1. The Brain and Cranial Nerves
Chapter 15

2. Introduction to the Brain
Weighs about 3 lbs. in adults
Structures
Divided into 5 areas
Contains ventricles
Functions
Controls the bare necessities of life
Location for primal drives and emotions
Intellectual thought, imagination, perception, etc.
Human Anatomy, 3rd edition
Prentice Hall, © 2001

3. Development of the Brain

4. Human Anatomy, 3rd edition
3-4 Weeks
FG15_ES1.JPG
Title: Embryology Summary: Development of the Brain and Cranial Nerves
Notes: Diagrammatic summary of the embryological events in the formation of the brain and cranial nerves.
Keywords: cephalic area, neural tube, prosencephalon, mesencephalon, rhombencephalon, neurocoel, metencephalon, myelencephalon, telencephalon, diencephalon, cranial nerves, pons, cerebellum, medulla oblongata, cerebral hemisphere
Human Anatomy, 3rd edition
Prentice Hall, © 2001

5. Human Anatomy, 3rd edition
4 Weeks
FG15_ES2.JPG
Title: Embryology Summary: Development of the Brain and Cranial Nerves
Notes: Diagrammatic summary of the embryological events in the formation of the brain and cranial nerves.
Keywords: cephalic area, neural tube, prosencephalon, mesencephalon, rhombencephalon, neurocoel, metencephalon, myelencephalon, telencephalon, diencephalon, cranial nerves, pons, cerebellum, medulla oblongata, cerebral hemisphere
Human Anatomy, 3rd edition
Prentice Hall, © 2001

6. Human Anatomy, 3rd edition
5 Weeks
FG15_ES3.JPG
Title: Embryology Summary: Development of the Brain and Cranial Nerves
Notes: Diagrammatic summary of the embryological events in the formation of the brain and cranial nerves.
Keywords: cephalic area, neural tube, prosencephalon, mesencephalon, rhombencephalon, neurocoel, metencephalon, myelencephalon, telencephalon, diencephalon, cranial nerves, pons, cerebellum, medulla oblongata, cerebral hemisphere
Human Anatomy, 3rd edition
Prentice Hall, © 2001

7. Human Anatomy, 3rd edition
11 Weeks
FG15_ES5.JPG
Title: Embryology Summary: Development of the Brain and Cranial Nerves
Notes: Diagrammatic summary of the embryological events in the formation of the brain and cranial nerves.
Keywords: cephalic area, neural tube, prosencephalon, mesencephalon, rhombencephalon, neurocoel, metencephalon, myelencephalon, telencephalon, diencephalon, cranial nerves, pons, cerebellum, medulla oblongata, cerebral hemisphere
Human Anatomy, 3rd edition
Prentice Hall, © 2001

8. Human Anatomy, 3rd edition
A Child’s Brain
FG15_ES6.JPG
Title: Embryology Summary: Development of the Brain and Cranial Nerves
Notes: Diagrammatic summary of the embryological events in the formation of the brain and cranial nerves.
Keywords: cephalic area, neural tube, prosencephalon, mesencephalon, rhombencephalon, neurocoel, metencephalon, myelencephalon, telencephalon, diencephalon, cranial nerves, pons, cerebellum, medulla oblongata, cerebral hemisphere
Human Anatomy, 3rd edition
Prentice Hall, © 2001

9. The Adult Brain

10. Adult Brain – Forebrain (Prosencephalon)
Cerebrum (telencephalon)
Thalamus, hypothalamus (diencephalon)
Human Anatomy, 3rd edition
Prentice Hall, © 2001

11. Adult Brain – Midbrain (Mesencephalon)
FG15_01D.JPG
Title: Major Divisions of the Brain
Notes: An introduction to brain regions and their major functions.
Keywords: brain function, introduction, cerebrum, telencephalon, diencephalon, thalamus, hypothalamus, mesencephalon, midbrain, pons, metencephalon, medulla oblongata, myelencephalon, cerebellum, metencephalon
Human Anatomy, 3rd edition
Prentice Hall, © 2001

12. Adult Brain – Hindbrain (Rhombencephalon)
Pons and cerebellum (metencephalon)
Medulla oblongata (myelencephalon)
Human Anatomy, 3rd edition
Prentice Hall, © 2001

13. Ventricles of the Brain
Lateral ventricles
Separated by the septum pallucidum
Connects to third ventricle
Interventricular foramen
Third ventricle
Connects to fourth ventricle
Cerebral aqueduct
Human Anatomy, 3rd edition
Prentice Hall, © 2001

