Ebook Introduction to sectional anatomy (3rd edition) Part 1

(BQ) Part 1 book Introduction to sectional anatomy presentation of content: Introduction, head, spine, neck, chest, describe the general concept of sectional imaging, maintain one’s perspective when viewing sectional images, describe the inferior boundary of the head, identify and describe the bones making up the skull,...

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Introduction to

Sectional Anatomy

Third Edition

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Medical Diagnostic Imaging Programs

Fort Hays State University

Hays, Kansas

Includes bibliographical references and index.

Summary: “By using Introduction to Sectional Anatomy, the reader will be

able to view images from several patients in each region of the body,

thereby allowing them to compare the anatomical appearance Similarly, the

patient images will be shown using a variety of current imaging modalities

such as CT, MR, PET/CT, and ultrasound, including three-dimensional (3D)

imaging of vascular and bony anatomy”–Provided by publisher.

ISBN 978-1-60913-961-2 (alk paper)

I Title II Title: Sectional anatomy

[DNLM: 1 Anatomy, Cross-Sectional 2 Magnetic Resonance Imaging 3.

Tomography, X-Ray Computed QS 4]

The authors, editors, and publisher have exerted every effort to ensure that drug selection and dosage set forth in this text are in accordance with current recommendations and practice at the time of publication However, in view

of ongoing research, changes in government regulations, and the constant flow of information relating to drug apy and drug reactions, the reader is urged to check the package insert for each drug for any change in indications

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This book is affectionately dedicated to my family, Theresa, Levi, and Luke; and my students who are my constant source of inspiration

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Even though everyone has more or less the same anatomy,

each individual is arranged and shaped slightly different

For example, every person has a mouth, nose, and two eyes

arranged together to make their face, but very few people

look the same because of variations in shape and

arrange-ment Similar to the outside, every person has the same

parts on the inside and very few people will look alike in

sectional images By using Introduction to Sectional

Anatomy, the reader will be able to view images from

sev-eral patients in each region of the body, thereby allowing

them to compare the anatomical appearance Similarly, the

patient images will be shown using a variety of current

im-aging modalities such as CT, MR, PET/CT, and ultrasound,

including three-dimensional (3D) imaging of vascular and

bony anatomy Although the book is considered to be at the

introductory level for learning sectional anatomy, students

are expected to have completed one or two semesters of

study in anatomy and physiology before attempting to

dis-cern sectional images

ORGANIZATION

The book begins with a brief and simple introductory

chap-ter to help the student understand the chap-terminology and

plane of sections described in subsequent chapters To help

the students adjust to the higher level of understanding

needed for sectional anatomy, it’s best to have a clear

un-derstanding of the anatomy within the region with a strong

emphasis on the relationship with adjacent structures (e.g.,

the esophagus lies posterior to the trachea) Each chapter is

focused on a region of the body and begins with an

anatom-ical overview to give the reader a clear understanding of

each region essential to understanding the anatomy shown

later in sectional images To demonstrate the clinical

appli-cation of this anatomy, the overview is followed by a series

of patient CT, ultrasound, and MR images shown in

multi-adopted by the International Federation on Anatomical sociations and published in 1998 by Thieme Publishing inStuttgart, Germany Also, to help the student learn the cor-rect pronunciation of unfamiliar terms, phonetic spelling isfound in parenthesis immediately after the name of theanatomical structure A key for pronunciation is found onpage xiii

As-FEATURES AND ITEMS NEW TO THIS EDITION

The content of the third edition of Introduction to Sectional

Anatomy has been expanded threefold to include the latest

3D and four-dimensional (4D) technology, including sound, CTA, MRA, and PET/CT images The contemporarylayout and added color were designed to facilitate readingand comprehension Similarly, the patient images have beenrevised to enable the reader to more quickly compare im-ages between several imaging planes

ultra-To provide a highly regimented learning tool, all of thechapters begin with a series of Chapter Objectives and con-clude with a brief series of Clinical Application questionsintended to evaluate the reader’s understanding of the chap-ter’s material To help students apply the anatomy to clini-cal practice, six selected cases with corresponding questionsare presented at the end of each chapter collectively calledClinical Correlations Selected images include directionalrosettes in the bottom right corner These are included tohelp readers orient themselves to the view seen on eachcross section

ANCILLARIES

For additional self-examination, an accompanying studentworkbook is also available and corresponds closely withthe textbook Using selected images from the textbook,

