chapter 10 the nervous system: the brain and cranial nerves filecopyright © 2015 wolters kluwer •...

Copyright © 2015 Wolters Kluwer Health | Lippincott Williams & Wilkins

Chapter 10

The Nervous System: The Brain and Cranial Nerves

Copyright © 2015 Wolters Kluwer • All Rights Reserved

Overview


Key Terms

aphasia corpus callosum meninges

basal nuclei diencephalon midbrain

brain stem electroencephalograph (EEG) pons

cerebellum gyrus (pl. gyri) reticular formation

cerebral cortex hematoma seizure

cerebrospinal fluid (CSF) hypothalamus stroke

cerebrum limbic system sulcus (pl. sulci)

concussion medulla oblongata thalamus

ventricle


Overview of the Brain

Learning Objectives

1. Give the locations of the four main divisions of the brain.

2. Name and describe the three meninges.

3. Cite the function of cerebrospinal fluid, and describe where and how this fluid is formed.


The Cerebrum

Learning Objectives

4. Name and locate the lobes of the cerebral hemispheres.

5. Cite one function of the cerebral cortex in each lobe of the cerebrum.


The Diencephalon

Learning Objective

6. Name two divisions of the diencephalon, and cite the functions of each.


The Brain Stem

Learning Objective

7. Locate the three subdivisions of the brain stem, and give the functions of each.


The Cerebellum

Learning Objectives

8. Describe the cerebellum, and identify its functions.

9. Name three neuronal networks that involve multiple regions of the brain, and describe the function of each.


Brain Studies

Learning Objective

10. Describe four techniques used to study the brain.


Learning Objective

11. Describe at least six disorders that affect the brain.

Disorders of the Brain and Associated Structures


Cranial Nerves

Learning Objectives

12. List the names and functions of the 12 cranial nerves.

13. Discuss five disorders that involve the cranial nerves.


Case Study

Learning Objective

14.Using information in the case study, list the possible effects of mild traumatic brain injury.


Word Anatomy

Learning Objective

15.Show how word parts are used to build words related to the nervous system.


Overview of the Brain

Division Description Functions

Cerebrum • Largest and most superior portion of the brain

• Divided into two hemispheres; each subdivided into lobes

• Cortex (outer layer) is site for conscious thought, memory, reasoning, and abstract mental functions, all localized within specific lobes.

Diencephalon • Between the cerebrum and the brain stem

• Contains the thalamus and hypothalamus

• The thalamus sorts and redirects sensory input.

• The hypothalamus maintains homeostasis; controls the autonomic nervous system and pituitary gland.


Overview of the Brain (cont.)

Division Description Functions

Brain stem

• Midbrain

• Pons

• Medulla

oblongata

• Anterior region below the cerebrum

• Below center of the cerebrum

• Anterior to the cerebellum

• Between the pons and

spinal cord

• Connects the cerebrum and diencephalon with the spinal cord

• Has reflex centers concerned with vision and hearing

• Connects the cerebrum with lower portions of the brain

• Helps regulate respiration • Links the brain with spinal cord • Centers for control of vital

functions

Cerebellum (means ‘little brain’)

• Below the posterior portion of the cerebrum

• Divided into two hemispheres

• Coordinates voluntary muscles • Maintains balance and muscle

tone


Figure 10-1 Brain, sagittal section.

What is the largest part of the brain? What part connects with the spinal cord?




Protective Structures of the Brain and Spinal Cord

•Meninges

– Dura mater

• Dural sinuses

– Arachnoid

– Pia mater


Figure 10-2 Frontal (coronal) section of the top of the head. The meninges and related parts are shown.

What are the channels formed where the dura mater divides into two layers? How many layers of meninges are there?




Protective Structures of the Brain and Spinal Cord (cont.)

• Cerebrospinal fluid (CSF)

– Supports nervous tissue, cushions from shock

– Carries nutrients to cells

– Transports waste products from cells

• Produced in ventricles

– Choroid plexus

– Lateral ventricles

– Foramina

– Cerebral aqueduct



Protective Structures of the Brain and Spinal Cord (cont.)