14. Ventricles of the Brain
Fourth ventricle
Connects to the subarachnoid space and spinal canal
Cerebrospinal fluid circulates down through the ventricles and into the spinal cord.
FG15_02A.JPG
Title: Ventricles of the Brain
Notes: These chambers contain cerebrospinal fluid, which transports nutrients, chemical messengers, and waste products. (a) Orientation and extent of ventricles. (b) Plastic cast of ventricles. (c) Anterior view. (d) Diagrammatic coronal section.
Keywords: brain, ventricles, mesencephalic aqueduct, third ventricle, interventricular foramen, lateral ventricles, fourth ventricle, median aperture
Human Anatomy, 3rd edition
Prentice Hall, © 2001

15. Protections and Coverings
Cranial bones – strong support
Cranial meninges – shock absorbers
Dura mater – 2 layers
Endosteal (periosteal)
Meningeal
Arachnoid
Pia mater
Human Anatomy, 3rd edition
Prentice Hall, © 2001

16. Human Anatomy, 3rd edition
Blood-Brain Barrier
Astrocytes
Secrete chemicals that maintain the BBB
Absorb materials from blood
Extract materials from brain
Endothelial cells of capillaries form tight junctions
Lipid-soluble compounds
Water-soluble compounds
Human Anatomy, 3rd edition
Prentice Hall, © 2001

17. Human Anatomy, 3rd edition
Cerebrospinal Fluid
Composition
Proteins, glucose, urea, salts
White blood cells
Functions
Shock absorber
Medium of transport for nutrients, gases, etc.
Formed by the choroid plexus (“vascular braid”)
Human Anatomy, 3rd edition
Prentice Hall, © 2001

18. Problems Associated with CSF
Hydrocephalus
Meningitis
Headaches

19. Forebrain Cerebrum, Hypothalamus, Thalamus
The Parts of the Brain
Forebrain
Cerebrum, Hypothalamus, Thalamus

20. Cerebrum – Gray & White Matter
Outer layer – cerebral cortex
Gray matter
Inner portion
White matter
Projection tracts
Association tracts
Commissural tracts (corpus collosum)
Masses of gray matter
Cerebral nuclei
Human Anatomy, 3rd edition
Prentice Hall, © 2001

21. Human Anatomy, 3rd edition
Cerebral Cortex
Gyri are separated by grooves (sulci)
Fissures – deeper grooves
Longitudinal fissure
Divides the cerebrum into cerebral hemispheres
Central sulcus
Precentral gyrus
Post-central gyrus
Human Anatomy, 3rd edition
Prentice Hall, © 2001

22. Human Anatomy, 3rd edition
Cerebral Lobes
Frontal lobe
Decision-making, planning
Broca’s area
Primary motor cortex
Parietal lobe
Speech comprehension, reading, taste
Primary sensory cortex
Occipital lobe
Visual cortex
Temporal lobe
Wernicke’s area
Olfactory cortex
Auditory cortex
Human Anatomy, 3rd edition
Prentice Hall, © 2001

23. Homunculus
Primary Motor Cortex
Primary Sensory Cortex

24. Human Anatomy, 3rd edition
Cerebral Nuclei
Collections of cell bodies (gray matter)
Mostly control the movement of skeletal muscles
Examples
Caudate nucleus
Amygdaloid body
Human Anatomy, 3rd edition
Prentice Hall, © 2001

25. Human Anatomy, 3rd edition
Limbic System
Functional unit
Emotional part of the brain
Feelings of fear, loss, love, rage, etc.
Includes parts of several anatomical structures
Cerebrum
Hypothalamus
Thalamus
Human Anatomy, 3rd edition
Prentice Hall, © 2001

26. Human Anatomy, 3rd edition
Hypothalamus
Location – floor of the third ventricle
Structure
Mammillary bodies
Feeding reflexes
Infundibulum
Autonomic centers
Nuclei
Human Anatomy, 3rd edition
Prentice Hall, © 2001

27. Functions of Hypothalamus
Initiates primal drives
Hunger, thirst, sex, rage, etc.
Controls “fight or flight” sympathetic response.
Sets emotional states (with limbic system)
Controls pituitary gland (“master gland” of endocrine system)
Secretes “releasing factors” and “inhibiting factors”
Infundibulum (“funnel”) funnels secretions to the pituitary gland

28. Thalamus and Epithalamus
Superior brain stem
Relay station between the body and cerebral cortex
Emotion (limbic system)
Integrates visual & auditory reflexes
Epithalamus
Roof of third ventricle
Contains pineal body
Secretes melatonin
Contains choroid plexus
Human Anatomy, 3rd edition
Prentice Hall, © 2001

29. Midbrain

30. Midbrain (Mesencephalon)
Cerebral peduncles – on anterolateral surface
Motor neurons from cerebral cortex to pons and spinal cord
Sensory neurons to the thalamus
Corpora quadrigemina
Superior colliculi receive visual information
Inferior colliculi receive auditory information
Human Anatomy, 3rd edition
Prentice Hall, © 2001

