The Brain and Cranial Nerves - Napa Valley College 218/15...The Brain and Cranial Nerves ... Figure...

C h a p t e r

15

The Nervous System:

The Brain and Cranial Nerves

PowerPoint® Lecture Slides

prepared by Jason LaPres

North Harris College

Houston, Texas

Copyright © 2009 Pearson Education, Inc.,

publishing as Pearson Benjamin Cummings

Introduction

The brain is far more complex than the spinal

cord.

The brain contains roughly 20 billion neurons.

Excitatory and inhibitory interactions among the

extensively interconnected neuronal pools ensure

that the response can vary to meet changing

circumstances.

Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

An Introduction to the Organization of the Brain

Figure 15.1 Major Divisions of the BrainCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings


Figure 15.2a Ventricles of the Brain (Lateral View)



Figure 15.2b Ventricles of the Brain (Lateral View)



Figure 15.2c Ventricles of the Brain (Anterior View)



Figure 15.2d Ventricles of the Brain (Coronal Section)


Protection and Support of the Brain

Protection, support, and nourishment of the brain involves:

Bones of the skull

Cranial meninges

Dura mater

Arachnoid mater

Pia mater

Cerebrospinal fluid

Blood–brain barrier

Vessels of the cardiovascular system



Figure 15.3a Relationships among the Brain, Cranium, and Meninges (Lateral View)



Figure 15.3b Relationships among the Brain, Cranium, and Meninges (Midsagittal View)



Figure 15.4a The Cranial Meninges



Figure 15.4b The Cranial Meninges



Figure 15.4c The Cranial Meninges


Protection and Support of the Brain Blood Supply to the Brain


Figure 22.13a Arteries of the Neck and Head

Protection and Support of the Brain Blood supply to the brain


Figure 22.15a Arteries of the Brain (Inferior View)

Protection and Support of the Brain Blood supply to the brain


Figure 22.22a Major Veins of the Head and Neck (Lateral View)

Protection and Support of the Brain Blood Supply to the Brain


Figure 22.22b Venous Drainage of the Brain (Inferior view)


Figure 15.8 Hydrocephalus

This infant has severe hydrocephalus, a condition usually caused by impaired circulation and removal of cerebrospinal fluid. CSF buildup leads to distortion of the brain and enlargement of the cranium.


The Cerebrum

The cerebrum is the largest, most superior portion of the human brain.

Each cerebral hemisphere receives sensory information from and generates motor commands to the opposite side of the body.

The two hemispheres have some functional differences, although anatomically they appear to be identical.


The Cerebrum

Figure 15.7a The Cerebral Hemispheres, Part I (Superior View)


The Cerebrum

Figure 15.7b The Cerebral Hemispheres, Part I (Anterior View)


The Cerebrum

Figure 15.7c The Cerebral Hemispheres, Part I (Posterior View)


The Cerebrum

Figure 15.9a The Cerebral Hemispheres, Part II (Lateral View of Intact Brain)


The Cerebrum

Figure 15.9b The Cerebral Hemispheres, Part II (The Left Cerebral Hemisphere)


The Cerebrum


The Cerebrum

Figure 15.10a The Central White Matter (Lateral View)


The Cerebrum

Figure 15.10b The Central White Matter (Anterior View)


The Cerebrum


The Cerebrum

Figure 15.11a The Basal Nuclei (Lateral View)


The Cerebrum

Figure 15.11b The Basal Nuclei (Horizonatal View, Dissected)


The Cerebrum

Figure 15.11d The Basal Nuclei (Frontal Section)


The Cerebrum

Figure 15.11c The Basal Nuclei (Horizontal Section)


The Cerebrum

Figure 15.11e The Basal Nuclei (Frontal Section)


The Cerebrum


The Cerebrum

Figure 15.12a The Limbic System


The Cerebrum

Figure 15.12b The Limbic System


The Cerebrum


The Diencephalon

The diencephalon connects the cerebrum to the brain stem both structurally and functionally.

The functions that occur in the diencephalon are almost exclusively subconscious.