• Ventricles

– Four fluid-filled spaces within the brain

• Lateral (two)

• Third

• Fourth

– Contain choroid plexus, which manufactures CSF

– Supports nervous tissue, cushions from shock

– Carries nutrients to cells

– Transports waste products from cells


Which ventricle is continuous with the central canal of the spinal cord?


Figure 10-3 Cerebrospinal fluid (CSF) and the cerebral ventricles.



Checkpoints

10-1 What are the main divisions of the brain?

10-2 What are the names of the three layers of the meninges from the outermost to the innermost?

10-3 Where is CSF produced?



Pop Quiz

10.1 Which division of the brain is physically connected to the spinal cord?

A) Brain stem

B) Cerebellum

C) Cerebrum

D) Diencephalon



Pop Quiz Answer

10.1 Which division of the brain is physically connected to the spinal cord?

A) Brain stem

B) Cerebellum

C) Cerebrum

D) Diencephalon


The Cerebrum

Learning Objectives

4. Name and locate the lobes of the cerebral hemispheres.

5. Cite one function of the cerebral cortex in each lobe of the cerebrum.


The Cerebrum (cont.)

Divisions of the Cerebral Hemispheres

• The cerebrum is divided into two cerebral hemispheres.

• Each hemisphere is divided into five lobes:

– Frontal

– Parietal

– Temporal

– Occipital

– Insula



The Cerebral Hemispheres

• Outer layer of nervous tissue is called the cortex.

• Cortex arranged into folds:

– Gyri

– Sulci

• Central sulcus

• Lateral sulcus



The Cerebral Hemispheres (cont.)

• The internal layer is composed primarily of white matter.

– Corpus callosum bridges cerebral hemispheres.


Figure 10-4 External surface of the brain.


What structure separates the frontal from the parietal lobe? The temporal lobe from the frontal and parietal lobes?



Functions of the Cerebral Cortex

Lobe Description

Frontal Contains motor area and speech centers

Parietal Contains sensory areas

Temporal Contains auditory, speech comprehension, and olfactory areas

Occipital Contains visual association areas


Figure 10-5 Functional areas of the cerebral cortex.

What cortical area is posterior to the central sulcus? What area is anterior to the central sulcus?




Memory and the Learning Process

• Short-term memory

– Information lost unless reinforced

• Long-term memory

– Rehearsal (repetition)

– Alertness



Checkpoints

10-4 Name the four surface lobes of each cerebral hemisphere.

10-5 Name the thin outer layer of gray matter where higher brain functions occur.



Pop Quiz

10.2 Which lobes are separated by the central sulcus?

A) Frontal and parietal

B) Parietal and occipital

C) Temporal and occipital

D) Temporal and frontal



Pop Quiz Answer

10.2 Which lobes are separated by the central sulcus?

A) Frontal and parietal

B) Parietal and occipital

C) Temporal and occipital

D) Temporal and frontal


The Diencephalon

Learning Objective

6. Name two divisions of the diencephalon, and cite the functions of each.


The Diencephalon (cont.)

Thalamus

• Sorts sensory impulses

• Directs impulses within the cerebral cortex

Hypothalamus

• Maintains homeostasis

• Controls sympathetic and parasympathetic divisions of the autonomic nervous system

• Influences heartbeat, blood flow, hormone secretion


Figure 10-6 The diencephalon, brain stem, and cerebellum.

To what part of the brain is the pituitary gland attached?




Checkpoint

10-6 What are the two main portions of the diencephalon, and what do they do?



Pop Quiz

10.3 Which structure controls the autonomic nervous system and the pituitary gland?

A) Basal ganglia

B) Cerebellum

C) Hypothalamus

D) Thalamus



Pop Quiz Answer

10.3 Which structure controls the autonomic nervous system and the pituitary gland?

A) Basal ganglia

B) Cerebellum

C) Hypothalamus

D) Thalamus


The Brain Stem

Learning Objective

7. Locate the three subdivisions of the brain stem, and give the functions of each.


The Brain Stem (cont.)

• Composed of the midbrain, pons, and medulla

oblongata

• Connects the cerebrum and diencephalon with the

spinal cord



Midbrain

• Superior part of the brain stem

• Four masses form superior part of the midbrain

– House reflexes involving eyes and ears

• Conducts impulses between higher centers of the cerebrum and lower centers of the pons, medulla, cerebellum, spinal cord



Pons

• Connecting link between the cerebellum and rest of the nervous system

• Regulates some reflexes involving respiration



Medullary Oblongata

• Respiratory center

• Cardiac center

• Vasomotor center

• Contralateral (opposite side) control



Checkpoint

10-7 What are the three subdivisions of the brain stem?



