Ebook Color atlas of human anatomy Vol.2 - Internal organs (5th edition): Part 1

(BQ) Part 1 book Color atlas of human anatomy Vol.2 - Internal organs presents the following contents: Cardiovascular system (overview, heart, heart, lymphaticsystem, arterialsystem,...), respiratory system (overview, nose, larynx, mediastinum,...), alimentary system (overview, topographical anatomy i, abdominal cavity, large intestine,...).

H.Fritsch W.Kuehnel

!!!!!:!=- :!;~::::!!:!!~A sound understanding of the structure and function of the human body in all of its intricacies is the foundation of a complete medical education This classic work-now enhanced with many new and improved drawings-makes the task of mastering this vast body of information easier and less daunting with its many user-friendly features:

~ Hundreds of outstanding full-color illustrations

~ Clear organization according to anatomical system

~ Abundant clinical tips

• Side-by-side images and explanatory text

elpful color-coding and consistent formatting throughout

~ Durable, compact design, fits in your pocket

~ Useful references and suggestions for further reading

Emphasizing clinical anatomy, the text integrates current information from an array of medical disciplines into the discussion of the inner organs, including:

~ Cross-sectional anatomy as a basis for working with modern imaging modalities

~ Detailed explanations of organ topography and function

~ Physiological and biochemical information included where appropriate

~ An entire chapter devoted to pregnancy and human development

Volume 2 Contents Overview: Cardiovascular System, Respiratory System, Alimentary System, Urinary System, Male Genital System, Female Genital System, Pregnancy and Human Development, Endocrine System, Blood and Lymphatic Systems, Integument.

Volume 2: Internal Organs and its companions Volume 1: Locomotor

System and Volume 3: Nervous System and Sensory Organs comprise a must-have resource for students of medicine, dentistry, and all allied health fields.

Library of CongressCotaloging-in-Publication Data

Fritsch, H (Helga),

1957-Color atlas of human anatomy Volume 2,

Internal organs/Helga Fritsch, Wolfgang

Kuehnel 5th ed

p.;cm

Includes bibliographical references and index

ISBN 978-3-13-533405-9 (alk paper)

ISBN 978-1-58890-097-5 (alk paper)

1 Human anatomy Atlases I Kuhnel, Wolfgang,

1934-11 Title III Title: Internal organs

[DNLM: 1 Anatomy Atlases QS 17 F919c 20071

QM25.F742007

611.022'2 dc22

This book is an authorized and revised translation

of the 9th German edition published and

copy-righted 2005 by Georg Thieme Verlag, Stuttgart,

Germany Title of the German edition:

Taschenatlas Anatomie, Band 2: Innere Organe

Translated by Stephanie Kramer, Berlin, Germany

Illustrated by Professor Gerhard Spitzer, Frankfurt,

Germany, with the cooperation of Stephan Spitzer

© 2008 Georg Thieme Verlag,

Rudigerstrasse 14,70469 Stuttgart, Germany

http://www.thieme.de

Thieme New York, 333 Seventh Avenue,

New York, NY WOOl, USA

http://www.thieme.com

Cover design: Thieme Publishing Group

Typesetting by Druckhaus Gbtz, Ludwigsburg,

Germany

Printed in Germany by APPL aprinta druck,

Wemding, Germany

ISBN 978-3-13-533405-9 (TPS, Rest of World)

ISBN 978-3-58890-097-5 (TPN, The Americas)

Important note: Medicine is an ever-changingscience undergoing continual development Re-

search and clinical experience are continually

ex-panding our knowledge, in particular our edge of proper treatment and drug therapy Insofar

knowl-as this book mentions any dosage or application,readers may rest assured that the authors, editors,and publishers have made every effort to ensure

that such references are in accordance with the

state of knowledge at the time of production of the book.

Nevertheless, this does not involve, imply, or press any guarantee or responsibility on the part ofthe publishers in respect to any dosage instructionsand forms of applications stated in the book Every

ex-user is requested to examine carefully the

manu-facturers' leaflets accompanying each drug and tocheck, if necessary in consultation with a physician

or specialist, whether the dosage schedules tioned therein or the contraindications stated by themanufacturers differ from the statements made inthe present book Such examination is particularlyimportant with drugs that are either rarely used orhave been newly released on the market Everydosage schedule or every form of application used isentirely at the user's own risk and responsibility Theauthors and publishers request every user to report

men-to the publishers any discrepancies or inaccuraciesnoticed If errors in this work are found after pub-lication, errata will be posted atwww.thieme.com

on the product description page

Some of the product names, patents, and registereddesigns referred to in this book are in fact registeredtrademarks or proprietary names even thoughspecific reference to this fact is not always made inthe text Therefore, the appearance of a namewithout designation as proprietary is not to be con-strued as a representation by the publisher that it is

in the public domain

This book, including all parts thereof is legally tected by copyright Any use, exploitation, or com-mercialization outside the narrow limits set bycopyright legislation, without the publisher's con-sent, is illegal and liable to prosecution This applies

pro-in particular to photostat reproduction, copying,mimeographing, preparation of microfilms, and

