DIS-DIAPASON. 



DISLOCATION. 



this famous statue several ancient copies are iu existence, one of the 

 very finest being that in the British Museum engraved below. The 



[The Discobolus, from tbe statue in the British Museum.] 



figure in represented in action at the precise moment of delivering the 

 discus. Ovid (' Metam.,' li. x., v. 175) and Statius (' Theb.,' vi., v. 64G) 

 have both described the diversion of the discus ; see also Petri Fabri, 

 ' Agonisticon, give de Re Athletica, Ludisque Veterum,' 4ia, li. ii., c. i., 

 Lugd. 1595. 



The term discus was likewise applied to circular shields or bucklers, 

 of a large size, placed in the temples, on which great actions were 

 represented, or the names inscribed of the ephebi, that is of the young 

 men, who had devoted themselves to the service of then- country. 

 One of these circular shields is in the Townley Collection of the 

 British Museum, containing the names of the ephebi of Athens, under 

 Alcamenes, when he held the office of cosmetes. It was found in a 

 church at Athens in 1748, by Dr. Askew, who was informed that it 

 had been brought there from the Parthenon. Such too was the shield 

 of Scipio Africanus, found in the Rhone hi 1656, engraved in Spon's 

 'Miscellanea Eruditce Antiquitatis,' p. 152, edit. 1685. Anacreon has 

 an ode on a disk of silver, representing Aphrodite rising from the 

 sea: Od. 51, EJI biaxov (xorra'AQpoSi-rriv. See likewise Montfaucon, 

 ' Supplem. de 1'Ant. Expliq..' liv. iii. p. 64. Discs sculptured on both 

 sides, with heads, bacchanal subjects, &c., were also suspended by 

 chains between the columns of Roman mansions and theatres. Several 

 specimens of these cli/pea, as they were called, may be seen in the 

 Grseco-Roman Basement Room of the British Museum. 



DIS-DIAPASON, the name given by the Greeks to a scale of two 

 octaves. [DIAPASON.] 



DISLOCATION. Various parts of the body are liable to be dis- 

 placed by the direct application of violence or by more gradual causes. 

 But the term didocation is commonly appropriated to displacements 

 occurring about the joints. In this sense it is nearly synonymous with 

 M, but not entirely ; for the latter term carries with it more of 

 the idea of external force, and it is not quite so generally applied. It 

 is usual, for instance, to speak of the ditlocation,noti the luxation, of 

 the internal cartilage of the knee ; and the latter term is seldom if ever 

 used in describing the displacements of the small bones of the wrist or 

 instep, or of single vertebrae. 



The injuries classed under this title may be effected by external 

 violence, or by the undue contraction of muscles, or by both of these 

 causes combined ; and they result in some instances from disease 

 within the joints themselves, by which their ligaments are weakened 



or destroyed, and their sockets rendered insecure by ulceratiou and 

 other gradual changes. 



AVhen, by the protrusion of the bone through the skin, or other- 

 wise, the dislocation is complicated with an external wound exposing 

 the cavity of the joint, it is said to be compound ; and, as in the parallel 

 case of fracture, this aggravation of the injury is very serious, and the 

 most skilful management is required to save the life or limb, where 

 the injury happens to one of the larger joints. 



The particular dislocation takes its name either from the joint 

 itself or from the farthest bone ; and various terms are added to indi- 

 cate the direction of the displacement, or the new situation of the 

 head of the bone. Thus, the most common form of the accident at 

 the hip is called " a dislocation of the head of the femur (thigh-bone) 

 backwards upon the dorsum Hit" (flat part of the haunch-bone). 



