1. 13 The Brain and Cranial Nerves C h a p t e r
PowerPoint® Lecture Slides prepared by Jason LaPres
Lone Star College - North Harris

2. An Introduction to the Brain and Cranial Nerves
The Adult Human Brain
Ranges from 750 cc to 2100 cc
Contains almost 97% of the body’s neural tissue
Average weight about 1.4 kg (3 lb)
Copyright © 2010 Pearson Education, Inc.

3. The Brain Six Regions of the Brain Cerebrum Cerebellum Diencephalon
Mesencephalon
Pons
Medulla oblongata
3D Peel-Away of the Brain
Copyright © 2010 Pearson Education, Inc.

4. The Brain Cerebrum Largest part of brain
Controls higher mental functions
Divided into left and right cerebral hemispheres
Surface layer of gray matter (neural cortex)
Copyright © 2010 Pearson Education, Inc.

5. The Brain Cerebrum Neural cortex Also called cerebral cortex
Folded surface increases surface area
Elevated ridges (gyri)
Shallow depressions (sulci)
Deep grooves (fissures)
Copyright © 2010 Pearson Education, Inc.

6. The Brain Cerebellum Second largest part of brain
Coordinates repetitive body movements
Two hemispheres
Covered with cerebellar cortex
Copyright © 2010 Pearson Education, Inc.

7. The Brain Diencephalon Located under cerebrum and cerebellum
Links cerebrum with brain stem
Three divisions
Left thalamus
Right thalamus
Hypothalamus
Copyright © 2010 Pearson Education, Inc.

8. The Brain Diencephalon Thalamus Hypothalamus Pituitary gland
Relays and processes sensory information
Hypothalamus
Hormone production
Emotion
Autonomic function
Pituitary gland
Major endocrine gland
Connected to hypothalamus
Via infundibulum (stalk)
Interfaces nervous and endocrine systems
Copyright © 2010 Pearson Education, Inc.

9. The Brain The Brain Stem Processes information between Includes
Spinal cord and cerebrum or cerebellum
Includes
Mesencephalon
Pons
Medulla oblongata
Copyright © 2010 Pearson Education, Inc.

10. The Brain The Brain Stem Mesencephalon Pons Also called midbrain
Processes sight, sound, and associated reflexes
Maintains consciousness
Pons
Connects cerebellum to brain stem
Is involved in somatic and visceral motor control
Copyright © 2010 Pearson Education, Inc.

11. The Brain The Brain Stem Medulla oblongata
Connects brain to spinal cord
Relays information
Regulates autonomic functions:
heart rate, blood pressure, and digestion
Copyright © 2010 Pearson Education, Inc.

12. The Brain
Figure 13–1 An Introduction to Brain Structures and Functions.
Copyright © 2010 Pearson Education, Inc.

13. The Brain Embryological Development
Determines organization of brain structures
Neural tube
Origin of brain
Enlarges into three primary brain vesicles
prosencephalon
mesencephalon
rhombencephalon
Copyright © 2010 Pearson Education, Inc.

14. The Brain Five Secondary Brain Vesicles Telencephalon Diencephalon
Mesencephalon
Metencephalon
Myelencephalon
Copyright © 2010 Pearson Education, Inc.

15. The Brain Origins of Brain Structures
Diencephalon and mesencephalon persist
Telencephalon:
Becomes cerebrum
Metencephalon
Forms cerebellum and pons
Myelencephalon
Becomes medulla oblongata
Copyright © 2010 Pearson Education, Inc.

16. The Brain
Copyright © 2010 Pearson Education, Inc.

17. The Brain Ventricles of the Brain Origins of ventricles
Neural tube encloses neurocoel
Neurocoel expands to form chambers (ventricles) lined with ependymal cells
Each cerebral hemisphere contains one large lateral ventricle
Separated by a thin medial partition (septum pellucidum)
Copyright © 2010 Pearson Education, Inc.

18. The Brain Ventricles of the Brain Third ventricle
Ventricle of the diencephalon
Lateral ventricles communicate with third ventricle:
via interventricular foramen (foramen of Monro)
Copyright © 2010 Pearson Education, Inc.

19. The Brain Ventricles of the Brain Fourth ventricle
Extends into medulla oblongata
Becomes continuous with central canal of the spinal cord
Connects with third ventricle:
via narrow canal in mesencephalon
aqueduct of midbrain
Copyright © 2010 Pearson Education, Inc.

20. The Brain Figure 13–2 Ventricles of the Brain.
Copyright © 2010 Pearson Education, Inc.

21. The Brain
The brain is a large, delicate mass of neural tissue containing internal passageways and chambers filled with cerebrospinal fluid
Each of the six major brain regions has specific functions
Ascending from the medulla oblongata to the cerebrum, brain functions become more complex and variable
Conscious thought and intelligence are produced in the neural cortex of the cerebral hemispheres
Copyright © 2010 Pearson Education, Inc.