v

Helmut Leonhardt, the revised atlas, under

new authorship since 2001, retains the

orig-inal work's emphasis on the use of

illustra-tions and images Modern imaging

making thorough knowledge of the

anato-my of organ systems more crucial than ever

for physicians and other healthcare

practi-tioners Current medical training needs to

changes In addition, new teaching methods

in medicine, especially integrated and

inter-active forms of teaching, require a

sys-tematic structure It was our aim in refining

this atlas to take all of these factors into

con-sideration while still maintaining its concise

format Each individual organ is presented

in a brief overview, followed by a systematic

discussion of its gross and microscopic

ana-tomic features This is followed by

descrip-tions of functional aspects, neurovascular

presented as well as useful tips for the

described when, in addition to organ

sys-tems, knowledge of general regional

topog-raphy should be known

Development," has been added to the

pres-ent book, now in its fifth edition This

his-tology, embryology, gynecology, obstetrics,and pediatrics, without losing sight of mor-phology Not only was it readily incor-porated into the fifth edition, it also sup-

methods of today's curricula This chapterwas written with the help of Dr K Hauser(editing), K.Wesker (graphics), and K Baum(graphic design) We are indebted to them

as well as to those who assisted with theprevious two editions, all of whom under-stood perfectly how to carry on the work ofthe "old crew," especially Dr P Kundmiillerand Professor G Spitzer, and how to inte-

es-pecially like to thank Professor A Bergant,

lnnsbruck for permission to use the images

would like to thank the secretary at the

Liibeck, R.Jiinsson, for preparing portions ofthe manuscript and providing a clean copy

We hope that the revised and expandedfifth edition will also be well received bymedical and dental students and that it will

Wolfgang Kuehnel Helga Fritsch

Heart """'''''''''''''''''''''''' 10

Layers of the Heart Wall Histology

Tributaries of the Superior Vena

Lymphatic System 78

Regional Lymph Nodes of the Head

Regional Lymph Nodes of the

Regional Lymph Nodes of the Pelvis

Structure and Function of Blood and Lymphatic Vessels 86

Table of Contents VII

Divisions of the Bronchi and

Inferior Surface of the Tongue (A) 152

Position of the Teeth in the Dental

VIII Table of Contents

Portal Vein System (C) 000000000000 216

Bile Ducts and Gallbladder 0 0 0 0 218

Gallbladder 0 0 0 0 0 0 0 0 0 0 0 218

Pancreas 0 0 0 0 0 0 0 0 0 0 0 0 0 220

Gross and Microscopic Anatomy 000 220

Topography of the Omental Bursa and Pancreas 0 0 0 0 0 0 0 0 0 0 0 222

Male Reproductive Organs 00000000 248

Testis and Epididymis 0 0 0 0 0 0 0 250

Table of Contents IX

'ernale Genital System [H Fritsch) 00000000000000000000000000000000000000000000 267

lvary and Uterine Tubes 0 0 0 0 0 0 0 0 0 0 0 270

Gross Anatomy of the Ovary 0 0 0 0 0 0 0 270

Microscopic Anatomy of the

Light Microscopic Classification of

General Principles of Endocrine

Diffuse Endocrine System 356

Appendages ofthe Skin 410

Skin as a Sensory

Breast and Mammary Glands 416

Microscopic Structure and Function

2 Viscera at a Glance

Viscera at a Glance

tho-racic abdominal and pelvic cavities are

col-lectively known as viscera The viscera are

human organism

The book is divided into chapters which are

arranged by organ function

blood vessels. and lymphatic vessels. Blood

lym-phatic organs. Endocrine system: organ

system consisting of numerous specialized

endocrine glands and glandular cells

occur-ring individually or in groups throughout

are released into the bloodstream or lymph

and distributed throughout the body

Respi-ratory system: organ system that is divided

organ system that is divided into the part of

which serve as large digestive glands

Uri-nary system: organ system that is divided

urine Jormation and the urinary passages.

Male genital system: system consisting of

the testes epididymis ductus aeierens,

semi-nal vesicle penis. and accessory sex glands.

Female genital system: system consisting

oftheJemale internal genitalia housed in the

located outside the pelvic floor

Organ systems can also be grouped

accord-ing to location in various regions of the body

(A)

The head and neck regions contain the

ini-tial parts of the respiratory and alimentary

and oral cavity (A2) Parts of these organsystems located in the neck also form pas-sageways connecting the head and thoracic

middle and deep layers of cervical fascia(Vol 1 p 330)

thoracic abdominal and pelvic organs Thethoracic cavity (A3) is subdivided into three

cavities. each of which contains one lung.

and the connective tissue region betweenthem near the midline of the body known asthe mediastinum. The mediastinum con-tains a number of structures including the

pericardium which encloses the heart.The

abdominal cavity (A4) which is lined with

peritoneum. and the connective tissue spacebehind it known as the retroperitoneal space.Below the abdominal cavity the pelvic or-gans lie in the lesser pelvis (AS) within thesubperitoneal connective tissue space.Serous Cavities and Connective TissueSpaces

There are two ways in which an organ can

that undergo significant changes in volumeaffecting adjacent organs are contained in

comp-letely enclosed space which contains a smallamount of serous fluid and is lined by asmooth glistening serous membrane Theserous membrane consists of two layers: a

visceral layer that is in direct contact with

lining the wall of the serous cavity Thevisceral and parietal layers become continu-

se-rous cavities are the pleural cavities whichhouse the lungs; the pericardial cavity whichcontains the heart; and the peritoneal cavity(C) which contains most of the abdominalorgans

Organs or parts of organs that are not tained in serous cavities usually lie in con-nective tissue spaces Smaller connectivetissue spaces (B) derive their names fromadjacent organs; larger ones are the medi-astinum retroperitoneal space and subperi-toneal space (D)

con-D Transverse section through pelvis

A Viscera median sagittal section

A-DGreen:

serous layer of peritoneum;