Epithalamus — controls the circadian rhythm

Thalamus — relays information

Hypothalamus — coordinates the nervous and endocrine systems


The Diencephalon

Figure 15.15a Sectional Views of the Brain (Midsagittal Section)


The Diencephalon

Figure 15.15b Sectional Views of the Brain (Coronal Section)


The Diencephalon

Figure 15.16a The Diencephalon and Brain Stem (Lateral View)Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Diencephalon

Figure 15.13a The Thalamus


The Diencephalon

Figure 15.13b The Thalamus


The Diencephalon


The Diencephalon

Figure 15.14a The Hypothalamus (Midsagittal Section)


The Diencephalon

Figure 15.14b The Hypothalamus


The Diencephalon


The Mesencephalon

The mesencephalon, or midbrain, is the most

superior portion of the brain stem.

Nuclei coordinate visual and auditory reflexes.

Corpora quadregemina

Superior colliculi — visual

Inferior colliculi — auditory

Limbic system nuclei

Coordinate involuntary movements of skeletal muscles

Cerebral peduncles

Nerve bundles to and from the brain/spinal cord


The Mesencephalon

Figure 15.16a The Diencephalon and Brain Stem (Lateral View)Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Mesencephalon

Figure 15.16b The Diencephalon and Brain Stem (Sagittal Section)Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Mesencephalon

Figure 15.16c The Diencephalon and Brain Stem (Posterior View)


The Mesencephalon

Figure 15.16d The Diencephalon and Brain Stem (Posterior View)


The Mesencephalon

Figure 15.17a The Mesencephalon (Transverse Section, Superior View)


The Mesencephalon

Figure 15.17b The Mesencephalon (Posterior View)Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Mesencephalon


The Pons

The pons mainly functions:

As a house for cranial nerve nuclei V, VI, VII, and

VIII

To help regulate respiration

To help coordinate involuntary skeletal muscle

movements and muscle tone

In relaying information to and from the

brain/spinal cord


The Pons

Figure 15.18 The Pons


The Pons


The Cerebellum

The cerebellum has two primary

functions:

Adjusts the postural muscles of the body to

maintain balance

Programs and fine-tunes voluntary and

involuntary movements


The Cerebellum

Figure 15.19a The Cerebellum (Posterior, Superior Surface)


The Cerebellum

Figure 15.19b The Cerebellum (Sagittal Section)Copyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cerebellum


The Medulla Oblongata

The medulla oblongata physically connects the

brain with the spinal cord.

It is so important that, if it is severely

compromised, the victim will likely die.

The medulla oblongata is a relay station, house

for cranial nerve nuclei, and most

importantly, controls visceral functions like

blood pressure, breathing, and heart rate.



Figure 15.20 The Medulla Oblongata


M


Brain Animation Review

The Brain

15Brain_3DPA_3D.mov

The Cranial Nerves

Cranial nerves are components of the

peripheral nervous system that connect to

the brain rather than to the spinal cord.

Twelve pairs of cranial nerves

Cranial nerves are numbered using Roman

numerals

Each cranial nerve attaches to the brain near the

associated sensory or motor nuclei


The Cranial Nerves

Figure 15.21a Origins of the Cranial NervesCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Nerves


Figure 15.21b Origins of the Cranial Nerves

The Cranial Nerves


The Cranial Nerves

Olfactory Nerve (N I)

Primary function: special sensory (smell)

Origin: receptors of olfactory epithelium

Passes through: cribriform plate of ethmoid

Destination: olfactory bulbs


The Cranial Nerves

Figure 15.22 The Olfactory NerveCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Nerves

The Optic Nerve (N II)

Primary function: special sensory (vision)

Origin: retina of eye

Passes through: optic canal of sphenoid

Destination: diencephalon by way of the optic

chiasm


The Cranial Nerves

Figure 15.23 The Optic NerveCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Nerves

The Oculomotor Nerve (N III)

Primary function: motor, eye movements

Origin: mesencephalon

Passes through: superior orbital fissure of sphenoid

Destination:

Somatic motor: superior, inferior, and medial rectus muscles; the inferior oblique muscle; the levator palpebrae superioris muscle

Visceral motor: intrinsic eye muscles


The Cranial Nerves

Figure 15.24 Cranial Nerves Controlling the Extra-Ocular Muscles


The Cranial Nerves

The Trochlear Nerve (N IV)


Origin: mesencephalon


Destination: superior oblique muscle


The Cranial Nerves



The Cranial Nerves

The Trigeminal Nerve (N V) Primary function: Mixed (sensory and motor)

