Metacarpal

“ Of the other four fingers, the metacarpal bones (g) are very long and slender, forming, indeed, the greater part of the fingers; they taper towards their tips, but at the tips themselves are slightly enlarged. The first, or index finger, in most Bats is composed of the metacarpal bone alone, but in some this is followed by two short phalanges. The other fingers possess either two or three phalanges. In general only the thumb possesses a claw, but in some Bats there is one also on the index finger. ”

“ The fourth has a long and rather slender metacarpal, and three phalanges diminishing in size, the terminal phalange being very small. The fifth has the metacarpal nearly as long, but not so stout as the fourth, and followed by two small phalanges, the last rudimentary and conical. Claws are developed upon all but the fifth. In walking the toes are kept bent, with their points turned upwards and inwards, the weight being supported on a pad over the end of the fifth digit, and the upper surfaces of the third and fourth digits. ”

“ The pisiform is large and prominent, flattened and curved; it articulates partly with the cuneiform and partly with the lower end of the radius. The large metacarpal is called in veterinary anatomy “cannon bone”; the small lateral metacarpals, which gradually taper towards their lower extremities, and lie in close contact with the large one, are called “splint bones.” The single digit consists of a moderate-sized proximal (os suffraginis, or large pastern) , a short middle (os coronae, or small pastern) , and a wide, semi-lunar, ungual phalanx (os pedis, or coffin bone) . ”

“ The superior extremity of this metacarpal presents plane surfaces, variously inclined, with which the bones of the inferior row of the carpus articulate. On the anterior surface, and a little to the inner side, is found a tuberosity, which is destined for the insertion of the anterior extensor of the metacarpus, the homologue of the radial muscles. The inferior extremity is formed by two condyles, an internal and an external; between which is found a median crest. ”

“ Both of these faces are concave in proximal view. Both faces form shallow fossae along the dorsal and ventral surfaces of the metacarpal shaft. The ventral process is directly opposite the dorsal process, and like the dorsal process it is low and rounded, bordered by the ventro-lateral and ventro-medial faces. The ventro-medial face possesses a shallow fossa which received the dorsal crest from Mc I. The distal end of the metacarpal is slightly expanded and divided into two distinct condyles. The medial condyle is missing the dorsal margin; however, it would be larger than the lateral condyle. ”

“ It is quite unnecessary to remove the head of the metacarpal, either for the sake of appearance, or to render healing more rapid, and its removal weakens the arch of the hand; where the cartilage is eroded by disease, the cartilage-covered portion can be scooped off by a gouge or removed entire by pliers, without interfering with the broad end to which the transverse ligament of the palm is attached. ”

“ Another character is the extreme shortness of the metacarpus, usually associated with immense strength of the wing metacarpal bone.
The hind limbs are relatively small and relatively short. The femur is usually shorter than the humerus, and the tibia is much shorter than the ulna. The bones of the instep, instead of being held together firmly as in the Lias genera, diverge from each other, widening out, though it often happens that four of the five metatarsals differ but little in length. The fifth digit is always shorter. ”

“ This definition will include the living and also most of the extinct forms, although in some of the latter the lateral metacarpal bones not only retain their lower ends, but are complete in their entire length. ”

“ There remains to be noticed only a single fractured metatarsal bone (fig. 1. Pl. XV.) This, from its bent and unsymmetrical figure, is evidently not a middle one, and having the side of the proximal end, which was articulated to the adjoining metatarsal in a nearly perfect state, it enables us to refer it with certainty to the hind-foot, since it does not agree with any of the corresponding surfaces at the proximal extremities of the metacarpal bones. ”

“ In form and size the metatarsals of any given mammal are usually so like the metacarpals, that it requires some experience to distinguish them, but when either manus or pes is especially adapted to some particular kind of work, there may be very decided differences between metatarsals and metacarpals. ”

“ The metacarpals are free, not united as in the adult, and there are separate distal carpals, which in the adult are united with the metacarpals. In other respects the modifications of wings and sternum are so obviously adaptive that it is difficult to believe that the reduction of digits was not due to disuse. This is another of those cases in which the function to which structure is adapted is constant from the beginning of independent life to the end, and there is some ground for believing that in course of time in such cases embryonic recapitulation may be much diminished or disappear. ”

“ The two distinct carpal bones are the radial carpal and the ulnar carpal. The radial carpal (fig. 57, 4) is a small somewhat cubical bone, wedged in between the manus and the radius and ulna. The ulnar carpal (fig. 57, 5) is a somewhat larger, more irregular bone, lying adjacent to the end of the ulna. It is deeply notched to receive the carpo-metacarpus.
The hand. In the adult bird the hand is in a much modified condition; only the first three digits are represented, and the metacarpals are all fused with one another and with the distal carpalia to form the carpo-metacarpus. ”

“ Broadest proximal end of all of the metacarpals. Proximal and distal ends expanded relative to shaft width. Undivided distal articular surface. A rounded tuberosity extends distally from the medial corner of the distal end. The transverse axis of the distal end is flat in side view. The external face is convex along its entire length, whilst the proximal-most third of the internal face of the shaft is concave. The mid-shaft cross-section is oval in shape. The distal articular end is subrectangular in distal view with a broader medial face. ”

“ Arterial blood passing through the several tissues, becomes once more venous. A considerable quantity of the oxy-hæmoglobin becomes reduced, and a quantity of carbonic acid passes from the tissue into the blood. The blood which comes from a contracting muscle, is not only richer in carbonic acid, but also, though not to a corresponding amount, poorer in oxygen, than the blood which flows from a muscle at rest.
A muscle is always producing carbonic acid, and when it contracts there is a sudden and extensive increase of the normal production. Oxygen is necessary for the life of the muscle. ”