Circulatory System and Lymphatic

Vessels

Circulation of blood occurs in a closed system

of tubes consisting of blood vessels with the

heart serving as the central pump The heart

Irrespective of blood oxygen level, vessels

that carry blood away from the heart are

re-ferred to as arteries and vessels that carry

blood to the heart are referred to as veins

differ-entiation A distinction is made in postnatal

life between pulmonary circulation and

sys-temic circulation In syssys-temic circulation,

ar-teries carry oxygen-rich blood away from

the heart and veins carry deoxygenated

blood toward the heart In terms of function,

can be illustrated schematically as a

figure-of-eight with the heart located at its

inter-section acting as a suction and pressure

pump (A)

blood from the systemic circulation flows

from the right atrium (A1) into the right

ven-tricle (Al) of the heart and from there into

circulation begins with the pulmonary trunk

(AJ) which bifurcates into right (A4) and left

pulmonary arteries (AS) These vessels divide

in the lungs (AG) parallel to the branchings

of the airways as far as the capillaries, which

surround the terminal portions of the

air-ways known as the alveoli There the blood

is enriched with oxygen and carbon dioxide

is released into the airways The oxygenated

blood leaves the lungs by the pulmonary

veins (A7) and flows to the left atrium (AS)

from the lung flows from the left atrium (AS)

of the heart into the left ventricle (A9) From

body Large arteries branch off the aorta anipass to the separate circuits where the:divide many times and finally ramify inn

capillaries where gas exchange and exchang

of metabolic products occur At the capillar:plexus, the arterial portion of the systemicirculation passes into the venous portion il

venules, which closer to the heart unite nform veins Venous blood from the legs anilower half of the trunk is conveyed to the inferior vena cava (A1S), that from the heacarms, and upper half of the trunk to the superiorvena cava (A1G).The inferior and superior venae cavae empty into the right atriun(Al)

systemic circulation Venous blood from un

pancreas, andspleen) does not flow direct!

into the inferior vena cava Instead sub

stances from these organs are absorbed b:the intestine, and the blood is carried by th'portal vein (A17) to a capillary bed in th,

blood is collected in the hepatic veins (A18and conveyed to the inferior vena cava.Lymphatic system The lymphatic systen(green) (see p 78) acts within the system!circulation to shunt lymph to the venouportion of the circulatory system Unlike thl

system of blood vessels, the lymph drainag:

that collect fluid from the extracellulaspace in the periphery of the body via Iym

phatic capillaries (A19) and conveys it vi,

larger lymphatic vessels and the main Iymphatic trunks, the thoracic duct (A20) ant

Biologic filters known as lymph nodes (All

(see pp 80-83)

Clinical note, Oxygen-rich blood is often

re-ferred to in clinical usage as arterial blood anddeoxygenated blood is referred to as venousblood

i

lema tic illustration

irculatory system

8 Cardiovascular System: Overview

Fetal Circulation (A)

During prenatal life, the fetus (unborn

off-spring from the ninth week after

fertiliza-tion to birth) receives oxygen and nutrients

from the mother's blood and releases

car-bon dioxide and metabolic waste products

into it The placenta (Al) serves as the

con-necting organ for exchange between mother

and fetus Oxygen-rich blood carrying

abun-dant nutrients passes from the placenta to

the fetus via the umbilical vein (A2) which

umbilical vein enters the fetal abdominal

cavity at the navel, or umbilicus (A3), and

passes to the visceral surface of the liver

(A4) where it connects to the left branch of

the portal vein (AS) Although some of the

blood from the umbilical vein thus enters

liver via a shunt called the ductus venosus

(AG) and is carried into the inferior vena cava

(A7) Blood from the ductus venosus thus

Due to the relatively minimal admixture of

oxy-genated and passes via the inferior vena

cava to the right atrium (A9) From there the

vena cava toward the foramen ovale (Al0)

that lies in the septum between the right

and left atria and connects them Most of

passes from there into the left ventricle (A12)

(AB) to the heart, head, and upper limbs

arms of the fetus flows through the superior

vena cava (A14) into the right atrium and

vena cava to reach the right ventricle (A1S),

passing from there into the pulmonary trunk

(A1G) A minimal amount of blood passes

the not yet aerated lungs and from there

left atrium (All) Most of the blood from the

aorta through the ductus arteriosus (A19), a

shunt connecting the bifurcation of the

pul-monary trunk or left pulpul-monary artery with

the aorta The branches given off by the tion of the aorta after the connection of theductus arteriosus thus receive blood with a

amount of blood from the fetal aorta is turned to the placenta through the pairedumbilical arteries (A20)

re-Circulatory Adjustments at Birth (B)

At birth the fetal circulation is convertedinto postnatal circulation With the first cry

aerated reducing resistance in the

pulmo-narycirculation which in turn increases thevolume of blood flowing from the pulmo-nary trunk into the pulmonary arteries Theblood is oxygenated in the lungs and trans-ported by the pulmonary veins into the left

fora-men ovale is thus converted into the ovalfossa which is normally completely closed.The shunts, i.e., ductus venosus and ductusarteriosus, are closed off by contraction ofthe muscle within the vessel walls After ob-

arte-riosus forms the ligamentum arteriosum(822) Cutting the umbilical cord disrupts

umbilical cord vessels, leading to sis and gradual obliteration of the vessels.The umbilical vein becomes the round liga-

ar-teriesbecome the cords of the umbilical ies (824)

