Lateral curvature of the spine and round shoulders

Front matter

l?jnai mtljeCitpofBrttJgark

COLLEGE OF

PHYSICIANS AND SURGEONS

Preface

The successful treatment of lateral curvature of the spine cannot in the past be counted as one of the achievements of orthopedic surgery. The affection is not only intrinsically resistant to treatment but the therapeutic measures employed have been on the whole largely empirical and have not been sufficiently correlated to its pathology and to the mechanism by which it is caused. In the last ten years, however, a good deal of progress has been made along new and promising lines, by means of experimental and clinical work, the records of which lie scattered through later medical literature. In the following pages I have attempted to bring together this literature and to add my own personal views and experience, in the hope of presenting the subject in English in a modern light and to call attention to the prospect offered of obtaining better results. That such a book is needed I have been led to infer from many inquiries in connection with this subject by physicians, medical students, and teachers of physical training. If I have devoted too large a part of the book to the question of treatment it is because of the scant attention paid to that part of the subject in most books dealing with deformities.

The anatomical part of the work is from the Anatomical Department of Harvard University, and much of the clinical work is from the Scoliosis Clinic of the Children's Hospital, Boston.

It is impossible to acknowledge my indebtedness individually to those of my colleagues and others who have helped me by contributing material and other assistance. I should, however, express my obligation to Professor Thomas Dwight for his advice given in connection with the anatomical part of my work, for the liberal supply of anatomical material with which he has provided me, and for criticising my chapter on x\natomy. To Miss Amy Morris Homans, Director of the Boston Normal School of Gymnastics, I wish to express my indebtedness for assistance given in many ways; and to my assistants, Fraiilein Helene Seltmann and Miss W. G. Wright, for great help in preparing the list of exercises.

I have used freely the chapters on Pathology and Occurrence in the admirable article on Scoliosis by Schulthess of Ziirich, recently published in Joachimsthal's " Handbuch der Orthopadischen Chirurgie."

Robert W. Lo\ett.

BosTO.v, 1907.

Table Of Contents

CHAPTER PAGE

j/*^- The Anatomy of the Vertebral Column and the Thorax i

• II. The Movements of the Spine 23

Chapter I. ANATOMY OF THE VERTEBRAL COLUMN AND THE THORAX

The spine is a flexible weight-bearing column made up of a series of vertebrae separated from each other by twenty-three intervertebral discs and connected with each other by ligaments and muscles. In early life the vertebrae are thirty-three in number. The upper twenty-four, remaining separate throughout life, are distinguished as true, movable, or presacral vertebrae. In the adult the lower nine are fused into two masses to form the sacrum and the coccyx, and are called the false, fixed, or immovable vertebrae. The spine forms the central axis of the skeleton, situated in the median plane of the body and posterior part of the trunk. By the term "the spine" is generally understood the part of the column above the sacrum.

In shape the spinal column is roughly pyramidal, the column of vertebral bodies tapering from beloAv upward, and after early infancy it shows four curves, two anterior and two posterior, in the sagittal or median anteroposterior plane. These are called the physiological curves.

The column is supported in unstable equilibrium on the sacrum. It receives the weight of the arms, the head, and the thorax, and their contents, which it transmits through the sacro-iliac joints to the pelvis and thence through the legs to the ground. The spine encloses and protects the spinal cord, and provides, with the sacrum, thirty-one pairs of intervertebral foramina through which the spinal nerves emerge. It serves by its intervertebral discs to diminish the jar of walking.

The total length of the spine is given as follows by different authors: Cunningham, 70 to 73 cm.; Morris, 70 cm.; and Krause, 72 to 75 cm. (along the curves), which is 45 per cent, of the body-length. The relative length of the separate regions is shown in the following table:

Cunningham. 1 Morris.- Beaunois. Dwight.s

Males. Females.

