Motor Axis Body movement
• Voluntary movement • Pyramidal tract = cor cospinal tr. + cor cobulbar tr. • Involuntary movement • Basal ganglia Control of movement
Necessary elements: 1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Re cular forma on 5. Spinal cord Control of movement
Necessary elements: 1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Re cular forma on 5. Spinal cord ”The left side of your brain controls the right side of your body” Corticospinal tracts
• First order neuron: UMN • Upper Second order neuron: LMN motor neuron Lateral cor cospinal tract: • Movement of limbs • Decussates at medulla
Lateral Anterior Anterior cor cospinal tract: cor cospinal cor cospinal tract • Movement of trunk tract • Decussates in spinal cord Upper motor neurons
• Start in motor cortex or brain stem • Send informa on to LMN
Upper motor neuron lesion: • Loss of voluntary ac vity • Increased muscle tone • Increased reflexes (e.g. Increased deep tendon reflex) • Babinski sign
Lower motor neurons
• Located in: 1. Cranial nerve nuclei of the brainstem - muscles of head and neck 2. Anterior grey column (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 innerva on) • Fascicula ons • Babinski sign nega ve • Necessary elements:
1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Re cular forma on 5. Spinal cord Basal ganglia
• Control scale of voluntary movement; combine planning with ac on • Adjust cor cal impulses with nega ve feedback • Five key components 1. Caudate nucleus 2. Putamen 3. Globus pallidus 4. Subthalamic nucleus 5. Substan a Nigra Striatum = 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 axons of unwanted movements striatum • D2 receptors on axons of • “D1RECT pathway” striatum • Hyperkinesia • Hypokinesia
Glu GABA – inhibitory Glutamate – excitatory Dopamine – excitatory Direct Pathway Motor Muscles Cortex
Striatum Thalamus
Globus pallidus internal
Substan a Subthalamic nigra nucleus Globus pallidus external Indirect Pathway Motor Muscles Cortex
Striatum Thalamus
Globus pallidus internal
Substan a Subthalamic nigra nucleus Globus pallidus external Dysfunctions of basal ganglia
Hun ngton’s Parkinson’s • CAG nucleo de repeat on • Loss of dopaminergic neurons in chromosome 4 substan a nigra • Caudate loses Ach and GABA • Slowed/ decreased movements • ⬆ dopamine, ⬇ cholinergic and • TRAP GABAergic release • Tremor • Repe ve/ rapid movements, • Rigidity decreased muscle tone • Akinesia • Cogni ve changes • Posture unstable • Necessary elements:
1. Cerebral cortex 2. Basal ganglia 3. Cerebellum 4. Re cular forma on 5. Spinal cord Cerebellum Tracts
• Ventral spinocerebellar tract • Tectocerebellar tract • Cuneocerebellar tract • Cerebello-ponto-cor cal tract • Cor co-ponto-cerebellar tract • Dorsal spinocerebellar tract • Olivocerebellar tract • Ves bulocerebellar tract But you already know these J Control of equilibrium
• Balances agonist and antagonist muscle ac vi es during rapid change in posi on • Signals: 1. Inform how fast movement is happening, and in which direc on 2. Inform about effector’s (i.e muscle’s) posi on, tone 3. Relay planned sequences of movement Control of movement
• Role: • Controls muscle tone • Postural control • Controls muscle contrac on • Assists in planning/ sequencing movement
• Lesions?? • Disturbed equilibrium • Dysmetria • Ataxia • Adiadochokinesis • Dysarthria • Inten on tremor • Nystagmus