10 Cardiovascular System: Heart

Heart

E

organ with a rounded, conical shape It is

situated in the thorax (A) where it is

posi-tioned obliquely to the body's axis so that

the apex of the heart (AB2) is directed to the

left, inferiorly and anteriorly, while the base

of the heart (A3) is directed to the right,

heart depends upon factors such as the sex,

age, and fitness level of an individual

External Features

Anterior Aspect

its natural position with an opened

peri-cardium shows the sternocostal surface (8)

which is mostly formed by the anterior wall

of the right ventricle (84) and a small portion

of the wall of the left ventricle (85) The left

ventricle extends toward the left to form the

apex of the heart (82) The boundary between

known as the anterior interventricular sulcus

(86) The sulcus contains a branch of the left

artery) and the accompanying cardiac vein

(anterior interventricular vein), embedded

in adipose tissue These vessels fill up the

the anterior surface of the heart The

con-tour of the right side of the heart is formed

by the right atrium (87) and superior vena

cava (88) The inferior vena cava is not

vis-ible in the anterior view The right atrium

auricle (89) which occupies the space

be-tween the superior vena cava and the root of

the aorta (810) The right atrium and right

ven-tricle by the coronary sulcus (811) which is

adipose tissue The contour of the left side of

the heart is formed by a small portion of the

left auricle (812) and the left ventricle The

left auricle lies adjacent to the pulmonary

trunk (813)

Adjacent vessels Viewing the sternocostalsurface of the heart, we can see that the pul-monary trunk (813), which arises from the

(810), which arises from the left ventricle

each other, with the aorta, which mences posteriorly, passing forward as theascending aorta (810 a) and continuing as theaortic arch (810 b) which crosses over the

pulmo-nary artery(814) andright pulmonary artery

(not visible from anterior view) The cutedges of the left pulmonary veins (815) arevisible below the left pulmonary artery Thevessels supplying the head and arms arise

trunk (816) with the right subclavian artery

left common carotid artery (819), and left subclavian artery (820).

The cut edges of the pericardium (821) (see p.30) are visible near the great vessels, i.e., thesuperior vena cava (88), ascending aorta(810 a), and pulmonary trunk (813) Passing

arch and the superior aspect of the nary bifurcation there is a short band, theligamentum arteriosum (822), a remnant of

boundary between the sternocostal surface

demar-cated on the right ventricle by the rightborder (823)

The use of color in the illustrations of internal andexternal cardiac structures represents as closely

as possible the proportions in the living body

External Anatomy of Heart 11

12 Cardiovascular System: Heart

E

j External Features, cont.Posterior Aspect (A)

Structure and adjacent vessels In its

the base ofthe heart (I) and part of the

of the heart, can be seen in the posterior

openings of the superior vena cava (AB1) and

inferior vena cava (AB2) into the nearly

per-pendicular right atrium (AB3) The long axis

of both venae cavae is tilted slightly

for-ward The venae cavae are separated from

the base of the right auricle by a groove

known as the sulcus terminalis cordis (A4)

The right pulmonary veins (AB6) and left

pul-monary veins (AB7) open into the

horizon-tally oriented left atrium (AS) The cut edge

of the pericardium (AS) is visible on the

pos-terior wall of the left atrium Above the left

atrium, the pulmonary trunk bifurcates into

theright pulmonary artery(A9) andleft

pul-monary artery (Al0) The aortic arch (All)

crosses over the bifurcation of the

pulmo-nary trunk after giving off the three main

right common carotid artery (A14) as well

asleft common carotid artery(A1S) andleft

subclavian artery(A16) After crossing over

con-tinues as the descending aorta (A17)

Inferior Aspect (8)

heart (II) rests on the diaphragm, and it can

only be fully visualized when the heart is

viewed from caudal The view into the right

atrium (AB3) is roughly along the axis of

both venae cavae, that is, looking from the

opening of the inferior vena cava (AB2) into

the opening of the superior vena cava (AB1)

chiefly formed by the left ventricle (B1S),

which is separated from the left atrium by

the coronary sulcus (B19) The coronary

artery. The left ventricle is separated from

the right ventricle (821), which is only

vis-ible in the posterior view, by the posterior

posterior interventricular branchand

poste-riorinterventricular vein).

Clinical note In clinical practice, especially indiagnosing heart attack the walls of the left ven-tricle are referred to as the anterior and poste-rior walls The anterior wall describes the part

of the left ventricular wall that forms the nocostal surface while the posterior wall is thatpart which forms the diaphragmatic surface.Myocardial infarctions involving the anteriorwall are divided intoanterobasal anterolateral, anteroseptal, and apical infarctions. In patientswith posterior wall involvement, posterobasal, posterolateral, andposteroseptal myocardial in-

ster-farctions are distinguished fromposteroinferior

ordiapilragmal myocardial infarctions.

