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46-583: Bites often result in serious puncture wounds , avulsion injuries , fractures , hemorrhages , infections , envenomation , and death . In modern human societies, dog bites are the most common type of bite, with children being the most common victims and faces being the most common target. Some other species that may bite humans include urban animals such as feral cats , spiders , and snakes . Other common bites to humans are inflicted by hematophagous insects and arthropods, such as mosquitoes , fleas , lice , bedbugs , and ticks (whose "bites" are actually

92-399: A blunt or non-penetrating trauma may have some deep damage, but the overlying skin is not necessarily broken and the wound is still closed to the outside environment. The penetrating object may remain in the tissues , come back out the path it entered, or pass through the full thickness of the tissues and exit from another area. A penetrating injury in which an object enters the body or

138-522: A carrying mechanism for species such as beavers and ants , the raw power of their species-specific teeth allowing them to carry large objects. Beavers have a large tooth adapted for gnawing wood. Their jaw muscles are tuned to power through big trees and carry them back to their dam. Ants use their powerful jaws to lift material back to the colony. They can carry several thousand times their weight due to their bite and are adapted to use this to forage for their colonies. Fire ants use their strong bite to get

184-417: A cell to migrate from the basal cell layer to the top of the granular cell layer, and an additional two weeks to cross the stratum corneum. The dermis is the layer of skin between the epidermis and subcutaneous tissue, and comprises two sections, the papillary dermis and the reticular dermis . The superficial papillary dermis interdigitates with the overlying rete ridges of the epidermis, between which

230-674: A form of stinging rather than true biting). The types of teeth that organisms use to bite vary throughout the animal kingdom . Different types of teeth are seen in herbivores , carnivores , and omnivores as they are adapted over many years to better fit their diets. Carnivores possess canine, carnassial , and molar teeth , while herbivores are equipped with incisor teeth and wide-back molars. In general, tooth shape has traditionally been used to predict dieting habits. Carnivores have long, extremely sharp teeth for both gripping prey and cutting meat into chunks. They lack flat chewing teeth because they swallow food in chunks. An example of this

276-419: A grip on prey, then inject a toxin via their stinger and carry the prey back to their territory. Some organisms have dangerous bites that inject venom . Many snakes carry a venomous saliva containing at least one of the major groups of toxins , which include cytotoxins , hemotoxins , myotoxins , and neurotoxins . Spider venom polypeptides target specific ion channels , which excites components of

322-468: A hospital. Injuries from firearms are the leading cause of TBI-related deaths. Penetrating head trauma can cause cerebral contusions and lacerations, intracranial hematomas , pseudoaneurysms , and arteriovenous fistulas . The prognosis for penetrating head injuries varies widely. Penetrating facial trauma can pose a risk to the airway and breathing ; airway obstruction can occur later due to swelling or bleeding. Penetrating eye trauma can cause

368-521: A large part of the lower abdomen, are also at risk of perforation . People with penetrating abdominal trauma may have signs of hypovolemic shock (insufficient blood in the circulatory system ) and peritonitis (an inflammation of the peritoneum , the membrane that lines the abdominal cavity ). Penetration may abolish or diminish bowel sounds due to bleeding, infection, and irritation, and injuries to arteries may cause bruits (a distinctive sound similar to heart murmurs ) to be audible. Percussion of

414-917: A number of diseases with streptococci, staphylococci, and anaerobic organisms being very severe causing infections. These bites are typically deep cutting into the skin where the infection forms. There are several creatures with non-lethal bites that may cause discomfort or diseases. Mosquito bites may cause allergic wheals that are itchy and may last a few days; in some areas, they can spread blood-borne diseases (e.g. malaria and West Nile fever ) via transmission of protozoic or viral pathogens . Similarly, tick bites spread diseases endemic to their location, most famously Lyme disease , but ticks also serve as disease vectors for Colorado tick fever , African tick bite fever , Tick-borne encephalitis , etc. Young children who bite others do so out of play or aggression whereas adults bite others out of aggression. Bites that occur from adults fighting are usually on

460-428: A risk of shock and infection . The severity of the injury varies widely depending on the body parts involved, the characteristics of the penetrating object, and the amount of energy transmitted to the tissues. Assessment may involve X-rays or CT scans , and treatment may involve surgery, for example to repair damaged structures or to remove foreign objects. Following penetrating trauma, spinal motion restriction

506-531: A small number of skin diseases account for most visits to the physician, thousands of skin conditions have been described. Classification of these conditions often presents many nosological challenges, since underlying causes and pathogenetics are often not known. Therefore, most current textbooks present a classification based on location (for example, conditions of the mucous membrane ), morphology ( chronic blistering conditions ), cause ( skin conditions resulting from physical factors ), and so on. Clinically,

