Quadrivium

“ Quadrilat′eralness. [L. quadrilaterus—quatuor, four, latus, lateris, a side.]
Quadriliteral, kwod-ri-lit′ėr-al, adj. of four letters.—n. a word or a root having four letters. [L. quatuor, four, litera, a letter.]
Quadrille, kwa-dril′, n. a square dance for four couples, consisting of five movements: music for such square dances: a game played by four with forty cards.—v.i. to play at quadrille: to dance quadrilles. [Fr.,—Sp. cuadra, a square—L. quadra, a square—quatuor, four.]
Quadrillion, kwod-ril′yun, n. a million raised to the fourth power, represented by a unit with twenty-four ciphers. ”

“ The curves of the vertebral column are, in quadrupeds, slightly different from those which characterize the human spine. First, instead of their being, as in the latter, curves in the antero-posterior aspect, because of the general attitude of the body, they are turned in the supero-inferior direction.
The cervical region is not a single curve, as in the human being. It presents two: one superior, with its convexity looking upwards; the other inferior, the convexity of which is turned downwards. ”

“ The powerful tendon of the quadriceps extensor muscle, in which the patella is developed as a sesamoid bone, protects and strengthens the front of the joint and functionates as the anterior ligament of the joint. In the attitude of complete extension in which the joint is locked, no demand is made on the quadriceps apparatus; with the commencement of flexion, the stability of the joint, and the weight-bearing capacity of the limb as a whole, depend largely on the controlling influence of the quadriceps muscle ”

“ We have now examined in detail the skeleton of an extinct quadruped of enormous magnitude; every bone of which presents peculiarities, that at first sight appear imperfectly contrived, but which become, intelligible when viewed in their relations to one another, and to the functions of the animal in which they occur. ”

“ And if the hips, which are the pole of a man, are by reason of his position, placed so, that the right is higher than the left, make the point of the higher shoulder in a perpendicular line above the highest prominence of the hip, and let this right shoulder be lower than the left. Let the pit of the throat always be over the centre of the joint of the foot on which the man is leaning. The leg which is free should have the knee lower than the other, and near the other leg. ”

“ Each vertebra except the Atlas is composed of a body and an arch; the arch is made up of two pedicles, short, thick plates of bone extending outward and backward from the postero-lateral surface of the body nearer its upper than its lower border, two laminae, thin plates of bone extending backward and inward from their union with the pedicles and joining behind to form the spinous process, and has projecting from it seven processes, two transverse, one spinous, and four articular, two of which are superior and two inferior. ”

“ Now, as we have pointed out in the section on osteology (see p. 34) , the forearm in quadrupeds is always in the position of pronation. Should we, then, in order to maintain the symmetry with human anatomy, first study the forearm in the position of supination? Evidently not. Besides the fact that this would in some cases be impossible since—as in the horse, for example—the radius and ulna [175] are fused together, we should not gain any advantage; this position being never completely realizable even in those quadrupeds which have the radius relatively movable—as, for example, in the cat. ”

“ Each of these little round flat pieces of the backbone is called a vertebra, and is of a very peculiar shape. Suppose you took a bung of bone, and fastened on to one side of its edge a ring of bone. That would represent a vertebra. The solid bung is what is called the body, and the hollow ring is what is called the arch of the vertebra. Now if you put a number of these bodies together one upon the top of the other, so that the bodies all came together and the rings all came together, you would have something very like the vertebral column (see Frontispiece, also Fig. 2) . ”

“ A spinal column may be a uniform solid axis, or a highly diversified segmented axis. A limb may be an arm, or a leg, a wing, or a paddle. In every case the anatomist recognizes a specific type. He assigns the uniformities to the uniformity of the substance thus variously shaped, under a history which has been similar; the diversities he assigns to the various conditions under which the processes of growth have been determined. He never expects a muscular tissue to develop into a skeleton, a nervous tissue into a gland, an osseous tissue into a sensory organ. ”

“ The form in which the sheets (of skin, parchment, bark, papyrus, or paper) were gathered, may have been rolls in which they were united to form a single page, or a square combination of successive leaves united only at one side. The former was of course the earlier mode, but the latter was also in use at a remote date. Greek and Roman scribes had evidently begun to prefer the square fashion during the early days of the Roman empire; and we may take it to have become the prevalent custom in the fourth century. ”

“ Why was the vertebral column at the back of the body as in quadrupeds, when it would have been more logical, in creating a man who stands on his feet, to place it in the centre of the body as a strong support, thus avoiding the curvatures and weakness of the spine that are now suffered by this disequilibrium in the support of its weight? ”

“ In any size of type there are four kinds of quads. Fig 2 shows the ends of the 8 and 12 point quads and spaces. An em quad is the square of the type body. The 10 point em quad is a square quad whose sides are 10 points wide. An eight point em quad is 8 points or one-ninth of an inch square.
An en quad of any size type is one-half the em quad of that size of type. A two em quad of any size type is equal to two of the square or em quads, and a three em quad is equal to three of the square or em quads laid side by side. ”

“ In the adult it may, in the more primitive forms (Cyclostomata, Dipneusti) , persist as an important part of the skeleton, but as a rule it merely forms the foundation on which the cartilaginous or bony vertebral column is laid down.
2. Cartilaginous or Chondral Skeleton.— (A) Vertebral column. [27] In the embryonic connective tissue or mesenchyme lying just outside the primary sheath of the notochord there are developed a dorsal and a ventral series of paired nodules of cartilage known as arcualia (fig. 13, d.a, v.a) . ”