“ The contact of the muscular fibre with blood-vessels is very close; but the chemical composition of the blood that moistens it varies according to the quantity of work yielded; thus it is indispensable that new fluid should be constantly transfused into the network of veins in the muscle. If the motor fibre is at rest, the blood passing through it is scarcely modified. If it is in a state of half contraction, the oxygen decreases in the blood, and the carbonic acid increases. If contraction is evident and powerful, combustion and production of carbonic acid are then at their maximum ”

“ In this other jar you see a muscle contracting in an atmosphere of nitrogen, and in this third jar a similar muscle contracting in an atmosphere of hydrogen. You observe this fourth one contracting even in a jar of carbonic acid. It is quite true a muscle will not live long in these circumstances, but even in an atmosphere containing no oxygen a muscle will go on producing carbonic acid. Now as carbonic acid is a compound made up of carbon and oxygen, it is evident that the muscle must have got oxygen from somewhere. ”

“ The amount of subepicardial fat, its color, translucency, occurrence of serous atrophy, œdema, subepicardial hemorrhage, etc., are to be noted. In marasmus a serous or mucoid degeneration of the subepicardial fat is not uncommon. The subepicardial fat increases with age, and is normally most abundant along the grooves and blood-vessels, particularly the auriculoventricular grooves and on the right ventricle. Normally the color of the heart-muscle of the ventricles should be seen through the epicardium. The fat is increased in obesity, chronic alcoholism, chronic anæmia, tuberculosis, etc. ”

“ From this point of view we must consider substances, which leave the cell and pass into the blood in a state of insufficient decomposition, as being out of harmony with the blood, or rather with the plasma; and, inversely, disturbances would certainly occur in the metabolism of certain cells, if, for instance, the insufficiently decomposed constituents of muscle cells were to penetrate the cells of the kidneys. The units of the muscle cells are out of harmony with the cells of the kidneys, and only a radical reconstruction could make them harmonious therewith. ”

“ Animals were placed in a mixture of 1 c.c. 0.1% pilocarpine + 10 c.c. m/6 CaCl2. These behaved exactly as though the water had not been replaced by CaCl2. In other words, the presence of the CaCl2 did not delay at all the action of the pilocarpine. This was repeated many times, and it seems that in Sida at least the action of pilocarpine is not at all antagonized by calcium chloride. In a mixture, however, of 10 c.c. 1% atropin sulphate + 1 c.c. 0.1% pilocarpine no evacuation of faeces took place and there was no increase in peristalsis. ”

“ The pericardium, or outer investing membrane of the heart, is frequently liable to inflammation, milked by a quickened and irregular respiration, and an action of the heart, bounding at an early period of the disease, but becoming scarcely recognisable as the fluid increases. The patient is then beginning gradually to sink. A thickening of the substance of the heart is occasionally suspected, and, on the other hand, an increased capacity of the cavities of the heart; the parietes being considerably thinner, and the frame of the animal emaciated. ”

“ At the same time the non-striped muscles slightly lose their tonicity, and when very large doses are given the haemoglobin of the blood becomes converted into the chocolate-coloured methaemoglobin. The volatile members of the group act much more rapidly and more transiently than the others.
Group XIX. Alkaloids.—This embraces a very large number of important pharmacological substances, which differ a good deal in the details of their action, but they all act upon muscle and nerve tissue. Some of them affect only certain portions of the nervous system, others have a much wider range of action ”

“ The degenerations in the arteries following the experimental lesions are of the nature of a fatty metamorphosis, and later proceed to calcification. Barium chloride, digitalin, physostigmin, nicotin and other substances, as well as adrenalin, have been found to exert a selective toxic action on the muscle cells of the middle coat of the aorta. The infundibular portion of the pituitary body, the portion which is developed from the infundibulum of the brain, possesses an internal secretion, which, injected intravenously, causes a marked rise of blood pressure and slowing of the heart beat. ”

“ The middle lobe was in part permeable to air; and there were several small cysts containing liquid carbon, connected with minute bronchial ramifications. Various indurated knotty bodies were extended throughout its substance. In the upper lobe, the carbon was confined principally to the interlobular cellular tissue, and when pressed in the hand, gave out thick, black, frothy serum. The mucous membrane of bronchial divisions, when freed from the black matter, was swollen and eroded as far up as the bifurcation of the trachea. ”

“ In the left ventricle the papillary columns and the layers of muscle just beneath the endocardium are most affected, and in a curious streaked or patchy way—the tabby mottling of some authors. A similar change may be seen in the right ventricle, particularly in the hypertrophy from mitral disease. In the auricles the right may show patches on the musculi pectinati, but on the left, which is most often affected, the thick endocardium usually obscures it. Chemically, it has been shown that in fatty degeneration the heart may contain from 3 to 5 per cent. more fat than normal. ”

“ We know that when the muscle contracts some of these constituents are disarranged through what is spoken of as chemical decomposition, and that there results a change in the substance of the protoplasm, accompanied by the excretion of a certain portion of its constituents, and by the liberation of heat. Carbonic acid gas, for example, is generated and is swept away from the muscular tissues in the ever active bloodstreams, to be carried to the lungs and there expelled—it being a noxious poison, fatal to life if retained in large quantities. ”

“ The venous blood which returns from every portion of the system comes back as a dark crimson, instead of being bright scarlet like the arterial blood. It contains carbonic acid, and returns it to the lungs, where it is exhaled by the breath. The oxygen is necessary to existence, while the carbonic acid is injurious. The effect of exercise, then, in any form, is thus to distribute healthy blood more rapidly through the system, while it removes the injurious matters quite as speedily. The effect of active exercise on the heart, as it is well known, is to make it beat faster ”