Ophthalmic and maxillary branches sensory

Mandibular branch mixed

Origin: Ophthalmic branch (sensory): orbital structures, nasal

cavity, skin of forehead, superior eyelid, eyebrow, and part of the nose

Maxillary branch (sensory): inferior eyelid, upper lip, gums, and teeth; cheek; nose, palate, and part of the pharynx

Mandibular branch (mixed): sensory from lower gums, teeth, and lips; palate and tongue (part); motor from motor nuclei of pons


The Cranial Nerves

The Trigeminal Nerve (N V)

Passes through:

Ophthalmic branch through superior orbital fissure

Maxillary branch through foramen rotundum

Mandibular branch through foramen ovale

Destination:

Ophthalmic, maxillary, and mandibular branches to

sensory nuclei in the pons

Mandibular branch also innervates muscles of

mastication


The Cranial Nerves

Figure 15.25 The Trigeminal Nerve


The Cranial Nerves

The Abducens Nerve (N VI)


Origin: pons


Destination: lateral rectus muscle


The Cranial Nerves



The Cranial Nerves

The Facial Nerve (N VII) Primary function: mixed (sensory and motor)

Origin:

Sensory from taste receptors on anterior two thirds of tongue

Motor from motor nuclei of pons

Passes through: internal acoustic meatus of temporal bone,

along facial canal to reach stylomastoid foramen

Destination:

Sensory to sensory nuclei of pons

Somatic motor: muscles of facial expression

Visceral motor: lacrimal (tear) gland and nasal mucous glands via

pterygopalatine ganglion; submandibular and sublingual salivary

glands via submandibular ganglion


The Cranial Nerves

Figure 15.26a The Facial NerveCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Nerves


Figure 15.26b The Facial Nerve

The Cranial Nerves

The Vestibulocochlear Nerve (N VIII)

Primary function: special sensory: balance and equilibrium (vestibular branch) and hearing (cochlear branch)

Origin: receptors of the inner ear (vestibule and cochlea)

Passes through: internal acoustic meatus of the temporal bone

Destination: vestibular and cochlear nuclei of pons and medulla oblongata


The Cranial Nerves

Figure 15.27 The Vestibulocochlear Nerve


The Cranial Nerves

The Glossopharyngeal Nerve (N IX) Primary function: mixed (sensory and motor)

Origin:

Sensory from posterior one third of the tongue, part of the pharynx

and palate, the carotid arteries of the neck

Motor from motor nuclei of medulla oblongata

Passes through: jugular foramen between occipital and

temporal bones

Destination:

Sensory fibers to sensory nuclei of medulla oblongata

Somatic motor: pharyngeal muscles involved in swallowing

Visceral motor: parotid salivary gland, after synapsing in the otic

ganglion


The Cranial Nerves

Figure 15.28 The Glossopharyngeal NerveCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Nerves

The Vagus Nerve (N X) Primary function: mixed (sensory and motor)

Origin:

Visceral sensory from pharynx (part), auricle, external acoustic meatus, diaphragm, and visceral organs in thoracic and abdominopelvic cavities

Visceral motor from motor nuclei in the medulla oblongata

Passes through: jugular foramen between occipital and temporal bones

Destination:

Sensory fibers to sensory nuclei and autonomic centers of medulla oblongata

Somatic motor to muscles of the palate and pharynx

Visceral motor to respiratory, cardiovascular, and digestive organs in the thoracic and abdominal cavities.


The Cranial Nerves

Figure 15.29 The Vagus NerveCopyright © 2009 Pearson Education, Inc., publishing as Pearson Benjamin Cummings

The Cranial Nerves

The Accessory Nerve (N XI)

Primary function: motor

Origin: motor nuclei of spinal cord and medulla oblongata

Passes through: jugular foramen between occipital and temporal bones

Destination:

Internal branch innervates voluntary muscles of palate, pharynx, and larynx

External branch controls sternocleidomastoid and trapezius muscles


The Cranial Nerves

The Hypoglossal Nerve (XII)

Primary function: motor, tongue movements

Origin: motor nuclei of the medulla oblongata

Passes through: hypoglossal canal of occipital

bone

Destination: muscles of the tongue


The Cranial Nerves

Figure 15.30 The Accessory and Hypoglossal Nerves


The Cranial Nerves


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