External Anatomy of Heart cont 13

E

j

A Posterior view of heart

84

B Caudal view of heart

14 Cardiovascular System: Heart

E

i Chambers ofthe HeartThe following sections discuss the

cham-bers of the heart in order of the direction of

blood flow

Right Atrium

The right atrium (A) consists of two parts

its posterior portion The posterior portion

of the right atrium has smooth walls arising

from its embryological origin and is referred

to as the sinus of venae cavae The true atrium

lies anterior to it and is derived from the

atrium, the cardiac muscle projects into the

muscles (AJ) The true atrium is continuous

anteriorly with the right auricle (A4)

Sinus of venae cavae, The opening of the

su-perior vena cava (Al a) is directed downward

and anteriorly and does not have a valve

The inferior vena cava opens at the lowest

point of the right atrium The opening of the

inferior vena cava (A2 a) is shielded by a

and directs blood from the inferior vena

p 8) in the interatrial septum (A6) into the left

fossa (A7), is found at this site It is bordered

ovalis(A7 a) Medial to the valve of the

structure, opens into the right atrium It

re-turns the greater portion of the backflow of

The opening of coronary sinus (A8) is also

coro-nary sinus. At various sites the tiniest

car-diac veins empty via minute openings, the

openings of smallest cardiac veins, into the

right atrium

True atrium and right auricle In the

inte-rior of the heart, this area is separated from

by a ridge referred to as the crista terminalis

(A9) On the outer surface of the heart, the

muscles originate, corresponds to a slight

p.12)

Right VentricleThe interior of the right ventricle (B) is

su-praventricular crest(Bl0) andseptomarginal trabecula (Bll) which form the inflow

the outflow tract, located anterosuperiorly(arrow) The muscular wall of the right ven-tricle (B12) is thin

Inflow tract Muscular ridges, the trabeculaecarneae (B13), project from the wall of theinflow tract in the direction of the lumen

atrioventricularori-fice, over the right atrioventricular valve

(tri-cuspid valve) (AB14), out of the right atriuminto the inflow tract of the right ventricle

papil-lary muscles are a special form of trabeculae

papil-lary muscle (B16) and posterior papillary muscle is constant, while that of theseptal papillary muscle varies(B17)

Outflow tract, The conus arteriosus (B18)

blood flow to the pulmonary valve orifice attheopening of the pulmonary trunk.The pul-monary valve (B19) is located at the origin ofthe pulmonary trunk (B20) and consists of

16 Cardiovascular System: Heart

E

j Chambers of the Heart, cont.Left Atrium

of the left atrium (A) is smaller than that of

the right Much of the cavity is occupied by

the right and left pulmonary veins (A1-2),

which are drawn into the left atrium during

side, which open into the upper portion of

the left atrium There are no valves at the

openings of the pulmonary veins The left

atrium is continuous anteriorly with the left

muscles that project into its lumen There is

portions Near the interatrial septum dividing

the right and left atria is the valve ofthe

oval fossa of the right atrium

Left Ventricle

Like the right ventricle, the inner space of

the left ventricle is divided into an inflow

(arrow) The muscular wall of the left

ven-tricle (B5) is about three times thicker than

that of the right

Inflow tract The left atrioventricular valve

(mitral valve), also called the bicuspid valve

orifice.It directs blood from the left atrium

into the inflow tract of the left ventricle The

bicuspid valve has two large leaflets, the

anterior (AB7) and posterior cusps (ABS)

These are attached via the thick and strong

chordae tendineae (B9) to the papillary

muscles which have two or more domed

pro-jections The papillary muscles consist of

theanterior papil/ary muscle (B10) and

pos-terior papil/ary muscle (B11) The anterior

sterno-costal surface of the left ventricle and the

dia-phragmatic surface The anterior cusp of the

with the wall of the aorta, dividing the

in-flow and outin-flow tracts

sep-tum (B12) to the aorta, at the origin of whichlies the aortic valve (B13) The aortic valve

largest portion of the interventricular septum

muscle A small portion lying just caudal tothe right and posterior aortic valve is mem-

mem-branous part(see p 40) The margins of the

anterior interventricular sulcus (B14) and

posterior interventricular sulcus on the face of the heart

sur-Clinical note Innammation involvingheart valvescan be FOllowed by scarring of the valve mar-gins Stenosis refers to narrowing of the valveopening caused by scarring IFscarring shrinksthe valve margins, insufficiency occurs as theyFail to meet completely upon closure of thevalve

A Left atrium, opened, posterior view

1314

B Left ventricle,

opened, left lateral view

E

i

18 Cardiovascular System: Heart

E

! Cardiac SkeletonThe heart valves all lie approximately in one

above the level of the coronary sulcus and

the base of the heart is viewed from cranial

(A) In the valvular plane the surrounding

connective tissue is thickened to form the

fibrous cardiac skeleton (A B) The cardiac

skeleton separates the muscle of the atria

con-densed connective tissue is found at the site

area is known as the right fibrous trigone (84)

or central fibrous body The site where the

aorticand bicuspid valvesmeet is referred to

as the left fibrous trigone (B5) The orifices of

the tricuspid valve and bicuspid valve are

rings, the right fibrous ring (B6) and left

fibrous ring (B7), which serve for the

skeleton

Layers ofthe Heart Wall

The wall of the heart is made up of three

different layers: the epicardium, myocardium,

and endocardium Its thickness is primarily

which varies in different areas of the heart,

walls of the atria contain little muscle while

those of the right ventricle are considerably

thinner than those of the left ventricle

Myocardium

Atrial muscle (C D) The atrial myocardium

can be divided into superficial and deep

lay-ers The superficial layer extends over both

atria and is thicker along its anterior aspect

(C) than its posterior aspect (D) The

fibers orannular fibers that pass to the

the openings of the veins

mor-phologically distinct subepicardial, middle,

sub-epicardial layer (C-E), the fibers of the rightventricle run nearly horizontally around thesurface, while those of the left ventricle are

two ventricles the superficial subepicardial

(E9) where they curve around to form the

thick middle muscular layer that is usuallycircular and is absent in the wall of the rightventricle The inner, subendocardial layer con-

cameae and papillary muscles.Thecoronary sulcus (CD10),anterior interventricular sul-

sulcus(DE12) are clearly visible on dissectedmyocardium

Endocardium and Epicardium

me-sothelium, a thin layer of connective tissue

adipose tissuethat serves to smooth out anyunevenness on the surface of the heart

cn Left auricle C014 Left ventricle, CD1S Rightventricle, C016 Right atrium, C017 Right auricle,C018 Superior vena cava, 019 Inferior vena cava

