Spinel

“ Spin′āte, covered with spines or spine-like processes.—Spinal column, the backbone; Spinal cord, marrow, the main neural axis of every vertebrate.
Spindle, spin′dl, n. the pin from which the thread is twisted: a pin on which anything turns: the fusee of a watch: anything very slender.—v.i. to grow long and slender.—adjs. Spin′dle-legged, -shanked, having long slender legs, like spindles.—ns.pl. Spin′dle-legs, -shanks, long slim legs—hence an over-long and slender person.—adj. Spin′dle-shaped, shaped like a spindle: thickest in the middle and tapering to both ends.—ns. ”

“ But I have first to speak of a set of lower centres, those which the Will can to a certain extent control, but which are not in such immediate relation to it as is the brain. You all know that there passes down our backbone a cord which is commonly called the "Spinal Marrow." Now, this spinal marrow gives off a pair of nerves at every division of the backbone; and these nerves are double in function—one set of fibres conveying impressions from the surface to the spinal cord, the other motor impulses from the spinal cord to the muscles. ”

“ The spine is a highly flexible column, made up of a number of bones called vertebræ, united by cartilages and ligaments, and movable in all directions by the action of the overlying muscles. In childhood the spine is most liable to yield and become weak or deformed at the neck and loins, for the neck has to support the weight of the head, and the loins that of the internal organs of the body. ”

“ Manifestly, at the end of the spine, Nature puts out smaller spines, as arms; at the end of the arms, new spines, as hands; at the other end, she repeats the process, as legs and feet. At the top of the column she puts out another spine, which doubles or loops itself over, as a span-worm, into a ball, and forms the skull, with extremities again: the hands being now the upper jaw, the feet the lower jaw, the fingers and toes being represented this time by upper and lower teeth. This new spine is destined to high uses. It is a new man on the shoulders of the last. ”

“ A. I thank you, Isabel. Now, what is this spine, of which there is so much "complaint" now-a-days?
I. I will answer you from Paley: "The spine, or backbone, is a chain of joints of very wonderful construction. It was to be firm, yet flexible; firm, to support the erect position of the body; flexible, to allow of the bending of the the trunk in all degrees of curvature. It was further, also, to become a pipe or conduit for the safe conveyance from the brain of the most important fluid of the animal frame, that, namely, upon which all voluntary motion depends, the spinal marrow ”

“ The habitual rigidity of the spine, as compared with its possible freedom, is more noticeable in training, of course, than is that of any other part of the body. Each vertebra should be so distinctly independent of every other, as to make the spine as smoothly jointed as the toy snakes, which, when we hold the tip of the tail in our fingers, curve in all directions. Most of us have spinal columns that more or less resemble ramrods. It is a surprise and delight to find what can be accomplished, when the muscles of the spine and back are free and under control. ”

“ In Man, in consequence partly of the disposition of the articular surfaces of the vertebrae, and largely of the elastic tension of some of the fibrous bands, or ligaments, which connect these vertebrae together, the spinal column, as a whole, has an elegant S-like curvature, being convex forwards in the neck, concave in the back, convex in the loins, or lumbar region, and concave again in the sacral region; an arrangement which gives much elasticity to the whole backbone, and diminishes the jar communicated to the spine, and through it to the head, by locomotion in the erect position. ”

“ Bend in two this supple spine that can lift itself, like a snake erect, with something better than mere balance—with life and the active will; bend the back, and at once gravitation takes hold of the loins and grasps the knees, and pulls upon the shoulders, and the neck feels the weight of an abject head. ”

“ The vertebræ, or joints of the spine, are excavated at each end in a conical cavity; the hollow thus formed between every joint and its neighbour is filled with a jelly-like substance, which is continuous through the whole spine, by means of a hole pierced through the centre of each vertebra. There is no true spinal marrow. ”

“ The back portion of the spinal marrow and the nerves that run from it are employed in sensation, or the sense of feeling. These nerves extend over the whole body, but are largely developed in the network of nerves in the skin. The front portion of the spinal marrow and its branches are employed in moving those muscles in all parts of the body which are controlled by the will or choice of the mind. These are called the nerves of motion. ”

“ A canal is hollowed out of the column for the safe passage of the spinal cord. (See Fig. 50.) Projections (processes) at the back and on either side are abundant for the attachment of the muscles. The packing acts as a cushion to prevent any jar from reaching the brain when we jump or run, while the double curve of the spine also tends to disperse the force of a fall. Thus on every side the utmost caution is taken to guard that precious gem in its casket.
THE PERFECTION OF THE SPINE surpasses all human contrivances. ”

“ The spine is composed of vertebrae, and it extends from the head down to the loins. The vertebrae are all perforated, and, above, the bony portion of the head is connected with the topmost vertebrae, and is designated the 'skull'. ”

“ When the spinal cord has been severed in the neck this scratching movement of the hind limb can be elicited with regularity as a spinal reflex by merely rubbing the skin of the side of the neck or shoulder, applying there a weak electric current to the skin. In this reflex the stimulus excites afferent nerves connected with the hairs in the skin and these convey impulses to the spinal centres in the neck or shoulder segments, and these in turn discharge impulses into nerve fibres entirely intraspinal passing backward along the cord to reach motor centres in the hind limb region. ”

“ At the other end of the scale is man, whose spine is in a vertical line, and his face occupies a like plane. Between these two extremes are types which tend in various degrees, from the lower to the higher form, and just in proportion as the spinal axis approaches a vertical line from one side, the plane of the face approaches it from the other. ”

