The chief limitation to motion in the dorsal region is perfectly obvious—it is the flatness of the top and bottom surfaces of the bodies, and the thinness of the intervertebral discs.  These do not prevent motion of pure rotation, but they do all but prevent any other kind of motion—except to slight degrees.  Motion to slight degrees is all that we find in other direction. A But it matters not how slight is that degree, the shape of articular surfaces is adjusted to it, and when it is exceeded, the danger of lesion is just as great as though it were wide.

    Limitation to motion of extension is from tension on discs and bony contact of articular processes with bone below.  Exaggeration of this motion and lesion is hardly possible.

    Limitation to flexion is first the flatness of the bodies and the thinness of the intervertebral discs.  Second it is the interspinous and other ligaments behind; yellow elastic cartilage where they are in line with the motion; white fibrous where they lie radially to it.  When the limitation to motion has been reached in flexion, the anterior edge of the body acts as a fulcrum and any other motion tends t o gap open the spinal and costal articulations behind.  But under the forward pressing weight which causes flexion, these may slide forward over the anterior edge of the one below, bringing the surface of the inferior articular processes (upper of the two in each joint) against the top edge of the surface below; with possibility of indentation and lesion.  The ligaments, all tensed by this exaggeration of motion, serve to drive it with greater force against this edge and to hold it there.  Lesion in the median line is not so frequent as lesions in other positions, merely because in the median line the ligaments are at maximum strength in resisting.  Yet pure flexion lesions are by no means infrequent in the dorsal region.  When, however, in a position of extreme flexion, other motion is added with exaggeration of motion, then is the greatest danger of lesion; because the ligaments of only one side, bearing the strain, are more stretched and allow greater exaggeration of motion for a given force, and cause engagement against a corner instead of a side, with greater indentation and more power to hold.

    In pure rotation the first limitation to motion is the costal articular surface on the inferior border; which allows rotation around a center not far from the center of the body, for a short distance, but deflects it upward, transforming it into rotation-side bendidng.  The spines rotating to the right, the side-bending carries the transverse processes up on the right.

    (Note that in the lumbar region the axis of rotation is behind; the bodies rotate while the spine is open, stationary; rotation means rotation of the bodies to the right and side-bending down on the right.  In the dorsal region this is reversed.  The axis of rotation is in front; the spines rotate, the body being often stationary at its front edge; and side bending is up on the same side.

    The limitation to motion in rotation-side bending in the dorsal region is wholly ligamentous, unless t he head of the rib may be regarded as slightly such a limitation.  Probably all of these ligaments are so adjusted that they reach the point of limitation at about the same time.  Pure rotation-side bending is added flexion.  Such lesions do occur, however.  The strongest of the retaining ligaments is beyond doubt the intervertebral disc, whose action is to throw the axis of rotation nearer the center of the body; causing on the convex side jamming of the upper articular surface against the upper and outer corner of the articular process below, with indentation and lesion, and on the concave side, gapping open; doubtless only a momentary state.  When to this motion  flexion is added without recovery from the rotation, it simply strains the point of contact to a point farther down on the articular surface with more distortion, greater ligamentous pressure, deeper indentation and more likelihood of lesion.
 
 
DIAGNOSIS
 
    Diagnosis of lesions in the dorsal region is made in the same way as in the lumbar region.
 
 
TECHNIC

    In the first technic described, that for examination, a corrective effect  is obtained, which is not positive but is often effective in slight lesions.
 
    Patient seated, operator stands in front; patient places hands on operator’s shoulders, and head against operator’s manubrium; operator reaches hands around patient and places fingers on either side of spines of vertebrae;

    And by pressing down, carries spine to full extension; at the same time by lifting patient’s arms by means of operator’s arms underneath he elevates ribs.  In the lesion, the upper edge of the lower articular process is engaged against the surface of the one above throwing the latter into flexion, or separation.  In this technic the fingers pressing against the articular processes below tend to carry them away from the point where they are engaged; or pressing against the spine above, tend to flatten it out, making the lower edge of the upper articulation the fulcrum for releasing the surface from its midway catch against the edge of the lower.

