Lumbar vertebrae

“ 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 portions of the spine situated in the region of the neck and loins are those most likely to yield at an early period of life; the reason of which is, that these parts are kept in the erect position merely by the action of the muscles. The neck has to support the weight of the head, while the lumbar vertebræ bear that of the thoracic and abdominal viscera. In early infancy, the muscles of the neck and back are totally inadequate for the performance of their functions, as, from not having been brought into action, they have not acquired sufficient strength ”

“ The lumbar vertebrae are often very loosely articulated together and the zygapophyses sometimes as in the Dolphins are placed high up on the neural spines. The centra are large, short in the anterior region but becoming longer behind. The epiphyses are prominent, and so are the neural spines and to a less extent the metapophyses. The transverse processes are well developed, anteriorly they arise high up on the neural arch, but when the vertebral column is followed back they come gradually to be placed lower down, till in the lumbar region they project from the middle of the centra. ”

“ 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. ”

“ 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. ”

“ 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. ”

“ The majority of subluxations do produce disease, to some degree, and do so by impinging nerves. Impingement may be either by pressure against a nerve or ganglion or by constriction of a nerve where it passes through an intervertebral foramen; the former occurs in the case of the80 Cervical sympathetic, the sub-occipital nerves, and the sacral nerves; the latter is the commoner form in Dorsal and Lumbar regions of the spine. Probably the most positive constriction of a nerve which can occur within the body is to be found in rotation of Lumbar vertebrae ”

“ 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. ”

“ Thoracic or Dorsal Region.—When the disease is confined to the thoracic region, stiffness of the back and boarding of the vertebral muscles are prominent features. On being asked to pick up an object from the floor, the patient reaches it by bending his knees and hips, while he keeps his back rigid. He refuses to make any movement that involves jolting of the spine, such, for example, as jumping from a chair to the ground. Children often attempt to take the weight off the diseased vertebræ by placing the palms of the hands on the edge of a chair so that the weight is borne by the arms. ”

“ 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) . ”

“ In the cervical region it is enlarged where the nerves forming the brachial plexus come off, while opposite the lower thoracic vetebrae the lumbar enlargement marks the region whence the lumbo-sacral nerves are derived. (See fig. 2.) Opposite the second lumbar vertebra the cylindrical cord becomes pointed and forms the conus medullaris from the apex of which a glistening membranous thread runs down among the nerves which form the cauda equina, and after blending with the termination of the dural sheath, is attached to the back of the coccyx. ”

“ 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. ”

“ The patient complains of severe pain in the neck, and inability to move the head, which is often rigidly held in the position of wry-neck. There is marked tenderness on attempting to carry out passive movements, and on making pressure over the affected vertebræ or on the top of the head. The maximum point of tenderness indicates the vertebra most implicated. In diagnosis, fracture and dislocation are excluded by the absence of any alteration in the relative positions of the bony points, and by the fact that passive movements, although painful, are possible in all directions. ”

“ The great degree of mobility in that portion of the spine which is formed by the superior cervical vertebræ, must render it, and the contained parts, liable to injury from sudden distortions. Hence therefore may proceed inflammation of quicker or of slower progress, disease of the vertebræ, derangement of structure in the medulla, or in its membranes, thickening or even ulceration of the theca, effusion of fluids, &c. ”

“ It is connected with the lateral reticular processes, and in its cephalo-caudal course becomes gradually attenuated, giving off its fibres to these processes, thus to be exhausted in the lower part of the lumbar enlargement of the cord, where it approaches, if it does not actually reach, the surface. The fibres controlling the voluntary motions of the lower limbs, and which have a longer course to run before they reach the brain than those which mediate the voluntary control of the arms, are situated nearest the lateral boundary of the cord. ”

“ 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. ”

“ 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. ”

“ The plastron is roughly indicated by a section through the middle line. Fe, Femur, foreshortened; Fi, fibula; H, humerus; Il, ilium; Is, ischium; P.P., pubis; R, radius; Scap, scapula; Tb, tibia; u, ulna; 3, third cervical vertebra; 1, 3, 5, first, third, and fifth fingers; XIII, thirteenth (fifth thoracic) vertebra.
The pelvis is strong. Ilium, pubis, and ischium meet at the acetabulum. The dorsal end of the ilium is generally broadened, and is attached to one or both sacral vertebrae, but it is also in contact with the superimposed last costal plate. ”

“ The reason is that in obtaining flexibility of movement security of attachment is somewhat lessened. If the ligaments at the shoulder were tight enough to prevent the joint from ever becoming dislocated they would bind it to a serious degree. Most of the ligaments are of inelastic connective tissue, but those that fasten the separate vertebræ of the spinal column together are elastic, allowing of the bending in every direction which makes our backs as flexible as they are. The only movable joints which are bound by other means than ligaments are the connections of the ribs with the breastbone. ”

“ Movement of a section of the spine composed of several vertebrae is not, in the true sense, an Adjustment. It is the single vertebra which must be moved.
The movement should be one calculated to bring the vertebra to its normal position in the most direct manner possible. Such a movement should be used as will reverse the direction of the forces which subluxated the vertebra. It should be applied to the transverse or spinous processes, or to the lamina, as is sometimes done in the case of the Atlas, according to the kind of subluxation. ”