Ebook Sectional anatomy for imaging professionals (3rd edition): Part 1

(BQ) Part 1 book Sectional anatomy for imaging professionals presents the following contents: Introduction to sectional anatomy, cranium and facial bones, brain, spine, neck, thorax. Invite you to consult.

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SECTIONAL ANATOMY FOR IMAGING PROFESSIONALS, ISBN: 978-0-323-08260-0 THIRD EDITION

Copyright © 2013 by Mosby, an imprint of Elsevier Inc.

Copyright © 2007, 1997 by Mosby, Inc., an affiliate of Elsevier Inc.

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This book and the individual contributions contained in it are protected under copyright by the Publisher (other than as may be noted herein).

Notice

Knowledge and best practice in this field are constantly changing As new research and experience broaden our understanding, changes in research methods, professional practices, or medical treatment may become necessary Practitioners and researchers must always rely on their own experience and knowledge in evaluating and using any information, methods, compounds, or experiments described herein In using such information or methods they should be mindful of their own safety and the safety of others, including parties for whom they have a professional responsibility.

With respect to any drug or pharmaceutical products identified, readers are advised to check the most current information provided (i) on procedures featured or (ii) by the manufacturer of each product to be administered, to verify the recommended dose or formula, the method and duration

of administration, and contraindications It is the responsibility of practitioners, relying on their own experience and knowledge of their patients, to make diagnoses, to determine dosages and the best treatment for each individual patient, and to take all appropriate safety precautions.

To the fullest extent of the law, neither the Publisher nor the authors, contributors, or editors, assume any liability for any injury and/or damage to persons or property as a matter of products liability, negligence or otherwise, or from any use or operation of any methods, products,

instructions, or ideas contained in the material herein.

ISBN: 978-0-323-08260-0

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Associate Content Development Specialist: Amy Whittier

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Printed in China

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their wisdom and encouragement in ways that strengthen and inspire me.

LLK

Thank you to my family and friends whose guidance, love, and support

carried me through my most trying times.

I dedicate this book to:

My greatest blessings, Brady and Trinity, for the countless joys you have

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are loved and how truly honored I am to be your mom.

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encouragement I love you both dearly.

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when I needed you most.

CMP

Many provided encouragement and direction as the

compilation of this text commenced Amy Whittier had

the tiresome duty of encouraging us to meet deadlines,

which she did with grace and humor Jennifer Geistler

had the daunting task of strategically pulling it all

to-gether We are indebted to them for their editorial

assis-tance in seeing this project through completion

We wish to extend our gratitude to everyone who

thought the first and second editions had value and to

those who took the time to provide constructive

criti-cism and suggestions for further improvements and

in-creased accuracy And to the many students who were

not shy in providing feedback so that we could see the

text from many different perspectives

The following individuals and institutions deserve

special acknowledgment:

• The faculty at Boise State University for their

sup-port and patience as we faced fast-approaching

deadlines

• Chris Hayden for his tremendous patience, edge, and time invested in helping us find and create all of the new CT images for the third edition And

knowl-St Alphonsus Regional Medical Center for providing the CT images

• Mary Pullin from Philips Medical Systems for providing some beautiful MR images

• Dave Arnold and St Luke’s Regional Medical Center,

as well as Kevin Bean and Intermountain Medical Imaging, for providing the majority of the MR images

We owe a debt of gratitude to Jeanne Robertson, who provided numerous new illustrations and revised many old drawings in record time Because of her efforts and talent, there is more consistency in the visual presentation

of the artwork throughout the text

Lorrie L Kelley Connie M Petersen

iv

A C K N O W L E D G M E N T S

Shore Medical Center

School of Radiologic Technology

Somers Point, New Jersey

Lisa Fanning, MEd, RT(R)(CT)

Radiography Program Director

Massachusetts College of Pharmacy

and Health Sciences

Radiologic Sciences Department

Northwestern State University of

Salt Lake City, Utah

Kathleen Kienstra, MAT, RT(R)(T)

Program DirectorRadiation Therapy ProgramSaint Louis University

St Louis, Missouri

Bob McGee, MEd, RT(R), CCI

Assistant Professor/Clinical Coordinator

South College/AshevilleAsheville, North Carolina

Marcia Moore BS, RT(R)(CT)

Instructor

St Luke’s CollegeSioux City, Iowa

Roger Preston, MSRS, RT(R)(CT)

Program DirectorSchool of Radiologic TechnologyRichmond, Indiana

Theresa Roberts, MHS, RT(R)(MR)

Program DirectorRadiologic TechnologyKeiser UniversityMelbourne, Florida

Kenneth Roszel, MS, RT(R)