^ Cunningham: "Text-book of Anatomy," Macmillan, 1902. ^Morris: "Human Anatomy," Blakiston, 1903. ^ Dwight: "Medical Record," Sept. S, 1S94.

It is frequently stated that the length of the spine in different individuals is pretty constant, but Dwight's figures show rather a wide variation. In fifty-six male spines the longest was 69.8 cm. and the shortest 56.4 cm.

In a straight line, the column measures in men from 66 to 70 cm.,

Fig. I.— The Spine Seen from the Side, Showing the Physiological Curves. — ( IFarreji Museum.)

Fig. 2.

Thk Sf'iNi Si;en from the Front. — ( Warren Museum.)

and in women from 66 to 69 cm., with an average of 67 cm. (Krause). The height along the chord of this arc is forty per cent, of the total height of the^ndividual. In the fetus and young child the column forms 1/ a greater proportion of the body-length. At puberty the more rapid growth of the rest of the body overtakes that of the spine, which

INTERVERTEBRAL DISCS. 3

completes its growth between the ages of twenty-three and thirty-one years.

The percentage of total length of the individual occupied by the spine without the sacrum is given for different ages by Moser as follows:

Per Gent, of Verte- Vertebral Column bral Column to Body-length. Length. Body-length.

3 86 31.7 36-8

5 112 35 30

14 152 44 28.9

15^ 162 45 28.1

The spine is divided into three regions corresponding to the parts of the trunk with which it is connected: (i) The cervical region; (2) the thoracic or dorsal region; (3) the lumbar region.

The cervical region comprises the upper seven vertebras, including the atlas and axis; the thoracic, twelve vertebrae; and the lumbar, five vertebrae. The lower part of the spine may be spoken of as the posterior end, while, the upper part may be called the anterior end of the column. The middle of the spine is placed at the eleventh dorsal vertebra.

The line of gravity in the upright position passes through the bodies of the second and twelfth dorsal vertebras, and touches the lower anterior border of the last lumbar vertebra.

INTERVERTEBRAL DISCS.

The bodies of the vertebrae, from the second cervical to the sacrum, are firmly held together by the intervertebral discs lying between them, twenty-three in number. The discs correspond in size and shape to the horizontal surfaces of the bodies of the vertebrae between which they are found, but they project slightly beyond the edges of the vertebrae. The sum of the heights of all the discs is greatest through the middle portion, next largest through the "Snterior borders, and least through the posterior borders. Singly the discs vary in height in the different regions of the spine. They are higher anteriorly in the cervical and lumbar regions and posteriorly in the dorsal region. The ratio of the height of the discs to the height of the bodies varies according to different authors. Weber gives the ratio of the average height of all the discs to the average height of all the vertebra?, not including the sacrum, as i : 5. According to the same author the ratio of the height of all the discs through the centers to the height of the vertebral column.

represented by a perpendicular from the highest point of the atlas to the sacrum, is as i : 4.

The influence of the discs in the formation of the physiological curves of the spine is shown by the two curves in Fig. 5. Curve (a) is formed by the bodies and the discs together, and curve (b) is the result obtained by placing the bodies one upon the other, forming a long curve with convexity backward, greatest in the lower dorsal region. The convexity of the thoracic spine is flattened in the upper part, and the lumbar

Fig. 3. — Median Section of a Portion of the Adult Lumbar Vertebral Column. The Right Half Seen from the Left. — {Pick.)

and cervical physiological curves almost completely disappear when the discs are removed.

" The discs become smaller and harder with age, shrinking to a greater extent where they are thickest than in the region where they are thin. For this reason the curve of the spine in old age approaches the long convexity backward represented by curve (h), and the bowed back of old age is substituted for the upright attitude with a lumbar forv\-ard curve which is largely due to the influence of intervertebral discs.