“ When the spines on being gently stimulated bend towards the point of stimulation, this is due to the contraction of the muscles on the side towards the point of stimulus, for if the superficial plexus of nerve-fibres be cut through so that the stimulus has to pursue a round-about course the spine will bend towards the direction from which the stimulus comes. The bending of the spines away from the stronger stimulus is likewise due to the muscles on the side towards the stimulus. ”

“ The spinal cord serves as a conductor of sensation and of motor impulses, and it also plays the part of a brain for those structures of the body which lie below the head. It gives off nerves like streamlets. ”

“ When the spine is erect, they are of the same thickness all around. When the spine is bent sidewise, say towards the right, the elastic cushions become thinner on that side, and if the bending is decided, the edges of the spinal bones themselves will nearly touch, while the mass of elastic or india-rubber substance will be pressed over to the left side. Now suppose that one follows an occupation requiring this position of the spine. ”

“ All along the spinal column, and between each two adjoining bones, are openings on each side, through which nerves pass out to be distributed to various parts of the body.
Between the vertebræ are pads or cushions of cartilage. These act as “buffers,” and serve to give the spine strength and elasticity and to prevent friction of one bone on another. Each vertebra consists of a body, the solid central portion, and a number of projections called processes. ”

“ We propose therefore, in this chapter, to give some general idea of the structure and functions of the spine, as well as a brief description of some of the curvatures to which it is subject.
The distinctive character of man is the erect posture. No other animal enjoys a physical conformation which will enable him to perma­nently assume this majestic attitude, although there are several in whom it may be maintained for a short time. ”

“ The spinal column is peculiarly adapted, with its strong ligaments, its cartilage cushions, its perfect flexibility and flexuousness, to withstand jars and shocks. Yet the spine is the door by which disease enters the organism. ”

“ Now, I impressed my audience as strongly as I could with the above fact, that if one wants to throw a quoit with certainty as to how it will alight, one gives it a spin; if one wants to throw a hoop or a hat to somebody to catch upon a stick, one gives the hoop or hat a spin; the disinclination of a spinning body to let its axis get altered in direction can always be depended upon. ”

“ A study of the spine will make clear the fact that if the cartilage between any two Dorsal vertebrae be thinned in front the bodies of the vertebrae will be closer together and the spinous processes more widely separated; the spinous process of the upper vertebra will be crowded against the one superior to it and that of the lower against the one inferior to it. ”

“ Make a man lean forwards, with his arms folded across the chest; this will make prominent the spines of the vertebræ. The lower border of the trapezius will guide you to the spine of the twelfth dorsal vertebra. ”

“ The use of this chair is more efficacious in straightening the spine, than simply lying down horizontally; as it not only takes off the pressure of the head and shoulders from the spine, but at the same time the inferior parts of the body contribute to draw the spine straight by their weight ”

“ The spinal cord is a bundle of nerves extending from the base of my brain, down through the whole length of my spine, or backbone. It is the largest nerve in my body.
10. From the spine, thirty-one pairs of nerves, called spinal nerves, pass to different parts of my body; some to the lungs, some to the heart, some to the stomach, some to the bones, and some to the muscles and skin.
11. If a nerve be destroyed it cannot carry messages to and from the brain. Before filling a tooth, the dentist sometimes destroys its nerve.
12. If a nerve be pressed upon too long it cannot perform its duty. ”

“ Now, the spine was not only to furnish the main trunk for the passage of the medullary substance from the brain, but to give out, in the course of its progress, small pipes therefrom, which, being afterwards indefinitely subdivided, might, under the name of nerves, distribute this exquisite supply to every part of the body. ”

“ The mass of nerve fibre which passes down within the back-bone constituting the spinal column, which is formed in two divisions equivalent to the hemispheres of the brain, gives out at each of the vertebræ or spinal joints a supply of nerve for the portion of the body contiguous. ”

“ The spine, on the top of which the head is articulated, is a highly-­flexible column, capable of moving in any direction which may be necessary, and during its movements forming a series of elegant curves, so truly described by the ancients as the serpentine line of beauty ”

“ In relation to the brain, the spinal cord is a great mixed motor and sensory nerve, but, in addition to this, it is also a distinct nervous centre, in which originate and terminate all those involuntary impulses which exert so potent an influence in the preservation and economy of the body. ”

“ The spine consists in an adult of twenty-six bones, in a young child of thirty-three, certain of the bones in the spine of the child becoming ankylosed or blended with each other in the adult. These blended bones lose their mobility and are called false vertebrae; whilst those which retain their mobility are the true verte- brae. The bones of the spine are arranged in groups, which are named from their position — vertebrae of the neck or cervical; of the chest, thoracic, formerly called dorsal; of the loins, lumbar; of the pelvis, sacral ”

“ Thus it follows, that the grey matter of the segment of the man’s spinal cord, though it is devoid of consciousness, nevertheless responds to a simple stimulus by giving rise to a complex set of muscular contractions, co-ordinated towards a definite end, and serving an obvious purpose. ”

“ It is the basis, pattern, or mould, in or around which the spinal column is to be formed, and around which the entire young body is to be developed by the wonderful and intricate processes of dividing and reduplication, and the folding and combination of cells. From one end of this "trace" develops the head; from the other end develops the lower end of the spine. ”

“ The complete erection of the spine means that the skull, instead of being suspended in front, is now poised upon the top of the spinal column. The field of vision is enormously enlarged, and it is possible to sweep a great extent of horizon at a moment's notice. ”

“ The first of the three dorsal spines is very strong, roughened in front like a file, and hollowed out behind to receive the second much smaller spine, which, besides, has a projection in front, at its base, fitting into a notch of the first. Thus these two spines can only be raised or depressed simultaneously, in such a manner that the first cannot be forced down unless the second has been previously depressed. ”