Lecture 6 - Movement

• Smooth • Cardiac • Skeletal

• under involuntary control (ANS) • 2 types: • Single unit - contracts as one, e.g. hollow visceral organs (but not heart), like digestive tract • Multi-unit - individual cells are innervated, allowing gradual responses, e.g. lining of airways, and arrector pilli muscle in skin

• Found in walls of heart - rhythmic contractions • Under involuntary control (ANS) - from neural inputs (stimulation) or hormons (adrenaline) • mix of striped and smooth muscle

• Under voluntary control/ reflexes • attaches to bones via tendons • Striated/striped muscle • 2 main casus of movements • Flexion - bending joint towards body • Extention - relaxing joint

• Extrafusal muscle fibers - outside muslce spindle - causes muscle contraction • Intrafusal muscle fibers - Inside muscle spindle - Functions as a stretch receptor - regulates muscle contraction by stopping unwanted stretch

Synapse between motor neuron and muscle fibre • Motor neuron synapses motor endplates on surface of muscle fibre - this regulates muscle contraction • muscle fibre contains myofibril • Where muscular contraction occurs

• Endplate potentials: axon fires, motor neuron releases ACH -> depolarises muscle fibre • rate of firing = strenght of contraction

• Intrafusal muscle fibers - sensory endings detect strength and tells brain if theres too much contraction, or too much relaxation • Tendons - GOLGI TENDON ORGAN - contains stretch receptors that detec tension - then tells brain same things

Involves the motor cortex, which includes: - Primary motor cortex - Frontal association cortex (Suppplementary motor area) - Pre-motor cortex -

Main player in execution of movement • ORganised somatotopically (motor homunculus) - so each part is mapped to a body part • Not every body part is equally sized, some need larger areas, e.g. fingers, hands tounge need more

Include: • Frontal association cortex • Supplementary motor area • pre-motor cortex • as well as Primary Somatosensory Cortex (S1)

• concerned with experience of bodily sense - so we can respond to environment • S1 neurons are in a particiular location - sends info to primary motor cortex about the specific muscules its responsibile for • provides rapid feedback to motor system - heart and reflexes for protecive function

• responsibile for learning, planning and performing behaviours, consisting of sequences of movements • e.g. walking • SMA & PRE-SMA = urge to move, or anticipation that a movement will occur (thoughts before moving) • PRE-SMA = Control of spontaneous movement

Cant execute well learned sequences of responses

• involved in learning and executing complex movements • individual movements, not sequence movements • movement when stimuli indirectly indicates what to do, “do you like that dress”? • Contains mirror neurons

• difficulty carrying out purposeful movements, but no an issue of paralysis, muscule weakness, faulty PNS, spinal cord damage etc - only cos of dysfunction in motor areas • often caused by damage to corpus callosum, frontal lobe, or parietal lobe 1. Limb apraxia 2. Constructional apraxia 3. Occulomotor apraxiq

Problems with movements of arms, hands, fingsers • wrong body part, wrong movement, or wrong sequence • caused by damage to: • anterior corpus callosum, left frontal or left parietal lobe

• Problems drawing 3d objects, making geometrical contstructions (brikcs etc), and map reading • damage to: right parietal lobe • cant make movements based on visual representation of angles/ lines

• problems making controlled, voluntary and purposeful eye movements, especially moving eyes horizontally • damage to corpus callosum

2 groups of descending motor tracts from brain to periphery • lateral group - 3 tracts including basal ganglia - Controls voluntary independent limb movements • Ventromedial group - 4 tracts - controls automatic movements (e.g. keeping us balanced when walking)

• Basal ganglia (telenhcephalon) • Cerebellum (hindbrain) • Reticular formation

• Voluntary movement under control of primary motor cortex and ventromedial stream -Motor nuclei of BG include: • Caudate nucleus (input nuclei) • Putamen (input nuclei) • Globus pallidus (output)

Inputs: • Cerebral cortex (primary motor cortex & primary somatosensory cortex) • Midbrain substantia nigra Outputs: - Motor cortex (primary motor cortex, premotor cortex and supplementary motor area) (via thalamus)

• huntingdons and parkinsons disease