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More on the Cerebrum. More on the Cerebrum: Cortex is grey matter, below cortex is white matter, deep inside is grey matter. (basal ganglion/nuclei) Highly convoluted ( gyri ) increases SA Shallow: sulci Deep: fissure
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More on the Cerebrum: • Cortex is grey matter, below cortex is white matter, deep inside is grey matter. (basal ganglion/nuclei) • Highly convoluted (gyri) increases SA • Shallow: sulci • Deep: fissure • Deep, long, central fissure (longitudinal fissure) separates left and right cerebral hemispheres
More on the Cerebrum: • Within CNS nerves are called ‘tracts’ • Three tract types: • Tracts connecting within cortex • Tracts connecting left and right hemispheres • Tracts connecting cortex to other regions of brain of spinal cord. • Basal nuclei (ganglia) also associated with subconscious skeletal muscle tone control and learned movements patterns
Control of Movement • Cerebral cortex • Motor association area (‘plan’ activity) Primary Motor area Upper motor neurons Lower motor neurons (spinal cord) muscle • In Primary motor area, various muscle movements are controlled by groups (folds) of cerebral cortex. (the more muscles, the bigger the fold)
More on Cerebellum • Control of balance: • Input from: • Cerebrum (conscious awareness of body position) • Semicircular canals in inner ear (movement of head) • Utricle & saccule in inner ear (position of head) • Eyes • Pressure receptors in skin • Stretch receptors in muscles & joints • Output to: • Cerebral cortex (interpretation • / further response) • Spinal cord muscles
Spinal Cord: • Two functions: • Carry impulses to/from CNS • Integrate reflexes • Approx 44cm long • Encased in vertebral canal, Meninges and cerebrospinal fluid • Grey matter roughly the shape of an H (central canal) surrounded by white matter • Ascending tracts: sensory axons (bundles of myelinatedfibres – white matter) • Descending tracts: motor axons (bundles of • myelinatedfibres – white matter)