Program DirectorGeisenger Medical CenterDanville, Pennsylvania

Rebecca Silva, MEd, MPH, RT(R)

Department ChairSouth Texas CollegeMcAllen, Texas

Karen Tillelli, RT, CT(R)

Program InstructorUniversity of Utah Hospital/ClinicsSalt Lake City, Utah

Diana Werderman, MSEd, RT(R)

Assistant ProfessorTrinity College of Nursing and Health Sciences

Rock Island, Illinois

v

This text was written to address the needs of today’s

practicing health professional As technology in

diagnos-tic imaging advances, so does the need to competently

recognize and identify cross-sectional anatomy Our goal

was to create a clear, concise text that would

demon-strate in an easy-to-use yet comprehensive format the

anatomy the health professional is required to

under-stand to optimize patient care The text was purposely

designed to be used both as a clinical reference manual

and as an instructional text, either in a formal classroom

environment or as a self-instructional volume

Included are close to 1000 high-quality MR and CT

images for every feasible plane of anatomy most

com-monly imaged An additional 350 anatomic maps and

line drawings related to the MR and CT images add to

the learner’s understanding of the anatomy being

stud-ied In addition, pathology boxes describe common

pathologies related to the anatomy presented, assisting

the reader in making connections between the images in

the text and common pathologies that will be

encoun-tered in clinical practice Tables that summarize muscle

group information include points of origin and insertion,

as well as functions, for the muscle structures pertinent

to the images the reader is studying

NEW TO THIS EDITION

• Nearly 150 new MR and CT images and 30 new line

drawings provide more 3D and vascular images to

bet-ter demonstrate anatomy seen with current technology

• Chapter Objectives will help readers prepare for the

material they will learn in each chapter

• Addition of full labels to scans will improve usability

of the images and allow readers to quickly and

effi-ciently see the anatomy displayed on the scan

• Addition of Test Bank to Evolve Instructor Resources

will provide readers with the tools for an enhanced

learning experience

CONTENT AND ORGANIZATION

The images include identification of vital anatomic tures to assist the health professional in locating and identifying the desired anatomy during actual clinical examinations The narrative accompanying these images clearly and concisely describes the location and function

struc-of the anatomy in a format easily understood by health professionals The text is divided into chapters by anatomic regions Each chapter of the text contains an outline that provides an overview of the chapter’s con-tents, pathology boxes that briefly describe common pathologies related to the anatomy being presented, tables designed to organize and summarize the anatomy contained in the chapter, and reference illustrations that provide the correct orientation for scanning the anatomy

of interest

ANCILLARIES

A Workbook and an Evolve site complement the text When used together, these additional tools create a vir-tual learning system/reference resource

Workbook: The Workbook provides practice

oppor-tunities for the user to identify specific anatomy The Workbook includes learning objectives that focus on the key elements of each chapter, a variety of practice items

to test the reader’s knowledge of key concepts, labeling exercises to test the reader’s knowledge of the anatomy, and answers to exercises

Instructor Resources on Evolve: These resources

in-clude a test bank with approximately 500 questions and

an image collection with approximately 1000 images

Lorrie L Kelley Connie M Petersen

P R E F A C E

vi

1  Introduction to Sectional Anatomy, 1

Coronary Circulation, 368 Off-Axis Cardiac Imaging, 377 Azygos Venous System, 386 Muscles, 389

Breast, 395

7  Abdomen, 397

Abdominal Cavity, 398 Liver, 412

Gallbladder and Biliary System, 431 Pancreas, 437

Spleen, 441 Adrenal Glands, 442 Urinary System, 446 Stomach, 453 Intestines, 458 Abdominal Aorta and Branches, 468 Inferior Vena Cava and Tributaries, 485 Lymph Nodes, 488

Muscles of the Abdominal Wall, 490

8  Pelvis, 494

Bony Pelvis, 495 Muscles, 505 Viscera, 517 Vasculature, 550 Lymph Nodes, 561

9  Upper Extremity, 563

Shoulder, 564 Elbow, 601 Wrist and Hand, 621 Neurovasculature, 646

10  Lower Extremity, 654

Hip, 655 Knee and Lower Leg, 682 Ankle and Foot, 714 Neurovasculature, 746

vii

Copyright © 2013, Elsevier Inc.

Anatomic Positions and Planes , 2

Terminology and Landmarks , 2

Multiplanar Reformation (Reformat) (MPR), 9Curved Planar Reformation (Reformat) (CPR), 9

3D Imaging, 9

Shaded Surface Display (SSD) , 12

Maximum Intensity Projection (MIP) , 12 Volume Rendering (VR) , 12

1

Introduction to Sectional

Anatomy

L R

Rectum

Acetabulum Femoral head

Gluteus maximus muscle Coccyx

Coccygeus muscle

FIGURE 1.1 Axial CT of hips.

