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The Management
of Disorders of the
Child’s Cervical Spine

Jonathan H. Phillips
Editor in Chief
Daniel J. Hedequist
Suken A. Shah
Burt Yaszay
Editors

123
The Management of Disorders
of the Child’s Cervical Spine
Jonathan H. Phillips
Editor in Chief
Daniel J. Hedequist • Suken A. Shah
Burt Yaszay
Editors

The Management
of Disorders of the
Child’s Cervical Spine
Editor in Chief
Jonathan H. Phillips, MD
Arnold Palmer Hospital
Orlando, FL, USA

Editors
Daniel J. Hedequist, MD Suken A. Shah, MD
Harvard Medical School Nemours/Alfred I. DuPont Hospital
Boston, MA, USA for Children
Wilmington, DE, USA
Burt Yaszay, MD
Rady’s Children’s Hospital Associate
San Diego, CA, USA

ISBN 978-1-4939-7489-4    ISBN 978-1-4939-7491-7 (eBook)

https://doi.org/10.1007/978-1-4939-7491-7

Library of Congress Control Number: 2017959606

© Springer Science+Business Media LLC 2018

This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or
part of the material is concerned, specifically the rights of translation, reprinting, reuse of
illustrations, recitation, broadcasting, reproduction on microfilms or in any other physical way,
and transmission or information storage and retrieval, electronic adaptation, computer software,
or by similar or dissimilar methodology now known or hereafter developed.
The use of general descriptive names, registered names, trademarks, service marks, etc. in this
publication does not imply, even in the absence of a specific statement, that such names are
exempt from the relevant protective laws and regulations and therefore free for general use.
The publisher, the authors and the editors are safe to assume that the advice and information in
this book are believed to be true and accurate at the date of publication. Neither the publisher nor
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Printed on acid-free paper

This Springer imprint is published by Springer Nature

The registered company is Springer Science+Business Media, LLC
The registered company address is: 233 Spring Street, New York, NY 10013, U.S.A.
This book is dedicated to all children who have disorders
of the cervical spine and to the people who care for them.
Foreword

In the early 1970s, I became interested in the cervical spine, specifically con-
genital anomalies. That led to the publication of a report on the Klippel-Feil
syndrome. I was fortunate to find a monograph entitled Upper Cervical Spine
published in 1972. The authors, Detlef von Torklus and Walter Gehle, were
from the Orthopedic Clinic and Outpatient Department of the University
Hospital in Hamburg, Germany. They had done an extensive review of the
literature and pathoanatomy of the cervical spine, and, importantly, nearly
half of their book was devoted to children. The authors identified many nor-
mal physiologic and anatomic variations that frequently mimic pathology.
Unlike the extremities, in spine issues, one cannot use a comparison X-ray of
the opposite side. Their work identified variations in the pediatric spine and
how they differed from the adult. This text became my go-to source for
insight in complex cervical spine problems.
The Management of Disorders of the Child’s Cervical Spine edited by
Jonathan Phillips, Daniel Hedequist, Suken Shah, and Burt Yaszay continues
that legacy. This text is comprehensive and includes an extensive review of
previous literature by individuals knowledgeable in the management of chil-
dren with complex cervical spine problems.
Part I, Basic Medical Science, is essential to effective diagnosis and treat-
ment. This section contains important chapters on anatomy, biomechanics,
radiology, advanced imaging, and current diagnostic techniques.
Part II, Clinical Aspects of Disorders of the Child’s Cervical Spine, con-
tains an extensive discussion of trauma to the immature spine and its potential
for serious morbidity and mortality. There is a special section on cervical
injury in the young athlete. The clinical aspects of many of the disorders that
can affect the child’s spine are presented in detail. This list is comprehensive
and includes inflammatory conditions, infection, tumors, congenital anoma-
lies, metabolic disorders, and bone dysplasias.
Part III, The Medical and Surgical Treatment of Cervical Disorders in
Children, covers management—including conservative techniques such as
immobilization and rehabilitation. Also included are surgical approaches,
including current instrumentation, anesthesia, and neurological monitoring.
There is a unique section on complications and revision surgery.

vii
viii Foreword

The strength of this text is that it is the product of an international panel of

experts, all of whom are recognized authorities. This is coupled with the skill-
ful oversight of Dr. Phillips and his colleagues to create a powerful text that
will be an important clinical resource for many years. This will be ­exceedingly
helpful to those involved in the management of cervical spine problems of
children, and it continues the legacy of von Torklus and Gehle.

Ann Arbor, MI, USA Robert N. Hensinger, MD

Preface

There is no one reason why we wrote this book. It came about, as so many
different things do, by way of a conversation at the dinner table. Suken Shah,
MD; Burt Yaszay, MD; and I were talking at such a dinner table in Orlando
at a meeting on early onset scoliosis. We all had a big interest in children’s
cervical spine problems, but agreed that they were pretty rare and there wasn’t
much of a forum for talking about them among us orthopedic surgeons who
specialize in pediatric problems.
I give Burt the credit for the statement that “peds cervical spine is the last
black hole in kids’ spinal knowledge” or something like that. And with that
prophetic statement the seed was sown.
Suken polled the membership of the Pediatric Orthopedic Society of North
America (POSNA), and within a very short time, we had a small but enthusi-
astic group of interested surgeons who formed the nidus of a new study group
which, for now at least, is called the Pediatric Cervical Spine Study Group
(PCSSG). The members of this international group have contributed most of
the chapters in this text, along with their fellows and other associates. We
meet a few times a year at POSNA and Scoliosis Research Society (SRS) and
International Congress on Early Onset Scoliosis (ICEOS) meetings and have
been supported by these organizations. I’m very happy to acknowledge their
support.
One of the early topics we discussed at PCSSG meetings was the possibil-
ity of writing a text that could guide the novice surgeon in this rare but dan-
gerous area. Both Fran Farley, MD, and Haemish Crawford, FRACS, were
the initial proponents of the idea and contributed chapters. Dan Hedequist,
MD, already was involved in writing a book for our publisher, Springer, and
put me in touch with Kris Spring in their New York office who has been
beyond patient in waiting for a long overdue final draft. Dan, Suken, Burt,
and I took on editorial responsibilities for this text, so the four of us are
responsible for its content.
There are many others who have put up with the long process of writing,
notably our families, of course. But I would also like to acknowledge the help
of my colleagues at Arnold Palmer Children’s Hospital in Orlando in disci-
plines apart from orthopedics, namely, neurosurgery, ENT, general surgery,
and physiatry, who have written chapters which complete the scope of this
book.

ix
x Preface

The final and most important thank you of all goes to my secretary and
friend of 20 years, Mary Regling, BA, who has been the “den mother” of the
PCSSG from its inception and the driving force behind getting this work
published. Without her, the project would have foundered and failed.

Orlando, FL, USA Jonathan H. Phillips, MD

Contents

Part I Basic Medical Science

1 Embryology and Anatomy of the Child’s Cervical Spine. . . . . . . . . 3

Jonathan H. Phillips
2 Biomechanics of the Growing Cervical Spine . . . . . . . . . . . . . . . . . 15
John Kemppainen and Burt Yaszay
3 Pathology of the Child’s Cervical Spine and Its Clinical
Implications. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Ehsan Saadat, Daniel J. Hedequist, and Patrick Wright
4 Radiology of the Growing Cervical Spine. . . . . . . . . . . . . . . . . . . . . 53
Paul D. Kiely, Gregory Cunn, Jonathan H. Phillips,
and Jahangir K. Asghar

Part II Clinical Aspects of Disorders of the Child’s Cervical Spine

5 Clinical Presentation and Physical Examination of Children

with Cervical Spine Disorders. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
William C. Warner and Ilkka Helenius
6 Pediatric and Adolescent Cervical Spine Trauma. . . . . . . . . . . . . . 87
Mitesh Shah, Martin J. Herman, Craig Eberson,
and John T. Anderson
7 Infections and Inflammatory Conditions
of the Pediatric Cervical Spine . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121
Kaela Frizzell, Archana Malik, Martin J. Herman,
and Peter Pizzutillo
8 Tumours of the Cervical Spine. . . . . . . . . . . . . . . . . . . . . . . . . . . . 133
Nanjundappa S. Harshavardhana and John P. Dormans
9 Congenital Disorders of the Child’s Cervical Spine . . . . . . . . . . . 155
Alejandro Dabaghi-Richerand, Robert N. Hensinger,
and Frances A. Farley
10 Dysplasias in the Child’s Cervical Spine. . . . . . . . . . . . . . . . . . . . . 169
Jennifer M. Bauer and William Mackenzie

xi
xii Contents

11 Congenital Muscular Torticollis . . . . . . . . . . . . . . . . . . . . . . . . . . . 183

Kaela Frizzell, Archana Malik, Martin J. Herman,
and Peter Pizzutillo
12 Cervical Spine Injuries in Athletes. . . . . . . . . . . . . . . . . . . . . . . . . 191
Firoz Miyanji

