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Brainstem (Medulla (medulla level structures (cranial nerves IX-XII…

- - - - formed by large descending corticospinal
        tracts from the primary motor cortex.
      - contains the pyramidal decussation, where
        the corticospinal tract decussates contralaterally.
    - - contains the inferior olivary nuclei which
        relays sensory / proprioceptive information to
        the cerebellum from the cerebral cortex.
  - - - in close association w/ the fourth ventricle (forms part of its floor).
    - - glossopharyngeal nerve
      - vagus nerve
      - accessory nerve
      - hypoglossal nerve
  - - - carries sensory information from
        the lower limbs of the body.
    - - carries sensory information from
        the upper limbs of the body.
  - - - cardiac centre regulates heart rate and contractile force.
      - vasomotor centre adjust vessel size to control blood pressure.
- - - - also involved in the generation of
        reflexive motor patterns.
  - - - contains the substantia nigra,
        which is functionally linked to the
        basal nuclei w/in the forebrain.
        
        contains melanin which attributes its dark colour
        and serves as a precursor for the chemical dopamine,
        a neurotransmitter that exists in high amounts in this nucleus.
        
        the degeneration of dopamine neurons in the substantia nigra leads to Parkinson's Disease.
        
        consists of two parts
        
        pars compacta
        
        the part of the substantia nigra that
        contains most of the dopamine neurons.
        
        pars reticulata
        
        localised ventrally to the pars compacta.
        
        has connections similar to the internal division of the basal
        ganglia globus pallidus ─ relaying inhibitory input to the
        thalamus, which relays it to the cerebral cortex
        
        damage leads to impaired inhibition of
        unwanted motion sequences, which leads to
        uncoordinated movement in the form of
        tremor (Parkinson's disease).
        
        in close association w/ the red nucleus, which
        is a highly vascular structure that lies deep to the
        substantia nigra ─ acts as a relay nucleus in some
        descending motor pathways.
    - - consists of the superior and inferior colliculi
        
        the superior colliculi receive inputs from
        the retina or the visual cortex, and project
        to vision-related areas in the cerebral cortex.
        
        the inferior colliculi receive inputs from
        auditory receptors in the ear to relay information to somatosensory cortices of the brain.
        
        superior colliculi functional properties:
        ● detection of object movement in visual field.
        ● coordination of eye movement responses.
        ● relay visual information to visuomotor neurons.
        ● responses coordinated via the oculomotor nerve
        
        inferior colliculi functional properties:
        ● each acts primarily as auditory relay nuclei.
        ● also acts in reflexive responses to sound.
        ● i.e. the "startle reflex"
    - - the oculomotor nerve is
        localised ventromedially.
      - the trochlear nerve is
        localised dorsally.
- - - - in close association to the fourth ventricle (forms its lateral walls).
    - - trigeminal nerve
      - abducen nerve
      - facial nerve
      - vestibulocochlear nerve
- - - - III. Oculomotor
      - IV. Trochlear
      - V. Trigeminal
      - VI. Abducens
      - VIII. Vestibulocochlear
      - IX. Glossopharyngeal
      - X. Vagus
      - XI. Accessory
      - XII. Hypoglossal