CHAPTER XXI

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WOUNDS AND THEIR REPAIR.

The old classification of wounds divides them into _contused_, _lacerated_, _punctured_, and _incised_. For descriptive purposes these adjectives are self-sufficient; they can be criticised only in case the injuries differ in character. The adjectives thus employed allude to the character of the injury as well as to its cause, but no meaning should be conveyed by any of them other than to indicate a severance of continuity in tissues. In either case cells are rudely torn apart. But whether the injury be subcutaneous and the tearing make a ragged surface; or whether the wound be an open one, with the possibility of introduction of germ-laden air and grosser impurities, even though the surfaces separated present an even plane, as in an incised wound; or a channel or tunnel, as when made by a pointed instrument or a gunshot missile, the principle is the same, and the same processes of repair are brought to work to undo the harm. There is but one natural method of repair, and that includes the exudate, or the utilization of the fluid portion of the blood already poured out, and the activity of cells, those which lie in the vicinity and those which are furnished from a distance, _i. e._, leukocytes and wandering corpuscles. It is of advantage to have the injury subcutaneous and protected from contact with the air, yet extensive injuries of this kind are often much longer in healing than those inflicted by the surgeon’s knife, when the parts can be brought into complete apposition with each other by sutures.

It is the writer’s intent to simplify the description of the healing processes and to insist that it is always the same, not modified in character but in duration and extent, according to the nature of the injury.

CONTUSION.

The term contusion implies a subcutaneous injury of varied extent, in which laceration cannot be left out of consideration. Even in the mildest contusion mechanical harm has been done, permitting a dilatation of the vessels and the escape of fluid. Should this occur in linear form, as by a whip-lash, there may be what is called a _wheal_. In loose tissues swelling occurs more easily, as in the eyelid, the scrotum, etc. Injuries of severity will produce laceration, at least of capillaries if not of arterioles, and the result is the escape of an amount of blood which will infiltrate the surrounding tissues and discolor them and produce an _extravasation_ or _ecchymosis_. The blood barely escapes and coagulates before its absorption begins. The fluid portion disappears before the solid, and the pigment is usually the last. There results a _black and blue spot_; the color when near the surface is at first indigo or purple, and fades out through bluish and greenish tints into a yellow, which may not disappear for two or three weeks. Should blood collect in a cavity or in large amount the mass is called a _hematoma_; this is especially common in the pelvis and in the cranial cavity. Should a vessel wall give way from weakness caused by disease instead of by accident the result is the same.

Contused wounds of the surface often cover excessive and even fatal injuries within, as when a heavy object falls upon or injures the abdomen or a limb. The skin is resistant, and the writer has seen a limb pulpified by being run over by a heavy car, the skin being but slightly torn. In such accidents exploratory incisions are imperative. Better results will follow opening the abdomen in cases of severe contusion, for the purpose of exploring the viscera, than will follow the “let-alone” policy of waiting for something serious to appear.

An outpour of blood should be expected in every contusion, save the most trifling, while clot formation may ensue. Whether the clot will be absorbed or require the aid of the surgeon will depend upon its size, its location, and its liability to infection. Clot in some locations, _e. g._, pressing upon the brain or spinal cord, may justify extensive operation for its removal.

_Pain produced by contusion_ is variable. When nerve trunks of considerable size have been injured pain is frequently aggravated. In general it is proportionate to the amount of swelling, _i. e._, to the density or laxity of the injured tissue. When exudate occurs beneath unyielding membranes, for instance the periosteum and the capsules of certain organs, the pain may be severe. The appearance of discoloration is proportionate to the depth of the injury and the amount of hemorrhage. The time of its appearance will depend upon the distance from the surface; after fracture of the neck of the femur it may not be observed for several days. The general condition of the patient will depend greatly upon his temperament. When there has been considerable extravasation the release of the fibrin ferment may produce a mild rise in temperature.

