Understanding the Central Nervous System: Brain and Spinal Cord

1. 13 PART 1 The CentralNervous System

2. The Central Nervous System Central nervous system The brain and spinal cord Directional terms unique to the CNS Rostral—toward the nose Caudal—toward the tail

3. The Brain Brain controls: Heart rate, respiratory rate, blood pressure Autonomic nervous system Endocrine system Is involved in innervation of the head through cranial nerves

4. The Brain Performs the most complex functions Intelligence Consciousness Memory Sensory-motor integration Emotion Behavior Socialization

5. Basic Parts and Organization of the Brain Classified into four regions Brain stem Cerebellum Diencephalon Cerebral hemispheres

6. Basic Parts and Organization of the Brain Organization Centrally located gray matter Externally located white matter Additional layer of gray matter external to white matter Cortex—outer layer of gray matter Formed from neuronal cell bodies Located in cerebrum and cerebellum

7. Figure 13.3 Pattern of gray and white matter in the CNS (highly simplified). Cortex ofgray matter Central cavity Inner graymatter Outer white matter Cerebrum Cerebellum Gray matter(brain nuclei) Region ofcerebellum Central cavity Inner graymatter Outer whitematter Gray matter(brain nuclei) Brain stem Centralcavity Outer whitematter Inner graymatter Spinal cord

8. Ventricles of the Brain Expansions of the brain’s central cavity Filled with cerebrospinal fluid Lined with ependymal cells Continuous with each other Continuous with the central canal of the spinal cord

9. Ventricles of the Brain Lateral ventricles—located in cerebral hemispheres Horseshoe-shaped Third ventricle—lies in diencephalon Connected with lateral ventricles by interventricular foramen Cerebral aqueduct—connects 3rd and 4th ventricles Fourth ventricle—lies in hindbrain Connects to the central canal of the spinal cord

10. Figure 13.4 Ventricles of the brain. Lateral ventricle Anterior horn Posteriorhorn Septumpellucidum Interventricularforamen Inferiorhorn Inferiorhorn Third ventricle Medianaperture Cerebral aqueduct Lateralaperture Fourth ventricle Lateralaperture Central canal Left lateral view Anterior view

11. The Brain Stem Includes the Midbrain Pons Medulla oblongata

12. The Brain Stem Several general functions Passageway for all fiber tracts running between the cerebrum and spinal cord Heavily involved with the innervation of the face and head 10 of the 12 pairs of cranial nerves attach to it Produces automatic behaviors necessary for survival Integrates auditory and visual reflexes

13. Figure 13.5 Ventral view of the brain showing the three parts of the brain stem: medulla oblongata, pons, and midbrain. Frontal lobe Olfactory bulb(synapse point ofcranial nerve I) Optic chiasma Optic nerve (II) Optic tract Mammillary body Midbrain Pons Temporallobe Medullaoblongata Cerebellum Spinal cord

14. The Brain Stem—The Medulla Oblongata Most of the caudal level of the brain stem Is continuous with the spinal cord Choroid plexus lies in the roof of the fourth ventricle External landmarks of medulla Pyramids of the medulla Lie on its ventral surface Decussation of the pyramids Crossing over of motor tracts Cerebellar peduncles Fiber tracts connecting medulla and cerebellum Olive (olive of the medulla) Contains inferior olivary nucleus

15. The Brain Stem—The Medulla Oblongata Four pairs of cranial nerves attach to the medulla oblongata VIII—vestibulocochlear nerve IX—glossopharyngeal nerve X—vagus nerve XII—hypoglossal nerve

16. Figure 13.6a Three views of the brain stem (shades of green) and diencephalon (purple). Thalamus Diencephalon Hypothalamus Midbrain View (a) View (c) Pons Brainstem Medullaoblongata View (b) Optic chiasma Diencephalon Optic nerve (II) Thalamus Optic tract Hypothalamus Mammillary body Oculomotor nerve (III) Trochlear nerve (IV) Cerebral peduncles (midbrain) Trigeminal nerve (V) Middle cerebellarpeduncle Pons Facial nerve (VII) Abducens nerve (VI) Glossopharyngeal nerve (IX) Vestibulocochlear nerve (VIII) Hypoglossal nerve (XII) Pyramid Vagus nerve (X) Ventral root of first cervical nerve Accessory nerve (XI) Decussation of pyramids Spinal cord Ventral view

17. The Brain Stem—The Medulla Oblongata The core of the medulla contains Much of the reticular formation Nuclei influence autonomic functions Visceral centers of the reticular formation include Cardiac center Vasomotor center The medullary respiratory center Centers for hiccupping, sneezing, swallowing, and coughing

18. The Brain Stem—The Pons A “bridge” between the midbrain and medulla oblongata Pons contains the nuclei of cranial nerves V—trigeminal nerve VI—abducens nerve VII—facial nerve

