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 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 myelinated fibres – white matter) Descending tracts: motor axons (bundles of myelinated fibres – white matter)