1. Anatomy and Physiology I Chapter 14 The Brain and Cranial Nerves

2. The Brain Cerebrum Cerebellum Brainstem

3. The Cerebrum 83% of volume Cerebral hemispheres- 2 halves Longitudinal fissure- deep groove that separates R and L hemispheres Central sulcus- vertical groove that divides frontal and parietal lobes

4. The Cerebrum Corpus callosum- thick bundle of nerve fibers connects R and L hemispheres Gyri- thick folds Sulci- shallow grooves

5. The Cerebrum Sensory perception, memory, thought, judgment, voluntary motor actions 4 lobes – Frontal lobe Voluntary motor functions, motivation, foresight, planning, memory, mood, emotion, social judgment, aggression – Parietal lobe receive and interpret signals of general senses Taste, touch, some visual – Occipital lobe Principal visual center – Temporal lobe hearing, smell, learning, memory, some vision and emotion

6. Sulci Central sulcus Parieto-occipital sulcus Lateral sulcus

7. The Cerebellum Posterior aspect, inferior to cerebrum – 2 nd largest region – 10% of volume

8. The Cerebellum Outer surface- gray matter Deeper layer- white matter Arbor vitae- branching, fernlike pattern Functions – Monitor muscle contraction – Learned movements – Motor coordination – Balance and – equilibrium

9. The Brainstem Brainstem- diencephalon, midbrain, pons, and medulla oblongata – Ends at foramen magnum

10. Meninges 3 connective tissue membranes Between brain and skull – Dura mater- very close to skull – Arachnoid mater- transparent – Pia mater- thin, delicate Closely follows contours of brain Protect the brain and provide structural framework for arteries and veins

11. Ventricles 4 internal chambers Lateral ventricles- largest, cerebral hemispheres 3 rd ventricle- connected to lateral ventricles – Inferior to corpus callosum 4 th ventricle- connects to 3 rd ventricle – b/t pons and cerebellum Produces CSF

12. CSF Clear, colorless liquid Fills ventricles Produced and reabsorbed at same rate Continually flows through and around CNS 3 purposes – Buoyancy- attain size, w/o being impaired by weight – Protection- protects from striking cranium when head is jolted – Chemical stability- rinses wastes from nervous tissue

13. Brain Barrier System Brain: 2% of body wt, 15% of blood consumption, 20% of O2 and glucose consumption Brain barrier system- strictly regulates what substances can get from bloodstream into brain tissue Blood-brain-barrier (BBB)- tight junctions b/t brain and capillaries – Astrocytes completely seal off gaps – Exclude harmful substances – Allow necessary ones to pass

14. Blood Brain Barrier Highly permeable to H2O, glucose, and lipid substances – O2, CO2, alcohol, caffeine, nicotine, anesthetics BBB is an important protective device – Obstacle to deliver meds Antibiotics Cancer drugs – Complicates treatment of brain diseases

15. The Medulla Oblongata Begins at foramen magnum Autonomic functions – Cardiac center Heart beat – Vasomotor center Blood pressure – Respiratory center breathing

16. The Pons Broad, anterior bulge, superior to medulla oblongata Involved in – Sleeping patterns – Facial expressions/ sensations – Eye movements – Equilibrium/ posture

17. The Midbrain Short segment of brainstem Anchors cerebrum to brainstem Collaborates in fine motor control Relays inhibitory signals to the thalamus – Preventing unwanted movements

18. The Reticular Formation Runs vertically through brainstem Functions – Somatic motor control maintain tone, balance, posture Relays signals from eyes and ears to cerebellum to integrate stimuli into coordinated motor movements – Cardiovascular control cardiac and vasomotor centers of medulla oblongata – Pain modulation Pain signals from lower body get to cerebral cortex – Sleep and consciousness alertness and sleep – Habituation ignore repetitive, inconsequential stimuli while remaining sensitive to others