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The image bank of the workbook images includes three

ver-sions of the images: one as seen in the workbook, one with

only leader lines for use in class or in assignments, and a

blank version A test generator and PowerPoint slides are

also included Even more Clinical Cases (approximately 20

per chapter) are provided for use as well

Altogether, these resources provide threefold more

pa-tient images as compared to the second edition, and many

of those included have been generated with 3D and 4D

imaging Likewise, the online resource centers provide

more supplemental materials designed to help students

learn sectional anatomy

The art of medical diagnostic imaging requires a strong

foundation in anatomy and a dedication to ongoing

educa-tion and change Medical diagnostic imaging continues to

be in a state of flux because of rapid advances in computer

imaging technology To best prepare students for their

clinical practice, dedicated teachers experiment with

for developing the art and science of medical diagnosticimaging

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This book would not have been possible without the contributions of many viduals and I would like to express my sincere gratitude to the following people.The staff at Wolters Kluwer/Lippincott, Williams & Wilkins—especially KristinRoyer, Jennifer Clements, Shauna Kelley, Christopher Johnson, and Peter Sabatini—for their expertise and considerable efforts in developing this projectfor publication The staff at Absolute Service especially Teresa Exley, ProjectManager, for her invaluable efforts in helping me through the production stages

This project was partially supported by grants from the National Center for Research Resources (5P20RR016475) and the National Institute of General Medical Sciences (8P20GM103418) from the National Institutes of Health

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Doris Abrishami

Head Clinical CoordinatorNorthridge Hospital Medical CenterNorthridge, California

Kelly Angel

Clinical Coordinator, RadiologyKaiser Permanente School of Allied Health SciencesRichmond, California

John Trombly

Director, Medical Imaging EducationRed Rocks Community CollegeLakewood, Colorado

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Dedication v

Preface vii

Acknowledgments ix

Reviewers xi

Pronunciation Key xiii

Chapter 1 Introduction 1

Chapter 2 Head 9

Chapter 3 Spine 125

Chapter 4 Neck 173

Chapter 5 Chest 231

Chapter 6 Abdomen 319

Chapter 7 Male and Female Pelvis 389

Chapter 8 Joints 527

Appendix A Answers to Clinical Application Questions 603

Appendix B Glossary 610

Appendix C Bibliography 613

Appendix D Figure Credits 615

Index 619

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Upon completion of this chapter, the student should be able to do the following:

1 Describe the general concept of sectional imaging

2 Maintain one’s perspective when viewing sectional images

3 Categorize sectional images as sagittal, coronal, or axial

4 Accurately classify joints within the body

5 Provide a basic overview of computed tomography (CT)

6 Describe the Hounsfield scale and basic absorption values of common tissues

7 Provide a basic understanding of magnetic resonance imaging (MRI)

8 Compare T1- and T2-weighted MRIs and relative signals generated in structures found within the body

9 Describe the basic principles and clinical application of positron emission tomography combined with computedtomography (PET/CT)

10 Give a basic overview of the principles and practice of ultrasound imaging

ANATOMIC OVERVIEW

Traditional anatomy courses tend to focus primarily on the

names and shapes of anatomic structures By comparison,

sectional anatomy places much more emphasis on the

phys-ical relationship among structures To identify anatomic

structures on sectional images, a complete understanding

of the basic anatomic information is a requisite from which

a three-dimensional understanding develops This textbook

follows this organization, beginning with an anatomic

overview of structures in the region followed by the labeled

CT and MRIs To demonstrate the application of this

knowledge, selected pathology is included as supplemental

(Fig 1-2) eliminate overlapping structures, allowing manystructures to be more clearly visualized in a nearly endlessvariety of planes Although CT and MRI will likely neverreplace conventional radiography because of affordabilityand diagnostic value in certain situations, these forms ofcomputerized imaging are found in most clinical facilities.Similar to conventional radiography, CTs and MRIs areextremely valuable diagnostic tools However, for these im-ages to be useful clinically, they must accurately depict theregion of the patient’s anatomy being studied Because theimage is generated by a computer, technical factors can sig-nificantly change or alter the resulting image If the opera-tor has an introductory knowledge of sectional anatomy, the

scanogram or scout image to provide a regional location

Sim-ilar to conventional radiographs, your right side should

corre-spond to the patient’s left side For orientation, when viewing

axial images you should picture yourself standing at the

pa-tient’s feet looking up into the body of the patient with your

right always on the left side of the patient Although right and

left are simple concepts, keeping the proper orientation on

sectional images is critical for correct identification ofanatomic structures Initially, the viewer should emphasizewhether the structure is on the left or right side of the body.When viewing sectional images, the initial impulse is

to start in the center of the image and identify eye-catchingstructures without first discerning the location of the scanwithin the body Attempting to identify anatomy withoutfirst determining the location of the slice will often result inconfusion and errors Besides the scanogram or scout imagethat provides general placement, additional information inthe image itself can help in more specifically locating thesectioned anatomy The bones can often provide much

of the information necessary to gain a more thoroughly defined perspective After this perspective is obtained,

Figure 1-1 A lateral skull radiograph.