“ As a knowledge of their actions enables us to know the possible from the impossible. A joint is formed by the junction of two bones, the extremities of which are perfectly adapted to each other, and every perfect joint consists of five parts, each of which has its function to perform. It is not our intention to treat with each part separately, as such would be beyond the application of anatomy to tailoring, but when we have to deal with the various kinds of joints, we have a subject of great interest to the tailor. ”

“ It does not seem to us as though there could be anything more harmless than dancing a cold-blooded quadrille. It is a simple walk around, and is not even exercise. Of course a man can, if he chooses, get in extra steps enough to keep his feet warm, but we contend that no quadrille, where they only touch hands, go down in the middle, and alamand left, can work upon a man's religion enough to cause him to backslide. ”

“ When then one leg is advanced it becomes the hypotenuse of a right-angled triangle. Its square then is equal to the square on the other side together with the square on the base. As the legs then are equal, the one at rest must bend either at the knee or, if there were any kneeless animal which walked, at some other articulation. ”

“ As the extract we have given from the Codex Peresianus relates only to one of the four groups of days—that on the right of the quadrilateral—I will supply in the following tables, Nos. VII, VIII, and IX, the arrangement of the groups of the other three sides; adding the other (Table VI) , also, so as to bring the four together in the order of the sides of the quadrilateral, commencing with the line on the right, next the upper one, and so on.
While this is undoubtedly the order in which they are to be taken; which is the proper one to commence with? is a question yet to be discussed. ”

“ For man bends his legs convexly, a bird has his bent concavely; again, man bends his arms and legs in opposite directions, for he has his arms bent convexly, but his legs concavely. And a viviparous quadruped bends his limbs in opposite directions to a man's, and in opposite directions to one another; for he has his forelegs bent convexly, his hind legs concavely. Again, quadrupeds which are not viviparous but oviparous have a peculiar curvature of the limbs laterally away from the body. Again, why do quadrupeds move their legs criss-cross? ”

“ It can therefore be easily shown that a sphere is a quadric which touches the fundamental quadric along its intersection with the polar plane of the centre of the sphere.
In discussing the general case of the displacement of a rigid system it will simplify matters to suppose that the fundamental quadric has real rectilinear generators. It must, however, be understood that the results are not on that account less general. A displacement must not alter the quadric, and must not deform a straight line. ”

“ As osseous union of the fragments is not essential to a good functional result, and as fibrous union does not necessarily entail any material interference with the usefulness of the limb, no attempt need be made to approximate the fragments, but every effort must be made to maintain the function of the quadriceps muscle and the mobility of the joint. ”

“ The first division takes in head, neck, chest, abdomen and pelvis. The second division takes in head, neck, lower and upper arm and hand. The third division takes in foot, leg, thigh, pelvis and lumbar vertebra. I make this division for the purpose of holding the explorer to the limits of all supplies. In the ellipse of the chest is found all vital supplies; then from that center of [Pg 30] life we have two branches only, one of the arm, and one of the lower limb. In each division we have five points of exploration. ”

“ All our joints are not hinge-joints.
Your shoulder has a joint that lets your [11] arm swing round and round, as well as move up and down.
Your hip has another that lets your leg move in much the same way.
The hip-joint.
This kind of joint is the round end or ball of a long bone, which moves in a hole, called a socket.
Your joints do not creak or get out of order, as those of doors and gates sometimes do. A soft, smooth fluid, much like the white of an egg, keeps them moist and makes them work easily. [12]
BONES.
What parts of our bodies are jointed together so nicely? Our bones. ”

“ I have stated that the angles formed by the bones of the human leg are larger than those formed by the bones of the leg of the quadruped and bird. This is especially true of the angle formed by the femur with the ilium, which, because of the upward direction given to the crest of the ilium in man, is so great that it virtually ceases to be an angle.
The bones of the superior extremities in man merit attention from the fact that in walking and running they oscillate in opposite directions, and alternate and keep time with the legs, which oscillate in a similar manner. ”

“ Elastic cartilage is found in the epiglottis and the cartilages of the larynx.
Fibro cartilage is found at the point of insertion of the ligaments, into the body of the bone, such as the cartilage which helps to hold the femur or long bone of the thigh into the hip.
Bones.
—Bone results from the calcification of cartilage or fibrous tissue. It is a highly specialized form of [49] connective tissue. There are two varieties of bone; dense or compact bone and cancellous, loose, or spongy bone. Compact bone is dense, like ivory, and is always found on the exterior of bones. ”

“ In quadrupeds, on the contrary, even should the skeleton be found entire, it would be difficult to apply to it characters derived, for the most part, from the hair, the colours, and other marks which have disappeared previous to their incrustation. It is even excessively rare to find a fossil skeleton approaching in any considerable degree to a complete state. The strata, for the most part, only contain separate bones, scattered confusedly, and almost always broken, and reduced to fragments ”

“ A ruled quadric surface contains two sets of straight lines. Every line of one set cuts every line of the other, but no two lines of the same set meet.
Any two lines of the same set may be taken as bases of two projective rows, or of two projective pencils which generate the surface. They are cut by the lines of the other set in two projective rows.
The plane at infinity like every other plane cuts the surface either in a conic proper or in a line-pair. In the first case the surface is called an Hyperboloid of one sheet, in the second an Hyperbolic Paraboloid. ”

“ The FEMUR is the longest bone in the system. It supports the weight of the head, trunk, and upper extremities. The large, round head of this bone is placed in the acetabulum. This articulation is a perfect specimen of the ball and socket joint.
107. The PATELLA is a small bone connected with the tibia by a strong ligament. The tendon of the ex-tens ́or muscles of the leg is attached to its upper edge. This bone is placed on the anterior part of the lower extremity of the femur, and acts like a pulley, in the extension of the limb. ”