Sectional anatomy has had a long history Beginning as early as the sixteenth century, the great anatomist and art-ist, Leonardo da Vinci, was among the first to represent the body in anatomic sections In the following centuries, numerous anatomists continued to provide illustrations of various body structures in sectional planes to gain greater understanding of the topographical relationships of the organs The ability to see inside the body for medical pur-poses has been around since 1895, when Wilhelm Conrad Roentgen discovered x-rays Since that time, medical imag-ing has evolved from the static 2-dimensional (2D) image

of the first x-ray to the 2D cross-section image of puted tomography (CT), and finally to the 3-dimensional (3D) imaging techniques used today These changes war-rant the need for medical professionals to understand and identify human anatomy in both 2D and 3D images.Sectional anatomy emphasizes the physical relationship between internal structures Prior knowledge of anatomy from drawings or radiographs may assist in understanding the location of specific structures on a sectional image For example, it may be difficult to recognize all the internal anatomy of the pelvis in cross-section, but by identifying the femoral head on the image, it will be easier to recog-nize soft tissue structures adjacent to the hip in the general location of the slice (Figure 1.1)

com-• Define the four anatomic planes

• Describe the relative position of specific structures within

the body using directional and regional terminology

• Identify commonly used external landmarks

• Identify the location of commonly used internal

landmarks

O B J E C T I V E S

• Describe the dorsal and ventral cavities of the body

• List the four abdominal quadrants

• List the nine regions of the abdomen

• Describe the gray scale used in CT and MR imaging

• Describe MPR, CPR, SSD, MIP and VR

ANATOMIC POSITIONS AND PLANES

For our purposes, sectional anatomy encompasses all the

variations of viewing anatomy taken from an arbitrary angle

through the body while in anatomic position

In anatomic position, the body is standing erect, face

and toes pointing forward, and arms at the side with the

palms facing forward Sectional images are acquired and

displayed according to one of the four fundamental

ana-tomic planes that pass through the body (Figure 1.2)

The four anatomic planes are defined as follows:

1 Sagittal plane: a vertical plane that passes through the

body, dividing it into right and left portions

2 Coronal plane: a vertical plane that passes through the

body, dividing it into anterior (ventral) and posterior

(dorsal) portions

3 Axial (transverse) plane: a horizontal plane that

passes through the body, dividing it into superior and

inferior portions

4 Oblique plane: a plane that passes diagonally between

the axes of two other planes

Medical images of sectional anatomy are, by

conven-tion, displayed in a specific orientation Images are viewed

with the right side of the image corresponding to the viewer’s left side (Figure 1.3)

TERMINOLOGY AND LANDMARKS

Directional and regional terminology is used to help describe the relative positions of specific structures within the body Directional terms are defined in Table 1.1, and regional terms are defined in Table 1.2 and demonstrated

in Figure 1.4

External Landmarks

External landmarks of the body are helpful in identifying the location of many internal structures The commonly used external landmarks are shown in Figures 1.5 and 1.6

Internal Landmarks

Internal structures, in particular vascular structures, can be located by referencing them to other identifiable regions or locations, such as organs or the skeleton (Table 1.3)

Sagittal

Transverse

Coronal

Median sagittal plane

Axial plane

Oblique plane

Anter ior (ventral ) Poster ior (dorsal)

A

S

I A

P S

Stomach Liver

Spleen

A

P

L R

Directional Terminology TABLE 1.1

or the sole of the foot

Regional Terminology TABLE 1.2

Abdominal

Thoracic (pectoral)

Occipital

Axillary Vertebral

Sacral Gluteal (buttock) Perineal

Popliteal Cutaneous (skin) Pedal

Femoral (thigh)

Plantar Tarsal

Leg (crural)

Oral Otic

Cranial Ophthalmic Cephalic

Buccal

Frontal

Pelvic

Costal Mammary Sternal Brachial

Antecubital

Carpal Palmar Navel (umbilical)

Inguinal (groin)

Vertebral prominens

Gonion

C7 C5 C3 C1 External auditory meatus (EAM)

FIGURE 1.5 Surface landmarks of the head and neck.

C5 and thyroid cartilage

T1 T2, T3, and jugular notch T4, T5, and sternal angle

T10 and xiphoid process

L3 and costal margin L3, L4, and level of umbilicus L4 and crest of ilium S1 and anterior superior iliac spine Coccyx, symphysis pubis, and greater trochanters

FIGURE 1.6 Surface landmarks of the body.