Figure 1-3 Axial slices through the head.

be somewhat different For example, when we look at

peo-ple’s faces, we see that everyone has two eyes, one nose, and

one mouth, but we do not expect the specific arrangement of

these structures to be exactly the same for everyone Just like

on the outside, although most people have two kidneys, one

superior vena cava, and one aorta, the specific arrangement

of these structures will vary from person to person

PLANES OF THE BODY

(FIG 1-5)

Sagittal (SAJ-i-ta˘l) A plane extending along the long axis

of the body dividing it into right and left sides

Median or midsagittal A sagittal plane through the

body dividing it into equal right and left halves

Coronal (KO¯R-o˘-na˘l) or frontal A plane extending

through the body dividing it into anterior and posterior parts

Axial (AK-se˘-a˘l) or transverse A plane extending across

or through the axis of the body, extending from side to side,

dividing the body into superior and inferior portions

CLASSIFICATION OF JOINTS

Synarthrosis (SIN-ar-THRO¯-sis) An immovable joint

Arthrodia (ar-THRO¯-de¯-a˘) A gliding joint where bones

slide face to face and movement is limited by restrainingligaments Examples include the intercarpal and intertarsaljoints

Ginglymus (JING-gli-mu˘s) A hinge joint that allows

movement in only one plane Examples include the elbowand the knee joints

Saddle joint The opposing bones fit the contour of the

other and increase the extent of the hinge movement to include other planes of movement An example is the firstcarpometacarpal joint

Ellipsoid (e¯-LIP-soyd) A modified ball-and-socket joint

in which the opposing surfaces are shaped like a spindle orare ellipsoidal instead of being spherical An example is thewrist joint

Trochoid (TRO¯-koyd) A pivot joint that resembles a

pul-ley and allows movement in a partial ring Examples includethe radioulnar joints

Enarthrosis (en-ar-THRO¯-sis) A ball-and-socket joint in

which the spherical head fits into a cuplike cavity and provides free movement Examples include the hip andshoulder joints

COMPUTED TOMOGRAPHY

In CT, X-rays are used to generate the diagnostic tion, much like conventional radiography However, theprinciple of tomography is used to better visualize overlap-ping structures Based on a series of complex mathemati-cal processes, the computer reconstructs the image from aseries of digital numbers The numbers generated are reg-istered on the Hounsfield scale, by which bone is ⫹1,000,water is 0, and air is ⫺1,000 (Fig 1-6) Because CT uses X-rays to generate the image, radiodensity and radiolucencyare used to distinguish various tissues within the patient Toenhance the visualization of structures with similar densi-ties, the window level and width can be adjusted to demon-strate only part of the Hounsfield scale

Figure 1-4 The aortic arch demonstrating differences in

axial sections taken at several levels

Figure 1-5 The human body demonstrating

planes of section

Depending on the chemical environment, the hydrogenatoms require different amounts of energy to flip out of themagnetic field After the termination of the external radiosignals, the nuclei within the patient gradually release radiosignals as they return to their original state within the mag-netic field Depending on their chemical environment, thehydrogen atoms require different times to return to theiroriginal position The energy released is gathered and used

to generate the image; a series of complex mathematicalprocesses produce the digital image If the technical factorsare varied, the signal intensity for a given tissue will change(Fig 1-7) Similar to CT, adjusting the technical factors can

ULTRASOUND

Ultrasound imaging, also called ultrasound scanning or

would not show the entirety of the organ since the kidneytypically lies at an oblique angle to the spine and sagittalaxis of the body During longitudinal views, the plane of imaging is adjusted to the long axis of the organ to includeboth the upper and lower poles of the kidney To generatethe transverse views, the plane of section is rotated 90º orperpendicular to the longitudinal views Similarly, coronalviews are used to section the organ from anterior to posterior

Normal organ parenchyma (glandular tissue) is scribed as having a homogeneous or uniform composition asseen by the echoes produced by the sound beam For exam-ple, liver parenchyma should have a uniform echogenicitythat is very similar in density to the kidneys By compari-son, muscles will have a low echogenicity and are described

de-as hypoechoic (few echoes reflected from the anatomy ofinterest) Unlike muscle, there are other parts of the body,including the pancreas, that are hyperechoic (more echoes

or brighter than surrounding tissue) Fluid-filled structureslike blood vessels or the urinary bladder are anechoic (noechoes or black) in the lumen, while the walls are highlyechogenic (many echoes or bright), making them easy todistinguish with sonography When viewed together, the dif-ferences in attenuation (absorption) or reflection of thesound beam are used to delineate boundaries and consis-tency and are most accurate in viewing anatomy besidefluid-filled structures

