OCR Text |
Show 160 or DISLOCATION. surgeon, for he has to consider the consequences of the bones remaining long displaced before he determines on attempting to reduce the dislocation. I need not remind my readers of the nature of the ligaments and cellular substance. The ligaments are dense, white, strong, and possessed of little vascularity; they are of two kinds; first, such as are weak, but destined to preserve the sinovia, and to separate the articulating surfaces from the surrounding parts ; these capsules are very weak. The second kind possess no elasticity, pass from point to point of adjoining bones, and are the strength of the articulation. Perhaps with these may be classed such tendons of muscles as surround the joint, and are incorporated with the capsular ligament. Now it is possible, that one side of a joint only is sprained, i g. 'i ‘uf "' tion betwixt the head of the bone and its former place. Be- sides, there is another unfavourable circumstance, the muscles adapt themselves to the state of the bones, and are permanently shortened, so that they strongly resist the reduction. The meaning of the distinction into recent and old disloca- tion will now be understood. IVhen the dislocation is of long standing, the new adhesions are to be torn up, and violence must be done to .the limb, as great, perhaps, as that which caused the displacement of the bone, before it can he reduced : while in a recent dislocation there is no obstruction to the reduction but in the muscles, or natural ligaments. In speaking of the degrees of derangement of the joint from violence, it is proper to mention sprains, and to explain that degree of weakness which remains after them. the stronger uniting ligaments are partially lacerated, and A sprain is a momentary derangement of the articulating surfaces of bones, by which a stress is put on the ligaments, and those of one side are either partially torn, or they are stretched so that they inflame. In every sense of the word I. deny that the capsules and ligaments of a joint are insensible --sensibility to pain is the grand safeguard to the body; and, although the joints do not feel in the same manner and degree with the skin and superficial parts, yet they have that degree of sensibility which suits their condition ; is there not excruciating pain when a man sprains his ancle ? and yet the pain is not in the skin, it is quite different from the shock of a superficial part ; and except the skin, there is nothing to suf~ fer pain but tendons, and sheaths, and ligaments, which phym siologists say are insensible. Physiologists have erred because they have not perceived the end of this sensibility, and the variety in kind, as well as in degree, which is suited to the functions of the several parts. If the end of a bone, and the capsule, were sensible as the skin or eye, or other delicate or From this it follows, that there can« not be a. noosing of the head of the dislocated bone in the slit of the capsule, as some have imagined to be the case, when the reduction has proved difficult. (See further under the head of Dislocated Shoulder.) In dislocation, then, the head of the displaced bone lies among the cellular membrane, and is either lodged betwixt the muscles, or presses upon a bone. Where the smooth ar ticulating cartilage is in contact with the cellular membrane. it presses and condenses the cellular membrane so that it be comes a substitution for the natural capsule, while the torn capsules and ligaments adhere to the surrounding parts. If the head of the dislocated bone presses on a flat bone, as the os innominatum, or scapula, an imperfect articfilating surface is at last formed. In the mean time, the head of the bone 9 161 there is a weakness and yielding of the joint, or there is, perhaps, a subluxation. But when there is a dislocation, and actual displacement of the bones, both the capsular and unit‘ing ligaments must be torn ; sometimes in the whole circle of the bones, always for more than one half the circumference of the head of the bone. I'M-J"? ~wwum- fw'ak .. M-.- or DISLOCATION. gen, their common and necessary function would lay the foundation of inflammation, a greater degree of sensibility Would be the consequence, and the evil would increase until no longer resting in the natural cavity, the surrounding soft the mobility of the joint were destroyed. parts encroach upon the cavity. and adhesion: form a parti< necessary motion of the joints there is no sensation, no injury ‘vor. 1r. x: In the common and . " "swift" wow Minerw H |