    Note that the articular process is opposite the base of the bone, (opposite the cartilaginous joint), while in the fifth to the tenth, the tip of the spinous process is directly opposite the articular process of the next one below, so that the finger may press on both spinous process of the bone above, and also on articular process of bone below, at the same time.

    In the horizontal position of the animal spine all tensions are such that the vertebrae are automatically held in normal relation, or if in lesion tend to be drawn to the normal.  The following technic utilizes this principle, reproduces the tensions as in the horizontal animal spine.

    Patient lies on face on table; rises on elbows, so that upper arms are vertical, forearms lying along the table.  In this position the tensions are as in the animal spine.  The ribs in this position support the spine.  The rib of the side in lesion belonging to the vertebra in lesion is thrust forward, and so bears a relatively heavier tension than the rest, tending to press the vertebra backward and so to release the lesion.  (Whatever be the direction of the lesion, certain fibres of the muscles will be stretched, and in this position which tenses all muscles these fibres act to put strong backward tension on the rib—since all muscles attached to ribs draw toward the spine.)

    Operator stands at either side of table, places thumb on articular process of lower of the two bones in lesion, pressing down (tending to directly release) or on upper of two bones, pressing down and out on spinous process, making fulcrum of lower border as in previous technic, to release the catch above.  Patient is directed to let his head hang down.  Operator then rotates head from side to side to the limit of motion in each direction, with extra tension down and to side if necessary, and with pressure from thumb as required, until lesion is felt to be released.

    If extra leverage with the head is necessary, the operator may brace the patient’s shoulder on either side against his abdomen to prevent pulling patient so that upper arms are not vertical.  It is an important point to keep the arms vertical.

    If patient’s shoulder-blades come so close together that ribs cannot be reached, operator may press patient’s shoulders to side, uncovering ribs of that side, until he is able to apply thumb to lesion.

    Caution.  The head in such technic should be kept low, and the face should be turned slightly to the side to which the head is being carried—the face should go first, in either direction; for it not the effect of the tension is on the vertebrae of the neck, in a position that is practically abnormal for the neck—extension and rotation.  With the face slightly turned in the direction of the pull, the effect is to cause side-bending of the opposite side well down in the dorsal region, with tendency to release the catch.

    This technic is available in some patients through the whole dorsal region, but is less likely to be effective in the lower three and the upper two, where indeed it is rarely effective.  It is effective also for rib lesions.  It is especially valuable in asthmatic patients.

    This same principle may be applied with the patient supine, but requires some strength of fingers.

    Patient supine on table, operator stands at either side; crosses arms of patient over breast, arm nearest the operator being below, other above (otherwise the patient’s elbows will be in line with the sternum of operator, whereas with near arm below they are on opposite sides of manubrium as operator presses breast against them in next phase; the elbows in this position present a broad surface for pressure of operator’s chest); operator draws patient’s  arms taut down against patient’s chest so as to bring pressure against ribs, and to tense pectoral muscles; operator then applies his own chest to patient’s elbows; not too low—about the second costal cartilages, pressing down slightly; he then passes his two hands around patient’s body and applies them to lesions; with knuckles resting against table and fingers raised against lesion, he exerts firm pressure upward against lesion or bone below, or both.  Then with his breast he makes a quick and firm pressure against the elbows in the direction of the lesion or slightly above, while maintaining firm upward pressure with fingers.  The effect of this is the same as above--it disengages the catch by carrying the lower of the two bones away from the upper, or by making a fulcrum of the lower border of the upper articular surface.

    Some practice is necessary to use this technic to the best advantage.  Properly used it is one of the most effective.  It is effective in some patients as low as the eleventh dorsal and as high as the third.  In adjusting the lower lesions the elbows should be carried farther down on the patient’s chest and the direction of pressure of the operator’s chest is lower.  In adjusting the upper vertebrae the patient’s arms and the pressure of the operator’s chest are more nearly vertical.  This is especially valuable in anterior upper dorsal warps.