POSITRON EMISSION TOMOGRAPHY COMBINED WITH COMPUTED

TOMOGRAPHY

The CT scan, using X-ray and measuring signals on theHounsfield scale, provides a detailed picture of the inter-nal anatomy that reveals the size and shape of abnormal cancerous growths By comparison, the highly sensitivePET scan picks up the metabolic signal of actively growing

Figure 1-7 A comparison of signal intensities in data

generated by T1 versus T2 weighting

A B

Figure 1-8 Even though both magnetic resonance images (MRIs) are of the same axial section of anatomy, the contrast is

substantially different due to changes in technical factors (A) The image on the left is classified as a

T1-weighted image, which is characterized as a bright or high signal from fat (found behind the eyes and underthe skin) with weak or low signal from water (dark inside eyes and ventricles) (B) By comparison, the T2-

weighted image shown on the right has a weak or low signal from fat and a bright or high signal from water.Typically, T1 images are used to visualize normal anatomy, whereas T2 images are used to show pathology because fluid often accumulates at the site of an injury

Figure 1-10 A composite image providing a representative series of axial images generated with positron emission

to-mography combined with computed toto-mography (PET/CT) In the upper right quadrant, the PET image is

2 When viewing an axial section with the patient in the supine position, the right side of the patient will be on

3 A plane or section dividing the body into anterior and posterior parts is classified as

4 A gliding joint where bones slide face to face and movement is limited by restraining ligaments is classified as

8 In an MRI, a -weighted image will have a bright or high signal from fat

9 In a PET scan, the cellular consumption of is measured and used to create diagnostic images

10 Briefly describe how ultrasound is used to make diagnostic images

Upon completion of this chapter, the student should be able to:

1 Describe the inferior boundary of the head

2 Identify and describe the bones making up the skull

3 Identify and describe the location of the central nervous system structures within the head

4 Describe the structures separating the skull cavity

5 Describe the dural venous system and the major arteries in the head

6 List the general functions of the cerebrum, cerebellum, basal ganglia, and brain stem and each structure’s locations on sagittal, coronal, and axial images

7 Follow the course of the cerebrospinal fluid (CSF) as it passes through the central nervous system

8 Describe the cranial nerves

9 Explain the relationships among structures located within the skull

10 Correctly identify anatomic structures on patient computed tomography (CT) and magnetic resonance (MR)

images of the head

ANATOMIC OVERVIEW

Most students consider the head to be one of the more

dif-ficult regions of the body to study, owing to the large

num-ber of structures in a relatively small area The major bony

structure, the skull, houses the brain and the organs of the

special senses When imaging the head, the base of the skull

is the inferior boundary of the head The bones making up

the skull will be reviewed first to provide a framework for

learning the soft tissue structures

from the mucous membrane within the nasal cavity to come the first pair of cranial nerves

be-Crista galli (KRIS-ta˘ GAL-li) A triangular process

pro-jecting upward from the cribriform plate that provides theattachment for the falx cerebri

Perpendicular plate Also called the vertical plate Part

of the ethmoid that is found below the cribriform plate thatjoins with the vomer and septal cartilage to separate thenasal cavity into right and left parts

Sinuses Also called air cells Their number and

arrangement within the ethmoid are highly variable; there

Frontal The bone forming the forehead, the anterior part

of the skull, and the roofs of the orbital cavities (Figs 2-1

and 2-2)

Sinuses Compartments of air centrally located within

the frontal bone that are usually separated by a septum and

drain into the nasal cavity in the middle meatus (opening

below middle concha)

Orbital plate The part of the frontal bone that forms

the roof of the orbital cavities The frontal sinuses extend

over the orbits in some individuals (Fig 2-1)

Lacrimal (LAK-ri-ma˘l) The small bone forming the floor

of the nasolacrimal duct on the anteromedial wall of the

orbit (Fig 2-2)

Maxilla (mak-SIL-a˘) Made up of the two maxillary

(MAK-si-la¯r-e¯) bones, which unite to form the upper part of the

mouth and the anterior three-quarters of the hard palate

of the face The bones form much of the inferior and lateralwalls of the orbit and have a process that articulates withthe temporal bone to form the zygomatic arch

Mandible Commonly called the jawbone The only

mov-able bone in the skull and the largest and strongest facialbone It is frequently divided into two major parts: The

ramus (RA¯-mu¯s), the vertical projection of bone on either

side, and the body, the horizontal projection containing theteeth

Condyles (KON-dı¯lz) The rounded processes above

the mandibular rami (RA¯-mi) that articulate with the poral bones to form the temporomandibular (TEM-po˘-ro¯-

tem-man-DIB-yu¯-la˘r) joints.

Vomer (VO¯-mer) Forms the posterior part of the nasal

septum A thin, flat bone extending from the hard palateand articulating with the perpendicular plate of the ethmoid

Figure 2-1 Drawing demonstrating a posterior coronal view of the nasal cavity.