=Treatment.=--So long as air or other infection can be excluded the treatment of contusions is simple. Cleanliness of the injured parts should be enjoined; also physiological rest, by their confinement within dressings or splints, or by placing the patient in bed. An antiseptic application, dry, watery, or in ointment form, should be applied upon a surface which has been abraded. Differences of opinion exist as to the respective values of heat and cold. When the case is seen early, before much swelling has occurred, the exudate may be limited by the application of cold dressings; whereas if seen after the swelling is at its height the use of moist heat may favor a more speedy re-absorption. The effect of extremes, either of heat or cold, is sedative, although hot applications afford more relief than do those of ice. Of domestic remedies in use among the laity it may be said that those which have any value owe it to the alcohol which they contain. Elastic constriction will reduce the amount of exudate and assist in the absorption of that already present. It is a measure, however, to be used with great caution lest venous return be interfered with and edema or gangrene be the consequence. A joint tensely distended with fluid as a result of combined contusion and laceration, called a _sprain_, may be emptied by aspiration, but this should be used only under antiseptic precautions. Finally any collection of blood which fails to disappear may be incised and cleaned, its cavity mopped out with compresses, and its surface made to come in contact by pressure. In hematomas and large extravasations of blood, sometimes in joints, but rarely in the pleural or peritoneal cavities, this method may also be used.

LACERATED WOUNDS.

Lacerated wounds differ from contused in the character of the tears in the tissues affected and in the exposure to infection by contact. They vary in extent and severity. Not infrequently tissues or organs of the greatest importance are lacerated, _e. g._, the globe of the eye, the liver, the intestines. The term laceration itself implies such open injury that part of it may be exposed to infection. The first danger is from hemorrhage. This may subside spontaneously, or may have been checked by some first aid, or may prove nearly fatal by the time the patient is seen by the surgeon. The first measure will be _hemostasis_ by the readiest and most effective measures at hand. This may mean the application of compresses or of a tourniquet, or even of manual pressure, until surgical procedures can be instituted. Shock should be treated by lowering the head and raising the extremities, or bandaging the latter, and the subcutaneous administration of morphine or atropine. Emergency treatment of these cases should include removal of foreign bodies, and such cleanliness and attention to antisepsis as may be possible at the time. Support of the injured part should be effected temporarily until dressings can be scientifically applied. If cane sugar will keep fruit and meat from decomposition it will have the same effect in human tissues, and a laceration with or without compound fracture of bone may be filled with granulated sugar until a suitable dressing can be applied.

The surgical treatment of laceration should include the following measures: _Hemostasis_; the _removal of foreign bodies_, as well as of tissue which is so injured as to make repair impossible or even questionable; a careful _study of nerve supply_, in order to be sure that no nerve suture should be made; a similar _study of muscles and tendons_, in order that tendon suture may be promptly made; careful _antisepsis_ throughout, asepsis being impossible; closure of the wound by buried and superficial sutures, and such drainage tubes or outlets as may permit free escape of whatever products of inflammation or disintegration may result. There should also be provision for physiological rest of the injured parts as well as of the patient’s mind and body.

When large areas of skin or deep tissues are destroyed or torn away, as in scalp wounds, avulsion of limbs or parts of limbs, it may be necessary to retain that which can be saved and to remove that which would slough if left to itself, thereby providing for flaps of skin by which the wound may subsequently be covered, or leaving them in case removal of a part must be made.

Everything which has vitality should be spared; on the other hand, that which has lost its vitality should be removed at once. Thus amputations may be sometimes called for because of extensive lacerations with destruction of vascular and nerve supply, even though the bones be uninjured.

In cases where the question of viability of tissues cannot be promptly decided it is best to keep the injured part immersed in water as warm as can be borne. In hospitals the entire body may be kept immersed for days. By the use of warm water parts which have been seriously injured may be restored. Ulcerations which are seen after the sloughing process has begun can be best treated by immersion or by the application of brewers’ yeast upon compresses or cotton. No other substance, perhaps, will so quickly clear up an indolent or foul surface as this; it hastens the time of separation of all that is dead or dying and restores healthful activity to the surrounding tissues.

Extensive lacerations leave frequent opportunity for operations by which function may be restored or improvement affected.

PUNCTURED WOUNDS.

