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• Three major divisions of the brain

  • Hindbrain
  • Midbrain
  • Forebrain

  
• Forebrain


  Prosencephalon ("forward-brain"), Diencephalon ("between-brain"), Telencephalon ("end-brain")
• Midbrain


  Mesencephalon ("middle-brain")
• Hindbrain


  Rhombencephalon ("parallelogram-brain"), Metencephalon ("afterbrain"), Myencephalon ("marrow-brain")
• Structures of the Hindbrain


  • Medulla
  • Pons
  • Cerebellum
• Medulla


  • Located just above the spinal cord, responsible for vital reflexes such as breathing, heart rate, vomiting, salivation, coughing and sneezing, damage can be fatal
• Cranial nerves


  • Allow the medulla to control sensations from the head, muscle movements in the head, and many parasympathetic outputs to the organs, cranial nerve nuclei for nerves V through XII are in the medulla and pons, nerves I through IV are in the midbrain and forebrain

  
• Cranial nerve I (Olfactory)


  Connects directly to the olfactory bulbs of the forebrain
• Cranial nerve VII (Facial)

  Taste from the anterior two thirds of the tongue and controls facial expressions, crying, salivation, and dilation of the head's blood vessels
• Cranial nerves III (Oculomotor), IV (Troclear), and VI (Abducens)


  Control eye movement
• Pons


  • Lies on each side of the medulla, location where axons from each half of the brain cross to the opposite side of the spinal cord, along with the medulla contains the reticular formation and raphe system
• Reticular formation


  Descending portion controls motor areas of the spinal cord, ascending portion sends output to much of the cerebral cortex, selectively increasing arousal and attention

  
• Raphe system


  Sends axons to much of the forebrain, modifying the brain's readiness to respond to stimuli, releases serotonin, regulates vigilance, alertness, and circadian rhythms
• Cerebellum


  • Helps regulate motor movement, balance and coordination, important for shifting attention between auditory and visual stimuli, damage causes clumsiness, loss of balance, trouble shifting attention, difficulty with timing
• Structures of the Midbrain

  • Tectum
  • Superior colliculus
  • Inferior colliculus
  • Tegmentum
  • Substantia nigra
• Superior colliculus


  Processes visual information
• Inferior colliculus


  Processes auditory information
• Tegmentum

  Intermediate level of the midbrain containing nuclei for cranial nerves III and IV, parts of the reticular formation, and extensions of pathways between the forebrain and the spinal cord or hindbrain

  
• Substantia nigra

  Gives rise to the dopamine containing pathway facilitating readiness for movement
• Forebrain


  Most anterior and prominent part of the mammalian brain, consists of two cerebral hemispheres, includes the outer cortex and subcortical regions

  
• Cerebral cortex


  Outer portion of the forebrain
• Subcortical regions


  Structures of the brain that lie underneath the cortex, include the thalamus and basal ganglia

  
• Thalamus


  Relay station from the sensory organs and main source of input to the cortex, exception is olfactory information which progresses directly to the cerebral cortex

  
• Basal ganglia


  Important for certain aspects of movement, planning of motor movement, and aspects of memory and emotional expression
• Limbic system


  Consists of a number of interlinked structures that form a border around the brainstem, associated with motivation, emotion, drives and aggression

  
• Hypothalamus


  Small area near the base of the brain, conveys messages to the pituitary gland to alter the release of hormones, associated with behaviours such as eating, drinking, sexual behaviour and other motivated behaviours
• Pituitary gland


  Hormone producing gland found at the base of the hypothalamus, contains neurons, blood vessels and connective tissue, responds to messages from the hypothalamus and synthesises and releases hormones into the bloodstream
• Basal forebrain


  Comprised of several structures that lie on the ventral surface of the forebrain, contains the nucleus basalis which receives input from the hypothalamus and basal ganglia, sends axons that release acetylcholine to the cerebral cortex, key part of the brain's system for arousal, wakefulness, and attention
• Hippocampus


  Large structure located between the thalamus and cerebral cortex, toward the posterior portion of the forebrain, critical for storing certain types of memory
• Central canal


  Fluid-filled channel in the center of the spinal cord
• Ventricles


  Four fluid-filled cavities within the brain containing cerebrospinal fluid
• Meninges


  Membranes that surround the brain and spinal cord, swelling of blood vessels causes migraine headache
• Subarachnoid spaces


  Narrow spaces between the brain and meninges

  
• Cerebrospinal fluid


  Clear fluid found in the brain and spinal cord, produced by choroid plexus, provides "cushioning" for the brain, reservoir of hormones and nutrition
• Obstruction of cerebrospinal fluid leads to hydrocephalus
• Cerebral cortex


  • Most prominent part of the mammalian brain, consists of the cellular layers on the outer surface of the cerebral hemispheres, divided into two halves joined by the corpus callosum and anterior commissure, cells within certain columns share similar properties, more highly developed in humans than other species

  
• Lobes of the cerebral cortex

  • Occipital lobe
  • Parietal lobe
  • Temporal lobe
  • Frontal lobe

  
• Occipital lobe


  Located at the posterior end of the cortex, known as the striate cortex or primary visual cortex, highly responsible for visual input, damage can result in cortical blindness
• Parietal lobe


  Contains the postcentral gyrus (primary somatosensory cortex) which is the primary target for touch sensations and information from muscle-stretch receptors and joint receptors, also responsible for processing and integrating information about eye, head and body positions

  
• Temporal lobe


  Located on the lateral portion of each hemisphere near the temples, target for auditory information and essential for processing spoken language, also responsible for complex aspects of vision including movement and some emotional and motivational behaviours, tumours may cause auditory or visual hallucinations