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MOVEMENTS Examining the actual bone we observe that the base of cervical vertebrae is prolonged downward and forward into an anterior lip; that this makes the base of the vertebrae not flat, as in the rest of the spine, but curved; and that this curve prolonged backward is continuous with the articular surfaces. This is true of all except the atlas and occiput. Experimenting with the actual bones we observe that in flexion the body of the vertebra slides forward over the one below in the arc of this curve; and that if it does not do so, if, that is, the bodies retain their vertical relation with each other, a gap is made between the articular processes. We observe also that in complete extension the inferior edges of the articular processes of the sixth and seventh cervical vertebrae fit into indentations in the bone below that fit them more or less exactly; that the superior edges of all articular processes fit into the space between the transverse and the articular processes; that the spines themselves, which are here often bifid and concave below, fit over each other. In this respect different spines vary very markedly; but as a rule the arrangements as above are found to obtain. These arrangements serve to reinforce the cervical vertebrae in extreme positions, except in extreme flexion, and in side-bending, where one side only is protected. Placing the thumbs on the tips of the spinous processes of the cervical vertebrae in some living subject, the fingers on the anterior borders of the costal processes, and asking the patient to turn the head from side to side, we observe that retraction on the concave side completes itself before forward motion (flexion) of the opposite or convex side begins. Since all motions are produced by contraction of muscles, it is therefore natural that movements of approximation under muscular action should occur first before movements of separation based on leverage action begin. Compare with this the movements of lumbar and probably of dorsal vertebrae, commented on in their respective chapters. Reproducing these motions in the actual bones we observe that the extension or approximation of one side implies necessarily a reverse motion of the other side around this disc as an axis; but that since there is at the same time rotation backward following the arc of the base of the vertebra, the forward motion on the convex side is offset and cancelled. The axis of the rotary part of this motion is, for each side, the opposite side; the axis of the flexion-extension part is below the body of the intervertebral disc, the center of the curve of the base. This motion continues until the grooves of transverse-articular processes are in contact (through intervening tissue) with the superior edge of the articular processes below on that side, that is, are interlocked. This point of contact then becomes the axis of further motion, that is, the axis of rotation shifts to this side, and the opposite side moves forward, following again the curve of the base of the bodies. In the cervical column as a whole, these points of contact form a flexible but non-contractable pole, which bends to the concave side as more motion is produced, but does not further shorten. Examining again the actual bones we note that the superior surfaces of the bodies are prolonged upward at the side to form lateral lips of considerable height so that the top surface, concave upward, and the bottom surface, concave downward, give the effect of two hands half clasped. These lateral lips we find to be covered with the
sort of smoothly polished bone that is peculiar to articular surfaces.
We sometimes find also on the lateral edges of the bone above indentations
for these lips, and again, to a less degree, the same sort of polished
bone. Evidently these lips are integral and important parts of the
joint. They are discovered toi be the homologues of the heads of
the ribs. The friction and pressure that led to this quasi-articular
surface occurs at the limits of the first phase of rotation, when the approximation
of the concave side is completed; and the friction contact continues while
the extension of the convex side is progressing. There is pressure
against this point.
Lesions of cervical vertebrae are found to be in all directions: bilaterally posterior, unilaterally posterior, directly lateral, and unilaterally anterior, rarely bilaterally anterior. In the bilaterally posterior it is evident that both articular surfaces have become separated from those below; a primary lesion of one side leading to a secondary gapping of the opposite side also, as in sacral lesions. Unilaterally posterior lesions are the most frequent. There is not found to be necessarily a corresponding anterior displacement of the opposite side; more often the reverse. The point of engagement is in some point of bony contact, as that of the lateral lip on that side. A flexion lesion of the opposite side may bring about a separation posteriorly on this side, with engagement of the transverse process against the superior edge of the articular process below. The mechanics of these so frequent lesions is not perfectly clear. It may be necessary to abandon the bony contact theory and to adopt a viewe of the mechanics of these lesions based on passing the dead-centre of ligaments, or on the much slighter retaining power of simple friction, effective only because the tension of ligament is radial to motion. Unilaterally anterior lesions, if maintained by points of bony contact, must be maintained by a catch of the superior border of the articular process of that side against the surface above, with flexion of the vertebral column. There are no other points of bony contact in anterior lesions. Directly lateral lesions, the least numerous of these,
are maintained evidently by a catch of the lateral lip against the tissues
of the base of the bone.