The essential features of punctured wounds are sufficiently indicated by the descriptive name; but harm may be done through a small external opening. An important subvariety of punctured wounds is inflicted by _gunshot_ missiles, which will receive consideration by themselves. Injury to important vessels may lead to serious hemorrhage; while injuries to nerve trunks may be followed by paralysis of sensation and motion, or, as in the case of a sympathetic trunk, by the well-known consequences of division of vasomotor nerves, _e. g._, in the neck. When the punctured wound bleeds freely and externally it may be assumed that some large vessel has been injured. When it bleeds into one of the cavities of the body delay in recognition may occur. This is true of a puncture of the skull by which the middle meningeal artery or one of the sinuses is wounded, when the symptoms of brain pressure may tardily or rapidly appear. In the chest the intercostal or internal mammary artery may be so injured as to bleed into the pleural cavity and cause death. A puncture of the heart frequently leads to fatal hemorrhage into the pericardial cavity, and in the abdomen puncture of the various viscera has led to consequences beyond help save when prompt relief could be afforded.

The dangers attending punctures pertain to the introduction of infectious material which may produce sepsis or may slowly produce tetanus. No ordinary weapon or tool is clean in a surgical sense, while a rusty nail is even less so. It will be seen, therefore, that the danger inherent in such a case is not to be measured by either the size or the depth of the wound.

In dealing with these cases the first attention is to be given to _hemorrhage_. Obviously punctures in certain regions are much more likely to be followed by hemorrhage, and any puncture in the vicinity of one of the large vessels should be managed with caution, especially if the surgeon ascertain that it had bled profusely when first inflicted. Such a puncture, when seen a few hours later, may have become occluded by clot, or a considerable hematoma may have formed beneath the skin. It is safe to presume that there is more danger of septic infection than can accrue from later attention, and it would be advisable in such cases to anesthetize the patient and lay open the parts freely under full aseptic precautions, in order that the clot be turned out and any bleeding vessel secured. A brief study of such a case will decide the question of injury to the principal nerve trunks. A principal nerve which has been injured or divided should be carefully sought for and its ends freshened and sutured. This is true also of any tendon whose function is evidently lost. If the thorax have been punctured and the physical signs indicate the presence of fluid, _i. e._, blood in the pleural cavity, it should be incised and the blood withdrawn. This method should also be applied to punctures of the heart. These measures will be more completely dealt with in treating of the surgery of the chest and its contents.

_Punctured wounds of the abdomen_ may give rise to great anxiety. If none of the viscera have been injured they may be let alone, but if doubt exists as to the safety or injury of any of them the abdomen should be opened. (See Surgery of the Abdomen.)

=Treatment.=--For emergency purposes antiseptic occlusion is the best procedure, and all punctures inflicted by ragged and infectious materials, as rusty nails, should be treated by free incision, with thorough cleansing and packing with antiseptic material, that the wounds may heal by granulation.

INCISED WOUNDS.

Incised wounds are those inflicted by a sharp object which divides the tissues abruptly and with a minimum amount of disruption. They invariably bleed, sometimes seriously, even to a fatal degree, the hemorrhage in such cases being due to severance of large vascular trunks. Like contused wounds they vary as infinitely in extent as in locality. According to their locality and dimensions important structures may be severed, _e. g._, the trachea, the large nerve trunks of the body, the tendons, etc., while visceral and joint cavities may be more or less widely opened. When death occurs soon after injury it is generally from hemorrhage. They are attended by the same dangers of septic infection as are punctures, especially when there is neglect in the emergency dressing. Should the pleural cavity be opened there may be collapse of the lung.

_Hemostasis_ is the paramount indication in all incised wounds which bleed seriously. Hemorrhage is to be controlled temporarily by any expedient, later by ligation or suture, or both. The remarks above in relation to possible injury to vessels and nerves are of equal force in this consideration. Every divided nerve trunk, as well as every severed tendon, should be reunited by suture. If a joint have been opened it should be cleansed and drained, even though the incision be closed. Should there be injury to any of the viscera, the wound may be enlarged in order that exploration may be made and suitable remedies applied. This is true of every punctured or incised wound. No hesitation need be felt about enlarging it so as to permit of investigation. Hemorrhage having been checked and all required attention having been given, the closure of an incised wound may be made partial or complete according to its condition. If fresh and clean it may be almost completely reunited, using deep and buried sutures in order to bring into contact its deeper portions, while superficial sutures will suffice for the skin. Drainage may be by tubes or gauze or by loose suturing of the surface; but no incised wound whose surfaces have become contaminated should be completely closed by primary suture until all such surfaces have been freely cut away and appear healthy and uninfected. An old infected and gaping incised wound may be cleaned by the application of brewers’ yeast, and when granulating it may be closed secondarily with sutures, by which granulating surfaces are brought into close contact.