Part III The Medical and Surgical Treatment of Cervical

Disorders in Children

13 Medical and Rehabilitative Techniques in Cervical

Disorders of the Child. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 211
Katrina M. Lesher
14 Surgical Approaches to the Child’s Cervical Spine. . . . . . . . . . . . 219
Haemish A. Crawford and William Warner
15 Spinal Cord Monitoring in Pediatric Cervical
Spine Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235
Jonathan H. Phillips and Michael Isley
16 External Immobilization of the Child’s Cervical Spine. . . . . . . . . 245
Michael B. Johnson and Leah McLachlan
17 Posterior Cervical Arthrodesis in Children. . . . . . . . . . . . . . . . . . 261
Daniel J. Hedequist and Anthony Stans
18 Anterior Cervical Arthrodesis in Children. . . . . . . . . . . . . . . . . . . 275
Emmanuel N. Menga, Michael C. Ain, and Paul D. Sponseller
19 Anterior Transoral Approaches to the Upper Cervical
Spine in Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 285
Joshua Gottschall and James Kosko
20 Chiari Malformations and Foramen Magnum Stenosis. . . . . . . . 291
Christopher A. Gegg and Greg Olavarria
21 Miscellaneous Conditions of the Head and Neck
in Infants and Children . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 303
David Miller
22 Complication Types and Rates in Pediatric
Cervical Spine Surgery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 325
Urvij M. Modhia and Paul D. Sponseller
Index. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 333
Contributors

Michael C. Ain, MD Pediatric Orthopedics, Department of Orthopedic

Surgery, Johns Hopkins Bloomberg Children’s Center, Baltimore, MD, USA
John T. Anderson, MD University of Kansas School of Medicine,
Department of Orthopedic Surgery, Children’s Mercy Hospital and Clinics –
Kansas City, Kansas City, MO, USA
Jahangir K. Asghar, MD Department of Orthopedics, Division of Spinal
Surgery, Nicklaus Children’s Hospital, Miami, FL, USA
Jennifer M. Bauer, MD, MS Pediatric Orthopaedic Surgery, University of
Washington, Department of Orthopaedics and Sports Medicine/Seattle
Children’s Hospital, Seattle, WA, USA
Gregory Cunn, MD Department of Internal Medicine, New York
Presbyterian–Brooklyn Methodist Hospital, Brooklyn, NY, USA
Haemish A. Crawford, FRACS Starship Children’s Hospital, Auckland,
New Zealand
Alejandro Dabaghi-Richerand, MD Department of Orthopedic Surgery,
C.S. Mott Children’s Hospital, University of Michigan, Ann Arbor, MI, USA
John P. Dormans, MD Texas Children’s Hospital, Houston, TX, USA
Craig Eberson, MD Division of Pediatric Orthopedic Surgery, Orthopedic
Surgery Residency, Alpert Medical School of Brown University, Providence,
RI, USA
Frances A. Farley, MD Department of Orthopedic Surgery, C.S. Mott
Children’s Hospital, University of Michigan, Ann Arbor, MI, USA
Kaela Frizzell, DO Department of Orthopedic Surgery, Philadelphia College
of Osteopathic Medicine, Philadelphia, PA, USA
Christopher A. Gegg, MD, FAANS, FACS Pediatric Neurosurgery, Arnold
Palmer Hospital, Orlando, FL, USA
Joshua Gottschall, MD Florida Pediatric Associates, LLC, Orlando, FL,
USA
Nanjundappa S. Harshavardhana, MS Golden Jubilee National Hospital,
Clydebank, Scotland, UK

xiii
xiv Contributors

Daniel Hedequist, MD Orthopedic Surgery, Children’s Hospital Boston/

Harvard Medical School, Boston, MA, USA
Ilkka Helenius, MD, PhD Department of Pediatric Orthopedic Surgery,
Turku University Central Hospital, Turku, Finland
Robert N. Hensinger, MD Department of Orthopedic Surgery, C.S. Mott
Children’s Hospital, University of Michigan, Ann Arbor, MI, USA
Martin J. Herman, MD Drexel University College of Medicine, St.
Christopher’s Hospital for Children, Philadelphia, PA, USA
Michael Isley, PhD, DABNM, FASNM Intraoperative Neuromonitoring
Department, Orlando Regional Medical Center and Arnold Palmer Hospital
for Children, Orlando, FL, USA
Michael B. Johnson, FRACS Department of Orthopedics, Royal Children’s
Hospital, Parkville, VIC, Australia
John Kemppainen, MD Helen DeVos Children’s Hospital, Grand Rapids,
MI, USA
Paul D. Kiely, MCh, FRCS Centre for Spinal Disorders, Mater Private
Cork, Cork, Ireland
James Kosko, MD Children’s Ear Nose & Throat Associates, Orlando, FL,
USA
Katrina M. Lesher, MD Children’s Hospital of the Kings Daughters,
Norfolk, VA, USA
William Mackenzie, MD Nemours/Alfred I. duPont Hospital for Children,
Wilmington, DE, USA
Archana Malik, MD St. Christopher’s Hospital for Children, Orthopedic
Center for Children, Philadelphia, PA, USA
Leah McLachlan, BPO Department of Orthotics and Prosthetics, Royal
Children’s Hospital, Parkville, VIC, Australia
Emmanuel N. Menga, MD Department of Orthopedic Surgery, The Johns
Hopkins University, Baltimore, MD, USA
David Miller, MD Children’s Surgical Associates, Orlando, FL, USA
Firoz Miyanji, MD, FRCSC British Columbia Children’s Hospital,
Vancouver, BC, Canada
Urvij M. Modhia, MD Department of Orthopedic Surgery, The Johns
Hopkins University, Baltimore, MD, USA
Greg Olavarria, MD Neurosurgery, Arnold Palmer Hospital for Children,
Orlando, FL, USA
Jonathan H. Phillips, MD APH Center for Orthopaedics, Orlando Health,
Arnold Palmer Hospital, Orlando, FL, USA
Contributors xv

Peter Pizzutillo, MD St. Christopher’s Hospital for Children, Philadelphia,

PA, USA
Ehsan Saadat, MD Emory Orthopedics and Spine Center, Atlanta, GA,
USA
Mitesh Shah, MD Orthopedic Surgery and Pediatrics, Drexel University
College of Medicine, St. Christopher’s Hospital for Children, Philadelphia,
PA, USA
Suken A. Shah, MD Nemours/Alfred I. DuPont Hospital for Children,
Wilmington, DE, USA
Paul D. Sponseller, MD, MBA Division of Pediatric Orthopedics, Johns Hopkins
Medical Institute, Bloomburg Children’s Center, Baltimore, MD, USA
Anthony Stans, MD Division of Pediatric Orthopedics, Mayo Clinic,
Rochester, MN, USA
William C. Warner Jr, MD LeBonheur Children’s Hospital, University of
Tennessee/Campbell Clinic, Germantown, TN, USA
Patrick Wright, MD Department of Pediatric Orthopedic Surgery,
University of Mississippi Medical Center, Jackson, MS, USA
Burt Yaszay, MD Children’s Specialty, San Diego, CA, USA
Introduction