DIAGNOSIS The spinous processes are utterly unreliable for diagnosis in the cervical region. In seated position, it is extremely difficult to secure perfect relaxation of all muscles. Patient supine, operator seated at head of table; places fingers of two h ands broadly under two sides of neck of patient, lifting slightly until neck presents an arch similar to that when standing. Finds posterior border of articular processes, being careful to avoid lateral ends in order not to bruise the cervical plexus; passes fingers from below upward, noting relation of each with one elbow. The seventh cervical has been called terra incognita, (Fiske) situated deep in the mass of the shoulder muscles and being difficult of examination both in front and in back. The literature of the profession shows a dearth of lesions of the seventh cervical, which is probably due to failure to examine or to detect them rather than to great strength of this articulation. Because of greater difficulty in examining this segment it should be given greater care. The axis stands normally somewhat more prominent posteriorly than the other cervical vertebrae. The atlas is rarely found to be in the median line with the axis, rotation here being extremely easy; deviation rarely means more than a difference in muscular tone. To examine for anterior displacements, life the tissues and the sterno-mastoid muscle with the thumb, and place the ball of the thumb flat on the front of the costal processes; carefully avoiding the lateral edges, for fear of bruising the delicate nerves there. Begin with the first dorsal if possible; examine the relation of each costal process with that of the one below. The cost al process of the sixth cervical carries the carotid tubercle, which makes it somewhat more prominent than the others, and in some cases very much more prominent; it will be mistaken for a lesion by inexperienced students. In some anterior lesions the tissues and the longissimus colli muscle will be lifted and tensed by the lesion, making a tented condition which masks the lesion and deceives the examining thumb. Only patient practice and concentrated attention makes perfect. In the upper half of the neck it is necessary to push the sterno-mastoid muscle out and below instead of lifting it above, the examining thumb. To examine for lateral lesions, place the fingers on the lateral aspects of the transverse processes, being careful to keep them on the posterior and outer corners and to avoid t he cervical nerves emerging from the groove between costal and transverse processes and inclining forward. Examine the relation of each vertebra with the one below. Examination for movement of cervical vertebrae may
be made in the same positions, the head supported between the forearms
and moved as desired.
For posterior lesions; patient supine, operator standing at head of table; places proximal joint of first finger behind and below prominent portion of lesion, other fingers of that hand supporting neck; face being in median line; carries face and neck to the side of the lesion, without turning; that is, in lesion posterior to right carries head to right, side-bending neck without turning face; to limit of motion, until all of the tissues of the left side are on tension; head being not raised but on level table without pillow. In this position the left side of the neck is flattened out and under tension; the right side is arched forward. Maintaining pressure against the lesion, an angle of bending is made here, the pressure lifting the lesion slightly forward. When all is ready, the operator then turns the face to an angle ot forty-five degrees at the same time drawing back slightly, and pressing with the finger across the lesion in the direction of the patient’s nose—parallel, that is, to the plane of the articulation. In the average lesion, a very slight pressure is sufficient to reduce. At the moment of reduction the arch is drawn by the pressure of the finger into two straight columns; the bones below are drawn taut and straight, holding the lower of the two bones in lesion; the bones above are also taut and straight, but at an angle with the lower bones, bent across the pressing finger. The complete extension of the left side makes it serve as a fulcrum. Caution: The reduction of cervical lesions is always attended by a conscious shock which is always unpleasant and often insupportable to the patient. The word care was invented to apply to technic of cervical lesions. Preparatory stretching is especially advisable here. Aside from the tensing of the ligaments on the opposite side, which must be maintained throughout, all motion must be focused on moving the bone in lesion, by means of the leverage of the tensed ligaments and the pressing finger, to the limit of motion in the plane of its natural motion; and all attention must be focused in the psyche of the patient to avoid shock. The force used must be so graduated as to go no further than the point of correction. Indiscriminate “cracking” of the neck without a definite planning for the correction of a lesion is a danger and often a damage to the patient, and should be regarded as little short of criminal. For correction of anterior lesions; patient supine, operator standing at side of head, same side as lesion; assuming lesion anterior on right, stands slightly to right of patient’s head; places palm of left hand beneath occiput, holding head as low as possible, without pillow, face in median line; then