The discs are very firmly attached to the bodies of the vertebrae. On the anterior surface of the column the free edge of the disc shows

LIGAMENTS OF THE SPINE.

vmh

Fig. 4.— Lines Representing THE Sum OK THE Thickness

OF THE InTERVER-

1 TEBRAL Discs. —

V, At the front border; ni, in the middle of the disc; h, at the posterior border.

lamellc-e consisting of fibers passing obliquely from one \ertebral body to the other. The fibers of successive lamelLne are at right angles to each other, and interlace, suggesting a closed lattice.

At the upper and under surfaces the fibers pass into the thin plates of half-calcified hyaline cartilage covering the horizontal surfaces of the bodies. The discs are also attached to the anterior and posterior common ligaments of the spine. The inter-" vertebral discs thus furnish a connecting structure of great strength between each two vertebrae, and

Fig. 5. — Curves of the Vertebral Column.— (i^/t/t.) A, With intervertebral discs; B, without intersertebral discs.

at the same time they furnish what amounts to a ball-and-socket joint, on account of the incompressible fluid pulp in the center of each disc, between each two vertebral bodies, except of course the first two cervical.

LIGAMENTS OF THE SPINE.

In addition to the connection of the bodies by means of the intervertebral discs the vertebrre are bound together by ligaments which serve to limit movement between them and contribute stabilitv and strength to the column. Ligaments are com-

0 ANATOMY OF VERIEBR.\L COLUMN AND THORAX.

posed of white fibrous tissue, the strongest tissue in the body, highly elastic, but non-extensible. Two of .the spinal ligaments, the ligamentum nuch^e and the subflava, form exceptions to this statement, being made up almost entirely of yellow fibrous tissue.

SACRO-ILIAC ARTICULATION.

The strong joint between the sacrum and the ilium through which the whole body-weight is transmitted is a synchondrosis which permits but little motion. \\Tiat motion occurs between the sacrum and the ilia consists of a forward and backward tilting of the sacrum on the ilia on a transverse axis passing through the second sacral vertebra. If the top of the sacrum is tilted backward because of the obliquity of the articular surfaces the ilia are separated.^

The sacro-iliac joint is made safe and strong in part by the wedge shape of the sacrum, but chiefly by the iliosacral ligaments. The corresponding articular surfaces of the tv\-o bones are covered more or less completely with hyaline articular cartilage and the ver}^ slight joint cavity between them is crossed by fibrous bands. The capsule is formed by the ligaments surrounding the joint. The anterior sacro-iliac ligament is thin, and consists of short strong fibers passing between the adjacent surfaces of the sacrum and the iliac fossae. The posterior sacro-iliac ligament is very strong, and is responsible for holding the weight of the trunk, head, and arms suspended upon the pelvis and is usually regarded as consisting of t^'O portions. The short posterior sacro-iliac ligament is formed by bundles of fibers passing from the first and second transverse tubercles of the sacrum to the rough posterior part of the inner surface of the ilium, above and behind the auricular surface. The long or oblique sacro-iliac ligament is a superficial part of the short ligament and is a band of fibers extending from the third and fourth transverse tubercles of the sacrum to the posterior superior spine of the ilium.

THOR-\X.

The thorax is a bony cage containing the principal organs of circulation and respiration. It is formed by the thoracic vertebrae, the ribs, the costal cartilages, and the sternum. The ribs, tn-elve on each side, form a double series of narrow, curved, flattened bones attached posteriorly to the thoracic vertebrae. They extend at first outward,

1 Goldthwait and Osgood: "Bos. Med. and Sur. Jour.," INIay 25 and June i, 1905, with literature.

THE THORAX.

and then forward, inward, and downward toward the median hne anteriorly. The seven upper ribs, called the true, sternal, or vertebrosternal ribs^are attached directly to the sternum by the costal cartilages anteriorly. /i he five lower ribs are called false or asternal ribs; the eighth, ninth, and tenth are distinguished as vertebrochondral, as they are anteriorly indirectly united to the sternum by the cartilage of the rib or ribs above; the eleventh and twelfth are called floating ribs, as their anterior extremities are loose in the abdominal wall. The ribs increase in length from the first to the seventh or eighth, decreasing from the eighth to the twelfth.

