Central Nervous System: The Brain and Spinal Cord The Nervous System Option E The Brain Most developed/complex organ of the body. Cephalization 4 Major Regions 1. 2. 3. 4. Cerebral Hemispheres Diencephalon 1. Thalamus 2. Hypothalamus 3. Epithalamus Brain Stem 1. Midbrain 2. Pons 3. Medulla Cerebellum Cerebrum Diencephalon Brain stem Cerebellum 4 Gray Matter Unmyelinated fibers Concentrated area of neuron cell bodies Found: Outer Cortex Surrounding Central Canal Scattered w/White Matter vs. White Matter Myelinated fibers Found: Between gray matter layers Ventricles Hollow chambers within the brain Flow into Central Canal Filled with Cerebrospinal Fluid (CSF) Divided into Segments: Lateral Ventricles in cerebral hemispheres Third Ventricle in diencephalon Fourth Ventricle in pons / medulla Lateral ventricles Third ventricle Fourth ventricle 8 1. CEREBRAL HEMISPHERES Most superior, largest part (83%) elevated ridges gyri (gyrus) shallow grooves sulci (sulcus) deep grooves fissures longitudinal fissure—btwn. hemispheres transverse fissure– btwn. cerebrum and cerebellum Are the Hemispheres Connected? CORPUS CALLOSUM Cerebrum Divided into 5 Major LOBES Frontal Lobe Parietal Lobe Temporal Lobe Occipital Lobe Insula Central sulcus Precentral gyrus Postcentral gyrus Frontal lobe Parietal lobe Occipital lobe Temporal lobe 18 INSULA Cerebral Hemispheres divided into 3 REGIONS 1. Cerebral Cortex 2. Cerebral White Matter Cerebral Basal Nuclei 3. The Cerebral Cortex Area of consciousness Composed of gray matter All interneurons ! No functional area acts alone! 3 areas of Cerebral Cortex 1. 2. 3. • • Motor Area Sensory Area Association Area Don’t confuse w/ Motor, Sensory Neurons! Areas detected by modern imaging techniques Motor Area of Cerebral Cortex Located in precentral gyrus Controls all voluntary movements Subdivided into: Premotor cortex Primary motor cortex Broca’s region Premotor cortex Located anterior to precentral gyrus Controls LEARNED, repetitive skills! Musical instrument playing Keyboarding, writing Broca’s Region Located anteriorly/inferiorly to premotor cortex Left hemisphere only Controls MOTOR SPEECH Talking! Primary Motor Cortex Controls voluntary movement of skeletal muscles! Precise motor control regions dominant here! Homunculus Sensory Area of Cerebral Cortex Located in postcentral gyrus Controls all sensation capabilities Subdivided into: 1. Somatosensory cortex 2. Association cortex 3. Visual cortex 4. Auditory cortex 5. Olfactory cortex 6. Gustatory cortex 7. Vestibular cortex SOMATOSENSORY CORTEX Controls tactile sensations in skin and skeletal muscles What part of the body is most sensitive to touch? ASSOCIATION CORTEX Receives information from somatosensory cortex Allows for understanding of tactile sensations! VISUAL CORTEX Receives information from eyes Segments allow for: identification of images location/position of images AUDITORY CORTEX Receives information from ears Allows for identification of sounds OLFACTORY CORTEX Receives information from smell receptors Allows for identification of SCENTS GUSTATORY CORTEX Receives information from the tongue Allows for identification of TASTES VESTIBULAR CORTEX Receives information from inner ear Allows for maintenance of BALANCE Prefrontal Cortex Controls intellect, learning, personality, abstract thinking, judgement, reasoning, planning, compassion, conscience, moral thought, etc. Develops slowly… Linked to Limbic System WERNICKE’S REGION Understanding spoken/written language Reminder: What region allows for ability to speak? VISCERAL AREA Perception of internal body sensations: full bladder nausea, etc.