This book was written for a wide audience. Some of its readers will be famil-
iar, or even expert, in the care of children with neck and cervical spine disor-
ders. Others will be completely new to the subject. Though its emphasis is on
the orthopedic and neurosurgical approach to children’s cervical spine, there
are chapters that are contributed by other disciplines. Thus, an ENT surgeon
who may be called upon to perform an anterior trans-oral approach to the
dens will be reassured by the account of this technique in Chapter 19. Chapter
21 focuses on non-spinal disorders which may present to physicians and oth-
ers encountering children with neck problems in their clinics. Knowing what
their significance is and which consultant to engage with in their management
is important.
While it is unwise to try to be all things to all people, it is hoped that this
is a reference that can be dipped into by the occasional reader looking for
something specific and also be a comprehensive guide to the young surgeon
embarking on a career which may include pediatric cervical spine surgery.
The area we cover is quite rare and quite dangerous for the unprepared.
Yet with the changing demographics of childhood trauma and increasing sur-
vival of children with previously lethal syndromes, we are encountering these
rare diagnoses with greater frequency.
The reader is encouraged to approach the text in a traditional fashion. We
are all anxious to know “how to do it,” but such enthusiasm must be tempered
by acquiring the building blocks of “why.” Thus, we start with basic science,
and it cannot be overemphasized how important a thorough knowledge of the
anatomy (both normal and abnormal), pathology, biomechanics, and radiol-
ogy is to treating these rare disorders. The chapters on clinical assessment
and presentation of the multitude of problems in this area follow. Only after
these basic areas are covered do we embark on accounts of the surgical and
nonsurgical management of the problems encountered.
Each chapter is written by experts in the area and can be taken as stand-­
alone treatises. It is hoped, however, that the whole will be greater than the
sum of its parts.

 Jonathan H. Phillips, MD
 Daniel J. Hedequist, MD
 Suken A. Shah, MD
Burt Yaszay, MD

xvii
 Part I
Basic Medical Science
 Embryology and Anatomy
of the Child’s Cervical Spine 1
Jonathan H. Phillips

result in highly differentiated anatomical areas in

Embryology and Definitions vertebrates. Nowhere is this specialization more
apparent than in the upper cervical spine of the
The process of embryological development and human. The formation of the skull base and upper
maturation of the fetus can be described in vari- two cervical vertebrae is unique in the axial
ous stages known as Carnegie stages. These refer human skeleton and departs quite markedly from
to levels of development rather than gestational the lower cervical, thoracic, lumbar, and sacral
age or crown-rump length in millimeters. Though morphology where there are more structural sim-
the three systems overlap, we will use the ilarities than differences. We will see that the par-
Carnegie stages as much as possible in this ticular embryology of this rostral area of the
discussion. spine has highly complex origins.
The terms rostral and caudal and ventral and Segmentation describes a phenomenon of
dorsal—while intuitive in embryology—are used division of building blocks of tissues into repeat-
less often in descriptive surgical anatomy, and the ing units and is similar in concept to metamer-
terms superior and inferior and anterior and pos- ism. There is a further twist to the idea of
terior are used interchangeably in this chapter. In segmentation in the human spine, however,
addition, descriptive names such as basiocciput, because a process of resegmentation occurs dur-
atlas, and axis are interchanged with skull, C1, ing embryogenesis in which the caudal and ros-
and C2, which better describe the approach of the tral parts of adjacent segments fuse together to
surgeon in the operating theater to ensure accu- form the completed vertebrae. When this process
rate surgical instrumentation at correct levels. is corrupted, the vertebrae are malformed. In the
Metamerism is an important concept that so-called hemimetameric shift, for instance, the
relates to the general pattern of segmental repeti- process of resegmentation can fail unilaterally,
tion of similar structures in the developing resulting in the appearance of a hemivertebra and
embryo. It is this basic symmetrical template resulting in congenital scoliosis. This occurs
which is modified by localized gene expression most frequently in the thoracic spine, where cor-
to form region-specific structural changes which onal plane decompensation is an expected out-
come for a fully segmented coronal hemivertebra,
depending on the specific pattern of malforma-
tion. It occurs also in the cervical spine, both in
J.H. Phillips (*)
the coronal and sagittal planes. Sagittal plane
APH Center for Orthopedics, Orlando Health, Arnold
Palmer Hospital, Orlando, FL, USA abnormalities are more common than coronal,
e-mail: jonathan.phillips@orlandohealth.com the prototypical example of which is that seen in

© Springer Science+Business Media LLC 2018 3

J.H. Phillips et al. (eds.), The Management of Disorders of the Child’s Cervical Spine,
https://doi.org/10.1007/978-1-4939-7491-7_1
4 J.H. Phillips

Klippel-Feil syndrome, a failure of segmentation cells of the somitic mesoderm have spread toward
rather than a hemimetameric shift, though this this structure, which induces the formation of the
last can and does occur in the child’s neck, result- sclerotome. The sclerotomal segments (and this
ing in cervical congenital scoliosis. tissue mass is segmented) will form the verte-
Somites, or more properly their derivatives, brae, whereas the notochord, under the negating
sclerotomes, are the building blocks of the spine. influence of the neural tube, remains in the
They appear in increasing numbers during mature human only as the nucleus pulposus of
embryogenesis, and the number of these segmen- intervertebral discs and the alar and apical liga-
tal tissue blocks correlates with the anatomical ments of the craniocervical junction. This seg-
staging of the embryo. Somites are just one part mented system develops in a rostral to caudal
of the mesoderm layer of the three-layered early direction (Fig. 1.1).
embryonic disc. This disc, a few days old, has an Somite count increases from about one to four
outer epidermal layer facing the amniotic cavity, at age 20 days, first appearing at the head of the
a middle layer of mesoderm, and an endodermal embryo, to 34–35 at age 30 days toward the tail.
layer facing the yolk sac. This pattern is apparent Ultimately, 44 pairs of somites occur and form
by about 3 weeks postfertilization. The meso- the left and right half of the sclerotome. The other
derm is itself divided into three parts, medial, two parts of the somites go on to form muscle and
intermediate, and lateral mesoderm. The most skin. The remaining parts of mesodermal layer
medial band is called the paraxial mesoderm and lateral to the somites form splanchnic structures.
once again divides into three, this time from dor- These include gut, vascular, and urological struc-
sal to ventral. The area nearest the dorsal surface tures. Insult to the embryo at this stage can affect
is the dermatome, next the myotome, and further all these systems and explains the concomitant
to the center of the embryo is the sclerotome. All appearances in clinical practice of multi-system
of these areas are arrayed surrounding two struc- congenital formation failure. The best known
tures which carry powerful molecular signaling example of this is VACTERL syndrome in which
properties—the notochord in the very center of heart, gut, renal, and vertebral malformations
the embryo and the neural tube which by now coexist.
(stage 10 or about 4 weeks) has formed from the At about the 5- to 8-week period, or Carnegie
original neural plate and which lies right behind stages 15–22, the emerging pattern of spinal forma-
the notochord on its dorsal aspect. The notochord tion is becoming evident. However, the contribu-
will regress quickly, but not before the ventral tion of somites to their sclerotomal structures is

Fig. 1.1 The relationship and control of somatic mesoderm to the notochord and neural tube (Reproduced with permis-
sion from Gilbert [7]; © Sinauer Associates, Sunderland, MA)
1 Embryology and Anatomy of the Child’s Cervical Spine 5