They are approximately parallel with the exception of the eleventh and twelfth, which slant somewhat more downward.

\ It must be remembered that

1 ribs are lower at their front ends

\ than at their vertebral connec-

1 tion, so that if it is desired to 1 rotate a vertebra by pressure on 1 a rib, the rib horizontally oppo- Isite the vertebra is not to be Vchosen. It has been shown' in me cadaver (i) that rotation of vertebras may be produced, when the extremities of the spine are fixed, by pressure upon any of the intermediate ribs; (2) that the vertebrae attached to the ribs on which pressure is made are the most affected; (3) that the rotation never equals the rib excursion; (4) that the most efi"ective points for pressure or counterpressure are as far as possible from the midline anteriorly and posteriorly except on the lowest four ribs.

Fig. 6.— Model of thk Spine Showing the Anato.mical Relations, Especially the Disposition of the Soft Parts in the Lumbar Region. — (U'arien Miiscmii.)

^ Keene: "Amer. Jour, of Orth. Sur.," July, 1906, page 69.

8 ANATOMY OF \'ERTEBRAL COLUMN AXD THORAX.

STERNUM.

The sternum or breast-bone is situated in the median line of the trunk, completing the thoracic cage anteriorly. As a whole, the sternum is a flat bone, and it lies directed obliquely fonvard and downward. It consists of three parts — the manubrium sterni, the gladiolus, and the ensiform cartilage or xiphoid process.

SHAPE AXD BOUNDARIES OF THE THORAX.

In shape the thorax is somewhat conical, larger behind than in front and compressed anteroposteriorly. The posterior wall is formed

Anterior radiate or stellate ligament

Fibrous ring of intervertebral fibro-cartilage

Costo-transverse synovial sac

Posterior costo-transverse ligament

-Horizontal Section through an Intervertebral Fibro-cartilage and the Corresponding Ribs. — (Morris'' s "Anatomy.'")

by the thoracic vertebrae, and by the ribs, from their heads to their angles, and is convex vertically and horizontally. Laterally the cage is formed by the shafts of the ribs; it is somewhat convex vertically, and sharply convex from before backward. The anterior surface, slightly convex and directed fom-ard and downward, is formed by the sternum and the costal cartilages. The plane of the superior opening or inlet of the thorax is inclined fonvard and do\vnward, showing a greater obliquity in women than in men. The inferior border of the thoracic cage is formed by the twelfth thoracic vertebra, the lower borders of the twelfth rib, and by two curved lines, extending from the anterior extremities of the last rib to the inferior angles of the gladio-

MUSCLES OF THE SPINE AND THORAX.

lus, touching the anterior extremities of the elevfenth rib and the costal cartilages of the tenth, ninth, and eighth ribs. The angle formed by these lines is known as the subcostal angle. The inferior surface of the thorax is directed forward and downward.

Fig. 8. — G. Herman Meyer. The Two Oblique Mcscle Pulls.— (j^^m.)

On the left the descending oblique, a, External intercostals ; b, descendingoblique or externus abdominis. On the right the ascending oblique muscle pull. c, Descending oblique or internus abdominis ; d, internal intercostals ; e, scalenus colli ; f, cremaster.

Fig. 9.— G. Herm.^n Meyer. The Scheme of the Torso Musculature Indicating the Direction of theVarious Muscle Pulls. — {Feiss.)

a, Posterior longitudinal muscle pull (sacrospinalis) ; <J, anterior longitudinal muscle pull ; c, oblique descending muscle pull ; d, oblique ascending muscle pull ; e, transverse muscle pull.

MUSCLES OF THE SPINE AND THOR.\X.