020 Pulmonary valves, 021 Left atrium

A Valvular plane cranial view

B Cardiac skeleton isolated cranial view

20 Cardiovascular System: Heart

Layers of the Heart Wall, Histology,

and Ultrastructure

Working Myocardium

in-dividual muscle cells which, in a manner

similar to skeletal muscle structure, exhibit

transverse striations produced by the

organi-zation of myofibrils As in skeletal muscle,

Car-diac muscle cells (AB1) are up to 120",m

long and in the average adult have an

cellswhich establish end-to-end connections

bundles, thus forming a complex

con-nective tissue(AB2) containing adense

capil-lary network in its spaces The nucleus (AB3)

of a cardiac muscle cell is located centrally

Surrounding the nucleus is a perinuclear zone

sarcoplasm and organelles and containing

lipo-fuscin droplets. The transverse cell

each other are referred to as intercalated discs

(AS)

(C6), of cardiac muscle cells are intricately

actin filaments of the adjacent cell continue

in the same direction Cardiac muscle cells

which supply the high amount of energy

sar-colemma. The system composed of tudinal tubules or L-tubules (C13) is formed

muscle cell

Cells of the conducting system of the heart

than those of the working myocardium and

glycogen, and are capable of producing

informa-tion please see textbooks of histology

Clinical note Cardiac muscle cells cannot generate Although damage resulting fromtemporary inadequate blood supply is reversi-ble prolonged inadequate supply or ischemia.causes irreversible damage involving necrosisand replacement of tissue by connective tissuescarring

re-Heart Wall Layers, Histology, and Ultrastructure 21

E

i

129

c

Cardiac muscle tissueappearance on electr~nmicroscopy

oCells of the conduction system, appearance on light microscopy

22 Cardiovascular System: Heart

Heart Valves

of connective tissue that is covered on both

vessels The atrial surface of the flap is

its free margins and inferior surface

three leaflets known as the anterior cusp

(A-Cl), posterior cusp (A-C2), and septal cusp

sep-tum The anterior cusp (A-Cl) is the largest

of the three; its chordae tendineae are

muscle (C4) that is derived from the

septo-marginal trabecula. The attachment site of

the septal cusp (C5) is at the level of the

membranous partof the septum, dividing it

atrioventricular portion between the right

three large cusps are small intermediate

seg-ments (A-C6) that do not reach the fibrous

ring

Bicuspid valve Possessing two leaflets, the

bicuspid valve (mitral valve) has an

antero-medial cusp, the anterior cusp (AB7), and a

The short and thick chordae tendineae are

papil-lary muscle in such a manner that each

papillary muscle supports adjacent sides of

both valve leaflets The anterior cusp is

con-tinuous at its septal origin with the wall of

the aorta (AB9) In addition to its two large

cusps, the mitral valve has two small ones,

the commissural cusps (AB10) which do not

extend as far as the fibrous annulus

Functional anatomy In the filling phase,

ventric-ular diastole,during which blood flows from the

atria into the ventricles, the margins of the cusps

move apart and the valves open (A) In the

ejec-tion phase, ventricularsystole,the ventricular

myo-cardium contracts and the column of blood is

forced into the outflow tract (8) During this

process the complex attachment of the

subvalvu-lar apparatus prevents the cusps from prolapsing

into the atrium

Semilunar CuspsThe valves of the pulmonary trunk (AB11)and aorta (AB9) each consist of three nearlyequally sized valves, the semilunar cusps,which are formed by folds of endocardium

curved, and the artery walls near the valvesare thin and bulging (0) Located in themiddle of the free margin of each valve is a

nodule of semilunar cusp (012) On eitherside of the nodule, running along the valve

consists of an anterior semilunar cusp (A14),right semilunar cusp (A15), and left semilunarvalve (A16) The wall of the pulmonary trunkopposite the valve protrudes to form a shal-lowsinus(A17)

Aortic valve The aortic valve has a posteriorsemilunar cusp (A1S), right semilunar cusp(A19), and left semilunar cusp (A20) Near thevalve, the wall of the aorta bulges out-

enlarging the luminal diameter of the vessel

(aortic bulb).Theleft coronary artery(AD22)arises from the aortic sinus of the left semi-

(AD23) from the aortic sinus of the rightsemilunar cusp

Functional anatomy In ventricular diastole (A)while the column of blood is exerting pressure onthe walls of the pulmonary trunk and aorta thecusps unfold and the valve closes.The nodules onthe margins of the cusps ensure that the valve isfully closed During ventricular systole (8) in-creased pressure in the upstream ventricle causesthe margins of the cusps to separate, althoughturbulent blood flow prevents them from lyingdirectly against the vessel wall

24 Cardiovascular System: Heart

E

which are situated at the base of the heart

The coronary vessels derive their name from

the location of their main stems in the

coro-nary sulcus The short corocoro-nary circulation

lying directly beneath the myocardial

the right atrium

Coronary Arteries (A-C)

