1. Chapter 13 Lecture 20 Brain and Cranial Nerves
Visual Anatomy & Physiology First Edition Martini & Ober
Chapter 13
Brain and Cranial Nerves
Lecture 20
94 min, 51 slides

2. Overview of the Brain Functions regulates visceral activities
coordinates muscular movements
interprets sensations
determines perception
stores memory
carries out reasoning
makes decisions
determines personality
Major Parts
cerebrum (two hemispheres)
diencephalon
thalamus
hypothalamus
brain stem
midbrain (mesencephalon)
pons
medulla oblongata
cerebellum

3. Protection of the Brain
The brain is protected
Mechanically by
The skull bones
The meninges
The cerebrospinal (CSF) fluid
Biochemically by the blood-brain barrier
Capillaries interconnected by tight junctions
Astrocytes/ependymal cells control permeability of general capillaries/choroid capillaries
May be obstacle to delivery of drugs
May become more permeable during stress
Two points of entry to brain: general capillaries and capillaries of the choroid plexuses.

4. Meninges of the Brain *Singular of meninges is meninx
Figure from: Hole’s Human A&P, 12th edition, 2010
- dura mater – outer, tough (anchoring dural folds)
- arachnoid mater – web-like
- pia mater – inner, delicate
Dura mater – thick, collagenous membrane (about thickness of rubber kitchen glove)
Arachnoid mater – simple squamous epithelium; loose meshwork of collagenous and elastic fibers spanning the gap (subarachnoid space)
Pia mater – delicate membrane, close follows contours of nervous tissue that it covers.
*Singular of meninges is meninx
- Subdural space – like interstitial fluid
- Subarachnoid space – CSF

5. Dural Folds
Figure from: Martini, Fundamentals of Anatomy & Physiology, Benjamin Cummings, 2004

6. Ventricles of the Brain
Figure from: Hole’s Human A&P, 12th edition, 2010
interconnected cavities
within cerebral hemispheres and brain stem
continuous with central canal of spinal cord
filled with cerebrospinal fluid (CSF)
lateral ventricles (1, 2)
third ventricle (3)
fourth ventricle (4)
cerebral aqueduct

7. Cerebrospinal Fluid
secreted by choroid plexus of ventricles (~500 ml/day)
circulates in ventricles, central canal of spinal cord, and subarachnoid space
completely surrounds brain and spinal cord
clear liquid (more Na+ and Cl-, but less K+, Ca2+, glucose, and protein than plasma)
nutritive and protective
helps maintain stable ion concentrations in CNS
About 500 ml of CSF produced per day; about ml present at any time.
Figure from: Hole’s Human A&P, 12th edition, 2010

8. Structure of Cerebrum corpus callosum connects hemispheres gyri
bumps or convolutions
sulci
grooves
longitudinal fissure
separates hemispheres
transverse fissure
separates cerebrum from cerebellum
lateral sulcus
separates the frontal from the temporal lobes
Figures from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

9. Lobes of Cerebrum Frontal Parietal Temporal Occipital Insula
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

10. Functions of Cerebrum interpretation initiating voluntary movements
storing memory
retrieving memory
reasoning
center for intelligence and personality
The cerebrum can be divided into several functional areas:
- Motor (frontal cortex) - Sensory (parietal, occipital, and temporal cortex) - Association (all lobes)
Points to keep in mind: - Each cerebral hemisphere receives information from, and sends information to, the opposite side of the body - Although symmetrical, the cerebral hemispheres are not entirely equal in function

11. Overview of Cerebral Cortex
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

12. Primary Motor Areas
Primary Motor Cortex - voluntary control of skeletal muscles
Figure from: Hole’s Human A&P, 12th edition, 2010

13. Motor Areas of the Cortex
Notice the relative amount of cortical tissue devoted to each motor function. What would this be proportional to?
The Motor “Homunculus” ?
Amount of cortex devoted to a particular body region is proportional to the number of muscle fibers and motor units in that area rather than the size of the area.
Figures from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

14. Broca’s Area (Motor) Broca’s Area
in one (dominant, usually left) hemisphere
controls muscles needed for speech
Speech production and aspects of comprehension. Damage to area may result in: decrease in speech fluency, word-finding difficulty, telegraphic speech (e.g., "Give cupcake" to express that they would like a cupcake), poor repetition and naming.
Figure from: Hole’s Human A&P, 12th edition, 2010