_Of wounds in general_ it may be said that there are mixed types as well as illustrative examples. Thus a wound made by a hatchet or axe may partake of the nature of contusion and of incision. In instances where personal violence has been applied multiple wounds of varied character may complicate the case. The statements made above pertain to their conventional and common characteristics. Treatment which would be proper in one case may be impossible in another. There is always room for discretion and good judgment, though there are fundamental rules which apply to all cases, and include exact hemostasis, surgical cleanliness, repair of severed nerves and tendons, removal of foreign bodies and involved tissue, and the enforcement of physiological rest.

REPAIR OF WOUNDS.

The process of repair is _essentially the same_, being modified only by the needs of the wound and the tissues involved, and by their environment. Whether soft tissues or bones are being repaired the differences are apparent rather than real, as bony tissue is temporarily decalcified, and then, as soon as the process permits, is once more stiffened by deposition of calcium salts.

The process of repair should be begun immediately after the cessation of the disturbance which has produced the wound, and as soon as the bleeding is checked. It may be materially influenced and retarded by the presence of bacteria or other foreign bodies, but its character remains unchanged. Healing has been described as occurring by _primary union_, or by “_the first intention_,” and by _granulation_, or the “_second intention_.”

Wounds which have been permitted to remain clean, with their edges brought together so that the surfaces are in contact, are healed with a minimum of waste of reparative material, the process being as follows: The small vessels are occluded with thrombi up to the first collateral branches; the leukocytes begin to penetrate the film of blood, which, having coagulated, serves as a cement to help hold the surfaces together. By their proliferation and more complete organization the gap between the surfaces is bridged with both fibrous and capillary bloodvessels, and within sixty or seventy hours the clot has become largely replaced by organized cells. Meantime from the endothelial cells of the vessels and vascular spaces, as well as from the fixed cells of the connective tissue, the so-called _fibroblasts_ are formed, which are later converted into connective tissue. Many of the cells which have wandered to the scene of activity, or have been there reproduced in unnecessary numbers, disappear again, either into the circulation or they serve as food for the fibroblasts. Branching cells attach themselves more intimately, and thus the original clot is completely converted into _fibrous and connective tissue_, and this becomes a _scar_, which extends as deeply as did the original injury. New capillaries are rapidly formed by a budding process, and supply the pabulum required for nourishment of the new cells. By fusion or amalgamation of neighboring vascular buds complete new vessels are formed, extending through the new tissue from one side to the other, while around them the fibroblasts or connective-tissue elements arrange themselves. From this it will appear that the coagulum which forms within a wound is desirable as a scaffolding upon which the process of repair may be begun. But it is desirable that this coagulum should be small in amount, in order that these processes may not be too long delayed; hence the advisability of removing all clots within a wound when closing it, and preventing the formation or leaving of _dead spaces_ in the tissues in which blood clots may collect.

_The process of granulation_ is not dissimilar to that described above, save only in its gross appearances. Granulations consist of vascular buds surrounded by leukocytes and lightly covered by them, while around the base of each bud epithelioid and spindle cells arrange themselves, these fixed cells organizing themselves more and more, as the wound fills up, with the more superficial layers of granulations. In time they are converted into a dense fibrous tissue which forms later what is known as the _scar_. As before, also, the spaces between the young capillary loops are filled with large nucleated cells derived from the fixed cells of the tissue, and from the endothelial lining of the newly formed vessels. Thus fibroblasts are produced in each case, and are often more or less mingled with giant cells, especially if some foreign body, such as a silk ligature, be embodied in the tissues. The

## particular function of the leukocytes seems to be the removal of red

corpuscles and fibrin from the original clot.