highly complex at the cranial extent of the vertebral Sclerotomes Vertebra

column. There are designated pairs of sclerotomes
inasmuch as the upper four form the basiocciput, 1 Basioccipital
the next eight form the cervical vertebrae (of which
there are only seven, but with eight spinal nerves), 2
and the more caudal pattern (12 thoracic, five lum-
bar, and five sacral, variable coccygeal) is more 3
easily understood based on the gross anatomy of
the fully formed human skeleton. It is the complex
4
variation from the typical pattern of vertebral
development which gives rise to the unique shape
and function of the atlas and axis. These two verte- 5
C1 C1
brae share a common origin with the basiocciput,
and as such should be considered as an embryo- C2
6
logical, anatomical, and functional unit very differ- C2 C2
ent from the subaxial spine. This unit is uniquely
7
designed to transmit the termination of the brain- C3 C3
stem and emerging spinal cord in a highly flexible C3
protective tube that allows very roughly 50% of the 8
C4 C4
total movement of the skull on the spinal column. C4
The remaining cervical motion is distributed over 9
the five lower cervical segments. All of these cervi- C5 C5
C5
cal vertebral segments except C7, however, carry
the responsibility of transmitting the vertebral
Fig. 1.2 Relative somatic contributions to the spinal col-
arteries, a function solely attributed to neck verte- umns (Redrawn with permission from Muller and
brae. Once again the pattern of the vertebral arterial O’Rahilly, © 1994 Wiley Publishing)
anatomy is radically different at the atlas and axis,
and a thorough understanding of this arterial anat-
omy is fundamental to safe posterior surgical cause caudal or rostral homeotic transformations
approaches to the upper cervical spine. [1]. The Hox-4.2 gene expression can transform
The relative somatic contributions to the spi- occipital bones into neural arches [2]. Finally,
nal column are shown in Fig. 1.2. The upper four transgenic mice can be found to exhibit a third
sclerotomes form the basiocciput but also borrow occipital condyle fusing the skull base to the dens
from somite five, which is a cervical one, thus the [3], and rostral vertebral shifts have been seen
intimate relationship of the atlas to the skull base after heat exposure.
embryologically. Sclerotome five (a cervical one) Though murine and avian genetic models
forms both the posterior arch of the atlas and should be interpreted with caution in the human,
occipital condyles. The anterior arch of the atlas it is easy to imagine that altered expression of
has an origin in the hypochordal bow which these homeobox genes may be the basis for well-­
appears ventral to the notochord and undergoes known malformations at the upper cervical spine
chondrification and fusion with the posterior neu- such as assimilation of the atlas, which can occur
ral arch elements. There is a transient proatlas posteriorly and anteriorly.
centrum which is dissolved. There is no vertebral The formation of the axis is in many ways
body in C1 under normal circumstances. perhaps the most bizarre in the human axial
Teratogenic influences at this stage have been skeleton. A review by Muller and O’Rahilly in
shown in mice. Interference with Hox genes by 2003 explains the process well [4]. The fact that
retinoic acid (most commonly used in the human two, not one, sclerotomes form the posterior
for the treatment of acne) has been shown to neural arch of C2 explains why it is so massive
6 J.H. Phillips

e­ lements of the neural arches at the neurocentral

synchondrosis. This junctional area fuses
completely around age 7. The spinous process
uniting the left and right neural arch growth
centers unites at age 3. Thus, radiographically
there appears to be a spina bifida occulta present
in the toddler, though usually the laminae meet
at a complete cartilaginous bridge. The same
appearance may be present in more caudal ver-
tebrae also.
At C2 there is predictably a much more com-
plex arrangement consequent upon its develop-
ment from three sclerotomes. Five ossification
centers appear and there are also two secondary
centers (the tip of the dens and the ring apophy-
sis of the inferior/caudal aspect of the body of
the axis). These centers result in two radio-
graphically significant synchondroses (see
Chap. 4). The dentocentral synchondrosis repre-
sents the fusion of two sclerotomes at the level
of the future body of C2. However the fusion
level, though less distinct, may also be apparent
Fig. 1.3 Ossification centers of C2. L is the dentocentral
in the young child, most commonly on CT scan
synchondrosis; J is the neurocentral synchondrosis. There
are two Is, two Cs, and one A, totaling five primary cen- or MRI reformatted in the sagittal plane. As
ters. G and H are secondary centers of ossification mentioned above, this may be a source of con-
(Reproduced with permission from Bailey [8]; © The cern in the injured child as a potential fracture
Radiological Society of North America)
line [5]. The possible relationship of these syn-
chondroses to later formation of an os odontoi-
(and therefore ideally suited to the placement of deum is discussed elsewhere (see Chap. 4). The
translaminar screws during cervical instrumen- neurocentral synchondrosis represents the junc-
tation). It also helps us to understand the some- tion of two sclerotomes anteriorly (ventrally)
times confusing radiological appearance of the with the left and right neural arches derived dor-
synchondroses of C2 in the immature child sally from the same tissue. There are therefore
(Fig. 1.3), an important goal to achieve since two of these junctions left and right, and they
these areas are often misinterpreted as fractures. are best seen in coronal imaging modalities. The
Perhaps mutations of gene expression in this growth centers of C1 and C2 are represented
area can also explain the retroflexed dens seen graphically in Figs. 1.3, 1.4, and 1.5. These
in Chiari malformation and congenital types of describe the prototypical arrangements, but it
basilar invagination. must be emphasized that many anatomical vari-
The third cervical vertebra and its subjacent ations can occur, which may be confusing on
levels exhibit the so-called typical cervical mor- imaging studies of the young child. This point is
phology. As noted above, this is still distinguish- well made by Karwacki and Schneider in their
able from thoracic and lumbar vertebrae but 2012 analysis of atlas and axis growth center
approximates more closely to the general pattern variability based on 550 CT scans of children
of vertebral development. aged 0–17 years [6].
There are three primary ossification centers Growth centers are present at various stages in
at C1. The anterior center, derived from the the human embryo. Initially seen as chondrifica-
hypochordal bow, fuses with the posterior/dorsal tion centers, they become ossified and visible
1 Embryology and Anatomy of the Child’s Cervical Spine 7

radiographically by birth and early childhood, arise from the ligamentum nuchae and spinous
though the adult pattern is not achieved until final processes C7 to T6. Cervicis inserts into the pos-
vertebral physeal closure in the 20s. terior tubercles of the upper two or three cervical
vertebrae, and capitis has a more proximal inser-
tion on the mastoid process and the lateral part of
Muscles of the Neck the superior nuchal line. Contraction of the sple-
nius rotates the head toward the side of the mus-
The musculature of the neck has a complex cle acting, and bilateral contraction extends the
arrangement predicated on the function of high head and neck. Innervation is from dorsal rami of
mobility of the skull on the spinal column. The C2 to C6. Deep to it lie erector spinae and semi-
most superficial muscle posteriorly is the trape- spinalis. Anteriorly the sternocleidomastoid
zius. This huge triangular muscle arises from the inserts more superficially to the capitis division at
superior nuchal line of the skull all the way to the the mastoid. This last muscle arises from both
spinous process of T12. Its lateral attachment is clavicle and sternum and opposes splenius rotat-
on the spine of the scapula. Thus it is, strictly ing the head to the opposite side of the muscle
speaking, a muscle of the upper limb. The true contracting, flexes, and laterally flexes the neck.
deep muscles of the neck lie deep to trapezius The erector spinae muscle group is repre-
and comprise five groups. The groups are sple- sented in the neck as iliocostalis cervicis, longis-
nius, erector spinae, transversospinal, interspinal, simus cervicis, and spinalis cervicis and
and intertransverse muscles. capitis—in other words, three subgroups
Splenius covers the deeper muscles of the (Fig. 1.7). Iliocostalis is lateral; spinalis medial
back of the neck and has capitis and cervicis divi- and longissimus are in between the other two.
sions (Fig. 1.6).The splenius capitis and cervicis The muscles lie in the costovertebral groove.

Fig. 1.4 Ossification

centers of C1. Not
unusually, the body
center is bipartite and
occasionally occurs in
three or other multiple
parts (Reproduced with
permission from Bailey
[8]; © The Radiological
Society of North
America)
8 J.H. Phillips

Iliocostalis cervicis arises form upper ribs and

inserts onto transverse processes of the lower cer-
vical vertebrae. Longissimus cervicis arises from
the uppermost ribs and inserts into the C2 to C6
transverse processes. Spinalis cervicis is a vari-
able muscle often not well defined. The erector
spinae muscles laterally flex and extend the neck.
Of the transversospinal group, one muscle is
important and forms the largest single muscle
of the posterior neck. It is the semispinalis capi-
tis and arises from transverse processes of the
upper thoracic and seventh cervical vertebrae
and the articular processes of C6 to C4
(Fig. 1.7). It inserts onto the undersurface of the
skull base posteriorly and is a powerful exten-
sor of the neck. Semispinalis cervicis is con-
tiguous with its thoracis component and passes
from thoracic transverse processes to spinous
processes several levels higher, ultimately
reaching the posterior axis.
Interspinal and intertransverse are small
segmental muscles represented by such groups
as multifidus and rotatores arising from trans-
verse processes of adjacent vertebrae. All are
segmentally innervated and perform functions
Fig. 1.5 Primary (stippled) and secondary (striped) ossi-
fication centers of the typical cervical vertebra. There are of local stabilization and small rotations at seg-
three. Note the ring apophyses (G) at superior and inferior mental levels.
parts of the body. These fuse late in life, sometimes in the At the base of the skull lies a unique triangular
early 20s (Reproduced with permission from Bailey [8]; arrangement of muscles which form the suboc-
© The Radiological Society of North America)
cipital triangle (Fig. 1.8). These suboccipital