Sphenoid sinus

Figure 2-2 Lateral view of the bony skull.

Clivus (KLI¯-vu˘s) The bony structure within the

poste-rior cranial fossa (FOS-a˘) between the dorsum sellae and

the foramen magnum (Fig 2-3) The upper part lies just

posterior to the dorsum sellae and is formed by the body of

the sphenoid bone On the other end, the lower part

ex-tends to the foramen magnum and is formed by the basilar

part of the occipital bone

Anterior and posterior clinoid (KLI¯-noyd) processes.

They surround the sella turcica and provide a site of ment for the dura mater, anchoring the pituitary glandwithin the sella turcica (Fig 2-4)

attach-Dorsum sellae (DO¯R-su˘m SEL-e¯) The posterior

boundary of the sella turcica, containing the posterior noid processes and forming the upper part of the clivus

cli-Ethmoid spine Orbital plate of frontal bone Lesser wing of sphenoid Greater wing of sphenoid

Internal auditory canal

Sulcus for sigmoid sinus

Superior orbital fissure

Anterior clinoid process Foramen ovale Foramen spinosum Dorsum sellae Petrous part of temporal bone

Posterior clinoid process

Sulcus for occipital sinus Internal occipital protuberance Sulcus for superior sagittal sinus

Sulcus for transverse sinus

Hypoglossal canal

Jugular foramen Foramen lacerum

Squamous part of temporal bone Foramen rotundum

Optic canal Cribriform plate

Foramen magnum

Figure 2-4 Superior axial view of the base of the skull.

Foramina (fo¯-RAM-i-na˘)

All are bilateral, except the foramen (fo¯-RA¯-men) magnum.

Carotid (ka-ROT-id) Located within the petrous portion

of the temporal bone Transmits the internal carotid artery

into the cranial cavity

Cribriform (KRIB-ri-fo¯rm) Found in the ethmoid bone

(Fig 2-4) Transmits bundles of nerve fibers originating

from mucous membranes lining the nasal cavity to the

olfac-tory bulbs

Hypoglossal (hı¯-po¯-GLOS-a˘l) canal Transmits the

hy-poglossal nerve out of the skull through the occipital bone

just above the occipital condyles

Internal auditory canal Also called the internal acoustic

meatus Located within the petrous part of the temporal

bone, it transmits the facial and the vestibulocochlear

(acoustic) nerves

temporal, and sphenoid bones Transmits small vessels,nerves, and lymphatics Internal carotid artery into the cra-nial cavity

Magnum (MAG-nu˘m) Found at the base of the occipital

bone Transmits the spinal cord

Optic Located within the lesser wing of the sphenoid

bone Transmits the optic nerve and the ophthalmic

(of-THAL-mik) artery into the orbital cavity (Fig 2-4).

Ovale (O¯-va˘-le¯) The opening through the greater wing of

the sphenoid bone Transmits the mandibular branch of thetrigeminal nerve to the lower face (Figs 2-2 and 2-4)

Rotundum An opening through the greater wing of the

sphenoid bone Transmits the maxillary branch of thetrigeminal nerve

Superior orbital fissure Found between the lesser and

greater wings of the sphenoid bone Transmits the motor, trochlear, and abducens nerves and the ophthalmicbranch of the trigeminal nerve