Any bone may be displaced in any direction, but the accident 

 happens most frequently in those joints and directions in which the 

 extent of motion is the greatest. Thus the most common dislocation 

 is that of the shoulder, which is the most movable joint ; and its most 

 frequent variety is that in which the head of the humerus (or bone of 

 the upper arm) is drawn downwards into the axilla (or arm-pit) by the 

 sudden contraction of certain strong muscles. This happens when the 

 arm is raised to the utmost, as in reaching to close a window ; that is 

 when it has moved through an angle of 180 degrees from its natural 

 position. The most usual dislocation of the hip is that, already men- 

 tioned, on the dorsum ilii, for the same reason. It is generally produced 

 by sudden pressure or a blow on the knee when the thigh is bent upon 

 the abdomen ; the head of the fern ur is thus driven backwards from 

 the socket, and is then drawn farther back and upwards by the power- 

 ful muscles of the buttock. 



The jaw is sometimes thrown out of joint by the mere act of 

 yawning ; and that accident happened to a gentleman known to the 

 writer in opening his mouth to make the usual response at church. 

 The word was cut short at the first syllable ; for in such cases the 

 chin suddenly drops and is thrown forward, and it is impossible by 

 any effort to shut the mouth. This distressing but irresistibly ludi- 

 crous accident may be relieved immediately by any bystander wrapping 

 a napkin round his thumbs and placing them firmly against the back 

 teeth, so as to press them downwards, while with the fingers and palms 

 the chin is steadily raised and pushed backwards. But the operator 

 should be on the alert to withdraw his hands the moment the jaw 

 snaps back into its place, or he may receive a very unpleasant inti- 

 mation of the success of his efforts. 



It will be easily seen from these instances how important a part is 

 played by the muscles in determining both the occurrence and 

 direction of these accidents. Hence arises in part their infrequency, 

 often wondered at, during infancy and childhood ; for though the 

 flexible joints of the young have a greater extent of motion than those 

 of the adult, their muscular power is not only weaker as compared 

 with the strength of their ligaments, but is much more tardily thrown 

 into action, as may be observed in their tottering gait. The fragility 

 of their bones is another cause of this infrequency, by rendering them 

 more liable to be broken than displaced 'by external violence. The 

 only dislocation that is at all common in children is that of the hip, 

 which is the consequence of scrofulous ulceration of the ligaments and 

 the socket, and of the ball-shaped head of the femur within it. 



The reader will be prepared by what has been said to learn that the 

 spasmodic and violent contraction of the muscles consequent upon 

 these displacements is the chief or only obstacle to their reduction. 



This object is effected by a process technically called extension, 

 consisting in the application of force in a proper direction, and steadily 

 kept up till the muscles are fatigued. The head of the bone is thus 

 drawn down a little below the level of the joint ; and being lifted over 

 the edge of the socket, slips easily into its place upon slightly relaxing 

 the extending force. This force is often required to be very con- 

 siderable, and in such cases it is customary to make use of a block of 

 pullies, the bone which contains the socket having been first securely 

 fixed to a staple in the wall by proper bandages. Luxation of the hip 

 is here supposed ; for the other joints are so inferior to that in strength 

 that then- displacements may generally be reduced by less imposing 

 means. It is sometimes necessary to favour the relaxation of the 

 muscles by emetics, warm baths, and bleeding, and it is reckoned a 

 point of good management to call off the attention of the patient 

 during the extension by annoying him with questions and even exciting 

 him to anger. 



Almost all dislocations arising from accident may be reduced in this 

 way, and the joint rendered nearly or quite as perfect as before : but 

 this can only be done on condition of perfect rest during a period 

 sufficient for the firm union of the ruptured ligaments ; for if this 

 precaution be not strictly observed, and the ligaments are suffered to 

 be stretched by motion while the uniting substance is soft and exten- 

 sible, the accident is ever afterwards liable to recur. No time should 

 be lost in seeking assistance, for the swelling that comes on soon 

 renders the nature of the accident obscure, and the reduction extremely 

 difficult and painful. When a joint has been unreduced for a certain 

 time, which varies with the particular joint, and with the bodily 

 strength of the individual the weaker having the advantage in this 

 respect it is unwise to make any attempt at reduction. The jiarts 

 have now become consolidated and adapted to their new situation, and 