The general grouping and arrangement of the muscles in their relation to the spine has an important practical bearing on scoliosis. The spine lies at the back of a more or less cylindrical muscular tube of which the abdominal muscles form the front. Of muscles directly lO

ANATOMY OF \T.RTEBRAL COLUMN AND THORAX.

attached to the spine there are two varieties: (i) muscles running from one part of the spine to another part and to the head; (2) muscles running from the spine to the pelvis or shoulder-girdle. The abdominal muscles by their attachment to the thorax, which is comparatively a,

Fig. 10.— G. Herman Meyer. The System OF the Sacrospinalis. — (Feiss.) Spinali.s; b, longissimus dorsi ; c, transversalis cervicis ; d, trachelomastoideus ; e, ileocostalis ; y, ascendens cervices; ^, ileolumbalis (hinder portion of m. quadratus luniborum Auct.); A, obliquus capitis inferior; /, obliquus capitis superior; k, rectus capitis posterior major; /, rectus capitis posterior minor.

Fig. II.— G.' Herman Meyer. Anterior Longitudinal Muscles of the Trunk. — {J^eiss. )

a, Sternocleido-mastoideus ; b, rectus abdominis ; c, pyramidalis.

rigid, have an action on the spine. By the combined action of these three the erect position is maintained, or any variation from it is accomplished.

In making a side flexion of the spine from the erect position, for

NERVE-SUPPLY. 1 1

example, no one muscle or group of muscles is alone active, but it implies a concerted and coordinated action of all the groups mentioned to keep the balance and perform the bending. The maintenance of the spine in the upright position by the muscles has been compared to the way in which a flagstaff is held upright by stays reaching from the top of the staff to the ground. Although there is no one muscle running from the head to the pelvis there is a continuous set of muscles supplementing each other's action. For example, in the anterior line the sternomastoid runs from the skull to the front of the top of the thorax, the sternum connects the vipper and lower ribs and forms a rigid piece, and the lower thorax is connected with the pelvis by the rectus abdominis muscle. In the back the continuity of muscular action is shown by the fact that before the top insertion of the longissimus dorsi has been reached the complexus and transversalis cervicis have begun. The whole conception of muscular action in its relation to gymnastics is simplified by remembering the continuity of the muscular tube from the head to the pelvis.

The thorax represents a comparatively fixed cage inserted in a structure quite movable above and below it; muscles attached to the thorax are therefore indirectly attached to the spine. The comparative rigidity of the thoracic part of the spine is due to the fact that the majority of the ribs are attached between two vertebrae, that they pass forward to be also attached to the sternum, and that the whole structure is one well calculated to prevent side bending or extensive forward or backward motion in that region; the cage must therefore largely move as a whole.

It has been pointed out that the dorsolumbar junction is a dividing point for important muscular origins and insertions above and below it, e. g., the psoas muscles originate largely below it and the trapezius above it, and that it forms a weak and movable part of the spine for this reason (Ludloff), but more important than this is the fact that muscles connecting the thorax and pelvis will move the spine where the rigid dorsal region changes to the movable lumbar region and that a large number of muscles will therefore express their contraction by motion at the dorsolumbar junction. A similar Aveak and movable part of the spine is said to exist at the cervicodorsal junction, where important muscles (splenius and rhomboids) have a dividing point.

NERVE-SUPPLY.

The spinal nerves emerge from the spinal canal through the intervertebral foramina and are distributed to the integument and muscles

ANATOMY OF VERTEBRAL COLUMN AND THORAX.

MOTOR

Sterno-:mastoid Trapezius

SENSORY

Neck and scalp I Neck and shoulder

Shoulder

Arm

Hand

REFLEX

Scapular

■ Front of thorax

-Xiphoid area

Abdominal muscles

Flexors, hip

Extensors, knee

I ^Adductors J i

Epigastric hip j- Abductors

J Extensors(?) . 'i Flexors, knee (?)