31. Human Anatomy, 3rd edition
Nuclei of Midbrain
Substantia nigra secretes dopamine
Modifies muscle tone & motor activity
Parkinson’s disease
Red nucleus – highly vascularized
Integrates information from cerebrum & cerebellum
Maintains muscle tone & posture
Human Anatomy, 3rd edition
Prentice Hall, © 2001

32. Cerebellum, Pons, & Medulla Oblongata
Hindbrain
Cerebellum, Pons, & Medulla Oblongata

33. Human Anatomy, 3rd edition
Cerebellum
2nd largest structure of the brain
Separated from cerebrum by transverse fissure
Divided into 2 lateral hemispheres
Vermis = “worm-shaped”
Cortex – gyri & sulci
Human Anatomy, 3rd edition
Prentice Hall, © 2001

34. Human Anatomy, 3rd edition
Cerebellum
Arbor vitae
Cerebellar nuclei
Within arbor vitae
Cerebellar peduncles
Inferior
Middle
Superior
Functions – controls subconscious movements in skeletal muscle
Coordination, posture, balance
Human Anatomy, 3rd edition
Prentice Hall, © 2001

35. Human Anatomy, 3rd edition
Pons
Pons = “bridge”
Consists of white fibers with scattered nuclei
Functions
Controls respiration rate (with medulla)
Contains nuclei for several cranial nerves
Human Anatomy, 3rd edition
Prentice Hall, © 2001

36. Human Anatomy, 3rd edition
Medulla Oblongata
Continuation of spinal cord
Forms the base of the “brain stem”
Pyramids
Just above the spinal cord
Large tracts cross from one side to the other
Contains reflex centers
Cardiac center, vasomotor center, respiratory rythmicity center
Human Anatomy, 3rd edition
Prentice Hall, © 2001

37. Cranial Nerves

38. Introduction to the Cranial Nerves
12 pairs
Leave the skull through foramina
Types
Mixed
Sensory
Motor
Part of the somatic nervous system
Some fibers of the ANS bundled with those of the cranial nerves
Human Anatomy, 3rd edition
Prentice Hall, © 2001

39. Cranial Nerve I – Olfactory Nerve
Sensory
Function – smell
Human Anatomy, 3rd edition
Prentice Hall, © 2001

40. Cranial Nerve II – Optic Nerve
Sensory
Function – vision
Human Anatomy, 3rd edition
Prentice Hall, © 2001

41. Nerves Controlling Extrinsic Eye Muscles (III, IV, VI)
Cranial Nerve III – oculomotor nerve
Motor
Function – controls raising of upper eyelid, movements of eyeball
Parasympathetic fibers to lens and pupil
Human Anatomy, 3rd edition
Prentice Hall, © 2001

42. Nerves Controlling Extrinsic Eye Muscles (III, IV, VI)
Cranial Nerve IV – trochlear nerve
Motor
Function – movements of eyeball
Cranial Nerve VI – Abducens
Human Anatomy, 3rd edition
Prentice Hall, © 2001

43. Craniel Nerve V – Trigeminal Nerve
Mixed
Sensory fibers receive information from cornea, scalp, forehead, face, teeth
Motor fibers to the muscles of mastication (control chewing)
Human Anatomy, 3rd edition
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44. Cranial Nerve VII – Facial Nerve
Mixed
Sensory fibers
Taste from anterior 2/3 of the tongue
Motor fibers
Facial expression
Parasympathetic fibers to:
Lacrimal glands
Tears
Submandibular and submaxillary salivary glands
Salivation
Human Anatomy, 3rd edition
Prentice Hall, © 2001

45. Cranial Nerve VIII – Auditory Nerve (Vestibulocochlear Nerve)
Sensory
Function – hearing and balance
Human Anatomy, 3rd edition
Prentice Hall, © 2001

46. Cranial Nerve IX – Glossopharyngeal Nerve
Mixed
Sensory fibers
Taste and touch from posterior l/3 of the tongue and pharynx
Motor fibers to pharyngeal muscles
Swallowing
Parasympathetic fibers to the parotid gland – salivation
Human Anatomy, 3rd edition
Prentice Hall, © 2001

47. Cranial Nerve X – Vagus Nerve
Mixed
Sensory fibers from external ears (hearing), rear of tongue (taste), viscera
Motor fibers to the muscles of the pharynx and larynx (motor)
Parasympathetic fibers to viscera
Human Anatomy, 3rd edition
Prentice Hall, © 2001

48. Human Anatomy, 3rd edition
Cranial Nerve XI – Spinal Accessory Nerve Cranial Nerve XII – Hypoglossal Nerve
XI – Spinal accessory nerve
Motor to trapezius and sternocleidomastoid muscles
Function – head movements
XII – Hypoglossal nerve
Motor to muscles of tongue
Function – speech and swallowing
Human Anatomy, 3rd edition
Prentice Hall, © 2001

49. Cranial Nerves “On old Olympus’ towering top, a Finn and
German viewed a hawk.”