Palatine process, maxillary bone Zygomatic process

Horizontal lamina, palatine bone

Left zygomatic arch

Vomer Zygomatic process, temporal bone Foramen ovale Foramen spinosum

Foramen lacerum

I: Olfactory (ol-FAK-to˘-re¯) Originate from the olfactory

bulb and terminate within the nasal cavity in the mucous

membranes Transmit the sense of smell

II: Optic Originates from the retina Transmits the sense

of sight

III: Oculomotor (OK-yu¯-lo¯-MO¯-to˘r) Originate from the

interpeduncular fossa Innervate the external muscles of the

eyes, except the superior oblique and lateral rectus muscles

IV: Trochlear (TROK-le¯-ar) Originate lateral to the

cere-bral peduncles Innervate the superior oblique muscles of

the eyes

V: Trigeminal (trI¯-JEM-i-na˘l) Emerge from the lateral

side of the pons and have both sensory and motor functions

The three branches provide sensory fibers to most of

the head, and the motor fibers innervate the muscles of

mastication

VI: Abducens (ab-DU¯-senz) Emerge from the groove

be-tween the pons and medulla Innervate the lateral rectus

muscles of the eyes

VII: Facial Attach to the brain stem at the

cerebellopon-tine (ser-e-BEL-o¯-PON-te¯n) angle and have both sensory

and motor functions The sensory fibers carry the sense of

taste from the anterior two-thirds of the tongue, and the

motor fibers innervate the muscles of facial expression

VIII: Vestibulocochlear (acoustic) Extend from the

brain stem beside the facial nerve Transmit the senses of

equilibrium and hearing

IX: Glossopharyngeal (GLOS-o¯-fa˘-RIN-je¯-a˘l) Emerge

from the medulla and have both sensory and motor

func-tions The sensory fibers transmit the sense of taste from

the posterior third of the tongue, and the motor fibers

in-nervate the muscles of the pharynx

X: Vagus (VA¯-gu˘s) Emerge from the medulla Carry both

sensory and motor fibers from the pharynx, larynx, thorax,

and abdomen

XI: Spinal accessory Emerge from the medulla and first

seg-ment of spinal cord Innervate the trapezius (tra-Pe¯-ze¯-u˘s) and

ing between the cerebellum and the brain stem The rior joins the midbrain, the middle connects with the pons,and the inferior extends to the medulla and spinal cord

supe-Cerebellar tonsils Located on the lower and medial part

of the cerebellar hemispheres, next to the foramen magnum

Cerebrum (SER-e˘-bru˘m) The largest part of the brain, it

consists of two hemispheres The cortex contains mostlynerve cell bodies and appears as gray matter in unstainedspecimens Below the cortex, nerve fibers traveling towardand away from the cortex form the white matter Most re-gions function as association areas related to memory, rea-soning, judgment, intelligence, and personality

Sylvian (SIL-ve¯-an) fissure Also called the lateral

cere-bral sulcus (SU¯L-ku˘s) Located on the lateral side of the

cerebrum (Fig 2-7), where many grooves or sulci are found

between rounded protrusions or gyri (JI¯-rı¯) It is deeper

than the sulci and divides the lateral cerebrum into the poral and frontal lobes

tem-Central sulcus A centrally located sulcus found on the top

of the cerebrum, extending around the upper hemispheresdividing the frontal and parietal lobes

Frontal lobe Part of the cerebral hemispheres, located

anterior to the central sulcus and above the Sylvian fissure.The motor, or muscle, control areas are found just in front

of the central sulcus, and the association areas are found inthe anterior frontal lobe

Parietal (pa˘-RI¯-e˘-ta˘l) lobe Located between the central

sulcus and the parieto-occipital fissure and found above theSylvian fissure The general sensory, or somesthetic, areasthat represent specific parts of the body are found directlyposterior to the central sulcus The remaining section func-tions as part of the association areas

Temporal lobe Located inferior to the Sylvian fissure and

anterior to an extension of the parieto-occipital fissure Theupper part contains the primary auditory area, and the rest

is thought to be part of the association areas

Hippocampal (hip-o¯-KAM-pa˘l) formation Deep within

hemisphere to the corresponding gyrus on the opposite side

(Fig 2-8)

Genu (JE¯-nu˘) Describes the anterior part of the corpus

callosum, which transmits commissural fibers between the

frontal lobes (Latin for “bend” or “kneel”)

Body The middle part of the corpus callosum, formed

by commissural fibers from the parietal and temporal lobes

extending to the opposite hemisphere

Splenium (SPLE-ne¯-u˘m) The posterior and thicker

Anterior commissure An oval-shaped bundle of fibers

traveling between the temporal and frontal lobes of theright and left cerebral hemispheres Found below the infe-rior end of the fornix, it forms part of the anterior wall of thethird ventricle

Posterior commissure A complex bundle of fibers

trav-eling between hemispheres from a variety of nuclei Formspart of the posterior wall of the third ventricle

Pineal (PIN-e¯-a˘l) body Pinecone-shaped endocrine gland

Arachnoid mater

Choroid plexus of lateral ventricle Choroid plexus of 3rd ventricle Superior cistern Straight sinus Confluence of sinuses Choroid plexus of 4th ventricle Cisterna magna

Spinal pia mater Spinal dura mater Spinal arachnoid mater Central canal

Spinal cord

Medulla oblongata Cerebral aqueduct

Meningeal dura mater dura mater

Cerebral dura mater

Figure 2-6 Median sagittal drawing of the central nervous system.

Figure 2-7 Lateral view of the cerebrum.

