Lumbar vertebra

“ The first is in shape like the seventh cervical, but has no foramen at the root of the transverse process, and has two articular facets on each side of the body ; the ninth has sometimes only one facet at the side of the body; the tenth, eleventh, and twelfth have invariably only a single facet on the side of the body, but the eleventh and twelfth have stunted transverse processes, and the twelfth has its lower articular processes shaped like those of a lumbar vertebra. The lumbar vertebrae in man are five in number. They are the lowest of the true vertebrae, and vertebrae. ”

“ That the eighth vertebra is a thoracic one is shown by the relation of the ribs in this specimen. Posteriorly there is no distinction, also, between the true thoracic vertebrae and those of the lumbar region. All the vertebrae anterior to the pelvis bear ribs, and will all be considered as dorsal vertebrae, the true thoracic vertebrae being restricted to those of which the ribs are elongated, and, probably, connected with the sternum. ”

“ The neural spine and zygapophyses are as in the lumbar region. Projecting laterally from each sacral vertebra, forming a close, sutural joint with both centrum [57] and neural arch, is a heavy bone shaped like a truncated pyramid (4) ; the base of the pyramid is ankylosed with the ilium. These bones seem to be much thickened transverse processes, but since they are not completely fused with their respective vertebræ and are said to ossify separately they should probably be called sacral ribs. The two sacral vertebræ do not seem to be any more closely united than are any other two vertebræ. ”

“ The simple fact of the overarching of the vertebral column, with excessive pressure against it from the intestinal mass, owing to the spasmodic action of the abdominal muscles, may account for it, and so also may the struggles of the animal to escape from the restraint of the hobbles while frantic under the pain of an operation without anesthesia. In these cases the fracture usually occurs in the body or the annular part, or both, of the posterior dorsal or the anterior lumbar vertebra. ”

“ Now in the Macrauchenia, as in the Pachyderms above cited, the transverse processes of the last lumbar vertebræ are of considerable thickness and extent, and are joined by enarthrosis to the transverse processes of the sacrum; but the bony structure of these joints would indicate that they were not subject to be obliterated by anchylosis. The articular surfaces which project from the posterior part of the transverse processes of the last lumbar vertebræ present a regular and smooth concavity, adapted to a corresponding convexity in the transverse processes of the first sacral vertebra. ”

“ The ribs of the five or six lumbar vertebrae are merely vestigial or absent. The ribs of the two sacral vertebrae are very stout, fusing in the adult with both centrum and neural arch. Some of the anterior caudal vertebrae also carry ribs, attached across the neuro-central suture; long before maturity they fuse with their vertebrae, and then look like transverse processes. Most of the caudal vertebrae carry also a {439}pair of chevron-bones, and these are continuous with the intercentral rings of cartilage. ”

“ On the seventh thoracic it becomes larger, thin, and upright, and widely separated from the articular facet for the tubercle of the rib. On the centrum of this vertebra lower down is a second much larger rugose articular facet. On the eighth thoracic vertebra the upper articular process disappears altogether and is replaced by a transverse process on a lower level, with a facet at the free end for the rib. On the ninth thoracic the transverse processes are larger and nearly straight. They are longer on the first lumbar and incline a little forward. ”

“ The move which is suited to a certain kind of subluxation156 of one vertebra may be quite out of place with another, in a different part of the spine. Thus the Recoil is quite proper for a posterior Lumbar and is contraindicated with a posterior middle Dorsal.
If all vertebrae were shaped exactly alike, if all were equal in size, if subluxation were possible only in one direction, then one method of adjustment would be quite sufficient. Diversity of technic is demanded, but a discriminating diversity, with a good reason for every move used. ”

“ In the Rodentia there are generally nineteen thoraco-lumbar vertebrae but occasionally the number rises as high as twenty-five. In the Hares (Leporidae) the number is nineteen, [450] twelve or thirteen of which are thoracic. The anterior thoracic vertebrae have short centra and high backwardly-directed neural spines, the lumbar vertebrae have large forwardly- and downwardly-directed transverse processes with expanded ends. Metapophyses, anapophyses and hypapophyses are all present. In the Agouti (Dasyprocta) the convergence of the neural spines to a centre of motion is very strongly marked. ”

“ The odontoid process of the axis is short and blunt, or may [354] be completely wanting. The lumbar and caudal vertebrae are large and numerous, and as zygapophyses are absent, are very freely movable on one another; zygapophyses are also absent from the posterior thoracic vertebrae. The lumbar vertebrae are sometimes more numerous than the thoracic. The epiphyses are very distinct, and do not unite with the centra till the animal is quite adult. None of the vertebrae are united to form a sacrum, but the caudal vertebrae have large chevron bones. ”