Fig. 1.6 Dorsal neck

muscles, superficial
layer

Semispinalis capitus
Mastoid Splenius capitus

Splenius cervicis
Sternocleidomastoid
Trapezius
1 Embryology and Anatomy of the Child’s Cervical Spine 9

Fig. 1.7 Dorsal cervical

musculature, deep layer

Obliquus
capitis superior

Rectus capitus
minor Semispinalis capitis
Rectus capitus Spinous process C2
major
Longissimus capitis

Semispinalis
cervicis

T3

Fig. 1.8 Suboccipital

musculature

Obliquus Rectus capitus

capitis superior posterior minor
Rectus capitus
posterior major Vertebral artery
Obliquus
capitis inferior
Posterior arch C1

Spinous process C2

muscles are part of the transversospinal group. structure during posterior C1 instrumentation
The four muscles are rectus capitis posterior (Fig. 1.9). Occasionally the nerve must be sacri-
major and minor and superior and inferior oblique ficed for this reason. A prolific venous plexus
muscles of the head, as seen in Figs. 1.2 and 1.5. also lies in this region and can cause troublesome
In the floor of this triangle lies the posterior bleeding during C1 lateral mass instrumentation.
atlanto-occipital membrane deep to which the The vertebral artery arises as the first branch
vertebral artery passes of the arch of the atlas into of the subclavian. It passes upward in the poste-
the foramen magnum. The suboccipital (C1) and rior part of the pyramidal space above the apex of
greater occipital nerve (C2) arise, respectively, the lung. It enters the cervical spine through the
above and below the posterior arch of the atlas. foramen transversarium of C6, not C7, and
The C2 root overlies the lateral mass of the atlas ascends to C2 where it passes backward then
and can obstruct the placement of a screw in this medially and then forward in a wide loop that
10 J.H. Phillips

Fig. 1.9 Cervical

nerves: first through
Greater
third occipital nerve
Vertebral
artery
Obliquus
Rectus minor
capitis
superior Third occipital
nerve
Suboccipital
nerve Rectus major
Atlas
Obliquus
capitis inferior
Second
cervical nerve
Semispinalis
cervicus
Third cervical
nerve
Splenius capitis

Facial artery

External carotid artery Lingual artery

Internal carotid artery Hyoid bone

Vertebral artery Thyroid cartilage
Inferior thyroid artery Superior thyroid artery
Cricoid cartilage
Thyrocervical trunk
Subclavian artery

Common carotid artery

Trachea

Fig. 1.10 Arteries of the anterior and lateral neck

allows for movement between atlas and axis Accompanying the vertebral artery is the verte-
(Fig. 1.10). As it passes anteriorly toward the bral vein or more properly a plexus of veins
foramen magnum, it leaves a groove on the supe- which pass both inside and outside of the foram-
rior surface of the atlas. It is highly vulnerable in ina transversaria. One branch exits at C6 and
this area to damage during surgical exposure of another at C7 transverse foramen, and both drain
the occipital and atlantoaxial region. Its position into the subclavian vein.
lateral to the midline plane effectively limits the Anterior vascular anatomy dictates the surgi-
lateral dissection in surgery of this area. cal approach to the anterior cervical spine
1 Embryology and Anatomy of the Child’s Cervical Spine 11

(see Chap. 18). The carotid sheath contains the the arch of the atlas is a tubercle to which the
common carotid artery, the internal jugular vein, anterior longitudinal ligament attaches. There is
and the vagus nerve. It extends from the base of no centrum; the proatlas has dissolved. In addi-
the skull to the aortic arch and is tightly opposed tion, the anterior arch of the atlas is formed not
to the posterior surface of the sternocleidomas- from the centrum remnant as would be imagined,
toid muscle above the sternoclavicular joint. At but rather from the hypochordal bow. This struc-
C3 level the common carotid bifurcates. The ture is important in cervical spine embryology,
internal carotid has no branches in the neck and but exists elsewhere only as the ligamentous fas-
passes up into the skull through the carotid fora- cicle running deep to the anterior longitudinal
men just anterior to the jugular foramen, which ligament joining two rib heads. Thus the hypo-
itself contains the internal jugular vein and lies chordal bow of the atlas is the ossified ligament
just deep to the external acoustic meatus. The joining its two costal elements. It often shows
carotid sheath and its contents, lying deep to the failure of complete ossification in the child, as
anterior border of sternocleidomastoid, form the does the posterior arch of the atlas, which is more
posterior border of the anterior surgical approach conventionally formed from neural arch ele-
to the mid cervical spine. Anteriorly the esopha- ments. The course of the vertebral artery over the
gus and trachea are retracted laterally to allow superior surface of the posterior arch has been
exposure of the anterior cervical vertebral bodies, described. One other anomaly is of interest. The
and their discs thus form the anterior border of articular elements of the upper two cervical ver-
this exposure (see Chap. 14, 18). tebrae are in series with the tiny synovial unco-
vertebral joints on the lateral aspects of the
subaxial cervical vertebrae and not their more
Cervical Osteology massive and functional cervical articular facets
aligning more posteriorly from C3 to C7. Thus
The atlas C1 is a gracile, almost circular, ring of the first and second cervical nerves send their
bone with articular facets above for the occipital anterior primary rami behind the joints and not in
condyles and below for the axis (Fig. 1.11a, b). front as the lower vertebrae do. The resulting
The neural arches are massively enlarged to form obstruction to surgical approaches to C1 has been
the lateral masses, which constitute the only sub- mentioned.
stantial bony elements allowing surgical screw The axis C2 has much more massive propor-
purchase. Their axes pass from posterior lateral tions than its cephalad neighbor (Fig. 1.12a, b).
to anterior medial. Above are the deeply concave We have seen that it is derived from a larger num-
kidney-shaped articular facets for the occipital ber of sclerotomes and not only has retained, but
condyles; below are the more circular facets for also co-opted, a greater centrum contribution
articulation with the axis. Lateral to the masses embryologically. Its characteristic features are
lies the foramen transversarium, formed from the upward pointing dens which articulates with
both neural and costal elements. Anteriorly on the posterior surface of the anterior arch of C1,

Lateral mass
Anterior tubercle
Anterior tubercle
Anterior arch
Transverse
Superior foramen
articular fovea
Transverse
Transverse Inferior
Sulcus for process
process articular
vertebral artery fovea
Posterior arch
A Posterior tubercle B Posterior tubercle

Fig. 1.11 (A, B) First cervical vertebra (atlas). (a) Cranial and (b) caudal
12 J.H. Phillips

Dens
Superior articular Dens
surfaces
Transverse
foramen Transverse process Anterior articular surface

Inferior articular
process Transverse
Lamina process

Spinous process Inferior articular

process Body
A B

Fig. 1.12 (A, B) Second cervical vertebra (axis). (a) Cranial and (b) anterior

Body Anterior tubercle of

Transverse transverse process
process
Transverse Posterior tubercle of
foramen transverse process
Superior articular surface
Superior articular
process Pedicle Sulcus for nerve Articular pillar
Inferior articular Anterior tubercle of
Lamina
process transverse process Spinous process
Spinous process Body
Posterior tubercle of
transverse process
A B