    Caution.  In some patients the coracoid processes are long and the arms in this position exert smart pressure against them so that the technic is very painful.  In such patients this technic should not be used or should be used with proper caution.  Sensitive shoulder muscles also may cause considerable pain and this also should be guarded against.  In patients with valvular lesions it is contra-indicated.

    This same principle but without use of the shoulder muscles may be used with the patient seated; operator standing behind; passes arms under patients arms and clasps hands against manubriium drawing patient back against operator’s chest; then lifting and drawing quickly backward on manubrium, patient being completely relaxed, the lesion is released through pressure of the ribs and drag of the rest of the vertebral column.  This technic is available in the upper two or three dorsal vertebrae.  It is necessary to be sure that the pressure of the clasped hands is against the ribs belonging to the two bones in lesion, and that the contact with operator is below that point.

    Caution.  This technic too vigorously applied has been known to injure the sternum, or the cartilages of the ribs.

    The spines of dorsal vertebrae extend sharply down and somewhat back, varying in the different regions (more sharply back in the upper and lower dorsal, more sharply down in the mid dorsals).  Pressure to the opposite side on a spine rotated to one side therefore tends to carry the articular surface down on the affected side and up on the opposite side, thus increasing the articular surface back on the affected side against the tension in the engaged point; but tends also to draw the fulcrum of the sound side, and so to release it.  Technic which offsets the first of these effects leaves the second of them effective in releasing the lesion.

    Patient seated on table, operator standing behind, passes arm under patient’s arm on affected side and grasps opposite shoulder; presses with thumb against prominent side of lesion; executes a modified corkscrew motion to secure relaxation of patient; then carrying trunk to the limit of rotation so that ligaments and articular surface on opposite side are all tense and so create a fulcrum, he lifts and draws back on near shoulder and draws forward on opposite shoulder, while pressing with thumb against lesion.  If this is not effective, he may while holding all in tension thus, carry patient first to full flexion and then to full extension, and repeat until lesion is overcome.  Release occurs in full flexion plus rotation.

    The technic for the upper three dorsals is more difficult than that for the rest.  Here motion is slight, and lesions frequent; and here the shoulder muscles have little value.  Recourse is usually had to the leverage of the neck.

    With patient seated, operator standing behind, thumb is placed against prominent side of spinous process of vertebra in lesion; patient’s head if drawn forward to full flexion and to side opposite to side of lesion, stretching ligaments of side in lesion; is then swung without releasing flexion to side of lesion, to limit of motion, then pressure down and back is added.  This tends to separate articular surfaces, aided by pressure of thumb.  Or pressure of thumb may be against articular processes of vertebra below; or thumb may press against spinous process of bone in lesion, knuckle of first finger against opposite side of spinous process of vertebra below.  Holding thumb and finger in this position, the head may be swung from side to side always in flexion to limit of side-bending, until lesion is released.

    For lesions that resist these corrective measures, a technic that involves side-bending only may be employed.  Patient lies on side on table, lesion side uppermost.  Lifting patient’s shoulders from table, operator places on table under patient’s shoulders his knee and thigh, using the leg nearest the foot of the table, and laying it flat against table on outer side of thigh (assuming lesion to right, patient lying on left side, he places his left leg on table); then lowers patient across thigh so that leg fits into axilla, patient’s arms being up and forward, out of the way.  Across this fulcrum he presses patient’s head down to limit of motion, stretching ligaments of lesion; then lifts head up to limit of motion (always remembering to keep face toward side of bending) with pressure against prominent side of lesion, repeating with wider stretching of head and heavier pressure (within limits) and if necessary with greater and greater degrees of flexion, or extension, until lesion is felt to be released.  In this technic the rib braced against the thigh aids in fixing the vertebra below and in focussing the corrective force.

    This technic is available from about the seventh dorsal to the first dorsal.  With traction upward instead of downward it is effective for lesions of opposite side (to left).  It is available also for many rib lesions.