Brain

Brain

1. Cerebrum

   • Cortex
     • Sensory
       • Primary somatosensory cortex: located in postcentral gyrus. receive somatic info for touch, pain, pressure, temp from dorsal column and spinothalamic tract
       • Primary visual area: Occipital Lobe
       • primary gustatory area: taste sense in parietal lobe
       • Primary olfactory area: temporal lobe
     • Motor
       • Primary Motor Area: located in precentral gyrus. Neurons direct voluntary movement by controlling somatic motor neurons in brain stem and spinal cord. Takes 2 nerves to go from primary motor area to muscle.
       • Broca's area: motor production of speech.
         • Aphasia - can understand what you say but cannot verbally produce words to respond back.
     • Cerebral Association Area: interpret sensory and motor info from other areas of cerebral cortex
       • Somatosensory association area: (parietal) tell what you "see" by touching it including memory of past touch to understand what you touch now.
       • prefrontal cortex: (frontal) sensory --> decision making and mood
       • auditory association area: (temporal)
       • wernicke's area: (temporal/parietal) interpret and understand language
         • receptive aphasia: can't understand language
       • premotor cortex: (frontal) planning muscle movement. Sends info to primary motor area which actually causes the movement.
       • frontal eye field: (parietal) muscles to voluntary track an object
       • Visual Association: (occipital) Visual and memory association
         • forgot this earlier
   • White matter
     • association fibers: interconnect portions of cerebral cortex in same hemisphere
       • arcuate fiber
       • longitudinal fasciculi
     • commissural fiber: connect corresponding loves of different hemispheres
       • corpus callosum
       • anterior commissure
     • projection fiber: interconnect cerebrum with other brain regions
       • internal capsule
     • Basal Nuclei: GREY MATTER IN WHITE MATTER. Subconscious control and integration of muscle tone, coordination of learned movement patterns, and info relays to thalamus (INDIRECT PATHWAY)
       • Caudate Nucleus
       • Putamen
       • Globus pallidus

2. Midbrain

   • Tectum: nuclei that process senses and generate reflexes
     • Superior colliculus: visual information
     • Inferior colliculus: Auditory information
   • red nucleus: integrate info from cerebrum and issues involuntary motor commands of muscle tone and posture
     • Red because it has lots of blood supply
   • reticular formation: involved in maintaining alertness
     • extends from diencephalon to spinal cord and has sensory and motor info. Fibers go to cerebral cortex and include RETICULAR ACTIVATING SYSTEM (RAS)
       • Impulses from ears, eyes, and skin activates RAS which then sends signals to "wake up" the cortex
         • Note: Smell doesnt go to RAS so the smell of smoke won't wake you but the sound of the alarm will!
   • Substantia nigra: regulate motor output of cerebral nuclei
     • make dopamine - inhibit excitatory neurons in basal nuclei
       • can cause parkinsons if not regulated well.

3. Cerebellum

   • Arbor vitae: white matter that looks like a tree. Connects cerebellar cortex with cerebral peduncles
   • Peduncle: white matter
     • Superior: connect cerebellum with mesencephalon, diencephalon, and cerebrum
     • Middle: communicate between cerebellum and pons (anterior to cerebellum)
     • Inferior: connect cerebellum with medulla oblongata (inferior)
   • Cortex: subconscious coordination of movements, contains purkinje cells
     • Lobes
       • Anterior/posterior Lobe: subconscious coordination of movements
       • Flocculonodular Lobe: equilibrum and balance. (alcohol impairs this)

4. Pons

   • Grey matter
     • Nuclei for CN 5-8
     • contains respiratory center (pontine respiratory group)
   • White matter
     • Ascending/descending tracts that interconnect parts of CNS
     • Transverse fibers

5. Medulla Oblongata: forms from foramen magnum and extends inferiorly to the pons. Relays all sensory and motor output between other parts of brain and spinal cord.

   • Pyramid: protrusions on anterior surface of M.O. contains motor tracts passing from cerebrum to spinal cord (90% will cross over)
   • Olive: contain inferior olivary nuclei that relay proprioceptor information to cerebellum
   • medullary Nuclei
     • Nucleus Gracilis, Cuneatus: relay info to thalamus where it is filtered to be sent to different lobes
     • Olivary nucleus (refer to olive notes)
     • Reflex Center: automatic (subconscious) responses
       • Respiratory rhythmicity: contains DRG/VRG
       • Cardiovascular: regulate heart beat
     • Cell body of CN 8-12

6. Meningeal stabilizing tissue

   • Falx Cerebri: Descend down longitudinal fissure between cerebral hemispheres
   • Falx Cerebelli: Divide cerebellar hemispheres
   • Tentorium Cerebelli: Separate cerebellum from cerebrum
   • Diaphragm Tursica: Surround sella tursica (sphenoid) and pituitary gland

7. Limbic system: located b.w cerebrum and diencephalon inferior to corpus callosum.

   • Establish emotional state.
   • Link conscious function with unconscious autonomic function (accelerate HR).
   • Facilitate memory storage and retrieval

8. Thalamus: (diencephalon) surrounds 3rd ventricle. Relay center for sensory and motor pathway (except smell). Acts as info filter so only small amount of sensory info gets through.

   • 7 groups of nuclei on each side. each acts as a terminal of different sensory info
   • Epithalamus: roof of 3rd ventricle that contains pineal gland (secrete melatonin)
   • Hypothalamus: forms floor of 3rd ventricle inferior to thalamus. Infundibulum connects hypothalamus to pituitary gland
     • control of autonomic function (HR, Resp rate)
     • APG regulation
     • Temperature regulation
     • Emotional and behavioral patterns
     • Eating, drinking, circadian rhythm (sleep cycle)
     • 4 nuclei
       • supraoptic (ADH)
       • Paraventricular (oxytocin)