19. The Brain Stem—The Pons The pons contains Motor tracts coming from the cerebral cortex Pontine nuclei Connect portions of the cerebral cortex and cerebellum Send axons to cerebellum through the cerebellar peduncles

20. The Brain Stem—The Midbrain Lies between the diencephalon and the pons Cerebral aqueduct The central cavity of the midbrain Cerebral peduncles located on the ventral surface of the brain Contain pyramidal (corticospinal) tracts

21. The Brain Stem—The Midbrain Periaqueductal gray matter surrounds the cerebral aqueduct Corpora quadrigemina The largest nuclei Divided into the superior and inferiorcolliculi Superior colliculi—nuclei that act in visual reflexes Inferior colliculi—nuclei that act in reflexive response to sound

22. Figure 13.6c Three views of the brain stem (shades of green) and diencephalon (purple). Thalamus Diencephalon Hypothalamus Midbrain View (c) View (a) Pons Brainstem Medullaoblongata View (b) Thalamus Diencephalon Midbrain Superiorcolliculus Corporaquadrigeminaof tectum Inferiorcolliculus Pineal gland Trochlear nerve (IV) Pons Facial nerve (VII) Floor of fourthventricle Medulla oblongata Vestibulocochlear nerve (VIII) Choroid plexus(fourth ventricle) Glossopharyngeal nerve (IX) Vagus nerve (X) Accessory nerve (XI) Dorsal root offirst cervical nerve Dorsal view

23. The Brain Stem—The Midbrain Embedded in the white matter of the midbrain Two pigmented nuclei Substantia nigra—neuronal cell bodies containing melanin Functionally linked to the basal nuclei Red nucleus—lies deep to the substantia nigra Largest nucleus of the reticular formation

24. The Cerebellum Located dorsal to the pons and medulla Smoothing and coordinating body movements Helps maintain equilibrium Consists of two cerebellar hemispheres Hemispheres each subdivided into Anterior lobe Posterior lobe

25. Figure 13.8b Cerebellum. Anterior lobe Arbor vitae Cerebellarcortex Anterior lobe Folia Cerebellar cortex Arbor vitae Pons Posteriorlobe Fourthventricle Choroidplexus Posteriorlobe Cerebellarpeduncles Medullaoblongata Choroid plexus offourthventricle Midsagittal section Medullaoblongata Illustration of parasagittal section

26. The Cerebellum Composed of three regions Cortex—gray matter Arbor vitae—Internal white matter Deep cerebellar nuclei—deeply situated gray matter To coordinate body movements, the cerebellar cortex receives three types of information Information on equilibrium Information on current movements of the limbs, neck, and trunk Information from the cerebral cortex

27. The Cerebellum Coordinating movement The cerebellum receives information on movement from the motor cortex of the cerebrum The cerebellum compares intended movement with body position The cerebellum sends instructions back to the cerebral cortex to continuously adjust and fine-tune motor commands

28. The Cerebellum Higher cognitive functions of the cerebellum Learning a new motor skill Participates in cognition Language, problem solving, task planning

29. The Diencephalon Forms the central core of the forebrain Surrounded by the cerebral hemispheres Composed of three paired structures Thalamus Hypothalamus Epithalamus Border the third ventricle Primarily composed of gray matter

30. Figure 13.9a Midsagittal section of the brain. Cerebral hemisphere Corpus callosum Septum pellucidum Fornix Interthalamicadhesion(intermediatemass of thalamus) Choroid plexus Thalamus(encloses third ventricle) Interventricularforamen Posteriorcommissure Epithalamus Pineal gland Anteriorcommissure Corporaquadrigemina Hypothalamus Midbrain Cerebralaqueduct Optic chiasma Pituitary gland Arbor vitae (of cerebellum) Mammillarybody Fourth ventricle Choroid plexus Pons Cerebellum Medullaoblongata Spinal cord

31. Figure 13.9b Midsagittal section of the brain. Corpus callosum Fornix Lateral ventricle Thalamus Posteriorcommissure Epithalamus Pineal gland Third ventricle Corporaquadrigemina Anteriorcommissure Midbrain Cerebralaqueduct Hypothalamus Arbor vitae Optic chiasm Fourth ventricle Cerebellum Mammillary body Pons Medulla oblongata

32. The Diencephalon—The Thalamus Makes up 80% of the diencephalon Contains approximately a dozen major nuclei Act as relay stations for incoming sensory message Every part of brain communicating with cerebral cortex relays signals through thalamic nuclei!