Landmark Location

Common iliac vein bifurcation Upper margin of sacroiliac joint

midclavicular line

cartilages behind sternum

abdominal aorta

mesenteric artery

inferior border of thyroid cartilage

Internal Landmarks

The body consists of two main cavities: the dorsal and ventral cavities The dorsal cavity is located posteriorly and includes the cranial and spinal cavities The ven-tral cavity, the largest body cavity, is subdivided into the thoracic and abdominopelvic cavities The thoracic cavity is further subdivided into two lateral pleural cavities and a single, centrally located cavity called the mediastinum The abdominal cavity can be subdivided into the abdominal and pelvic cavities (Figure 1.7) The structures located in each cavity are listed in

Table 1.4

ABDOMINAL AND PELVIC DIVISIONS

The abdomen is bordered superiorly by the diaphragm and inferiorly by the superior pelvic aperture (pelvic inlet) The abdomen can be divided into quadrants or regions These divisions are useful in identifying the general location of internal organs and provide descrip-tive terms for the location of pain or injury in a patient’s history

Dorsal cavities

Ventral

cavities

A

Brain in cranial cavity

Mediastinum Trachea

Lung Heart

Diaphragm Liver

Transverse colon Small

intestine Ascending colon

Appendix

Thoracic cavity

Abdominal cavity

Spleen Stomach Pancreas

Descending colon

Pelvic cavity

Pleural cavity

B

FIGURE 1.7 A, Sagittal view of body cavities B, Anterior view of body cavities.

LLQ RLQ

RUQ

Midsagittal plane

Transverse plane

B

FIGURE 1.8 A, Four abdominal quadrants B, Nine abdominal regions.

Quadrants

The midsagittal plane and transverse plane intersect at

the umbilicus to divide the abdomen into four quadrants

(Figure 1.8, A):

Right upper quadrant (RUQ)

Right lower quadrant (RLQ)

Left upper quadrant (LUQ)

Left lower quadrant (LLQ)

For a description of the structures located within each quadrant, see Table 1.5

Regions

The abdomen can be further divided by four planes into nine regions The two horizontal planes are the transpy-loric and transtubercular planes The transpyloric plane

is found midway between the xiphisternal joint and the umbilicus, passing through the inferior border of the L1 vertebra The transtubercular plane passes through the tubercles on the iliac crests, at the level of the L5 vertebral body The two sagittal planes are the midcla-vicular lines Each line runs inferiorly from the midpoint

of the clavicle to the midinguinal point (Figure 1.8, B)

The nine regions can be organized into three groups:Superior

• Right hypochondrium

• Epigastrium

• Left hypochondriumMiddle

• Right lateral

• Umbilical

• Left lateralInferior

• Right inguinal

• Hypogastrium

• Left inguinal

Body Cavities TABLE 1.4

Main Body Cavities Contents

esophagus, and pericardium

Abdominal and Pelvic

pan-creas, spleen, stomach, intestines, kidneys, ureters, and blood vessels

female reproductive system

Organs Found within Abdominopelvic Quadrants TABLE 1.5

IMAGE DISPLAY

Each digital image can be divided into individual regions

called pixels or voxels that are then assigned a numerical

value corresponding to a specific tissue property of the

structure being imaged (Figure 1.9) The numerical

value of each voxel is assigned a shade of gray for image

display In CT, the numerical value (CT number) is

refer-enced to a Hounsfield unit (HU), which represents the

attenuating properties or density of each tissue Water is

used as the reference tissue and is given a value of zero

A CT number greater than zero will represent tissue that

is denser than water and will appear in progressively

lighter shades of gray to white Tissues with a negative

CT number will appear in progressively darker shades of

gray to black (Figure 1.10) In magnetic resonance (MR), the gray scale represents the specific tissue relaxation properties of T1, T2, and proton density The gray scale

in MR images can vary greatly because of inherent tissue properties and can appear different with each patient and across a series of images (Figure 1.11)

The appearance of digital images can be altered to include more or fewer shades of gray by adjusting the gray scale, a process called windowing Windowing

is used to optimize visualization of specific tissues or lesions Window width (WW) is a parameter that allows for the adjustment of gray scale (number of shades of gray), and window level (WL) basically sets the density

of the image (Figure 1.10)

Pixel

Voxel

FIGURE 1.9 Representation of a pixel and voxel.

Bone window

Mediastinal window

Lung window

CT number (HU)

Bone

Lung tissue

Air 0

Muscle Water = 0

Dense bone

Soft tissue Fat

Black

FIGURE 1.10 CT numbers and windowing on axial CT of chest.