15. Frontal Eye Field (Motor)
Controls voluntary movements of eyes and eyelids
Figure from: Hole’s Human A&P, 12th edition, 2010

16. Sensory Areas Cutaneous Sensory Area parietal lobe
interprets sensations on skin
Visual Area
occipital lobe
interprets vision
Auditory Area
temporal lobe
interprets hearing
Figure from: Hole’s Human A&P, 12th edition, 2010

17. Sensory Areas of the Cortex
Notice the relative amount of cortical tissue devoted to each sensory function.
The Somatosensory “Homunculus”
Figures from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

18. Association Areas
Figure from: Hole’s Human A&P, 12th edition, 2010
regions of cortex that are not primary motor or primary sensory areas
widespread throughout the cerebral cortex
analyze and interpret sensory experiences; coordinate motor responses
memory, reasoning, verbalization, judgment, emotions

19. Tracts of Cerebral White Matter
Figures from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
Projection tracts – vertical between cortex and lower brain and spinal cord.
Commisural tracts from one cerebral hemisphere to the other (most via corpus callosum).
Association tracts – connect regions within the same cerebral hemisphere.

20. Hemispheric (Cerebral) Lateralization
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Categorical hemisphere
Representational hemisphere

21. Basal Nuclei nuclei are masses of gray matter in CNS
deep within cerebral hemispheres
caudate nucleus, putamen, globus pallidus (together called the corpus striatum)
subconscious control certain muscular activities, e.g., learned movement patterns
Figure from: Hole’s Human A&P, 12th edition, 2010
Relay motor impulses originating in the cerebral cortex and substantia nigra of the midbrain.

22. Limbic System The motivational system Consists of
portions of frontal lobe
portions of temporal lobe
hypothalamus
thalamus
basal nuclei
other deep nuclei
associated with sense of smell (less significant)
Functions
controls emotions
produces feelings
interprets sensory impulses
facilitates memory storage and retrieval (learning!)
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007
The motivational system

23. Memory
A “Memory” is the persistence of knowledge that can be accessed (we hope!) at a later time.
Memories are not stored in individual “memory cells” or neurons; they are stored as pathways called engrams, or memory traces that use strengthened or altered synapses.
Immediate memory lasts a few seconds, e.g., remembering the earliest part of a sentence to make sense of it.
Short-term memory (STM) lasts a few seconds to a few hours
Working memory is a form of this (repeating a phone number over to yourself just long enough to dial it – and then forget it!)
Limited to a few ‘bits’ of information (about 7-9). So, ‘chunk up’!
Long-term memory (LTM) can last a lifetime
Can hold much more information that STM
Declarative (events and facts)
Procedural (motor skills)

24. Diencephalon between cerebral hemispheres and brainstem
surrounds third ventricle
thalamus
hypothalamus
epithalamus
optic tracts
optic chiasm
infundibulum
posterior pituitary
mammillary bodies
pineal gland
(Tectum)
Figure from: Hole’s Human A&P, 12th edition, 2010

25. Diencephalon Thalamus
gateway for sensory impulses heading to cerebral cortex
receives all sensory impulses (except smell)
channels impulses to appropriate part of cerebral cortex and to the basal nuclei for interpretation
Hypothalamus
maintains homeostasis by regulating visceral activities
Heart rate and blood pressure - Body temperature - Water and electrolyte balance - Hunger and body weight - Movement/secretions of glands and intestines
Stimulation of the pituitary (links nervous and endocrine) - Sleep and wakefulness

26. Diencephalon
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

27. Brain Stem Three Parts Midbrain Pons Medulla Oblongata (Tectum)
Figure from: Hole’s Human A&P, 12th edition, 2010
Three Parts
Midbrain
Pons
Medulla Oblongata
(Tectum)

28. Midbrain
between diencephalon and pons
contains bundles of fibers that join lower parts of brainstem and spinal cord with higher part of brain
cerebral aqueduct
cerebral peduncles – bundles of nerve fibers
contains red nucleus (rubro-) and substantia nigra
corpora quadrigemina – centers for visual and auditory reflexes
Major connecting center between spinal cord and brain and parts of brainstem
(Tectum)
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