carries head to left to limit of motion, without turning; or even rotates face slightly to left; with right thumb operator presses down gently on prominent portion of lesion. K When all is ready, operator first relaxes pressure to left, by a fraction of an inch, then without lifting occiput, carries it with quick motion to limit of motion to left with slight extra pressure, at same time turning head, occiput to left, face to right. The effect of this technic is as follows: carrying head to limit of motion to left locks all of the processes on that side against further motion, making that side the fulcrum for any further motion; at the same time the ligaments of the right side are all tense, tending to separate bones in lesion; allowing face to turn back to right as neck is sharply carried to limit of motion draws back on right transverse processes of all cervical vertebrae; fulcrum being opposite side, but especially on one in lesion, that being farthest from normal anteriorly. Since all are separated already by tension, the quick motion usually suffices to release the catch and carry the vertebra to normal. For lesions directly lateral; the catch being on
prominent side, between lateral lip and tissues of base of bone.
Assume lesion to right; patient supine, operator standing at head, places
proximal joint of right first finger against right side of vertebra
below, and left forefinger against left side of bone in lesion; side-bends
to right, stretching tissues of right side until catch is released by exaggeration;
then reverse fingers against right side of bone in lesion and left side
of bone below, inserting finger so far as possible between vertebra in
lesions and one below; then reverses position of neck, drawing across fulcrum
of finger on right; as in technic for posterior lesion, and repeats until
lesion is reduced. Flexion may be used before reversing position
of neck, to make a fulcrum of posterior ligaments.
The scientific designation for lesions of this joint is lesion of the occiput. But in ordinary conversation the term atlas lesion is usually employed, and serves; for lesion between atlas and axis is rarely more than a functional change of position, secondary to uneven tension of muscles; and the least unevenness postulates rotation here; true lesions are rare here on account of the odontoid process; and in any case can be only rotations. Posterior atlas means therefore necessarily a lesion of the atlanto-occipital joint. The atlanto-occipital joint is composed of two parts, an anterior and a posterior; usually there is a division between them. The posterior part is a modification of the articular surface proper; the anterior is a modification of the costal articulation. The articular surface of the lumbar region is likewise composed of two parts, the articular surface proper being the part flat toward the spinal column, the costal element being the part perpendicular thereto, the two making the curve of the articulation. The costal element moves farther forward as we approach the dorsal region, until it is found at the posterior corner of the bodies, still forming the lateral protection of the joint. In the cervical region it forms the lateral lips of the superior surface. In the atlas it forms the anterior half of the superior surface. The two together form a cup-shaped surface with a symmetric curve. The atlanto-occipital articulation is thus a shallow ball-and-socket joint. The axis of all motion is the same—the center of the sphere of which these four surfaces (two on each side) form four parts. All motions are possible therein. Of these the chief is the nodding motion, the second is the rotary motion, limited by the contact of the transverse processes with the occipital bone. The nodding motion (flexion and extension) is limited by the contact of the anterior and posterior arches with the occipital bone; but as there is neither body in front nor process in rear of the atlas, this motion is freer. To examine the occiput in relation with the atlas, the proper point to examine is the relation of the posterior border of the transverse process with the posterior border of the mastoid process of the occiput; which should be almost in line; the margin of the atlas a trifle posterior to the mastoid line, in the average person (the mastoid line being a continuation of the posterior border of the mastoid bone). There is no change of motion beyond these points of contact, unless there is sufficient force to separate the whole articulation. There are no bony edges or prominences to come into contact with surfaces and make indentations. Lesions nevertheless exist. For the mechanics of these lesions we shall have to assume either a dead-centre or a friction action, as commented on in cervical vereabrae. Or these may be warp lesions, from relaxation of some ligaments or contracture of some muscles. Ligaments, acting radially to the motion, do not here draw the articulation back toward the normal but easily allow the maintenance of a warp lesion, even perhaps allowing the wrinkles to form and maintain lesion. Of muscles between the atlas and occiput there is
only one in front, and a small one as well, whereas behind there are several
large and well developed muscles. Moreover, the special senses of
the face protect the front of the head from violence as from strain, whereas
the back of the occiput is more subject to abnormal strain than any other
part of the body, except perhaps the tuberosities of the ischii.