MULTIPLANAR REFORMATION

AND 3D IMAGING

Several postprocessing techniques can be applied to the

original 2D digital data to provide additional 3D

infor-mation for the physician All current postprocessing

techniques depend on creating a digital data stack from

the original 2D images, thereby generating a cube of

digital information (Figure 1.12)

Multiplanar Reformation (Reformat) (MPR)

Images reconstructed from data obtained along any

pro-jection through the cube result in a sagittal, coronal, axial,

or oblique image (see Figures 1.13 and 1.14)

Curved Planar Reformation (Reformat) (CPR)

Images are reconstructed from data obtained along an arbitrary curved projection through the cube (Figure 1.15)

3D Imaging

All 3D algorithms use the principle of ray tracing in which imaginary rays are sent out from a camera view-point The data are then rotated on an arbitrary axis, and the imaginary ray is passed through the data in specific increments Depending on the method of recon-struction, unique information is projected onto the view-ing plane (Figure 1.16)

T1 for solid tissue

T1 for free water

g. , w at

e r)

Sh ort T2 e.

FIGURE 1.11 MR tissue relaxation and image contrast.

1

1 4

4

4 2

2

2

2

2 6

5

5

5 5

9 9 9 3

1 4

4

4 2

2

2

2

2 6

5

5

5 5

9 9 9 3

3

3 1

1 4

4

4 2

2

2

2

2 6

5

5

5 5

9 9 9 3

3

3 1

1 4

4

4 2

2

2

2

2 6

5

5

5 5

9 9 9 3

FIGURE 1.14 Multiplanar reformations of brain.

Overview

Axial

Coronal Sagittal

Shaded surface display

Volume rendering

MIP

FIGURE 1.13 Multiplanar reformation and 3D.

Shaded Surface Display (SSD) A ray from the

cam-era’s viewpoint is directed to stop at a particular

user-defined threshold value With this method, every voxel

with a value greater than the selected threshold is

ren-dered opaque, creating a surface That value is then

projected onto the viewing screen (Figure 1.17)

Maximum Intensity Projection (MIP) A ray from

the camera’s viewpoint is directed to stop at the

voxel with the maximum signal intensity With this

method, only the brightest voxels will be mapped into

the final image (Figure 1.18)

Volume Rendering (VR) Contributions of each voxel

are summed along the course of the ray from the camera’s viewpoint The process is repeated numerous times to determine each pixel value that will be displayed in the final image (Figure 1.19)

1

1 4

4

4 2

9 9 9 3

3

3

MPR

CPR Voxels

FIGURE 1.15 Curved planar reformation MPR, Multiplanar

refor-mation CPR, curved planar reforrefor-mation.

Displayed pixel

Pix els along ray

FIGURE 1.16 Ray tracing.

S

I Displayed pixel

Pix els along ray

FIGURE 1.17 Shaded surface display (SSD).

I

Pix els a long ray

Maximum intensity

Projected value

FIGURE 1.18 Maximum intensity projection (MIP).

S

I Displayed pixel

Pix els a long ray

FIGURE 1.19 Volume rendering (VR).

Frank E, Long B: Radiographic positions and radiologic procedures,

ed 12, St Louis, 2011, Mosby.

Curry RA, Tempkin BB: Sonography: Introduction to normal

structure and functional anatomy, ed 3, St Louis, 2010,

Saunders.

Seeram E: Computed tomography; physical principle, clinical applications, and quality control, ed 3, Philadelphia, 2008,

Saunders.

• Identify the structures of the osteomeatal unit.

• Identify the bones that form the orbit and their associated openings

• Describe the structures that constitute the globe of the eye

• List the muscles of the eye and describe their functions and locations

2

Cranium and Facial Bones

Gentlemen, damn the sphenoid bone!

Oliver Wendell Holmes (1809-1894), Opening of anatomy lectures at Harvard Medical School

The complex anatomy of the cranium and facial bones can

be intimidating However, with three-dimensional (3D) imaging and multiple imaging planes, the task of learning these structures can be simplified It is important to under-stand normal sectional anatomy of the cranium and facial bones to identify pathologic disorders and injuries that may occur within this area (Figure 2.1) This chapter demon-strates the sectional anatomy of the following structures:

FIGURE 2.1 3D CT of skull Trauma resulting from a gunshot wound.

Mandible, 59

Temporomandibular Joint , 62

Bony Anatomy, 62Articular Disk and Ligaments, 63Muscles, 65

Paranasal Sinuses , 68

Ethmoid, 69Maxillary, 71Sphenoid, 72Frontal, 73Osteomeatal Unit, 74

Orbit , 75

Bony Orbit, 75Soft Tissue Structures, 79Optic Nerve, 81

Muscles of the Eye, 83Lacrimal Apparatus, 86Copyright © 2013, Elsevier Inc.