29. Pons rounded bulge on underside of brainstem
Figure from: Hole’s Human A&P, 12th edition, 2010
(Tectum)
rounded bulge on underside of brainstem
between medulla oblongata and midbrain
helps regulate rate and depth of breathing
relays nerve impulses to and from medulla oblongata and cerebellum
Ventral view
Dorsal view

30. Medulla Oblongata enlarged continuation of spinal cord
conducts ascending (olive) and descending (pyramids) impulses between brain and spinal cord
contains cardiac, vasomotor, and respiratory control centers
contains various nonvital reflex control centers (coughing, sneezing, vomiting)
Figure from: Hole’s Human A&P, 12th edition, 2010
(Tectum)
Ventral view
Dorsal view

31. Reticular Formation
complex network of nerve fibers scattered throughout the brain stem
extends into the diencephalon
connects to centers of hypothalamus, basal nuclei, cerebellum, and cerebrum
filters incoming sensory information; habituation
modulates pain
arouses cerebral cortex into state of wakefulness
Figure from: Hole’s Human A&P, 12th edition, 2010
Ascending portion is called the ‘reticular activating system’ (prefix = reticulo-)

32. Cerebellum
integrates sensory information concerning position of body parts
coordinates skeletal muscle activity
maintains posture
May also be involved in several sensory, linguistic, emotional and non-motor functions
Cerebellum controls ipsilateral muscles (on the
Cerebellum is connected to the brainstem by three pairs of peduncles:
Superior peduncles connect to midbrain (output to midbrain and thalamus)
Middle peduncles connect to pons (input from cerebrum about muscle movements and hearing/equilibrium from inner ear)
Inferior peduncles connect to medulla (input from spinocerebellar tracts with proprioceptive information)
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

33. Peripheral Nervous System
You are here
CNS
PNS
Figure from: Hole’s Human A&P, 12th edition, 2010

34. Peripheral Nervous System
Cranial nerves arising from the brain
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera
Spinal nerves arising from the spinal cord
Somatic fibers connecting to the skin and skeletal muscles
Autonomic fibers connecting to viscera

35. Cranial Nerves
Paired. Numbered (roughly) in the order of their occurrence from anterior to posterior. Abbreviated using N or CN.
Figure from: Hole’s Human A&P, 12th edition, 2010

36. The Cranial Nerves You should know this table Numeral Name Function
Sensory, Motor, or Both (Mixed Nerve) I
OLFACTORY (OLD)
OLFACTION/SMELL
SENSORY (SOME)  II
OPTIC (OPIE)
VISION
SENSORY (SAY) 
III
OCULOMOTOR (OCCASIONALLY)
MOVE EYE
MOTOR (MARRY) IV
TROCHLEAR (TRIES)
MOVE EYE (superior oblique)
MOTOR (MONEY) V
TRIGEMINAL (TRIGONOMETRY)
MAJOR SENSORY NERVE FROM FACE
BOTH (BUT) VI
ABDUCENS (AND)
MOVE EYE (lateral rectus)
MOTOR (MY)
VII
FACIAL (FEELS)
MAJOR MOTOR NERVE OF FACE
BOTH (BROTHER)
VIII
VESTIBULOCOCHLEAR (VERY)
HEARING AND EQUILIBRIUM
SENSORY (SAYS)  IX
GLOSSOPHARYNGEAL (GLOOMY)
MOVE MUSCLES OF TONGUE AND PHARYNX
BOTH (BIG) X
VAGUS (VAGUE)
INNERVATE VISCERAL SMOOTH MUSCLE; MUSCLES OF SPEECH
BOTH (BOOBS) XI
ACCESSORY (AND)
MOVE NECK MUSCLES
MOTOR (MATTER)
XII
HYPOGLOSSAL (HYPOACTIVE)
MOVE TONGUE
MOTOR (MOST)
You should know this table

37. Cranial Nerves I and II Olfactory (I) sensory
fibers transmit impulses associated with smell
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001
Optic (II)
sensory
fibers transmit impulses associated with vision

