Major Structures of the Brain

Major Structures of the Brain

1. Hindbrain- posterior part of the brain. Certain structures constitute the brainstem.

   • Medulla- controls vital reflexes through the cranial nerves.
     • Damage is fatal
   • Pons- contains nuclei for several cranial nerves. Known as a bridge as the axons from one side of the brain crosses to the other in the spinal cord via the pons.
   • Cerebellum- a large hindbrain structure. Contributes to controlling of movements.
     • Damage leads to problems shifting attention between auditory and visual stimuli

2. Midbrain- middle of the brain. The roof of this section is known as the tectum.

   • Superior/inferior colliculus- swellings on each side of the tectum. Important for sensory processing.
     • Superior- visual processing
     • Inferior- sensory processing
   • Tegmentum- under the tectum and is the intermediate level of the midbrain. Includes the nuclei for the third and fourth cranial nerves.
   • Substantia nigra- gives rise to a dopamine containing pathway that facilitates readiness for movement.

3. Forebrain- most prominent part of the brain that consists of two hemispheres that receive information and control muscles on the contralateral side

   • Cerebral cortex- outer portion which contains strucutres such as the thalamus, basal ganglia and the limbic system.
     • Limbic system- forms the border around the brainstem. Includes olfactory bulb, hypothalamus, hippocampus, amygdala, and cingulate gyrus.
       • Hypothalamus- conveys messages to the pituitary gland altering it's release of hormones.
         • Damage leads to abnormalities in motivated behaviours
         • Pituitary gland- endocrine (hormone producing) gland at the base of the hypothalamus.
       • Hippocampus- stores certain kinds of memories (especially individual memories)
         • Damage leads to troubles storing new memories. Do not lose previous memories.
     • Thalamus- main source of input to the cerebral cortex. Most sensory information goes first into the thalamus where it is processed and sends cerebral output.
     • Basal ganglia- group of subcortical structures including the caudate nucles, putamen and globus pallidus. Are critical for movement, learning and remembering.
       • Damage can lead to Parkinson's disease