Fig. 1.13 (A, B) Typical cervical vertebrae showing a body, neural arch, spinous, and complex lateral processes

the large lateral masses, and the huge spinous formed cervical ribs, the brachial plexus may
process, which even in small children may be big exhibit precession arising from C4 to C8 instead
enough to allow passage of translaminar screws. of C5 to T1.
In contrast to the atlas, it may have discrete Typical cervical vertebrae show a body, neural
­pedicles, though their size in children is variable arch, spinous, and complex transverse processes
and often does not allow for accommodation of a which contain the vertebral artery and its veins
true pedicle screw. Alternative techniques of (Fig. 1.13a, b). The lateral part of the body at the
C1-C2 arthrodesis, such as a Magerl screw, are interface with the intervertebral disc shows an
discussed in later chapters of this text. In addi- upward turn into the uncus, and it is here that tiny
tion, sublaminar wiring techniques have a long uncovertebral synovial joints exist. They limit
history in orthopedics and utilize the posterior lateral flexion and, described by Lushka, only
arch of C1 and the lamina or spinous process of exist in the cervical spine. Pedicles are much bet-
C2. Again, see later chapters. ter formed in the typical cervical vertebrae and
The orientation of the articulations between allow screw instrumentation. In addition, the
occiput and atlas and atlas and axis allows for a greatly broadened lateral masses, which exhibit
very large range of motion, nodding at the former superior and inferior articulations that sandwich
and rotation at the latter. Approximately 50% of the bony masses, allow for strong screw fixation,
rotation is lost by atlantoaxial arthrodesis, but the again explained later in this text. The choice of
effect on atlanto-occipital fusion is less obvious lateral mass or medial pedicle trajectory is predi-
because of the large flexion extension range of cated on the position of the vertebral artery which
the subaxial spine. lies directly anterior to the lateral masses and
From C3 to C7 the vertebral morphology is thus precludes a straight anteriorward approach
more typical and reproducible. Usually the costal in surgical fusions. However, purchase under the
elements are limited to the contribution to the substantial laminae of C3 to C6 is available, if
foramen transversarium, but occasionally true not as stable in fusion constructs. At C7 the pedi-
cervical ribs appear at C7 or are represented by cle is usually so well formed, even in children,
sometimes troublesome fibrous bands, causing that it has become the preferred location for spi-
thoracic outlet symptoms. In the case of properly nal instrumentation at this level. Between C3 and
1 Embryology and Anatomy of the Child’s Cervical Spine 13

C6, careful analysis of the specific anatomy with stem of the “cross” is adherent to the inferior pos-
advanced imaging is mandatory for safe place- terior body of the axis below the dens. One addi-
ment of instrumentation, indeed all levels should tional and important connective tissue structure
be examined with CT preoperatively, and this also adds stability to the skull-to-atlas-to-axis
idea is discussed in Chap. 4. complex. The tectorial membrane passes from the
posterior rim of the anterior lip of the foramen
magnum to the posterior axis body. It is continu-
 igamentous Support of the Child’s
L ous with the posterior longitudinal ligament and
Cervical Spine blends with the dura on its deep or posterior sur-
face. It can be imaged with MRI and if ruptured in
In the lower cervical spine, a familiar pattern is this modality implies instability at the occipito-
found. The anterior longitudinal ligament support- atlantal level (Figs. 1.14 and 1.15).
ing the anterior vertebral bodies, with interverte-
bral disc annulus and posterior longitudinal
AD
ligament at the posterior margin of discs and bod-
ies, is very similar to the thoracic and lumbar pat- AL
TR
tern. At C2 and above a very different construct
exists, uniquely suited to the previously mentioned
function of allowing large degrees of motion
between the head and neck. The cruciform liga-
ment joins the posterior body of the dens to the
base of the occiput at the anterior margin of the
foramen magnum, bypassing the atlas. Its strong
transverse ligament component captures the dens
axis against the posterior part of the anterior arch
of the atlas, where a synovial joint and significant
bursa exists. The apical ligament is the continua- Fig. 1.15 Axial view showing transverse, alar, atlanto-
tion of the cruciform into the skull. Inferiorly the dental ligaments

Superior longitudinal band

of cruciform ligament Occipital bone

Anterior atlantooccipital
Vertebral artery membrane
Apical ligament of dens
Posterior atlantooccipital Anterior arch of atlas
membrane
Transverse ligament of atlas
Posterior arch of atlas
Inferior longitudinal band
Membrana tectoria of cruciform ligament
Posterior longitudinal Dens
ligament
Anterior longitudinal ligament

Ligamentum flavum

Posterior Anterior

Fig. 1.14 Occipito-cervical level, showing ligaments and membranes, sagittal view
14 J.H. Phillips

Summary bones of the skull by ectopic expression of a homeo-

box gene. Nature. 1992;359(6398):835–41.
3. Charite J, de Graaff W, Vogels R, Meijlink F,
The development of the human neck shows Deschamps J. Regulation of the Hoxb-8gene: syn-
unique aspects of specialization to fulfill the ergism between multimerized cis-acting elements
functions of great flexibility and range of motion increases responsiveness to positional information.
Dev Biol. 1995;171(2):294–305.
not seen elsewhere in the spinal column. The
4. Muller F, O’Rahilly R. Segmentation in staged human
uppermost two vertebrae show major departures embryos: the occipitocervical region revisited. J Anat.
from the pattern seen subaxially. A common 2003;203(3):297–315.
embryological origin of the skull base and parts 5. Piatt JH Jr, Grissom LE. Developmental anat-
omy of the atlas and axis in childhood by com-
of the atlas and axis explains their unique shape
puted tomography. J Neurosurg Pediatr. 2011;
and the fact that these parts function as a unit. 8(3):235–43.
6. Gm K, Schneider JF. Normal ossification patterns
of atlas and axis: a CT study. Am J Neuroradiol.
2012;33(10):1882.
References 7. Gilbert SF. Developmental biology. 7th ed. (258–5),
Sinauer, Fig 14.11, page 473. Sunderland: Sinauer
1. Gruss P, Kessel M. Axial specification in higher verte- Associates. 2003.
brates. Curr Opin Genet Dev. 1991;1(2):204–10. 8. Bailey DK. The normal cervical spine in infants and
2. Lutkin T, Mark M, Hart CP, Dollé P, LeMeur M, children. Radiology. 1952;59:712–9.
Chambon P. Homeotic transformation of the occipital
 Biomechanics of the Growing
Cervical Spine
2
John Kemppainen and Burt Yaszay

their distinct differences, the two regions of the

 ormal Cervical Spine
N cervical spine are discussed separately. A thor-
Biomechanics ough discussion of the anatomy and embryology
of the growing cervical spine can be found in
The cervical spine functions to provide motion of Chap. 1, but here we discuss the osseous and
the head atop the axial skeleton and to protect the ligamentous structures of the cervical spine as
neural elements of the spine as they traverse the they relate to its kinematics and stability.
neck. The cervical spine can be divided into two
distinct segments, the occipitocervical junction
extending from the occiput to C2 and the subax-  unctional Anatomy and Normal
F
ial cervical spine from C3 to C7, each having dis- Biomechanics
tinct anatomic and biomechanical features.
Together, they provide several degrees of motion Occiput to C2
for the head on the axial skeleton, including flex-
ion, extension, and lateral rotation and bending to Osseous Anatomy
the right and left; distraction and compression are The craniocervical junction is made up of the
theoretical and not desirable. The normal active base of the occiput, C1 (the atlas), and C2 (the
range of motion of the child’s cervical spine is axis) that function as a unit to control head move-
slightly greater than that of an adult, with average ment on the subaxial spine. The primary motion
values of 60° of flexion, 90° of extension, 45° of of the occipitoatlantal joint is flexion and exten-
lateral bending in each direction, and 70° of axial sion, with the atlantoaxial joint contributing pri-
rotation in each direction [1, 2]. Reasons for this marily axial rotation. The underside of the
include maturing osseous structures and increased occipital bone includes the foramen magnum,
ligamentous laxity in children, which will be dis- through which the spinal cord passes into the cer-
cussed further throughout the chapter. Because of vical spine. The anterior midline of the occiput is
known as the basion, and the posterior margin is
known as the opisthion. The transverse diameter
J. Kemppainen of the foramen magnum is slightly less than the
Helen DeVos Children’s Hospital,
Grand Rapids, MI, USA anterior posterior diameter. On the lateral side,
just anterior to the midline are the occipital con-
B. Yaszay (*)
Children’s Specialty, San Diego, CA, USA dyles, which are convex in the sagittal plane but
e-mail: byaszay@rchsd.org oblique and rest on the concave lateral mass of

© Springer Science+Business Media LLC 2018 15

J.H. Phillips et al. (eds.), The Management of Disorders of the Child’s Cervical Spine,
https://doi.org/10.1007/978-1-4939-7491-7_2
Another random document with
no related content on Scribd:
 Can you not see that these would have been too frail to work their
way uninjured through the earth?
But by crooking its stout stem the plant opened quite easily a path
for itself and for its leaves, and no harm was done anywhere (Figs.
106, 107). Was not this a clever thought? But really every step in the
life of the plant is full of interest, if we watch it with sharp eyes and a
brain in good order.
 Part III—Roots and Stems

ROOT HAIRS

C AREFULLY pull up one of your bean plants and look at its root
(Fig. 108).
You see that the root grows downward from the lower part of the
stem.