The _granulation tissue_ thus constituted by capillary loops and proliferating cells constitutes the basis of all wound repair. Later this tissue assumes more of the fibrous and less of the cellular character, while the fibroblasts arrange themselves in accordance with the mechanical requirements of the tissues and the stress or strain placed upon them. This tissue is at first vascular, but as it condenses its capillaries become less numerous and smaller, and the final white fibrous scar is usually almost bloodless.

When there has been loss of skin, or when skin edges are not brought together, the deeper process of granulation needs an epithelial covering, which cannot be afforded by mesoblastic or endothelial cells. The formation of an epithelial or epidermal covering is a process peculiar to epithelial tissue alone, and takes place mainly from the cells of the rete Malpighii.

Epithelial elements of the skin will afford a large amount of covering, and yet even their activity sometimes is insufficient and has to be atoned for by _skin grafting_. Should the granulating surface be small, and so situated that the fluid upon its surface may dry by evaporation, there will result a crust or scab, which, while it conceals from observation what is going on beneath, serves as an admirable protection, beneath which proliferation of epithelium takes place. A spontaneous detachment of the scab may take place when this process is complete, and with the loosening of the crust it is apparent that repair has become complete. This is known as _healing under a scab or under a crust_.

Two clean and healthy granulating surfaces may be so placed in contact with each other as to blend together by exactly the same process as that by which granulations are first formed. This is called _secondary adhesion_, or by the older writers the “_third intention_.” Advantage is taken of this possibility in the application of what are called _secondary sutures_, which may be placed some days before they are utilized, with the intent to bring together surfaces so soon as they shall present granulations.

One of the most interesting of all healing processes is that by which _severed tissues_, when promptly replaced, often reëstablish vascular communication and grow again in a satisfactory manner. Thus a severed ear, nose, or finger-tip may be replaced, and, if carefully held _in situ_, the parts being kept at rest, will prevent disfigurement and the loss of important tissues. In these cases the severed tissue remains passive several days until it has become vascularized. Meantime its nutrition seems to be maintained through the medium of the living tissues to which it has been affixed, probably by absorption of their blood plasma.

Two human tissues are essentially non-vascular, the _cornea_ and _cartilage_. The former appears to be nourished by cellular interspaces which may admit leukocytes from the surrounding tissues, and through these proliferation and vascularization occur; while a scar in the cornea remains permanent, and the new tissue by which repair is brought about never becomes transparent like the cells composing the cornea proper. In cartilage scar tissue is produced, as in other tissues, by a similar process, in spite of the extent of the cartilaginous layer and its non-vascularity. In general the more specialized a tissue the less completely does it heal, and the specialized tissues, like the retina, etc., seem to be incapable of reproducing themselves. Low down in the animal scale some parts can be more or less reproduced. In the ascending forms there is less tendency in this direction; in man there is little reproduction of an original tissue, scar tissue taking the place of most of that which has been lost. An apparent exception to this is seen in the osseous system, where a large amount of bone may often be reproduced. Epithelium, also, whether on the external or internal surfaces of the body, can regenerate itself in large degree and amount. From every small island or mass of epithelial cells which can be retained new cells may thus be reproduced; hence accrues the advantage of leaving such epithelial collections whenever possible, and wherever they may be beneficial. If upon a burnt area it happens that epithelium has not been completely destroyed, new skin may be confidently looked for from each clump of epidermal cells. It should be remembered, however, that with the epidermization of a surface under these circumstances merely an epithelial covering is secured. The distinctively dermal appendages, such as hair, sweat glands, and sebaceous glands, are not reproduced. If the highest ideal results are to be secured in any case the parts must be put in the most favorable condition, which means early surgical attention to every wound.

INJURIES TO VESSELS.