The main stems of the right coronary artery

(Al) and left coronary artery (A2) arise in the

aortic sinusesof the right and left semilunar

valves

Right coronary artery (Al) At the site of its

entry into the coronary sulcus (AJ) on the

right side the right coronary artery is

ini-tially covered by the right auricle (A4) After

and anterior surface of the right ventricle

and giving off the right marginal artery (AS).it

travels posteriorly in the coronary sulcus to

the posterior interventricular sulcus (86)

where it gives rise to the posterior

inter-ventricular artery (87) In most people (in

artery supplies the right atrium the

con-ducting system of the heart the greater

por-tion of the right ventricle the posterior part

(AS) and left auricle (A9) before dividing

into the anterior interventricular artery (Al0)

inter-ventricular sulcus(All) and circumflex artery

sulcus.The stems of the coronary arteries

lying superficially in the sulci are located in

myo-cardium or myocardial bridges In balancedcirculation the left coronary artery suppliesmost of the left ventricle and the anterior

of the right ventricle at the sternocostal face of the heart, and the left atrium

sur-Clinical note Although coronary arteries formsmall anastomoses with one another these areinsufficient for developing collateral circula-tion if vessels become occluded Coronary ar-teries are therefore considered end arteries interms of function Occluded arteries lead to in-sufficient blood supply to a portion of myo-cardium resulting in a heart attack

Coronary Veins (A-B)Most of the deoxygenated blood leaving thelwalls of the heart flows through the veins.which accompany the arteries to the coro-nary sinus (813) lying in the posterior por-

sinus are the anterior interventricular vein(A14) which becomes the great cardiac vein(815) in the left coronary sulcus the middle

inter-ventricular sulcus.and the small cardiac vein(817) from the right side About two-thirds

the right atrium via larger veins and the

ventricular veins.open directly into the right

cardiac veins.empty directly into the innerspaces of the heart

Lymphatic VesselsThe dense lymphatic network of the heartcan be divided into a deep endocardial middlemyocardial and superficial epicardial network.Larger collecting vessels travel in the epi-

lymph nodes belong to the anterior nal nodes (see p 82)

mediasti-Heart Vasculature 25

A Coronary vessels onsternocostal surface

26 Cardiovascular System: Heart

Conducting System of the Heart

heart These cells are collectively known as

they differ in terms of histology and

func-tion from the rest of the cardiac muscle, the

working myocardium. Clusters of cells are

found at two sites where they form nodular

structures known as the sinuatrial nodeand

atrioventricular node (AV node). Most of

bundles which can be divided into the

atrio-ventricular bundle and the right bundle and

left bundle, the bundle branches of the

path-way traveled by an impulse from where it

was generated to its functional spread to the

working myocardium is discussed in the

fol-lowing sections on the basis of identifiable

node) lies beneath the epicardium near the

opening of the superior vena cava (A2) in

the sulcus terminalis cordis. The

spindle-shaped node is referred to as the cardiac

pacemaker as it generates 60-80 impulses

per minute which travel to the rest of the

conducting system The second component

of the specialized cardiac muscle tissue is

node) (A3), located at the atrioventricular

be-tween the opening of the coronary sinus

(AS) and the septal cusp of the tricuspid

working myocardium of the right atrium to

bundles belonging to the conducting system

begin These consist of the atrioventricular

bundle (A7) or bundle of His, whose trunk,

toward the ventricles The atrioventricular

bundle reaches the superior margin of the

side of the right ventricle and divides into

These travel bilaterally beneath the

toward the apex of the heart The right

bundle (AS) curves downward and entersthe septomarginal trabecula (A9) to reachthe anterior papillary muscle (A10) Its pe-

branches (All) which form a subendocardial

plexus The plexus terminates in functional

theventricular myocardium near the apex of the heart and then passes with recurrent

the myocardium of the base of the heart. A

which pass to the papillary muscles

The left bundle (B12) fans out in flat bundles

bundles which proceed to the base of the papillalY muscles, branch off to formsuben- docardial networks, form functional connec-

the apex of the heart,and travel as recurrent

of the heart.

Functional anatomy All components of the ducting system of the heart are theoreticallycapable of generating impulses Yet the impulsefrequency of the sinuatrial node at a rate of about

con-70 per minute, is faster than that of the AV nodewith 50-60 impulses per minute and that of theventricles with 25-45 per minute Thus theheartbeat is normally determined and coordi-nated by the sinuatrial node (sinuatrial nodal rhythm) while subsequent components of theconducting system remain silent

Clinical note Pathological conditions can

dis-rupt the conducting system of the heart nosis of abnormalities can be assisted by an

Diag-electrocardiogram (ECG).

Conduction System of Heart 27

A Conducting systern of heart,

viewed frorn the right

E

!

89

B Conducting systern of heart,

viewed frorn the left

28 Cardiovascular System: Heart

E

i InnervationThe heartbeat which is initiated by the

auto-nomic (vegetative) nervous system (Vol 3

p 292ff.) Nerve supply to the heart (A) is

derived from the sympathetic and

fibers

portion of the sympathetic trunk at the level

of the cervical ganglia: the superior cervical

cardiac nerve (A1 ) middle cervical cardiac nerve

(A2) and inferior cervical cardiac nerve (A3)

bundle they travel caudally to the cardiac

branches (AS) arise from the upper thoracic

ganglia and likewise pass to the cardiac

plexus The cardiac nerves of the

autonomic fibers whose preganglionic

seg-ments arise from the upper segseg-ments of the

fibers particularly pain fibers whose

peri-karya lie in the cervical and thoracic spinal

ganglia

Stimulation of sympathetic cardiac nerves leads

to an increased heart rate greater force of

contraction and excitation and accelerated

node

vagus nerve (A6) They branch off at various

levels from the cervical portion of the vagus

cervical cardiac branches and pass to the

(A9) also radiate from the thoracic portion

of the vagus nerve and pass to the cardiac

plexus The vagal cardiac nerves contain

sub-epicardial neurons at the base of the heart

The viscerosensory fibers of the

parasympa-thetic cardiac branches mainly conduct

recep-tors.