“ Between it and the spina lumbalis there is a broad furrow, the bottom of which is formed by the dorsal surface of the lumbar vertebræ. The sulcus ilio-lumbalis dorsalis is formed by the rims of the ilia, so that a ridge is observable. The cavum ilio-lumbale dorsale is formed by the iliac rims on either side. Anteriorly is the canalis ilio-lumbalis, which is formed by the ilium and the lumbar vertebral spines. It is located longitudinally to the vertebræ. The anterior opening of this canal is the larger. Posterior to the acetabulum is the post-acetabular ridge. ”

“ No proper new bony socket forms like that in traumatic dislocations that remain unreduced because in the congenital variety the thickened capsule intervenes between the head of the bone and the dorsum ilii. The displacement of the head is most frequently backwards (dorsal luxation) , and as the point of support thus falls behind the acetabulum the pelvis tilts forwards, and the lumbar spine becomes unduly concave (lordosis) . ”

“ The Lumbars, with patient erect, should curve anteriorly and the first Sacral spinous process should complete the regular curve. This is rarely found, however; the normal is the exception in any part of the spine.
In the Lumbars we usually choose the rotated rather than the posterior vertebra, but solely because rotation here produces the greatest degree of impingement. The laterality of spinous processes, indicating rotation of the whole vertebra around an axis lying in the transverse line between the articular processes, can best be perceived, as a rule, with patient sitting quite erect. ”

“ The last two cervical vertebrae bear long movable ribs which articulate by distinct capitular and tubercular processes, but do not meet the sternum. The thoracic ribs are eight in number, and each is divisible into a vertebral and a sternal portion. The first five thoracic ribs are flattened curved bars of bone, which articulate by a prominent capitulum with the centrum of the corresponding vertebra, and by a tuberculum with the transverse process. Projecting backwards from each is a large hooked uncinate process. ”

“ A careful examination will discover not only the great rigidity of the spine, and as it were fusion en masse of its joints, but in these persons the bony outgrowths may be felt. Occasionally the alteration in the vertebræ by compressing the cord or its membranes, or the spinal nerves and ganglia, may produce neuralgic pains in the cervical, dorsal, lumbar, or sciatic nerves, wasting of the muscles, more or less paralysis, and even vasomotor disturbances. ”

“ These true sacrals alone are connected with the ilium by processes which are really equivalent to modified ribs; but the pelvis of birds extends considerably farther forwards and backwards, gradually coming into contact with other vertebrae, which in various ways send out connecting transverse processes or buttresses, and thus become pre- and post-sacral vertebrae (fig. 9) . The most anterior part of the ilium often overlaps one or more short lumbar ribs and fuses with them, or even a long, complete thoracic rib. ”

“ The lumbar curve is greater in the European than in the Australian, but it is decidedly greater in the chimpanzee. The difference in curvature is brought about mainly by the discs of cartilage which exist between the vertebræ, and that is why there is a considerable movement possible in the lumbar portion of the spine of the lower races of man; and it is quite possible that the lumbar curvature alters according to the position adopted by the individual, that is, according to whether he be in a standing or in his favourite squatting posture. ”

“ The 3-7th rib are thus appended to the 5 proper thoracic vertebræ, which stand in the signification of the pulmonary vertebræ. To these succeed the 5 short ribs which belong to the abdomen; their vertebræ are thus intestinal vertebræ. The succeeding vertebræ belong to the sexual system, and are indeed the 5 lumbar or pedal vertebræ, because they furnish the pedal or foot-nerves, the 5 sacral vertebræ being the proper sexual vertebræ. The coccygeal or caudal vertebræ correspond to the cervical vertebræ, and are present for the sake of the sexual branchiæ; usually one and the other is arrested. ”

“ It is true that division of the roots of the brachial plexus causes a slight dilatation of the vessels of the arm, but this is so much increased when the dorsal nerve-roots are divided that it is evident that it is through them that the constrictor fibres chiefly pass. The vaso-constrictors of the leg, which can be traced into the second and third lumbar ganglia and lumbar sympathetic cord, are derived from the five lower dorsal and first lumbar nerves, and only join the crural and sciatic nerves after passing through the abdominal sympathetic. ”

“ Bone diseases such as rachitis osteomalacia, etc., and especially Potts’ Disease, or spinal caries, make marked changes in the shape of vertebrae. Also a subluxated vertebra may gradually assume a shape suited to the abnormal position it occupies, the commonest change being the assumption of a wedge shape by the centrum. This is a great obstacle to adjustment, as the abnormal shape of the vertebra makes it tend to settle after each movement into the old abnormal position.
There are few spines without some more or less misshapen vertebrae. ”

“ The gluteal, posterior femoral, gastrocnemial, and outer pedal surfaces are affected together with the muscles moving the foot, while the thigh and inner side of the leg and foot become anæsthetic, with lesion of the upper part of the lumbar enlargement accompanying paralysis of the quadriceps and deep muscles. ”