Bloodvessels are subject to contusion, to laceration, and to incision. They may be contused by superficial blows, compressed against underlying bone, torn in the replacement of old dislocations, or punctured or incised by accidental or homicidal injuries. A vessel which is not abruptly divided but is seriously injured will usually sustain a separation of its internal and middle coats, which curl up within the external coat, occlude the channel, and lead to _thrombosis_. A vessel thus occluded may tend to gangrene of the parts supplied by it or to a temporary ischemia, with numbness and pallor if an artery, or to passive edema if a vein. In cases of such injury it is always hoped that the blood supply will be provided through the collateral circulation. If a vessel be torn or cut across there may result a hematoma which may lead to immediate prostration, from hemorrhage, and to gangrene by stopping the blood supply. Such blood tumor rarely pulsates, but may cause extreme pain. The character and the size of the swelling will depend upon the tissues which surround the injured vessel. Cessation of the pulse on the distal side of an injury nearly always implies temporary occlusion. _Traumatic aneurysm_ may be produced by lateral injury to an arterial trunk, by which its continuity as such is yet not completely disrupted.

If a large outpour of blood has occurred it will be safer to incise and turn out the clot and secure the injured vessel. In milder cases the surgeon should do all that he can by rest and by position to favor restoration of blood circulation. After the subsidence of acute symptoms massage and gentle motion will serve to promote absorption of the escaped blood. Cases will occasionally occur in which the principal arterial trunk of a limb should be tied, hoping thereby to save the member. Amputation may be the last resort when gangrene is impending.

_Injury to the veins_ is of a less serious nature in so far as immediate consequences are concerned; nevertheless a punctured wound or a large vein is always a serious matter. The pressure of the blood may produce gangrene, or cause so large a hematoma that it should be incised.

Fine silk sutures may be applied to wounded vessels, arteries or veins, when they have been partially severed.

The healing process in all these cases is essentially the same. It may mean the formation of a clot in or around a vessel, followed by absorption of its principal portion and organization of what remains. A vessel itself which has once been occluded by thrombus will usually remain closed, a cord of fibrous tissue taking its place. Only in rare instances is continuity of the blood channel preserved or regained. In such cases the collateral circulation affords the life-saving feature. The granulations which intrude themselves into the clot gradually substitute tissue for coagulum, the conversion beginning promptly, but often occupying weeks for its completion.

_Lymph vessels_ may be lacerated in almost any injuries and more or less lymph escape with the blood. When the skin is torn from the underlying parts lymph collects in the cavity thus made, while its wall may undergo more or less organization, and formation of a _lymph cyst_ results. Should one of these connect with a good-sized lymph duct, as, for instance, in the neck the thoracic duct, then lymph cysts of considerable size might form. Should these rupture or be opened lymph fistulæ might result.

INJURIES OF NERVES.

By small hemorrhages into a nerve sheath nerve function may be either temporarily or permanently disturbed. A compression too long-continued may lead to degeneration within the nerve fibers. Providing this do not occur there may be complete restoration of function, or there may result chronic neuritis, with pain and irritation. A later consequence of all nerve injuries is more or less serious disturbance of sensation, while still later parts supplied by the affected nerves may undergo more or less atrophy as well as spastic contraction, by which loss of function and deformity are produced.

There is a form of nerve injury which is due to the temporary pressure of the elastic tourniquet, frequently applied around limbs previous to operations, or to pressure which is made by crutch handles upon the axillary plexus, and called _crutch paralysis_. _Limbs carelessly allowed to hang over the edge of the operating table_ during prolonged operations also have suffered in the same way. Such lesions are of the character of a contusion, but are often followed by paresis, paralysis, and by various sensory disturbances.

Injury to a nerve trunk having been recognized by a study of the local features of a given case requires special treatment in case laceration or more localized division can be assumed. The nerve known to be lacerated and torn across should have its ends freshened and be reunited by fine catgut sutures; also a nerve trunk known to be punctured or divided. Such injury is not necessarily inflicted from without, as it may be produced by a fragment of bone; in this case the operation should be directed toward the bone as well as toward the nerve trunk itself. A divided nerve trunk, if neatly sutured, heals by the organization of blood clot, as in other instances, actual nerve communication being made across the intervening clot by a process of regeneration or reduplication of the true nerve elements, the peripheral neurilemma playing an important part. Autogenetic power decreases with the age of the individual. By careful nerve suturing disability may be prevented.