Lesions of the occiput are therefore ninety per cent anterior, or more,
(posterior atlas) and ten per cent posterior, or less (anterial atlas).
The technic for anterior occiput (posterior atlas) and for rotated occiput
is the same. In rotation, the posterior arch of the affected side
is treated; in the other, one side at a time is treated.
Assume atlas posterior on right. Patient supine; operator stands at head of table; turns patient’s head to left side and flexes it, focusing motion on atlanto-occipital joint so as to gap open right side and bring arch of atlas into prominence on that side; inserts fingers or thumb as it were between arch of atlas and the occiput until they come into contact with the arch, pressing between the two but strongly forward, then, keeping the face turned to the left, and maintaining pressure on atlas, draws the neck back to limit of motion to right, until all articulations on left are tensed; then with slight but quick further turning of the head with extension, the bone is lifted into place. The mechanics in this technic is the same as in posterior cervical lesions. Directly lateral displacements of the atlas are on careful examination found to be really approximations on the opposite side; in an atlas apparently displaced to the right, the left transverse praocess will be found drawn close against the underside of the occiput, as by the spasm of the rectus capitis lateralis. The displacement to the left is an appearance, due to the effort to bring the head to the median line. To correct this lesion the tense muscle must be relaxed. The tension may be then reduced by the above technic applied to the prominent side. For occiput-posterior (anterior atlas) lesions; patient supine, top of head slightly beyond top of table; operator places one hand under chin and other under occiput and lifts, holding face upward until occipito-atlantal articulation is in full extension and the weight of the body is dragging downward on the atlas; then carrying the head from side to side, focusing motion at the atlas, he endeavors to gap open first one side and then the other, until the lesion is reduced. The same technic may be applied with operator half
seated, thigh across head of table, patient’s occiput on thigh, lifting
under chin and rotating.
There is a very good natural reason for the extreme sensitiveness of the joints of the body, especially those of the cervical region, and especially in lesions. In the ligaments of the joints are developed nerves whose function is to protect the joints. Just as the eye is automatically closed by its nerves when some object moves rapidly toward it, so are the muscles of the joints automatically contracted by these nerves of the joints when the joints are threatened. Hilton’s law states that “the nerve that supplies the joint supplies the muscles that move the joint, and the skin over the insertion of the muscles”—i.e., the skin against which pressure would threaten the joint. The nerve irritated by the strained ligaments is the nerve that contracts the muscles to protect the joint. In lesion, the tension of these ligaments is already abnormal, except so far as compensation has been made. In them therefore this sense of threat to the joint is already excited—the fear or “dread” as it is usually called, is barely below the plane of consciousness. When the corrective effort is made, this fear or dread is acutely stirred. The cervical region is more exposed than any other region of the spine. Nature has therefore made this sensation more acute here. By reason of the nearness of the ear, the shock of correction is carried with great acuteness to the ear, and the unpleasant sensation is redoubled. Care is therefore necessary, especially in treating the neck. When a patient is lost because he “could not stand the treatment,” he could not have been more truly or completely lost to the profession if he had died. |