22. Brain Protection and Support
Physical protection
Bones of the cranium
Cranial meninges
Cerebrospinal fluid
Biochemical isolation
Blood–brain barrier
Copyright © 2010 Pearson Education, Inc.

23. Brain Protection and Support
The Cranial Meninges
Have three layers:
Dura mater
Arachnoid mater
Pia mater
Are continuous with spinal meninges
Protect the brain from cranial trauma
Copyright © 2010 Pearson Education, Inc.

24. Brain Protection and Support
The Cranial Meninges
Dura mater
Inner fibrous layer (meningeal layer)
Outer fibrous layer (endosteal layer) fused to periosteum
Venous sinuses between two layers
Arachnoid mater
Covers brain
Contacts epithelial layer of dura mater
Subarachnoid space: between arachnoid mater and pia mater
Pia mater
Attached to brain surface by astrocytes
Copyright © 2010 Pearson Education, Inc.

25. Brain Protection and Support
Dural Folds
Folded inner layer of dura mater
Extend into cranial cavity
Stabilize and support brain
Contain collecting veins (dural sinuses)
Falx cerebri, tentorium cerebelli, and falx cerebelli
Copyright © 2010 Pearson Education, Inc.

26. Brain Protection and Support
Dural Folds
Falx cerebri
Projects between the cerebral hemispheres
Contains superior sagittal sinus and inferior sagittal sinus
Tentorium cerebelli
Separates cerebellum and cerebrum
Contains transverse sinus
Falx cerebelli
Divides cerebellar hemispheres below the tentorium cerebelli
Copyright © 2010 Pearson Education, Inc.

27. Brain Protection and Support
Figure 13–3a The Relationship among the Brain, Cranium, and Meninges.
Copyright © 2010 Pearson Education, Inc.

28. Brain Protection and Support
Figure 13–3b The Relationship among the Brain, Cranium, and Meninges.
Copyright © 2010 Pearson Education, Inc.

29. Brain Protection and Support
Cerebrospinal Fluid (CSF)
Surrounds all exposed surfaces of CNS
Interchanges with interstitial fluid of brain
Functions of CSF
Cushions delicate neural structures
Supports brain
Transports nutrients, chemical messengers, and waste products
Copyright © 2010 Pearson Education, Inc.

30. Brain Protection and Support
Cerebrospinal Fluid (CSF)
Choroid plexus
Specialized ependymal cells and capillaries:
secrete CSF into ventricles
remove waste products from CSF
adjust composition of CSF
Produces about 500 mL of CSF/day
Copyright © 2010 Pearson Education, Inc.

31. Brain Protection and Support
Cerebrospinal Fluid (CSF)
CSF circulates
From choroid plexus
Through ventricles
To central canal of spinal cord
Into subarachnoid space around the brain, spinal cord, and cauda equina
Copyright © 2010 Pearson Education, Inc.

32. Brain Protection and Support
Cerebrospinal Fluid (CSF)
CSF in subarachnoid space
Arachnoid villi:
extensions of subarachnoid space
extend through dura mater to superior sagittal sinus
Arachnoid granulations:
large clusters of villi
absorb CSF into venous circulation
Copyright © 2010 Pearson Education, Inc.

33. Brain Protection and Support
Figure 13–4 The Formation and Circulation of Cerebrospinal Fluid.
Copyright © 2010 Pearson Education, Inc.

34. Brain Protection and Support
Figure 13–4a The Formation and Circulation of Cerebrospinal Fluid.
Copyright © 2010 Pearson Education, Inc.

35. Brain Protection and Support
Figure 13–4b The Formation and Circulation of Cerebrospinal Fluid.
Copyright © 2010 Pearson Education, Inc.

36. Brain Protection and Support
Blood Supply to the Brain
Supplies nutrients and oxygen to brain
Delivered by internal carotid arteries and vertebral arteries
Removed from dural sinuses by internal jugular veins
Copyright © 2010 Pearson Education, Inc.

37. Brain Protection and Support
Figure 19–22 Arteries of the Neck and Head.
Copyright © 2010 Pearson Education, Inc.

38. Brain Protection and Support
Figure 19–23 Arteries of the Brain.
Copyright © 2010 Pearson Education, Inc.

39. Brain Protection and Support
Figure 19–28 Major Veins of the Head, Neck, and Brain.
Copyright © 2010 Pearson Education, Inc.

40. Brain Protection and Support
Figure 19–28 Major Veins of the Head, Neck, and Brain.
Copyright © 2010 Pearson Education, Inc.