Fornix Hypothalamus Choroid plexus

of 3rd ventricle

Intermediate mass Thalamus

Pineal body Posterior commissure Quadrigeminal plate Cerebral aqueduct Cerebellum Medulla oblongata

Pons

Midbrain (cerebral peduncle)

Pituitary Infundibulum Optic chiasm Mammillary body

Anterior commissure

Septum pellucidum

Body of corpus callosum

Genu of corpus callosum

Splenium of corpus callosum

Hypothalamus (HI¯-po¯-THAL-a˘-mu˘s) Forms the floor

and part of the lateral walls of the third ventricle The

nu-cleus includes the mammillary body and is protected by the

upper part of the sphenoid bone Although relatively small,

it controls many bodily functions related to maintaining

homeostasis, or stability, within the body

Pituitary (pi-TU¯-i-ta¯r-e¯) Also called the hypophysis

(hı¯-POF-i-sis) Located within the sella turcica of the sphenoid

bone An endocrine gland that regulates so many of the body’s

activities it is often called the “master gland”; the hormones

are absorbed by a capillary plexus surrounding the gland

Infundibulum (in-fu˘n-DIB-yu˘-lu˘m) The stalk

connect-ing the pituitary to the hypothalamus

Midbrain The bundle of nervous tissue connecting the

cerebrum with the cerebellum and spinal cord Although

the majority of the area consists of nerve fibers, a variety of

nuclei are found embedded within the white matter

Cerebral peduncles (pe-DU˘NG-klz) Found on the

an-terior portion of the midbrain A pair of large fiber bundles

that carry motor impulses from the cerebral cortex to the

pons and spinal cord

Red nucleus Found below the thalamus in the

supe-rior part of the cerebral peduncles An oval-shaped region

of gray matter considered to be a motor nucleus Fibers

from the cerebral cortex and cerebellum terminate here

and give rise to fibers traveling downward in the spinal cord

Substantia nigra (su˘b-STAN-she¯-a˘ NI¯-gra˘) The layer

of deeply pigmented gray matter lining much of the

poste-rior surface of the cerebral peduncles Fibers from the cell

bodies within the nucleus project to the cerebral cortex,

basal nuclei, thalamus, hypothalamus, and other regions of

the brain

Quadrigeminal (KWAH-dri-JEM-i-na˘l) plate Also

called the corpora quadrigemina The posterior portion of

the midbrain, behind the cerebral aqueduct Consists of

four rounded eminences containing small nuclei

Respon-sible for reflex movements in response to auditory and

vi-sual stimuli

lum, it consists of both gray and white matter; however, like the cerebrum and cerebellum, its outer layer is whitematter

un-Caudate (KAW-da¯t) nucleus C-shaped area of gray

mat-ter found following the curve of the lamat-teral ventricle volved in muscle control (Fig 2-9)

In-Head The enlarged part of the caudate nucleus bulges

into the floor of the anterior horn of the lateral ventricle

Body The central portion of the caudate nucleus

ante-rior to the collateral trigone (TRI¯-go¯n) of the lateral ventricle.

Tail The tapered part of the caudate nucleus in the

roof of the inferior horn of the lateral ventricle

Internal capsule The group of sensory and motor nerves

connecting the cerebral cortex with the brain stem andspinal cord (Fig 2-10) Because the tracts separate the thal-amus from the basal ganglia (globus pallidus, putamen, andcaudate), they form what appears as a “capsule” for the thalamus

Lenticular (len-TIK-YU˘-la˘r) nuclei Found lateral to the

internal capsule and the thalamus Shaped like an acorn,with the pointed end surrounded by internal capsule Con-sist of the globus pallidus and the putamen

Globus pallidus (GLO¯-bu˘s PAL-i-du˘s) The medial

lenticular nucleus located next to the internal capsule erally, it is separated from the putamen by a small lamina offibers Considered primarily a motor nucleus Cellular ex-tensions from the structure connect with most of the nucleiwithin the brain and the cerebral cortex

Lat-Putamen (pyu¯-TA¯-men) The lateral lenticular nucleus

found next to the globus pallidus and medial to the externalcapsule Has numerous connections and is generally con-sidered a motor nucleus thought to inhibit function of cor-tical-induced motor activity

External capsule A thin layer of white matter between

the putamen and the claustrum Its fibers are derived fromthe insula; the subthalamic connections are unknown

Claustrum (KLAWS-tru˘m) A sheet of gray matter

bounded by laminae of white matter on either side, the

Head of

caudate nucleus

Thalamus

Figure 2-9 Drawing from the lateral view of the brain demonstrating the location of the basal ganglia and thalamus.

function is not clearly understood, stimulation results in

vis-ceral sensations and autonomic responses

Corona radiata (ko¯-RO¯-na˘ RA¯-de¯-a˘-ta˘) Found above the

thalamus and basal ganglia Fibers radiating between the

in-ternal capsule and the cerebral cortex form sheets, creating

a crown of white matter above the nuclei (Fig 2-11)

Enclosing Structures

Dura mater (DU˘-ra˘ MA-ter) The fibrous outermost of

the three membranes covering the brain and spinal cord

(Latin for “hard mother”) The meningeal layer located

with CSF and contains most of the major arteries supplyingblood to the brain

Pia (PI¯-a˘) mater The innermost membrane surrounding

the brain and spinal cord In a cadaver specimen, it is cult to separate from the nervous system structures because

diffi-it is tightly adhered and intimately related to the surface ofthe brain and spinal cord