The cranium is composed of eight bones that surround

and protect the brain These bones include the parietal

(2), frontal (1), ethmoid (1), sphenoid (1), occipital (1),

and temporal (2) (Figures 2.2 through 2.5) The cranial

bones are composed of two layers of compact tissue

known as the internal (inner) and external (outer)

tables Located between the two tables is cancellous tis-sue or spongy bone called diploe (Figures 2.6 through

2.9) The base of the cranium houses three fossae called

the anterior, middle, and posterior cranial fossae

The anterior cranial fossa (frontal fossa) is composed

primarily of the frontal bone, ethmoid bone, and lesser wing of the sphenoid bone and contains the frontal

lobes of the brain The middle cranial fossa (temporal

fossa) is formed primarily by the body of the sphenoid and temporal bones and houses the pituitary gland, hypothalamus, and temporal lobes of the brain The

posterior cranial fossa (infratentorial fossa) is formed

by the occipital and temporal bones and contains the cerebellum and brainstem (Figures 2.6 and 2.7) For additional details of the contents found within the cra-nial fossa, see Table 2.1 Each cranial bone is structur-ally unique, and thus identification of the physical components can be challenging

FIGURE 2.2 Anterior view of skull.

Temporal bone

Sphenoid bone (greater wing)

Glabella

Supraorbital foramen

Coronal suture

Parietal bone

Sphenoid bone

Superior orbital fissure

Optic canal

Optic strut

Lambdoidal suture

Parietomastoid suture

Ethmoid bone FIGURE 2.3 Lateral view of skull.

FIGURE 2.4 3D CT of anterior skull.

Parietal bone Superior orbital fissure Temporal bone

Zygoma

Maxilla

Mandible

Sphenoid bone

Coronal suture S

I

FIGURE 2.5 3D CT of lateral skull.

Pterion

Sphenofrontal suture

External

occipital

protuberance

Ethmoid bone Zygomatic arch

Maxilla Zygoma

Mandible

Frontal bone

S

I

FIGURE 2.6 Superior view of cranial fossae.

Middle cranial fossa

Posterior cranial fossa

Anterior cranial fossa

Crista galli

Orbital plate of frontal bone

Sella turcica

Lesser wing of sphenoid bone

Foramen rotundum

Foramen lacerum Foramen ovale

Foramen spinosum Internal auditory canal

Hypoglossal canal

Internal occipital protuberance OCCIPITAL BONE

TEMPORAL BONE SPHENOID BONE

ETHMOID BONE FRONTAL BONE

Internal table

Diploë External table

Ethmoid notch of frontal bone

End of carotid canal

Jugular foramen

Mastoid foramen

Foramen magnum

Cribriform plate

FIGURE 2.7 3D CT of cranial fossae, superior view.

Middle cranial fossa

Cribriform plate

Orbital plate of frontal bone

Sella turcica

Lesser wing of sphenoid bone

Foramen lacerum

Foramen ovale Foramen spinosum

Petrous portion of temporal bone

Diploë

Internal table Foramen

magnum Clivus

Temporal bone Sphenoid bone

Ethmoid bone Frontal bone

Ethmoid notch of frontal bone

Occipital bone

External table A

P

ETHMOID BONE

FRONTAL BONE

Coronal suture Sphenofrontal suture

Frontal sinus

MAXILLARY BONE

MANDIBLE VOMER

Sella turcica

Styloid process Clivus

Squamous suture

Lambdoidal suture

External table Diploë Internal table Meningeal grooves

Sphenoid sinus

Vertex

Parietal bone Sphenosquamosal suture

NASAL BONE

PALATINE BONE

FIGURE 2.8 Lateral view of inner skull.

FIGURE 2.9 3D CT of inner skull, lateral view.

Nasal bone Crista galli

Sella turcica

Ethmoid bone

Dorsum sella Temporalbone

Anterior clinoid process

Lambdoidal suture

Occipital bone

Diploë

External table

Sphenoid bone

Vomer

Internal auditory canal

External occipital protuberance

Internal table Frontal bone Vertex Meningealgrooves

Frontal sinus

S

I

P A

rior point between the parietal bones is the vertex, which is

the highest point of the cranium (Figures 2.9 and 2.10)

FIGURE 2.10 3D CT of lateral surface of cranium.