19. The Thalamus Superior end of the brainstem “Gateway to cerebral cortex” All info passes through thalamus to cerebrum – Taste, smell, hearing, equilibrium, vision, touch, pain, pressure, heat, cold Memory and emotional functions – Limbic system

20. The Hypothalamus Control center of autonomic nervous system and endocrine system Homeostatic regulation – Hormone secretions – Autonomic effects – Thermoregulation – Food and H2O intake – Sleep and circadian rhythms Memory Emotional behavior

21. The Limbic System Center of emotion and learning Memory – Gratification center Sense of pleasure and reward when stimulated – Aversion center Unpleasant sensations when stimulated

22. The Cranial Nerves 12 pair (I-XII) Communicates with body – Arise from base of brain – Lead to muscles and sense organs mainly in head and neck Sensory- I, II, VIII Motor- III, IV, VI, XI, XII Both- V, VII, IX, X

24. I. Olfactory Nerve Function: Sense of smell Composition: Sensory Clinical Test: Determine whether subject can smell aromatic substances – Coffee, vanilla, clove, oil, soap Effect of Damage: impaired sense of smell

25. II. Optic Nerve Function: Vision Composition: Sensory Clinical Test: Test peripheral vision and visual acuity Effect of Damage: Blindness in part or all of visual field

26. III. Oculomotor Nerve Functions: Controls muscles that turn eyeballs up, down, medially – Controls iris, lens, and upper lid Composition: Motor Clinical Test: Look for pupil shape differences – Test pupillary response to light – Test ability to track moving objects Effect of Damage: Drooping eyelid, dilated pupil, inability to move eye in some directions, double vision, difficulty focusing

27. IV. Trochlear Nerve Function: Controls a muscle that rotates eyeball medially Composition: Motor Clinical Test: Test ability of eye to rotate inferolaterally Effect of Damage: double vision, inability to rotate eye inferolaterally

28. V. Trigeminal Nerve Function: Important in facial sensations Composition: Both Clinical Test: Test facial sensation of forehead, cheeks, and chin. – Test subjects ability to open mouth against resistance Effect of Damage: Loss of sensation from face and impaired chewing

29. VI. Abducens Nerve Function: Controls a muscle that turns eyeball laterally Composition: Motor Clinical Test: Test lateral eye movement Effect of Damage: Inability to turn eye laterally, at rest eye will turn medially

30. VII. Facial Nerve Function: Important nerve of facial muscles and taste Composition: Both Clinical Test: Test tongue for taste response, test ability to make facial expressions Effect of Damage: inability to control facial muscles, sagging due to loss of muscle tone, distorted sense of taste

31. VIII. Vestibocochlear Nerve Function: Hearing and equilibrium Composition: Sensory Clinical Test: Look for nystagmus, test hearing, balance, ability to walk in a straight line Effect of Damage: deafness, dizziness, nausea, loss of balance, nystagmus

32. IX. Glossopharyngeal Nerve Function: Food ingestion, salivation – Sensations from the tongue, throat, and outer ear Composition: Both Clinical Test: Test gag reflex, swallowing, and coughing Effect of Damage: impaired swallowing

33. X. Vagus Nerve Function: Control of cardiac, pulmonary, digestive, and urinary functions Composition: Both Clinical Test: Speech abnormalities, swallowing abnormalities, absence of gag reflex, weak or hoarse voice, inability to cough Effect of Damage: Hoarseness or loss of voice, impaired swallowing

34. XI. Accessory Nerve Function: Controls swallowing and neck and shoulder muscles Composition: Motor Clinical Test: Test ability to rotate head and shrug shoulders against resistance Effect of Damage: impaired movement of head, neck, and shoulders, difficulty shrugging shoulder on damaged side

35. XII. Hypoglossal Nerve Function: Controls tongue movements Composition: Motor Clinical Test: Note deviations of the tongue as subject protrudes and retracts it Effect of Damage: impaired speech and swallowing, inability to protrude tongue if both sides damaged, deviation of tongue toward injured side