Fig. 108

This bean root looks not unlike a bunch of dirty threads, some
quite thick, others very thin. If you look at these thread-like roots in a
good light, perhaps you may be able to see growing from them a
quantity of tiny hairs.
Now, what is the use of such a root as this?
 Surely some of you are able to guess at the object of this root, and
I will help the others to the answer.
Give a firm though gentle tug to one of the larger plants,—one of
those that are growing in the pot of earth.
Does it come out easily in your fingers?
Not at all. Unless you have been really rough, and used quite a
good deal of strength, the little plant has kept its hold.
What holds it down, do you suppose?
Ah! Now you know what I am trying to get at. Its root is what holds
it in place; and this holding of the plant in place is one of its uses.
Its thread-like branches are so many fingers that are laying hold of
the earth. Each little thread makes it just so much the more difficult
to uproot the plant.
I think you know already that another use of the root is to obtain
nourishment for the plant.
These thread-like roots, you notice, creep out on every side in
their search for food and drink. The water they are able to suck in
easily by means of tiny mouths, which we cannot see. But the plant
needs a certain amount of earth food, which in its solid state could
not slip down these root throats any more easily than a young baby
could swallow a lump of sugar.
Now, how is the plant to get this food, which it needs if it is to grow
big and hearty?
Suppose the doctor should tell your mother that a lump of sugar
was necessary to the health of your tiny baby brother, what would
she do about it?
Would she put the great lump into the baby’s mouth?
You laugh at the very idea. Such a performance might choke the
baby to death, you know quite well.
Perhaps you think she would break the lump into small pieces,
and try to make the baby swallow these; but even these small pieces
might prove very dangerous to the little throat that had never held a
solid morsel.
“She would melt the sugar in water, then the baby could swallow
it,” one of you exclaims.
That is exactly what she would do. She would melt, or dissolve as
we say, this sugar in water. Then there would be no difficulty in its
slipping down the little throat; for you know when anything is
thoroughly melted or dissolved, it breaks up into such tiny pieces that
the eye cannot see them. When you melt a lump of sugar in a glass
of water, the sugar is all there as much as it ever was, although its
little grains no longer cling together in one big lump.
And so when the plant needs some food that the little root hairs
are not able to swallow, it does just what the mother does. It melts or
dissolves the solid food so that this is able to slip quite easily down
the root throats.
But how does it manage this?
No wonder you ask. A root cannot fill a glass with water, as your
mother did. Even if it could, much of this solid food which is needed
by the plant would not melt in water, or in anything but certain acids;
for you know that not everything will dissolve, like sugar, in water.
If I place a copper cent in a glass of water, it will remain a copper
cent, will it not? But if I go into a drug shop and buy a certain acid,
and place in this the copper cent, it will dissolve almost immediately;
that is, it will break up into so many tiny pieces that you will no longer
see anything that looks at all like a cent.
And as much of this earth food, like the copper cent, can only be
dissolved in certain acids, how is the plant to obtain them? Certainly
it is not able to go to the drug shop for the purpose, any more than it
was able to fill a glass with water.
Fortunately it does not need to do either of these things.
If you will look closely at the root of a plant that has been raised in
water, you will see that it is rough with a quantity of tiny hairs. These
little hairs hold the acid which can dissolve the solid earth food.
When they touch this food, they send out some of the acid, and in
this it is soon dissolved. Then the little mouths suck it in, and it is
carried up through the root into the rest of the plant.
Would you have guessed that plants were able to prepare their
food in any such wonderful way as this? It surprised me very much, I
remember, to learn that a root could give out acids, and so dissolve
the earth food it needed.
 ROOTS AND UNDERGROUND STEMS

I N the last chapter you learned that the root of the bean plant has
two uses.
It holds the plant in place, and it provides it with food and drink.
Such a root as this of the bean plant—one that is made up of what
looks like a bunch of threads—is called a “fibrous” root.
The next picture shows you the root of a beet plant (Fig. 109).
Such a thick, fat root as this of the beet is called a “fleshy” root.
The carrot, turnip, radish, and sweet potato, all have fleshy roots.
This beet root, like that of the bean, is useful both in holding the
plant in place and in providing it with food and drink.
But the fleshy root of the beet does something else,—something
that is not attempted by the fibrous root of the bean.
Here we must stop for a moment and look into the life of the beet
plant.
During its first year, the beet puts out leaves; it neither flowers nor
fruits, but it eats and drinks a great deal. And as it does not use up
any of this food in flowering or fruiting, it is able to lay by much of it in
its root, which grows large and heavy in consequence. When the
next spring comes on, the beet plant is not obliged, like so many of
its brothers and sisters, to set out to earn its living. This is provided
already. And so it bursts into flower without delay, its food lying close
at hand in its great root.
 Fig. 109

So you see that a fleshy root, like that of the beet, does three
things:—
1. It holds the plant in place.
2. It provides it with food and drink.
3. It acts as a storehouse.
These plants that lay by food for another year are useful as food
for man. Their well-stocked roots are taken out of the ground and
eaten by us before the plant has had the chance to use up its food in
fulfilling its object in life, that of fruiting. Of course, when it is not
allowed to live long enough to flower and fruit, it brings forth no
young plants. So a habit which at first was of use to the plant
becomes the cause of its destruction.
Perhaps you think that the white potato (Fig. 110) is a plant with a
fleshy root.
 Fig. 110

If so, you will be surprised to learn that this potato is not a root at
all, but a stem.
You think it looks quite unlike any other stem that you have ever
seen. Probably you do not know that many stems grow underneath
the ground, instead of straight up in the air.

Fig. 111

Fig. 112

If you find something in the earth that you take to be a root, you
can feel pretty sure that it really is a stem, if it bears anything like
either buds or leaves. A true root bears only root branches and root
hairs. But in this white potato we find what we call “eyes.” These
eyes are buds from which new potato plants will grow. Close to these
are little scales which really are leaves. So we know that the potato
is a stem, not a root. But this you could not have found out for
yourselves, even with the sharpest of eyes.
 Fig. 111 shows you the thick, fat, underground stem of the
cyclamen. From its lower part grow the true roots.
Next you have that of the crocus (Fig. 112), while here to the right
is that of the wood lily (Fig. 113). This is covered with underground
leaves.

Fig. 113

All these stems are usually called roots. In the botanies such an
underground stem as that of the Jack-in-the-pulpit (Fig. 114) is
named a “corm,” while one like that of the crocus is called a “bulb”
(Fig. 112). All have a somewhat rounded shape.

Fig. 114

Fig. 115

During our walks in the woods last fall, often we found the
Solomon’s seal, and stopped to admire its curved stem, hung with
blue berries. I hope one of you boys whipped out your pocketknife
and dug into the earth till you found its underground stem (Fig. 115).
This was laid lengthwise, its roots growing from its lower side. From
its upper side, close to one end, sprang the growing plant. But what
causes those round, curious-looking scars?
These scars are what give the plant its name of “Solomon’s seal.”
They are supposed to look like the mark left by a seal upon wax.
They show where the underground stem has budded in past
years, sending up plants which in turn withered away. Each plant has
left a scar which shows one year in the life of the underground stem.
Next spring when you find in the woods the little yellow bells of the
Solomon’s seal, I think you will have the curiosity to dig down and
find out the age of some of these plants.
Another plant with an underground stem is the beautiful bloodroot.
As its name tells you, this so-called root contains a juice that looks
something like blood. Such underground stems as those of the
Solomon’s seal and bloodroot are called “rootstocks.” Rootstocks,
corms, and bulbs are all storehouses of plant food, and make
possible an early flowering the following spring.
 ABOVE-GROUND ROOTS

B UT before we finished talking about roots we were led away by

underground stems. This does not matter much, however, for
these underground stems are still called roots by many people.
Just as stems sometimes grow under ground, roots sometimes
grow above ground.
Many of you know the English ivy. This is one of the few plants
which city children know quite as well as, if not better than, country
children; for in our cities it nearly covers the walls of the churches. In
England it grows so luxuriantly that some of the old buildings are
hidden beneath masses of its dark leaves.
This ivy plant springs from a root in the earth; but as it makes its
way upward, it clings to the stone wall by means of the many air
roots which it puts forth (Fig. 116).
Our own poison ivy is another plant with air roots used for climbing
purposes. Often these roots make its stem look as though it were
covered with a heavy growth of coarse hair.