Parietal eminence Vertex

Frontal bone

Coronal suture

Parietomastoid suture

Lambdoidal suture

Sagittal suture

Asterion Occipital bone

Occipitomastoid suture

Squamous suture

Temporal

bone

Pterion Sphenofrontal

forehead and anterior vault of the cranium (Figures 2.2 through 2.5) The vertical portion contains the frontal

sinuses, which lie on either side of the midsagittal plane

(Figures 2.8, 2.9, 2.11, and 2.12) Two elevated arches, the supraciliary arches, are joined to one another by a smooth area termed the glabella (Figures 2.2 and 2.4)

The horizontal portion forms the roof over each orbit, termed the orbital plate, and the majority of the anterior

cranial fossa (Figures 2.6, 2.7 and 2.13) Located in

the superior portion of each orbit is the supraorbital

foramen, or notch, which exists for the passage of the

supraorbital nerve (Figures 2.2 and 2.11) Between the

fossa Temporal lobes of cerebrum, pituitary gland, optic nerves and chiasm, cavernous sinus,

trigeminal ganglion, internal carotid artery, hypothalamus and the following cranial nerves: trigeminal, oculomotor, trochlear, abducent, and ophthalmic

Posterior cranial

fossa Cerebellum, pons, medulla oblongata, midbrain, and the following cranial nerves:

facial, vestibulocochlear, glossopharyngeal, vagus, accessory, hypoglossal

Contents of the Cranial Fossae TABLE 2.1

Each parietal bone has a central prominent bulge on its

outer surface termed the parietal eminence (Figure 2.4) The

width of the cranium can be determined by measuring the

distance between the two parietal eminences

FIGURE 2.11 Coronal CT of frontal bone.

Supraorbital foramen

Nasal bone

Maxilla

Frontal sinus

Squamous portion

of frontal bone

Perpendicular plate of ethmoid

Ethmoid air cells

Sphenoid sinus

Inferior nasal conchae

Clivus of occipital bone

Occipital bone

Frontal bone Sella turcica S

A

I

P Dorsum sella

Frontal sinus

FIGURE 2.13 Axial CT of orbital plates.

Occipital bone

Temporal bone

Anterior clinoid processes

of sphenoid bone

A

Frontal sinus Orbital plate offrontal bone

P

FIGURE 2.15 Axial CT of ethmoid bone.

Anterior clinoid process of sphenoid bone

Zygoma Perpendicular plate of ethmoid bone

Cribriform plate

Dorsum sellae

of sphenoid bone

Sphenoid sinus

Cribriform plate

Anterior ethmoid air cells

Posterior ethmoid air cells

Olfactory foramina

portion, vertical portion, and two lateral masses (laby-rinths) (Figures 2.14 through 2.17) The horizontal

portion, called the cribriform plate, fits into the

as an attachment for the falx cerebri, which is the con-tion of the ethmoid bone, called the perpendicular plate, projects inferiorly from the cribriform plate to

) Con-cells (ethmoid sinuses), one of the largest being the

ethmoid bulla (Figures 2.14 through 2.17) Projecting

FIGURE 2.17 Coronal CT of ethmoid bone with crista galli.

Orbital plate

of frontal bone

Ethmoid bulla

Superior nasal conchae

Middle nasal conchae

Bony nasal septum

Vomer

Crista galli

External table Diploë

Internal table

Cribriform plate Orbital plate

of frontal bone

Middle nasal meatus

Uncinate process

of ethmoid bone Infundibulum

Orbital plate

of ethmoid bone (lamina papyracea) S

I

FIGURE 2.16 Anterior view of ethmoid bone.

Superior nasal concha

Ethmoid bulla Infundibulum Uncinate process

Ethmoid air cells

Middle nasal concha

Crista galli

Lateral mass (labyrinth)

Perpendicular plate (vertical portion)

FIGURE 2.18 Superior view of sphenoid bone.

Foramen ovale Foramen spinosum

Optic groove

Optic canal

Carotid sulcus Dorsum

sellae Sella turcica

sinuses

Sphenoid sinus

Tuberculum

sella

Sella turcica Dorsum sella

Posterior arch of C1

Occipital bone

S

I

2.20, 2.21, and 2.22) The triangular-shaped lesser wings

attach to the superior aspect of the body and form two

sharp points called anterior clinoid processes, which, along

with the posterior clinoid processes, serve as attachment sites for the tentorium cerebelli (Figures 2.18 and 2.22)

The optic canal is completely contained within the lesser

mic artery (Figure 2.22) The optic canal is separated from

wing and provides passage of the optic nerve and ophthal-the superior orbital fissure by a bony root termed the optic

strut (inferior root) (Figure 2.2

, see bony orbit) The supe-rior orbital fissure is a triangular-shaped opening located

between the lesser and greater wings that allows for the transmission of the oculomotor, trochlear, abducens, and ophthalmic division of the trigeminal nerves, as well as the superior ophthalmic vein (Figures 2.2, 2.22, 2.24, also see

(Figure 2.18) Located within the body of the sphenoid

bone is a deep depression called the sella turcica, which

houses the hypophysis (pituitary gland) Directly below

the sella turcica are two air-filled cavities termed sphenoid

sinuses (Figures 2.15 and 2.19) The anterior portion of the

sella turcica is formed by the tuberculum sellae, and the

posterior portion by the dorsum sellae The dorsum sellae

gives rise to the posterior clinoid processes (Figures 2.18,

FIGURE 2.20 Lateral view of sphenoid bone.