41. Brain Protection and Support
Cerebrovascular Disease
Disorders interfere with blood circulation to brain
Stroke or cerebrovascular accident (CVA)
Shuts off blood to portion of brain
Neurons die
Copyright © 2010 Pearson Education, Inc.

42. Brain Protection and Support
Blood–Brain Barrier
Isolates CNS neural tissue from general circulation
Formed by network of tight junctions
Between endothelial cells of CNS capillaries
Lipid-soluble compounds (O2, CO2), steroids, and prostaglandins diffuse into interstitial fluid of brain and spinal cord
Astrocytes control blood–brain barrier by releasing chemicals that control permeability of endothelium
Copyright © 2010 Pearson Education, Inc.

43. Brain Protection and Support
Blood–CSF Barrier
Formed by special ependymal cells
Surround capillaries of choroid plexus
Limits movement of compounds transferred
Allows chemical composition of blood and CSF to differ
Copyright © 2010 Pearson Education, Inc.

44. Brain Protection and Support
Four Breaks in the BBB
Portions of hypothalamus
Secrete hypothalamic hormones
Posterior lobe of pituitary gland
Secretes hormones ADH and oxytocin
Pineal glands
Pineal secretions
Choroid plexus
Where special ependymal cells maintain blood–CSF barrier
Copyright © 2010 Pearson Education, Inc.

45. Brain Protection and Support
Meninges stabilize brain in cranial cavity
Cerebrospinal fluid protects against sudden movement
CSF provides nutrients and removes wastes
Blood–brain barrier and blood–CSF barrier
Selectively isolate brain from chemicals in blood that might disrupt neural function
Copyright © 2010 Pearson Education, Inc.

46. The Medulla Oblongata The Medulla Oblongata
Allows brain and spinal cord to communicate
Coordinates complex autonomic reflexes
Controls visceral functions
Nuclei in the Medulla
Autonomic nuclei: control visceral activities
Sensory and motor nuclei: of cranial nerves
Relay stations: along sensory and motor pathways
Copyright © 2010 Pearson Education, Inc.

47. The Medulla Oblongata Figure 13–5a The Diencephalon and Brain Stem.
Copyright © 2010 Pearson Education, Inc.

48. The Medulla Oblongata Figure 13–5b The Diencephalon and Brain Stem.
Copyright © 2010 Pearson Education, Inc.

49. The Medulla Oblongata Figure 13–5c The Diencephalon and Brain Stem.
Copyright © 2010 Pearson Education, Inc.

50. The Medulla Oblongata The Medulla Oblongata
Includes three groups of nuclei
Autonomic nuclei
Sensory and motor nuclei of cranial nerves
Relay stations along sensory and motor pathways
Copyright © 2010 Pearson Education, Inc.

51. The Medulla Oblongata Autonomic Nuclei of the Medulla Oblongata
Reticular formation
Gray matter with embedded nuclei
Regulates autonomic functions
Reflex centers
Control peripheral systems:
cardiovascular centers:
cardiac center
control blood flow through peripheral tissues
respiratory rhythmicity centers
sets pace for respiratory movements
Copyright © 2010 Pearson Education, Inc.

52. The Medulla Oblongata
Sensory and Motor Nuclei of the Medulla Oblongata
Associated with 5 of 12 cranial nerves (VIII, IX, X, XI, XII)
Copyright © 2010 Pearson Education, Inc.

53. The Medulla Oblongata Relay Stations of the Medulla Oblongata
Nucleus gracilis and nucleus cuneatus
Pass somatic sensory information to thalamus
Solitary nucleus
Receives visceral sensory information
Olivary nuclei (olives)
Relay information about somatic motor commands
Copyright © 2010 Pearson Education, Inc.

54. The Medulla Oblongata Figure 13–6a The Medulla Oblongata and Pons.
Copyright © 2010 Pearson Education, Inc.

55. The Medulla Oblongata Figure 13–6b The Medulla Oblongata and Pons.
Copyright © 2010 Pearson Education, Inc.

56. The Pons
The Pons
Links cerebellum with mesencephalon, diencephalon, cerebrum, and spinal cord
Sensory and motor nuclei of cranial nerves V, VI, VII, VIII
Copyright © 2010 Pearson Education, Inc.

57. The Pons The Pons Nuclei involved with respiration Nuclei and tracts
Apneustic center and pneumotaxic center:
modify respiratory rhythmicity center activity
Nuclei and tracts
Process and relay information to and from cerebellum
Ascending, descending, and transverse tracts:
transverse fibers (axons):
link nuclei of pons with opposite cerebellar hemisphere
Copyright © 2010 Pearson Education, Inc.