Fig. 116

There are some plants which take root in the branches of trees.
Many members of the Orchid family perch themselves aloft in this
fashion. But the roots which provide these plants with the greater
part of their nourishment are those which hang loosely in the air. One
of these orchids you see in the picture (Fig. 117). It is found in warm
countries. The orchids of our part of the world grow in the ground in
everyday fashion, and look much like other plants.

Fig. 117

These hanging roots which you see in the picture are covered with
a sponge-like material, by means of which they suck in from the air
water and gases.
In summer, while hunting berries or wild flowers by the stream that
runs through the pasture, you have noticed that certain plants
seemed to be caught in a tangle of golden threads. If you stopped to
look at this tangle, you found little clusters of white flowers scattered
along the thread-like stems (Fig. 118); then, to your surprise, you
discovered that nowhere was this odd-looking stem fastened to the
ground.
It began and ended high above the earth, among the plants which
crowded along the brook’s edge.
 Fig. 118

Perhaps you broke off one of these plants about which the golden
threads were twining. If so, you found that these threads were
fastened firmly to the plant by means of little roots which grew into its
stem, just as ordinary roots grow into the earth.
This strange plant is called the “dodder.” When it was still a baby
plant, it lay within its seed upon the ground, just like other baby
plants; and when it burst its seed shell, like other plants it sent its
roots down into the earth.
But unlike any other plant I know of, it did not send up into the air
any seed leaves. The dodder never bears a leaf.
It sent upward a slender golden stem. Soon the stem began to
sweep slowly through the air in circles, as if searching for something.
Its movements were like those of a blind man who is feeling with his
hands for support. And this is just what the plant was doing: it was
feeling for support. And it kept up its slow motion till it found the plant
which was fitted to give it what it needed.
Having made this discovery, it put out a little root. This root it sent
into the juicy stem of its new-found support. And thereafter, from its
private store, the unfortunate plant which had been chosen as the
dodder’s victim was obliged to give food and drink to its greedy
visitor.
 And now what does this dodder do, do you suppose? Perhaps you
think that at least it has the grace to do a little something for a living,
and that it makes its earth root supply it with part of its food.
Nothing of the sort. Once it finds itself firmly rooted in the stem of
its victim, it begins to grow vigorously. With every few inches of its
growth it sends new roots deep into this stem. And when it feels
quite at home, and perfectly sure of its board, it begins to wither
away below, where it is joined to its earth root. Soon it breaks off
entirely from this, and draws every bit of its nourishment from the
plant or plants in which it is rooted.
Now stop a moment and think of the almost wicked intelligence
this plant has seemed to show,—how it keeps its hold of the earth till
its stem has found the plant which will be compelled to feed it, and
how it gives up all pretense of self-support, once it has captured its
prey.
You have heard of men and women who do this sort of thing,—
who shirk all trouble, and try to live on the work of others; and I fear
you know some boys and girls who are not altogether unlike the
dodder,—boys and girls who never take any pains if they can
possibly help it, who try to have all of the fun and none of the work;
but did you ever suppose you would come across a plant that would
conduct itself in such a fashion?
Of course, when the dodder happens to fasten itself upon some
wild plant, little harm is done. But unfortunately it is very partial to
plants that are useful to men, and then we must look upon it as an
enemy.
Linen is made from the flax plant, and this flax plant is one of the
favorite victims of the dodder. Sometimes it will attack and starve to
death whole fields of flax.
But do not let us forget that we happen to be talking about the
dodder because it is one of the plants which put out roots above
ground.
 Fig. 119

There is one plant which many of you have seen, that never, at
any time of its life, is rooted in the earth, but which feeds always
upon the branches of the trees in which it lives.
This plant (Fig. 119) is one of which perhaps you hear and see a
good deal at Christmas time. It is an old English custom, at this
season, to hang somewhere about the house a mistletoe bough (for
the mistletoe is the plant I mean) with the understanding that one is
free to steal a kiss from any maiden caught beneath it. And as
mistletoe boughs are sold on our street corners and in our shops at
Christmas, there has been no difficulty in bringing one to school to-
day.
The greenish mistletoe berries are eaten by birds. Often their
seeds are dropped by these birds upon the branches of trees. There
they hold fast by means of the sticky material with which they are
covered. Soon they send out roots which pierce the bark, and, like
the roots of the dodder, suck up the juices of the tree, and supply the
plant with nourishment.
Then there are water roots as well as earth roots. Some of these
water roots are put forth by plants which are nowhere attached to the
earth. These are plants which you would not be likely to know about.
One of them, the duckweed, is very common in ponds; but it is so
tiny that when you have seen a quantity of these duckweeds,
perhaps you have never supposed them to be true plants, but rather
a green scum floating on the top of the water.
But the duckweed is truly a plant. It has both flower and fruit,
although without a distinct stem and leaves; and it sends down into
the water its long, hanging roots, which yet do not reach the ground.
There are other plants which have at the same time underground
roots and water roots.
Rooted in the earth on the borders of a stream sometimes you see
a willow tree which has put out above-ground roots. These hang
over the bank and float in the water, apparently with great
enjoyment; for roots not only seem to seek the water, but to like it,
and to flourish in it.
If you break off at the ground one of your bean plants, and place
the slip in a glass of water, you will see for yourselves how readily it
sends out new roots.
I have read of a village tree the roots of which had made their way
into a water pipe. Here they grew so abundantly that soon the pipe
was entirely choked. This rapid, luxuriant growth was supposed to
have been caused by the water within the pipe.
So you see there are underground roots and above-ground roots
and water roots. Usually, as you know, the underground roots get
their food from the earth; but sometimes, as with the Indian pipe,
they feed on dead plants, and sometimes, as with the yellow false
foxglove, on other living roots.
 WHAT FEW CHILDREN KNOW

T O-DAY we must take another look at the plants in the

schoolroom garden.
By this time some of them have grown quite tall. Others are just
appearing above the earth.
Here is a young morning-glory (Fig. 120). We see that its stem,
like that of the bean, was the first thing to come out of the seed. This
stem has turned downward into the earth. From its lower end grows
the root, which buries itself deeper and deeper.
An older plant shows us that the upper part of the stem straightens
itself out and grows upward, bearing with it a pair of leaves (Fig.
121).

Fig. 120

From between these starts a tiny bud, that soon unfolds into a
fresh leaf, which is carried upward by a new piece of stem.
On the tip of this new piece of stem grows another bud, which also
enlarges into a leaf, and in the same way as before is borne upward
(Fig. 122).
 Fig. 121

In this fashion the plant keeps growing bigger and bigger. Soon
branches start from the sides of the stem, and later flowers and
fruits.
So we see that it is the stem which bears all the other parts of the
plant.
Most people think that the plant springs from the root; but you
children know better. With your own eyes, here in the schoolroom,
you have seen that instead of the stem growing from the root, the
root grows from the stem.

Fig. 122

That more people have not found this out, is because they do not
use their eyes rightly.
Every spring hundreds and thousands of baby plants make their
way out of the seed shell into the world, just as you saw the baby
bean plant do, sending out first its little stem, which pointed
downward into the earth and started a root. And every spring there
are hundreds of thousands of men and women, and boys and girls,
who go through the woods and fields, and across the parks and
along the streets, as though they were blind, taking no notice of the
wonders all about them.
 PLANTS THAT CANNOT STAND ALONE

A LREADY we have learned that some stems grow under ground,

and that by most people these are called roots.
And among those which grow above the ground we see many
different kinds.
The stem of Indian corn grows straight up in the air, and needs no
help in standing erect.
Fig. 123 shows you the morning-glory plant, the stem of which is
unable to hold itself upright without assistance. A great many plants
seem to need this same sort of help; and it is very interesting to
watch their behavior.