Muscles of leg moving foot

•Abdomen (Umbilicus loth)

(.Buttock, upper j part

Groin and scrotum (front)

outer side

. Thigh

[ iimer side Leg, inner side f Buttock, lower I part i Back of thigh

Leg)

and -except in- Ifoot) ner part

Abdominal

Cremasteric I Knee-jomt

Gluteal

Foof-clonus Plantar

I Perinseal and anal |- Perinceum and anus muscles

'- Skin from coccyx j to anus

Fig. I2.-DIAGRAM and Table showing the Approxi.mate Relation to the Spinal Nerves OF the Various Motor, Sensory, and Reflex Functions of the Spinal Cord. (Arranged by Dr. Gowers from anatomical and pathological data.)-(7l/or7-Ji s '■'Anatomy .")

OSSIFICATION. 13

all over the body. Eight are cervical nerves (the first passing over the atlas), twelve dorsal, five lumbar, five sacral, and one coccygeal. Each is formed by the union of two nerve roots, which occurs outside the spinal cord and just inside of or at the intervertebral foramen. The anterior, motor, or efferent fibers come from the cells of the .anterior horn of the cord ; the posterior, sensory, or afferent fibers emerge from the cells of the posterior horn on the same side of the cord. The nerve formed by these two roots on leaving the intervertebral foramen divides into an anterior and posterior branch, each with motor and sensory fibers. The posterior divisions are small and supply the skin and muscles of the back. The anterior divisions are distributed to the neck, the front and sides of the trunk, and to the extremities. Each anterior division is connected with a plexus, ganglion, or nerve of the sympathetic system.

EVOLUTION OF THE SPINE.

The history of the spine in its evolution is of interest. In the Cyclostomata the vertebral column consists of a non-segmented, homogeneous, cartilaginous rod. Articular processes first appear in the Rays and Teleostei. The backbone of the lower fishes consists of a series of bony discs bound together by elastic intervertebral discs. It would seem from the history of the spine as if articular processes developed concomitantly with the elaboration of structure, as if they were incidental to its use rather than factors determining of themselves its types of motion.

OSSIFICATION.

The ossification of a vertebra occurs from three primary centers, one for the body and one for each lateral mass. These appear in the sixth week, and in the cervical region the lateral centers are the first to appear, while in the dorsal region the one for the body is the first seen. The center for the body is often double in appearance if not in reality. The centers for the lateral masses are found near the bases of the articular processes and from them form the pedicles, laminae, articular processes, and a large part of the transverse and spinous processes, the bodies of the vertebrae forming from the other center. The vertebral epiphyses serve to assist in the formation of joints, to provide for the attachment of ligaments and tendons, and to increase the development in length of the bone of which they form a part. At about puberty appear five other secondary or complementary centers, one at the tip of the spinous process, one at the tip of each transverse process, and one at the upper and one at the lower surface of each body, occur-

ANATOMY OF VERTEBRAL COLUMN AND THORAX.

ring as a flat meniscus at about the seventeenth year and uniting to the vertebral body a few years later (twenty years). The arrest of the development of one-half of one of these latter may become a serious matter.

PLANES OF THE BODY.

The planes of the body will be frequently spoken of and should be defined. The frontal plane is a vertical and transverse one. The sagittal or anteroposterior plane runs in the anteroposterior axis. The term horizontal plane is self-explanatory-

Epiphyseal plate or disc

Mammillary tubercle Transverse process

— Spinous process

EpipliNseal plate or disc

Fig. 13.— Lumbar Vertebra at the Eighteenth Year with Secondary Centers.- {Morris's "Anafotny.")

Pedicle

Fig. 14.— Ossification of the Fifth Lumbar Vertebra— (Morris' s "Aiiatonir.")

PHYSIOLOGICAL CURVES.