Falx cerebri (falks se-RE¯-bri) Separates the cerebral

hemispheres A reflection of dura mater that extendscaudally from the upper calvarium and ends just abovethe corpus callosum (Fig 2-13) Its anterior end attaches

to the crista galli of the ethmoid bone, and the posterior

Anterior horn of lateral ventricle Head of caudate nucleus Claustrum

Putamen Globus pallidus

Lenticular nuclei Thalamus

Posterior horn of lateral ventricle

Splenium of corpus callosum

Tail of

caudate nucleus

External capsule

Fornix Extreme capsule

Internal capsule

Insula

Figure 2-10 Axial section through the head demonstrating the basal ganglia and thalamic nuclei.

Dural Sinuses and Veins

Superior sagittal (SAJ-i-ta˘l) sinus Within the upper

margin of the falx cerebri, the layers of dura form a sinus for

venous blood draining from the upper cerebral

hemi-spheres Following the superior margin of the falx cerebri,

it lies near the inner surface of the calvarium

Inferior sagittal sinus Within the lower margin of the falx

cerebri, venous blood from the medial part of the cerebral

hemispheres is collected in a space between the layers of

Confluence of sinuses The opening formed between the

layers of dura mater where the superior sagittal, straight,occipital, and transverse sinuses meet

Transverse sinuses Within the posterior margin of the

tentorium cerebelli, they extend laterally on either side(Fig 2-14) Within the layers of dura, each one drains ve-nous blood from the confluence of sinuses to the petrouspart of the temporal bone, where it bends caudally to jointhe sigmoid sinus

Sigmoid (SIG-moyd) sinuses Drain venous blood from

Corpus callosum Caudate nucleus Claustrum Putamen Globus pallidus

Subthalamic nucleus

Lateral ventricle, inferior horn

Substantia nigra Pons

Cerebral peduncle

Internal capsule External capsule Extreme capsule

Thalamus

Figure 2-11 Coronal section through the brain demonstrating relationships between the basal ganglia and thalamic nuclei.

To help you learn the location of the major arteries, think of

a stick man named Willis Willis’s legs are formed by the

vertebral arteries, his trunk is formed by the basilar artery,

his arms are the posterior cerebral arteries, and his head is

formed by the circle of Willis (Fig 2-15)

Vertebral (VER-te˘-bra˘l) Originating from the

subcla-vian arteries in the thorax, these bilateral arteries ascend

through the transverse foramina of C6 through C1

Supe-rior to C1, they pass through the foramen magnum and the

dura mater to enter the subarachnoid space Found on

ei-Circle of Willis A ring of vessels located within the

sub-arachnoid space below the hypothalamus and midbrain thatsupplies arterial blood to the cerebrum

Posterior cerebral Located along the upper border of

the pons, these bilateral arteries originate from the basilarartery and extend above the tentorium cerebelli to supplythe occipital lobes with arterial blood The right and left ar-teries are separated by the falx cerebri and appear to wraparound the splenium of the corpus callosum, joining theright and left cerebral hemispheres

Posterior communicating Shortly after the posterior

cerebral artery originates from the basilar artery, a small

Superior sagittal sinus Falx cerebri Vein of Galen Straight sinus Tentorium cerebelli (cut)

Confluence of sinuses Falx cerebelli Transverse sinus Internal jugular vein XII

IX, X, XI VII/VIII V

Cavernous sinus

Figure 2-13 Dural reflections and associated venous sinuses within the head.

branch to form the posterior communicating, middle

cere-bral, and anterior cerebral arteries

Middle cerebral The major branches from the internal

carotid arteries, these arteries extend laterally through the

Sylvian fissures to supply blood to the temporal and

pari-etal lobes

Anterior cerebral Slightly smaller than the middle

cerebral artery, these branches of the internal carotid

arter-ies travel anteriorly in the interhemispheric fissure The

right and left arteries are found on either side of the falx

cerebri and appear to wrap around the genu of the corpus

by ependyma (ep-EN-di-ma˘), which in certain regions is highly vascularized, forming the choroid plexus (KO-royd

PLEK-su˘s) The choroid plexus produces CSF from the

blood to fill the ventricles

Anterior horn The part of the lateral ventricles found

within the frontal lobe The roof is formed by the corpuscallosum, the floor and lateral wall are formed by the head

of the caudate nucleus, and the medial wall is formed bythe septum pellucidum

Body The anterior horn continues posteriorly to join

with the body of the lateral ventricle within the parietal

sagittal sinus Inferior sagittal sinus Vein of Galen Straight sinus

Transverse sinus Occipital sinus Sigmoid sinus

External jugular vein Internal jugular vein

Figure 2-14 Major venous structures within the head.