33. The Diencephalon—The Hypothalamus Lies between the optic chiasm and the mammillary bodies Pituitary gland projects inferiorly Contains approximately a dozen nuclei Main visceral control center of the body

34. The Diencephalon—The Hypothalamus Functions include the following Control of the ANS Control of emotional responses Regulation of body temperature Regulation of hunger and thirst sensations Control of behavior Regulation of sleep-wake cycles Control of the endocrine system Formation of memory

35. The Diencephalon—The Epithalamus Forms part of the “roof” (top) of the third ventricle Consists of a tiny group of nuclei Includes the pineal gland (pineal body) Secretes the hormone melatonin Under influence of the hypothalamus Aids in control of circadian rhythm

36. The Cerebral Hemispheres Account for 83% of brain mass Fissures—deep grooves that separate major regions of the brain Transverse fissure—separates cerebrum and cerebellum Longitudinal fissure—separates the right and left cerebral hemispheres

37. The Cerebral Hemispheres Sulci Grooves of tissue on the surface of the cerebral hemispheres Gyri Twisted ridges (spaces) between sulci Prominent gyri and sulci are similar in all people

38. The Cerebral Hemispheres Deeper sulci divide cerebrum into lobes Lobes are named for the skull bones overlying them Central sulcus separates frontal and parietal lobes Bordered by two gyri Precentral gyrus Postcentral gyrus

39. Figure 13.11c Lobes, sulci, and fissures of the cerebral hemispheres. Centralsulcus Postcentral gyrus Precentral gyrus Parietallobe Parieto-occipitalsulcus Lateralsulcus Occipitallobe Temporallobe Fissure(a deepsulcus) Gyrus Cortex (gray matter) Sulcus White matter Lobes and sulci of the cerebrum

40. The Cerebral Hemispheres Parieto-occipital sulcus Separates the occipital from the parietal lobe Lateral sulcus Separates temporal lobe from parietal and frontal lobes Insula—deep within the lateral sulcus

41. Lobes of the Cerebral Cortex Centralsulcus Frontal lobe,retracted Gyri of insula,deep in lateralsulcus Temporal lobe,retracted Location of the insula lobe Figure 13.11d Lobes, sulci, and fissures of the cerebral hemispheres. Frontal lobe Parietal lobe Occipital lobe Temporal lobe Insula

42. The Cerebral Cortex Home of our conscious mind Enables us to Be aware of ourselves and our sensations Initiate and control voluntary movements Communicate, remember, and understand Composed of gray matter Neuronal cell bodies, dendrites, and short axons Folds in cortex—triples its size Approximately 40% of brain’s mass

43. The Cerebral Cortex Functional regions Traditionally studied brain-injured people and animals Regions of the cerebral cortex Perform distinct motor and sensory functions Memory and language spread over wide area Three general kinds of functional areas Sensory, Association, and Motor areas Rotating Brain

44. The Cerebral Cortex There is a sensory area for each of the major senses A “primary sensory cortex” Each primary sensory cortex Has an association area that processes sensory information Sensoryassociation areas Multimodal association areas Receive and integrate input from multiple regions of the cerebral cortex Motor cortex Plans and initiates voluntary motor functions

45. The Cerebral Cortex—Information Processing Sensory information received by primary sensory cortex Information relayed to sensory association area Multimodal association areas receive input in parallel from sensory areas Motor plan enacted

46. Figure 13.13a Functional areas of the cerebral cortex. Sensory areas and relatedassociation areas Motor areas Central sulcus Primary motor cortex Primary somatosensorycortex Premotor cortex Somaticsensation Somatosensoryassociation cortex Frontaleye field Broca’s area(outlined by dashes) Gustatory cortex(in insula) Taste Anterior association area(Prefrontal cortex) Wernicke’s area(within the posteriorassociation areaoutlined by dashes) Working memoryfor spatial tasks Executive area fortask management Primary visualcortex Working memory forobject-recall tasks Vision Visualassociationarea Solving complex,multitask problems Auditoryassociation area Hearing Primaryauditory cortex Lateral view, left cerebral hemisphere Primary sensory cortex Multimodal association cortex Primary motor cortex Sensory association cortex Motor association cortex

47. Figure 13.13b Functional areas of the cerebral cortex. Primarymotor cortex Premotorcortex Central sulcus Corpuscallosum Primary somatosensorycortex Frontal eye field Parietal lobe Somatosensoryassociation cortex Prefrontalcortex Parieto-occipitalsulcus Limbic association area Cingulate gyrus Occipitallobe Processes emotionsrelated to personaland social interactions Visual associationarea Orbitofrontalcortex Olfactory bulb Primaryvisual cortex Olfactory tract Calcarinesulcus Fornix Primaryolfactorycortex Parahippocampalgyrus Temporallobe Uncus Parasagittal view, right hemisphere Primary sensory cortex Multimodal association cortex Primary motor cortex Sensory association cortex Motor association cortex

48. Sensory Areas Cortical areas involved in conscious awareness of sensation Located in Parietal lobes Temporal lobes Occipital lobes Distinct regions of each lobe interpret each of the major senses Rotating Sectioned Brain

49. Sensory Areas—Primary Somatosensory Cortex Located along the postcentral gyrus Involved with conscious awareness of general somatic senses Spatial discrimination Precisely locates a stimulus

50. Sensory Areas—Primary Somatosensory Cortex Projection is contralateral Cerebral hemispheres Receive sensory input from the opposite side of the body Sensory homunculus A body map of the sensory cortex