38. Cranial Nerves III, IV, and VI
Abducens (VI)
primarily motor
motor impulses to the lateral rectus (LR) muscles that move the eyes
Oculomotor (III)
primarily motor
motor impulses to muscles that
raise eyelids
move the eyes
focus lens
adjust light entering eye
Trochlear (IV)
primarily motor
motor impulses to the superior oblique (SO) muscles that move the eyes
What’s a ganglion?
Figure from: Martini, Anatomy & Physiology, Prentice Hall, 2001

39. Cranial Nerve V Major sensory nerve of face Trigeminal (V)
Figure from: Hole’s Human A&P, 12th edition, 2010
Trigeminal (V)
both sensory and motor
opthalmic division
sensory from surface of eyes, tear glands, scalp, forehead, and upper eyelids
maxillary division
sensory from upper teeth, upper gum, upper lip, palate, and skin of face
mandibular division
sensory from scalp, skin of jaw, lower teeth, lower gum, and lower lip
motor to muscles of mastication and muscles in floor of mouth
Major sensory nerve of face

40. Cranial Nerve VII Major MOTOR nerve of face Facial (VII)
both sensory and motor
sensory from taste receptors
motor to muscles of facial expression, tear glands, and salivary glands
Major MOTOR nerve of face
Figures from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

41. Cranial Nerves VIII and IX
Vestibulocochlear (VIII)
sensory
sensory from equilibrium receptors of ear
sensory from hearing receptors
Glossopharyngeal (IX)
both sensory and motor
sensory from pharynx, tonsils, tongue, and carotid arteries
motor to salivary glands and muscles of pharynx
Figures from: Martini, Anatomy & Physiology, Prentice Hall, 2001

42. Cranial Nerve X Vagus (X) both sensory and motor
somatic motor to muscles of speech and swallowing
autonomic motor (parasympathetic) to viscera of thorax and abdomen
sensory from pharynx, larynx, esophagus, and viscera of thorax and abdomen
Figure from: Saladin, Anatomy & Physiology, McGraw Hill, 2007

43. Cranial Nerves XI and XII
Accessory (XI)
primarily motor
motor to muscles of soft palate, pharynx, larynx, neck, and back
Hypoglossal (XII)
primarily motor
motor to muscles of the tongue
Figure from: Martini, Fundamentals of Anatomy & Physiology, Pearson Education, 2004

44. Review The brain is protected by the
Skull bones
Meninges
CSF
Blood-brain barrier
The meninges of the brain and spinal cord consist of the
Dura mater
Arachnoid (membrane)
Pia mater

45. Review Important motor areas of cerebral cortex
Precentral gyrus (Primary motor area)
Broca’s area
Frontal eye field
Important sensory areas of cerebral cortex
Postcentral gyrus (Primary cutaneous sensory)
Visual area (occipital lobe)
Auditory area (temporal lobe)

46. Review
Table from: Hole’s Human A&P, 12th edition, 2010

47. The Cranial Nerves Numeral Name Function
Sensory, Motor, or Both (Mixed Nerve) I
OLFACTORY (OLD)
OLFACTION/SMELL
SENSORY (SOME) II
OPTIC (OPIE)
VISION
SENSORY (SAY)
III
OCULOMOTOR (OCCASIONALLY)
MOVE EYE
MOTOR (MARRY) IV
TROCHLEAR (TRIES)
MOTOR (MONEY) V
TRIGEMINAL (TRIGONOMETRY)
CHEWING, MASTICATION AND SENSORY FROM FACE
BOTH (BUT) VI
ABDUCENS (AND)
MOTOR (MY)
VII
FACIAL (FEELS)
FACIAL EXPRESSION
BOTH (BROTHER)
VIII
VESTIBULOCOCHLEAR (VERY)
HEARING AND EQUILIBRIUM
SENSORY (SAYS) IX
GLOSSOPHARYNGEAL (GLOOMY)
MOVE MUSCLES OF TONGUE AND PHARYNX
BOTH (BIG) X
VAGUS (VAGUE)
INNERVATE VISCERAL SMOOTH MUSCLE
BOTH (BOOBS) XI
ACCESSORY (AND)
MOVE NECK MUSCLES
MOTOR (MATTER)
XII
HYPOGLOSSAL (HYPOACTIVE)
MOVE TONGUE
MOTOR (MOST)