Superior orbital fissure

Greater wing

Medial pterygoid plate

Lateral pterygoid plate

Pterygoid hamulus

Dorsum sellae Posterior clinoid process Anterior clinoid processes

Sella turcica (contains pituitary gland)

Tuberculum sella

Foramen rotundum

Foramen lacerum

Parietal bone

Condylar process of mandible

Dorsum sella

Temporal bone

Posterior clinoid process S

I

L R

FIGURE 2.21 Coronal CT of dorsum sella.

FIGURE 2.22 Axial CT of anterior clinoid processes and sphenoid bone.

Lesser wing

of sphenoid

Sphenoid sinus

Optic canal

Ethmoid sinuses

Greater wing

of sphenoid Anterior clinoid process

Dorsum sella Posterior clinoid

processes

Sella turcica

Superior orbital fissure

Zygoma A

P

bony orbit) The greater wings extend laterally from

of the pterygoid process is the pterygoid (vidian) canal, an

opening for the passage of the petrosal nerve (Figures 2.23 through 2.25) The pterygoid processes articulate with the palatine bones and vomer to form part of the nasal cavity

FIGURE 2.23 Axial CT of sphenoid bone with foramina ovale and spinosum.

Greater wing of sphenoid bone

Ethmoid sinuses

Sphenoid

Carotid canal

Jugular fossa

Foramen ovale

Foramen spinosum

Pterygoid

canal

Medial pterygoid plate

Body

Pterygoid

hamulus

Lateral pterygoid plate

Foramen rotundum Superior orbital fissure

The sphenoid bone is considered the keystone of the cranial bones because it is the only bone that articulates with all the other cranial bones.

Foramina and Fissures of the Skull TABLE 2.2

trigeminal nerve (V), abducens nerve (VI), ophthalmic vein Sphenoid and

Stylomastoid foramen and facial

Temporal and

occipital bone

accessory nerve (XI) Temporal, sphenoid, and

occipital bones Foramen lacerum Fibrocartilage, internal carotid artery as it leaves carotid canal to enter cranium, nerve of pterygoid canal and a meningeal branch from the

ascending pharyngeal artery

FIGURE 2.25 Coronal CT of sphenoid bone.

Greater wing of sphenoid bone

Zygomatic arch

Ramus of mandible

Pterygoid hamulus

on medial pterygoid plate

Pterygoid process (lateral pterygoid plate)

Anterior clinoid process of sphenoid bone Sphenoid sinus Foramen rotundum Pterygoid canal S

I

to the foramen magnum are the hypoglossal canals

through which the hypoglossal nerve (CN XII) courses (Figures 2.8, 2.27, 2.28, and 2.30; Table 2.2) The basilar

Clivus

Sphenoid bone

Zygomatic arch

Temporal bone

Pterygoid

plates

FIGURE 2.27 Lateroinferior aspect of occipital bone.

Squamous portion

Occipital condyles for articulation with the atlas Foramen magnum

External occipital protuberance (inion)

Hypoglossal canal Basilar portion

(clivus)

FIGURE 2.28 Coronal CT reformat of occipital condyles.

Dens of C2 (odontoid process)

Lateral mass of C1

Occipital condyle

Temporal bone

Jugular fossa S

I

Hypoglossal canal

Atlantooccipital joint

FIGURE 2.29 Axial CT of occipital bone at level of foramen magnum and lateral condyles.

Styloid process

of temporal bone

Ramus of mandible

Maxillary sinus

Clivus

Foramen magnum

Occipital condyle

Zygomatic arch Coronoid process of mandible

Pterygoid process

of sphenoid bone A

P

FIGURE 2.30 Axial CT of occipital bone at level of clivus.

Ethmoid air cells A

P

Sphenoid sinus

Condyle of mandible

Temporal bone

Hypoglossal canal Clivus

Foramen magnum

Occipital bone

Zygomatic process of temporal bone

Zygoma Pterygopalatine

fossa

Stylomastoid foramen

FIGURE 2.31 Sagittal CT reformat of occipital bone.

Sphenoid sinus Clivus of occiptal bone

External occipital protuberence

Internal occipital protuberence

Squamous portion of occipital bone

Pituitary gland

Cerebellum I

S