulla

Lateral Anterior Anterior corcospinal tract: corcospinal corcospinal tract • Movement of trunk tract • Decussates in spinal cord Upper motor

• Start in or brain stem • Send informaon to LMN

Upper motor neuron lesion: • Loss of voluntary acvity • Increased muscle tone • Increased reflexes (e.g. Increased deep tendon reflex) • Babinski sign

Lower motor neurons

• Located in: 1. Cranial nerve nuclei of the - muscles of head and neck 2. Anterior (ventral horn) - muscles of the body 3. Spinal lower motor neurons • All voluntary movement relies on spinal lower motor neurons • Act as a link between upper motor neurons and muscles • Alpha, beta, gamma types • Lower motor neuron lesion à everything is Lowered • Decreased reflexes • Decreased muscle tone • Flaccid paralysis • Muscle atrophy possible (lack of innervaon) • Fasciculaons • Babinski sign negave • Necessary elements:

1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Recular formaon 5. Spinal cord Basal ganglia

• Control scale of voluntary movement; combine planning with acon • Adjust corcal impulses with negave feedback • Five key components 1. Caudate nucleus 2. Putamen 3. Globus pallidus 4. 5. Substana Nigra = putamen + caudate nucleus Basal ganglia pathways

Direct pathway Indirect pathway • Excites motor cortex • Inhibits motor cortex • Allows us to make wanted • “INdirect is INhibitory” movements • Allows us to NOT make • D1 receptors on of unwanted movements striatum • D2 receptors on axons of • “D1RECT pathway” striatum • Hyperkinesia • Hypokinesia

Glu GABA – inhibitory Glutamate – excitatory Dopamine – excitatory Motor Muscles Cortex

Striatum

Globus pallidus internal

Substana Subthalamic nigra nucleus Globus pallidus external Indirect Pathway Motor Muscles Cortex

Striatum Thalamus

Globus pallidus internal

Substana Subthalamic nigra nucleus Globus pallidus external Dysfunctions of basal ganglia

Hunngton’s Parkinson’s • CAG nucleode repeat on • Loss of dopaminergic neurons in chromosome 4 substana nigra • Caudate loses Ach and GABA • Slowed/ decreased movements • ⬆ dopamine, ⬇ cholinergic and • TRAP GABAergic release • Tremor • Repeve/ rapid movements, • Rigidity decreased muscle tone • Akinesia • Cognive changes • Posture unstable • Necessary elements:

1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Recular formaon 5. Spinal cord Cerebellum Tracts

• Ventral • Tectocerebellar tract • Cuneocerebellar tract • Cerebello-ponto-corcal tract • Corco-ponto-cerebellar tract • Dorsal spinocerebellar tract • • Vesbulocerebellar tract But you already know these J Control of equilibrium

• Balances agonist and antagonist muscle acvies during rapid change in posion • Signals: 1. Inform how fast movement is happening, and in which direcon 2. Inform about effector’s (i.e muscle’s) posion, tone 3. Relay planned sequences of movement Control of movement

• Role: • Controls muscle tone • Postural control • Controls muscle contracon • Assists in planning/ sequencing movement

• Lesions?? • Disturbed equilibrium • Dysmetria • Ataxia • Adiadochokinesis • Dysarthria • Intenon tremor • Nystagmus