Stimulation of parasympathetic cardiac nervesleads to decreased heart rate and force of

node

Cardiac Plexus

travel along the base of the heart wherethey join to form the cardiac plexus (A4).Based on topographical features the cardiacplexus can be divided into superficial (A4ai

plexus are smaller and larger collections of

(AlO) The superficial or anterior portion ofthe plexus lies below the aortic arch in front

of the right pulmonary artery and is

nerves on the left side.The deep or posterior.portion of the plexus lies behind the aorticarch and anterior to the tracheal bifurcation

nerves on bott: sides.The two portions of the

lying along the coronary arteries and atria

4a

30 Cardiovascular System: Heart

E

Like all visceral organs that undergo

signifi-cant changes in volume and displacement

relative to adjacent organs, the heart is

peri-cardial cavity (B)

and portions of the great vessels near its

se-rous pericardium The fibse-rous pericardium is a

sac formed by collagenous connective tissue

with dense fibers that surrounds the heart

without actually being connected to it The

system within the fibrous pericardium Like

layerorepicardium lies directly on the

sur-face of the heart and roots of the great

ves-sels It turns back on itself to become the

parietal layer(B2) which lines the inner

sur-face of the fibrous pericardium (B3)

peri-cardium is fused at various sites with

sur-rounding structures, anchoring the heart in

its position in the thorax Its caudal portion is

dia-phragm Its anterior portion is attached by

the stemopericardial ligaments, variable

bands, to the posterior surface of the

ster-num (B4) Thicker connective tissue bands

also pass posteriorly to the trachea and

peri-cardium is separated from the parietal layer

of the pleural cavity by loose connective

tissue

visceral layer can only be visualized when the

pericardial cavity is laid open This also

re-veals the lines of reflection between these

two layers which form a cranial border

about 3 cm long is contained within the

pulmonary veins(Be9) are also covered by

ar-ranged to form two complex tubes (e), oneenclosing the aorta and pulmonary trunk atthe arterial opening (red line) and the otherenclosing the pulmonary veins and venae

venous openings there is a groove, the verse pericardial sinus (arrow in C) The aorta

passageway and the great veins lie posterior

to it The sites of reflection of the venous

as the pericardial recesses Between the rior pulmonary veins, the inferior vena cava(Be8) and the posterior surface of the leftatrium there is the large oblique pericardialsinus (810)

infe-The pericardium is covered on its right andleft sides by the pleura (All) Passing be-

phrenic nerve(A12) runs bilaterally

blood supply to the pericardium is mainly

thoracic artery.Venous drainage runs via the

bra-chiocep/wlic vein Innervation of the

(A12), vagus nerve, and sympathetic trunk

Clinical note Under pathological conditions,larger amounts of fluid can collect in the peri-cardial recesses (pericardial effusion) Followingfibrinous infiammation adhesions between lay-ers of the serous pericardium can form, poten-tially severely restricting motion of the heart

A rupture in the wall of the aorta can lead to arapid outpouring of blood into the pericardialcavity resulting in pericardial tamponade

32 Cardiovascular System: Heart

E

thorax. The mediastinum is bounded

aperture (Al), where it becomes continuous

with the visceral space of the neck, and

vertebral column(A4) in the sagittal plane Its

mediasti-nal part of parietal pleura.The mediastinum

can be divided into the superior mediastinum

(A red) and inferior mediastinum (A blue) The

plane(AS) extending from thesternal angle.

vessel and nerve pathways as well as the

divided by the anterior and posterior wall of

medi-astinum (blue-green), middle mediastinum

the anterior thoracic wall and the anterior

surface of the pericardium The middle

peri-cardium. The posterior mediastinum

ex-tends between the posterior wall of the

large blood vessel and nerve pathways and

theesophagus (see p 176)

Cardiac borders (8) In the living body, the

by a space containing a capillary layer, so

that their contours largely conform to each

other For the purposes of describing their

location, it is thus sufficient to limit

discus-sion to the heart

following are based on the average adult In

its normal position, two-thirds of the heart

lies on the left of the midline The borders of

thoracic wall form a trapezoid The rightborder runs from the sternal attachment ofthe third rib to the connection to the 6th rib

paral/eling the right sternal border, andabout 2 cm away from it This line corre-

atrium. The continuation of this line

supe-riorvena cava,while its caudal continuation

infe-rior vena cava.The right border becomescontinuous at the connection to the 6th rib

left border of the heart extends from its apex,located in the fifth intercostal space about,

curv-ing with a left convexity, to a point located

2 cm lateral to the attachment of the secondrib

A portion of the heart is in direct contactwith the anterior thoracic wall, i.e., the ster-num Sternal percussion reveals an area of

Thepleural cavity(red) extends from eitherside in front of the heart, covering its lateralportions Depending on the volume of air in

(blue) expands into the pleural cavity though the percussion sound is clearer atthis site than absolute cardiac dullness, it isnot as resonant as over adjacent lung tissue.For this reason, the term relative cardiac dull-ness is used This indicates the true size ofthe heart, with its area corresponding to theborders of the portion of the heart project-ing to the thoracic wall

Al-Position of Heart and Cardiac Margins 33