Pop Quiz

10.4 Which part of the brain stem contains relay centers for eye and ear reflexes?

A) Pons

B) Thalamus

C) Medulla oblongata

D) Midbrain



Pop Quiz Answer

10.4 Which part of the brain stem contains relay centers for eye and ear reflexes?

A) Pons

B) Thalamus

C) Medulla oblongata

D) Midbrain


The Cerebellum

Learning Objectives

8. Describe the cerebellum, and identify its functions.

9. Name three neuronal networks that involve multiple regions of the brain, and describe the function of each.


The Cerebellum (cont.)

• Three parts

– Vermis

– Left hemisphere

– Right hemisphere

• Functions

– Helps coordinate voluntary muscles

– Helps maintain balance

– Helps maintain muscle tone


Figure 10-7 The cerebellum.




Checkpoint

10-8 What are some functions of the cerebellum?


Widespread Neuronal Networks

Limbic System

– Between the cerebrum and diencephalon

– Involved in emotional states, behavior

– Involved in learning, long-term memory

– Stimulates reticular formation (consciousness)

– Links functions of the cerebral cortex and brain stem

Basal Nuclei

Reticular Formation

– Reticular activating system (RAS)


Figure 10-8 The limbic system.

Which part of the cerebral cortex contributes to the limbic system?

Widespread Neuronal Networks (cont.)



Checkpoints

10-9 What are four structures in the limbic system?

10-10 What is the function of the basal nuclei?

10-11 What is the function of the reticular activating system?


The Cerebellum

Pop Quiz

10.5 Which of the following is NOT a function of the cerebellum?

A) Maintaining muscle tone

B) Maintaining balance

C) Coordinating voluntary muscles

D) Initiating movements of voluntary muscles



Pop Quiz Answer

10.5 Which of the following is NOT a function of the cerebellum?

A) Maintaining muscle tone

B) Maintaining balance

C) Coordinating voluntary muscles

D) Initiating movements of voluntary muscles


Brain Studies

Learning Objective

10.Describe four techniques used to study the brain.


Brain Studies (cont.)

Brain Imaging Techniques

• Computed tomography (CT) scan

• Magnetic resonance imaging (MRI)

• Positron emission tomography (PET)


Figure 10-9 Imaging the brain.




Electroencephalography

• Record electric currents given off by brain nerve cells

• Used to

– Study sleep patterns

– Diagnose disease

– Locate tumors

– Study drug effects

– Determine brain death


Figure 10-10 Electroencephalography.



Learning Objective

11.Describe at least six disorders that affect the brain.



Disorders of the Brain and Associated Structures (cont.)

Seizures and Epilepsies

• Seizure

• Epilepsy

Inflammation

• Meningitis

– Inflammation of brain and spinal cord coverings

• Encephalitis

– Inflammation of the brain

Hydrocephalus

– Abnormal CSF accumulation within the brain


Figure 10-11 Hydrocephalus.




Stroke and Other Brain Disorders

• Stroke

– Most common brain disorder

• Tumors

– Gliomas


Figure 10-12 Brain tumor.




Head Injury

• Head trauma can lead to injury within the skull.

• Hematomas

– Epidural

– Subdural

– Intracerebral

• Cerebral concussion


Figure 10-13 Hematomas.

What type of hematoma forms outside of the dura mater? What type forms below the dura mater?




Degenerative Diseases

• Alzheimer disease

• Multi-infarct dementia

• Parkinson disease

• Huntington disorder


Figure 10-14 Effects of Alzheimer disease.




Checkpoints

10-12 What is the common term for cerebrovascular accident (CVA)?

10-13 What type of cells are commonly involved in brain tumors?



Pop Quiz

10.6 Which of the following symptoms is suggestive of Alzheimer disease?

A) Memory loss

B) Tremor

C) Impaired balance

D) Limb rigidity



Pop Quiz Answer

10.6 Which of the following symptoms is suggestive of Alzheimer disease?

A) Memory loss

B) Tremor

C) Impaired balance

D) Limb rigidity


Cranial Nerves

Learning Objectives

12.List the names and functions of the 12 cranial nerves.

