The Nervous System: The Brain and Cranial Nerves AHS 101

Regions of the Brain Cerebral hemispheres Diencephalon Brain stem Cerebellum Figure 7.12 Slide 7.27 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Protection of the Central Nervous System Scalp and skin Skull and vertebral column Meninges Figure 7.16a Slide 7.44a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Protection of the Central Nervous System Cerebrospinal fluid Blood brain barrier Figure 7.16a Slide 7.44b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Meninges Dura mater Double-layered external covering Periosteum – attached to surface of the skull Meningeal layer – outer covering of the brain Layers separate in certain places to form large veins called dural sinuses Folds inward in several areas Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Meninges Arachnoid layer Pia mater Middle layer Web-like Internal layer Clings to the surface of the brain Slide 7.45b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cerebrospinal Fluid Clear liquid similar to blood plasma composition Formed by the choroid plexus Forms a watery cushion to protect the brain Circulated in arachnoid space, ventricles, and central canal of the spinal cord Returns to blood via villi in the dural sinuses Slide 7.46 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Ventricles and Location of the Cerebrospinal Fluid Figure 7.17a Slide 7.47a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Ventricles and Location of the Cerebrospinal Fluid Figure 7.17b Slide 7.47b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Blood Brain Barrier Includes the least permeable capillaries of the body Excludes many potentially harmful substances Useless against some substances Fats and fat soluble molecules Respiratory gases Alcohol Nicotine Anesthesia Slide 7.48 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cerebral Hemispheres (Cerebrum) Paired (left and right) superior parts of the brain Include more than half of the brain mass Figure 7.13a Slide 7.28a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cerebral Hemispheres (Cerebrum) The surface is made of ridges (gyri) and grooves (sulci) Figure 7.13a Slide 7.28b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Lobes of the Cerebrum Fissures (deep grooves) divide the cerebrum into lobes Surface lobes of the cerebrum Frontal lobe Parietal lobe Occipital lobe Temporal lobe Slide 7.29a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Lobes of the Cerebrum Slide 7.29b Figure 7.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Specialized Areas of the Cerebrum Somatic sensory area – receives impulses from the body’s sensory receptors Primary motor area – sends impulses to skeletal muscles Broca’s area – involved in our ability to speak Slide 7.30 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Sensory and Motor Areas of the Cerebral Cortex Figure 7.14 Slide 7.31 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Specialized Area of the Cerebrum Cerebral areas involved in special senses Gustatory area (taste) Visual area Auditory area Olfactory area Slide 7.32a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Specialized Area of the Cerebrum Interpretation areas of the cerebrum Speech/language region Language comprehension region General interpretation area Slide 7.32b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Specialized Area of the Cerebrum Figure 7.13c Slide 7.32c Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Memory and Learning Short-term memory Long-term memory Retention of information for few seconds or minutes Information lost unless reinforced Long-term memory Storage of information that can be recalled later

Diencephalon Sits on top of the brain stem Enclosed by the cerebral hemispheres Made of three parts Thalamus Hypothalamus Epithalamus Slide 7.34a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Diencephalon Slide 7.34b Figure 7.15 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Thalamus Surrounds the third ventricle The relay station for sensory impulses Transfers impulses to the correct part of the cortex for localization and interpretation Slide 7.35 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hypothalamus Under the thalamus Important autonomic nervous system center Helps regulate body temperature Controls water balance Regulates metabolism Slide 7.36a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Hypothalamus An important part of the limbic system (emotions) The pituitary gland is attached to the hypothalamus Slide 7.36b Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Epithalamus Forms the roof of the third ventricle Houses the pineal body (an endocrine gland) Includes the choroid plexus – forms cerebrospinal fluid Slide 7.37 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Brain Stem Attaches to the spinal cord Parts of the brain stem Midbrain Pons Medulla oblongata Slide 7.38a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Brain Stem Slide 7.38b Figure 7.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Midbrain Mostly composed of tracts of nerve fibers Has two bulging fiber tracts – cerebral peduncles Has four rounded protrusions – corpora quadrigemina Reflex centers for vision and hearing Cranial nerves III and IV originate from the midbrain Slide 7.39 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Pons The bulging center part of the brain stem between the midbrain and medulla Mostly composed of fiber tracts that carry impulses between the cerebellum and the rest of the nervous system Includes nuclei involved in the control of breathing Slide 7.40 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Medulla Oblongata The lowest part of the brain stem Merges into the spinal cord Includes important fiber tracts Contains important control centers Heart rate control Blood pressure regulation Breathing Swallowing Vomiting Slide 7.41 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Medulla Oblongata Motor fibers from motor cortex extend through the medulla and most cross from one side to the other. Results in contralateral control Right hemisphere controls muscles in the left side of the body Left hemisphere controls muscles in the right side of the body

Cerebellum Two hemispheres with convoluted surfaces Provides involuntary coordination of body movements Helps maintain balance in standing, walking and sitting Helps maintain muscle tone Slide 7.43a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cerebellum Slide 7.43b Figure 7.15a Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cranial Nerves 12 pairs of nerves that mostly serve the head and neck Numbered in order, front to back Most are mixed nerves, but three are sensory only Slide 7.58 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Distribution of Cranial Nerves Figure 7.21 Slide 7.59 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cranial Nerves I Olfactory nerve – sensory for smell II Optic nerve – sensory for vision III Oculomotor nerve – motor fibers to eye muscles IV Trochlear – motor fiber to eye muscles Slide 7.60 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cranial Nerves V Trigeminal nerve – sensory for the face; motor fibers to chewing muscles VI Abducens nerve – motor fibers to eye muscles VII Facial nerve – sensory for taste; motor fibers to the face VIII Vestibulocochlear nerve – sensory for balance and hearing Slide 7.61 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cranial Nerves IX Glossopharyngeal nerve – sensory for taste; motor fibers to the pharynx X Vagus nerves – sensory and motor fibers for pharynx, larynx, and viscera XI Accessory nerve – motor fibers to neck and upper back XII Hypoglossal nerve – motor fibers to tongue Slide 7.62 Copyright © 2003 Pearson Education, Inc. publishing as Benjamin Cummings

Cranial Nerves Mnemonic (a memory aid) On Old Olympus Towering Top, A Finn And German Vaulted A Hedge Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Acoustic (vestibulocochlear), Glossopharyngeal, Vagus, Accessory, Hypoglossal

Aging of the Nervous System Brain decreases in size and weight Speed of processing information slows Movements slowed Memory diminishes