Even months after injury much can be accomplished by nerve suture properly performed. Symptoms similar to those of division may occur when a nerve trunk is surrounded and compressed by bone callus after fracture, as when the ulnar nerve is thus caught. If too long a time have intervened it may be necessary to exsect the injured portion and then bring the ends into apposition by sutures. Other methods of atoning for these nerve injuries by nerve grafting, etc., will be described in the chapter on Surgery of the Peripheral Nerves.

Neuritis may be overcome by counterirritation, preferably with the _actual cautery_, _i. e._, the “flying cautery,” by massage, and by galvanization. The pain in many of these cases can be mitigated, if not completely relieved, by the x-rays, or by the high-frequency current. In some cases nerve elongation may be brought to bear and a tender and irritable nerve be thus brought under subjection.

INJURIES TO MUSCLES AND TENDONS.

Lacerations or divisions of muscles are usually repaired at first by fibrous tissue, the result of organization of a clot. Later a true muscle regeneration takes place and muscle scar finally disappears. Atrophy of a muscle is not a sign of injury directly to itself, but often results from injury to the nerve which supplies it; for example, the circumflex nerve may be injured in shoulder dislocations, while the deltoid muscle, which is supplied by it, speedily undergoes atrophy.

Muscle fibers may be torn by violent exertion. Such an accident may be followed by pain and loss of function. An interval can often be felt, even from the outside, between the torn muscle ends. The injury will produce considerable hemorrhage. The amount of function regained in a muscle will depend to some degree on the extent of its injury. If it have been injured by an incised wound it will depend upon the way in which it is brought together after an open incision. The origin and insertion of such a muscle should be approximated by proper position, and so maintained by the dressings, in order that perfect rest may be more easily maintained. When a portion of the fascia or aponeurosis is torn the muscle fiber may protrude and form a _hernia of muscle_.

_Tendons_ often suffer from _contusion_, in consequence of which they may become adherent within their tendon sheaths; this leads to stiffness of the part and more or less loss of function. Sometimes they calcify, as does the adductor magnus tendon in the formation of the so-called _rider’s bone_. The tendon most frequently injured is that of the quadriceps, near the knee.

If it can be decided that a tendon has been divided or torn across its prompt reunion by suture should be always practised. Also a divided muscle, if exposed, should be drawn together with sutures, chromic or hardened, so as to make them more reliable. Tears of aponeuroses and fasciæ should also be sutured. Tendon suturing is nearly always successful, especially if it can be done in a cleanly manner; while tendon grafting is a measure which may be reserved to overcome the consequences of injuries to muscles and tendons not disposed to repair.

INJURIES TO BONES.

Aside from simple and compound fractures, which are essentially bone wounds, there may be seen hemorrhages beneath the periosteum or in the immediate vicinity of bones, which are usually small in amount, yet may cause considerable disturbance. The _traumatic hematoma of the scalp_ which often follows delivery is an illustration of an injury of this class, the periosteum itself being sometimes separated. Collections of blood under these circumstances which fail to disappear by absorption may be incised and the contained clot turned out.

[Illustration: PLATE XII

FIG. 1

Young Granulation Tissue Following Bur., _a_, _aa_, thin-walled capillaries. Large nuclei, fibroblasts horseshoe nuclei, leukocytes. × 250.

FIG. 2

Young Scar. Numerous capillaries perpendicular to surface. Spindle elements, fibroblasts considerably smaller than in Fig. 1. × 250.

FIG. 3

Mature Scar. Dense fibrous connective tissue with a few fibroblasts. At _a_, a small bloodvessel. × 250.

Granulation Tissue organizing into Cicatricial Tissue. (Karg and Schmorl.)

Illustrating statements made on several of the foregoing pages.]

CONTUSIONS OF THE VISCERA.

Contusions of the viscera may be followed by many and disastrous consequences. They compromise such lesions as rupture of the liver, kidney, spleen, laceration of the bowel, bladder, or gall-bladder, and may occur by blows which do not break the surface; or any of the viscera may be lacerated, punctured, or gashed by gunshot, punctured, or incised wounds. These will be more completely considered in Chapter XLV .

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