2. Chapter 11 The Nervous System
The Brain, Cranial Nerves, Autonomic Nervous System, and the Special Senses

3. Introduction Brain is divided into four main parts
Brainstem: controls breathing, heartbeat rates and reactions to auditory and visual stimuli
Diencephalon: controls homeostasis
Cerebrum: controls intellectual processes and emotions
Cerebellum: maintains body posture and balance

4. The Principal Parts of the Brain

5. The Principal Parts of the Brain (cont’d.)
Main parts: brainstem, diencephalon, cerebrum, and cerebellum
Protection
Cranial bones
Meninges
Cerebrospinal fluid
Ventricles
Interventricular foramen

6. The Principal Parts of the Brain (cont’d.)

7. The Anatomy and Functions of the Brainstem

8. The Anatomy and Functions of the Brainstem (cont’d.)
Medulla oblongata
Ascending and descending tracts
Connect spinal cord with the brain
Some tracts cross over in medulla
Reticular formation: controls consciousness
Reflex centers

9. The Anatomy and Functions of the Brainstem (cont’d.)
Pons varolii
Connects spinal cord with brain
Connects parts of brain with each other
Helps control breathing

10. The Anatomy and Functions of the Brainstem (cont’d.)
Midbrain
Ventral cerebral peduncles: convey impulses from cortex to pons and spinal cord
Dorsal tectum: reflex center
Controls movement of head and eyeball (visual stimuli)
Controls movement of head and trunk (auditory stimuli)

11. The Anatomy and Functions of the Diencephalon

12. The Anatomy and Functions of the Diencephalon (cont’d.)
Optic tracts
Mamillary bodies: memory and emotional responses
Thalamus
Relay station for sensory impulses
Interpretation center for pain, temperature, and touch
Epithalamus: contains pineal gland

13. The Anatomy and Functions of the Diencephalon (cont’d.)
Hypothalamus: homeostasis
Controls and integrates autonomic nervous system
Receives sensory impulses from internal organs
Controls pituitary gland and links endocrine and nervous systems

14. The Cerebrum: Structure and Function

15. The Cerebrum: Structure and Function (cont’d.)
Needs Fig 11-4

16. The Cerebrum: Structure and Function (cont’d.)
Cerebral cortex: gray matter surface
Longitudinal fissure separates two hemispheres
Gyri: folds
Sulci: grooves
Corpus callosum: bridge connecting two hemispheres

17. The Cerebrum: Structure and Function (cont’d.)
Surface of the cortex
Motor areas control muscular movements
Sensory areas interpret sensory impulses
Association areas process emotions and intellect

18. The Cerebrum: Structure and Function (cont’d.)
Cerebral hemispheres
Frontal lobe: muscle movement, moods, aggression, smell, motivation
Parietal lobe: touch, pain, balance, taste, temperature
Temporal lobe: hearing, smell, memory, abstract thought, judgment
Occipital lobe: vision

19. The Cerebrum: Structure and Function (cont’d.)

20. The Cerebellum: Structure and Function

21. The Cerebellum: Structure and Function (cont’d.)
Butterfly-shaped
Two partially separated hemispheres connected by vermis
Functions
Coordinating muscular movements
Maintaining posture
Maintaining balance

22. The Autonomic Nervous System

23. The Autonomic Nervous System (cont’d.)
Subdivision of efferent PNS
Functions without conscious effort
Regulates functions of internal organs
Assists in maintaining homeostasis
Helps deal with emergency situations

24. The Autonomic Nervous System (cont’d.)
Sympathetic
Energy and stressful situations
Increases heartbeat and breathing rates
Neurotransmitters: acetylcholine and norepinephrine

25. The Autonomic Nervous System (cont’d.)
Parasympathetic
Restores body to nonstressful state
Neurotransmitter: acetylcholine
Stimulates digestion, urination, and defecation

26. The 12 Cranial Nerves and Their Functions

27. The 12 Cranial Nerves and Their Functions (cont’d.)
(I) Olfactory: smell
(II) Optic: sight
(III) Oculomotor: movement of eyeball, constriction of pupil
(IV) Trochlear: movement of eyeball

28. The 12 Cranial Nerves and Their Functions (cont’d.)
(V) Trigeminal: chewing, sensations in teeth
(VI) Abducens: movement of eyeball
(VII) Facial: facial expression, taste, tear and salivary glands
(VIII) Vestibulocochlear: equilibrium, hearing

29. The 12 Cranial Nerves and Their Functions (cont’d.)
(IX) Glossopharyngeal: swallowing, taste, salivary glands
(X) Vagus: certain muscle movements, sensory impulses
(XI) Accessory: swallowing, head movement
(XII) Hypoglossal: swallowing, speech

30. The Special Senses

31. The Sense of Smell Molecules in air dissolve in nasal mucus
Bipolar sensory neurons transfer chemical impulse
Olfactory bulbs receive impulse
Impulse sent to olfactory cortex
Odor variety dependent on brain interpretation

32. The Sense of Smell

33. The Sense of Taste Taste buds on tongue, palate, and pharynx
Taste bud cell types
Exterior capsule: epithelial cells
Interior: taste cells
Taste depends on chemicals dissolved in saliva
Taste influenced by olfactory sensations

34. The Sense of Taste

35. The Sense of Sight Eyes protected by eyelids and eyelashes Tears
Lubricate the eyes
Contain bacteriolytic lysozyme enzyme
Contain salt and gamma globulin

36. The Sense of Sight (cont’d.)
Needs Fig 11-10

37. The Sense of Sight (cont’d.)
Needs Fig 11-10

38. The Sense of Hearing and Equilibrium
Outer ear
Auricle: external, visible, flexible part
External auditory meatus
Lined with hair and ceruminous glands
Tympanic membrane: vibrates in response to sound

39. The Sense of Hearing and Equilibrium

40. The Sense of Hearing and Equilibrium

41. The Sense of Hearing and Equilibrium (cont’d.)
Middle ear
Auditory ossicles: malleus, incus, and stapes
Openings: oval and round windows
Eustachian tube: equalizes pressure

42. The Sense of Hearing and Equilibrium (cont’d.)
Inner ear
Cochlea: hearing
Equilibrium
Static: vestibule
Kinetic: semicircular canals

43. Summary Named the principal parts of the brain
Discussed the functions of the major parts of the brain
Named the 12 cranial nerves
Discussed the role of the autonomic nervous system and its divisions
Described the special senses and the organs involved