13.Discuss five disorders that involve the cranial nerves.


Cranial Nerves (cont.)

• 12 pairs

• Four categories:

– Special sensory impulses

– General sensory impulses

– Somatic motor impulses

– Visceral motor impulses



Names and Functions of the Cranial Nerves

Nerve Name Function

I Olfactory Carries impulses for the sense of smell toward the brain

II Optic Carries visual impulses from the eye to brain

III Oculomotor Controls contraction of eye muscles

IV Trochlear Supplies one eyeball muscle

V Trigeminal Carries sensory impulses from eye, upper jaw, and lower jaw toward the brain

VI Abducens Controls an eyeball muscle

VII Facial Controls muscles of facial expression; carries sensation of taste; stimulates small salivary glands and lacrimal (tear) glands



Names and Functions of the Cranial Nerves (cont.)

Nerve Name Function

VIII Vestibulocochlear Carries sensory impulses for hearing and equilibrium from inner ear toward the brain

IX Glossopharyngeal Carries sensory impulses from tongue and pharynx (throat); controls swallowing muscles and stimulates the parotid salivary gland

X Vagus Supplies most of organs in thoracic and abdominal cavities; carries motor impulses to the larynx (voice box) and pharynx

XI Accessory Controls muscles in the neck and larynx

XII Hypoglossal Controls muscles of tongue


Figure 10-15 Cranial nerves.



Disorders Involving the Cranial Nerves

• Destruction of optic fibers

• Damage to hearing nerves

• Paralysis of muscles

• Bell palsy

• Neuralgia



Checkpoints

10-14 How many pairs of cranial nerves are there?

10-15 What are the three types of cranial nerves? What is a mixed nerve?



Pop Quiz

10.7 Which cranial nerve is concerned with the sense of smell?

A) Vagus nerve

B) Trigeminal nerve

C) Olfactory nerve

D) Hypoglossal nerve



Pop Quiz Answer

10.7 Which cranial nerve is concerned with the sense of smell?

A) Vagus nerve

B) Trigeminal nerve

C) Olfactory nerve

D) Hypoglossal nerve


Effects of Aging on the Nervous System

• Decreased brain size and weight

• Decreased speed of information processing

• Slowed movements

• Diminished memory

• Reduced blood flow to the brain


Learning Objective

14.Using information in the case study, list the possible effects of mild traumatic brain injury.

Case Study


Case Study (cont.) Symptoms of a Concussion

• Headache

• Slurred speech

• Blurred vision

• Slow to arouse

• Nausea and vomiting

• Changes

– Cognitive

– Physical

– Emotional

– Behavioral

Treatment

• Close observation of the injured person

• Quiet and rest

• Avoidance of overstimulation and alcohol

• Avoidance of using electronics


Word Anatomy

Learning Objective

15.Show how word parts are used to build words related to the nervous system.


Word Anatomy (cont.)

Word Part Meaning Example

Protective Structures of the Brain and Spinal Cord

cerebr/o brain Cerebrospinal fluid circulates around the brain and spinal cord.

chori/o membrane The choroid plexus is the vascular membrane in the ventricle that produces CSF.

contra- opposed, against The cerebral cortex has contralateral control of motor function.

encephal/o brain The diencephalon is the part of the brain located between the cerebral hemispheres and the brain stem.

gyr/o circle A gyrus is a circular raised area on the surface of the brain.

latero lateral, side See “contra-” example.


Word Anatomy (cont.)

Word Part Meaning Example

Brain Studies

tom/o cut Tomography is a method for viewing sections as if cut through the body.


cephal/o head Hydrocephalus is the accumulation of fluid within the brain.

-rhage bursting forth A cerebral hemorrhage is a sudden bursting forth of blood in the brain.

phasia speech, ability to talk

Aphasia is a loss or defect in language communication.

Cranial Nerves

gloss/o tongue The hypoglossal nerve controls muscles of the tongue.

chapter 10 the nervous system: the brain and cranial nerves filecopyright © 2015 wolters kluwer •...

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