In examining the literature relating to the physiological curves such contradictory and unsatisfactory information was found that the whole subject was taken up by the writer for investigation, the results of which are presented here.^

In this investigation the position of the spine in the human embryo was studied. The spinal curves of the skeletons of mammalia were observed. Measurements were made of the anterior and posterior borders of the bodies of the vertebras in sagittal section of the spine of new-born children and of a child two years old, and

iprom a paper presented at the Italian Congress of Orth. Sur., "Arch, di Ortop.," 1906, V and vi, page 372, Milan, Sept. 22, 1906.

PHYSIOLOGICAL CURVES.

lead strip tracings were taken of the back of two hundred normal children between the ages of four days and thirteen years in the positions of slack standing, natural standing, and in prone lying.

Measurements of medial sections of detached spines showed in new-born infants a slight bony curve in the lower dorsal region, convex backward. This curve was visible on the anterior surface of the column and reappeared after corrective manipulation of the spine. The curve of the spine of a child two years old was more developed than in the new-born. Measurement of the anterior and posterior borders of the vertebral bodies showed in the cervical region a difference of 0.5 mm. in favor of the anterior borders, in the dorsal region a difference of 16 mm. in favor of the posterior borders, and in the lumbar spine 9.5 mm. in favor of the anterior borders. In this spine therefore the three physiological curves were present in the bodies of the vertebrae.

Tracings over the spinous processes were taken by means of flexible lead strips and the curves transferred to paper for study. The tracings showed clearly the form and development of the dorsal and lumbar curves in standing and in lying prone. The natural sitting position assumed by all the children was practically the same, a convexity backward of the dorsal and lumbar spines with a maximum at the dorsolumbar junction. In the younger children this curve included the sacrum. Only four of the children between the ages of nine and thirteen showed a lumbar curve in sitting. " The character of the curves varied most in the youngest children, and became more constant with age.

The variations from the accepted normal type of tracing were most numerous in the youngest children, and decreased in percentage and in variety with age.

In lying the backward dorsal curve was found in 86 per cent, of cases under one year, and in all but two of the 178 children over one year old. The curve was marked at fourteen months, and increased with age. In children under six

months the curve included the lumbar and sacral regions; in those over six months it did not. The lumbar curve in lying showed frequently after the age of one year, and in a very large majority of cases after the age of three years. The cervical curve could not be observed to advantage in lying, or in standing, in the }'oungest children, but over the age of fourteen months a cervical curve with anterior convexity was observed in standing. The dorsal curve appeared in standing in the earliest tracing in this position, that of a child ten months old, and persisted absolutely. The curve was well marked at fourteen months and increased with age, changing in character as it became limited to the dorsal spine, and the maximum receded from the dorsolumbar junction to the middorsal region. The dorsal

Fig. 15.— Section of the Spine OF A New-born Infant.

i6

ANATOMY OF VERTEBRAL COLUMN AND THORAX.

curve was greater in standing than in lying. The lumbar curve in standing appeared first in a child of seventeen months, and from the age of two years persisted in a very large majority of cases, the exceptions being usually children under three years who had not walked. The curve increased ai the expense of the dorsal curve, and was usually greater in standing than in lying.

GIRL

1/2 YRS

Sitting Front

Standing

.7THC

4THL.

Fig. 16. — Tracings of Physiological Curves of Normal Children, on the Left of A Girl of One and a Half Years, on the Right of a Girl of Eleven.

In the adult, the part played by the bodies of the vertebrae and the discs in producing the physiological curves is shown by the following table:

DiiTERENCE Between the Sums of the Anterior and Posterior Borders.

VERTEBR.3E. DiSCS.

Cervical region 1.3 mm. 7.8 mm.

Dorsal region 13.3 mm. 9.2 mm.

Lumbar region 6.7 mm. 21. i mm.

PELVIC INCLINATION.

The cervical curve is formed principally by the intervertebral discs. It is a fairly mobile curve, and may be straightened by suspension. The dorsal curve is formed chiefly by the bodies of the vertebrae ; it is a rigid curve and cannot be obliterated. The lumbar physiological curve is produced mainly by the greater anterior height of the intervertebral discs and is therefore mobile.