BIOS1171 Lecture Notes - Lecture 19: Pocketknife, Pars Compacta, Muscle Tone

• School: University of Sydney
• Department: Biomedical Science
• Course: BIOS1171
• Professor: Jin Huang

Document Summary

Motor neurons: motor neurons: neurons that control the activity of skeletal muscles; there are 2 types . Gastrocnemius muscle = >1000 fibres; e. g. walking (less control: e. g. Extraocular muscle = ~ 3 -8 fibres = precise control (1mn innervated); e. g. focus eye on something that is moving (more control: activity depends on convergence of information from peripheral sensors, spinal connections. Corticospinal pathway: originate at pyramidal cells (layer 5) of primary motor cortex. [pyramidal cells] contain 3 pairs of descending tracts: corticobulbar tracts, axons given off to cn voluntary control of cranial nerves) Internal capsule contains ascending & descending (sensory & motor) projection fibres. Pathology of basal nuclei: dysfunction results in movement disorders & postural behaviours, hypokinetic disorders: too little movement, parkinson"s disease, hyperkinetic disorders: excessive movement, huntington"s disease, subtypes of. Parkinson"s disease: most common basal nuclei disorder, characterized by muscular rigidity, shuffling gait, droopy posture, muscular tremors & mask-like facial expression.