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The diagnosis of contraction of tendons is an easy matter because of the fact that relations between the phalanges are constantly changed with tendinous contraction. If one bears in mind the attachments and function of the digital flexors, no difficulty is encountered in recognizing contraction of either tendon.
Locate five muscles that act as flexors; five that act as extensors; two that act as adductors; and two as abductors. Locate sphincter and radiating muscles. By what means does the nervous system control the muscles? Give proofs of the change of potential into kinetic energy during muscular contraction. Define the essential properties of muscular tissue and state the purpose served by each.
If the body be properly covered, the animal heat is being conserved, and laid up for expenditure during the waking hours that are to follow; the respiration is reduced, the inspirations being lessened in the proportion of six to seven, as compared with the number made when the body is awake; the action of the heart is reduced; the voluntary muscles, relieved of all fatigue, and with the extensors more relaxed than the flexors, are undergoing repair of structure, and recruiting their excitability; and the voluntary nervous system, dead for the time to the external vibration, or, as the older men called it, 'stimulus' from without, is also undergoing rest and repair, so that, when it comes again into work, it may receive better the impressions it may have to gather up, and influence more effectively the muscles it may be called upon to animate, direct, control."
Thus the biceps serves as one of the antagonists to the triceps, and the various flexors and extensors of the limbs are antagonistic to one another. The Tendons. The muscles which move the bones by their contraction taper for the most part, as before mentioned, into tendons. These are commonly very strong cords, like belts or straps, made up of white, fibrous tissue.
The articular parts of bones rest upon or against an inhibitory apparatus, and are slightly flexed, as in the carpus, or considerably flexed such as in the fetlock joint when weight is being supported. In the first instance, for example, the flexors of the carpus and the superior check ligament assisted by the flexors of the phalanges constitute the inhibitory apparatus.
The muscles of the limbs are almost as numerous as those of the trunk of the body, and even more complex. Most of them, on both arms and legs, are in two great groups one known as the "benders," or flexors, which, when they shorten, bend the limb; and the other, the "straighteners," or extensors, which straighten or extend it.
The same two classes of differences become obvious when the muscles of the hand are compared with those of the foot. Three principal sets of muscles, called "flexors," bend the fingers and thumb, as in clenching the fist, and three sets the extensors extend them, as in straightening the fingers.
The set of muscles that open the wing are called the extensors, and those that close it, the flexors. The former lie upon the back of the upper arm and the front of the forearm and the hand, their tendons passing over the convexities of the elbow and wrist, while the flexors occupy the opposite sides, and their tendons run up into the concavities of the joints.
Where practically all of the anterior surface of the radius has been denuded, recovery is tardy and there is in some cases imperfect extension of the leg for months after the wound has healed. But in such instances, animals gradually regain complete use of the affected member and in the course of a year function is fully restored. Inflammation and Contraction of the Carpal Flexors. Anatomy.
Careful discrimination should be employed in selecting cases for neurectomy for this operation; otherwise, it is very likely to prove disappointing. Open Sheath of the Flexors of the Phalanges.
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