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552-602: A structure and passes all the way through an exit wound is called a perforating trauma , while the term penetrating trauma implies that the object does not perforate wholly through. In gunshot wounds , perforating trauma is associated with an entrance wound and an often larger exit wound. Penetrating trauma can be caused by a foreign object or by fragments of a broken bone. Usually occurring in violent crime or armed combat , penetrating injuries are commonly caused by gunshots and stabbings . Penetrating trauma can be serious because it can damage internal organs and presents

598-493: Is any medical condition that affects the integumentary system —the organ system that encloses the body and includes skin , nails , and related muscle and glands . The major function of this system is as a barrier against the external environment. Conditions of the human integumentary system constitute a broad spectrum of diseases, also known as dermatoses, as well as many nonpathologic states (like, in certain circumstances, melanonychia and racquet nails ). While only

644-415: Is associated with worse outcomes and therefore it should not be done routinely. As a missile passes through tissue, it decelerates , dissipating and transferring kinetic energy to the tissues. The velocity of the projectile is a more important factor than its mass in determining how much damage is done; kinetic energy increases with the square of the velocity. In addition to injury caused directly by

690-544: Is no more effective in preventing wound infection than standard care when used on open traumatic wounds. Before the 17th century, medical practitioners poured hot oil into wounds in order to cauterize damaged blood vessels, but the French surgeon Ambroise Paré challenged the use of this method in 1545. Paré was the first to propose controlling bleeding using ligature . During the American Civil War , chloroform

736-405: Is shown by the broad, serrated teeth of great white sharks which prey on large marine animals. On the other hand, herbivores have rows of wide, flat teeth to bite and chew grass and other plants. Cows spend up to eleven hours a day biting off grass and grinding it with their molars. Omnivores consume both meat and plants, so they possess a mixture of flat teeth and sharp teeth. Biting can serve as

782-621: Is significantly torn, or it may cause pericardial tamponade if the pericardium is not disrupted. In pericardial tamponade, blood escapes from the heart but is trapped within the pericardium, so pressure builds up between the pericardium and the heart, compressing the latter and interfering with its pumping. Fractures of the ribs commonly produce penetrating chest trauma when sharp bone ends pierce tissues. Penetrating abdominal trauma (PAT) typically arises from stabbings, ballistic injuries (shootings), or industrial accidents. PAT can be life-threatening because abdominal organs, especially those in

828-477: Is the adipocyte , or fat cell. The structure of this tissue is composed of septal (i.e. linear strands) and lobular compartments, which differ in microscopic appearance. Functionally, the subcutaneous fat insulates the body, absorbs trauma, and serves as a reserve energy source. Diseases of the skin include skin infections and skin neoplasms (including skin cancer ). In 1572, Geronimo Mercuriali of Forlì , Italy , completed De morbis cutaneis ('On

874-472: Is the most important aspect of the cutaneous examination. Over time, these primary lesions may continue to develop or be modified by regression or trauma, producing "secondary lesions". However, with that being stated, the lack of standardization of basic dermatologic terminology has been one of the principal barriers to successful communication among physicians in describing cutaneous findings. Nevertheless, there are some commonly accepted terms used to describe

920-435: Is transferred, the liver may disintegrate. Temporary cavitation can be especially damaging when it affects delicate tissues such as the brain , as occurs in penetrating head trauma. While penetrating head trauma accounts for only a small percentage of all traumatic brain injuries (TBI), it is associated with a high mortality rate , and only a third of people with penetrating head trauma survive long enough to arrive at

966-462: The American South where there was once a common belief that the bite of a "blue-gum negro " (i.e., a Black person with darkly pigmented gums ) was lethally poisonous. Puncture wound Penetrating trauma is an open wound injury that occurs when an object pierces the skin and enters a tissue of the body, creating a deep but relatively narrow entry wound . In contrast,

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1012-479: The peripheral , central and autonomic nervous systems , causing hyperactive neurotransmitter release and subsequently refractory paralysis. Spider bites , or arachnidism , are mainly a form of predation, but also means of self-defense — when trapped or accidentally tampered with by humans, spiders retaliate by biting. The recluse spider and widow species have neurotoxins and necrotizing agents that paralyze and digest prey. Humans biting each other can cause

1058-431: The retroperitoneal space , can bleed profusely, and the space can hold a large volume of blood. If the pancreas is injured, it may be further injured by its own secretions , in a process called autodigestion . Injuries of the liver , common because of the size and location of the organ, present a serious risk for shock because the liver tissue is delicate and has a large blood supply and capacity. The intestines, taking

1104-654: The Human Female . Biting may also occur in physical fights or in self-defense. Criminally, Forensic Dentistry is involved in bite-mark analysis. Because bite-marks change significantly over time, investigators must call for an expert as soon as possible. Bites are then analyzed to determine whether the biter was human , self-inflicted or not, and whether DNA was left behind from the biter. All measurements must be extremely precise, as small errors in measurement can lead to large errors in legal judgment. Human bites have historically been viewed superstitiously, particularly in

1150-547: The abdomen may reveal hyperresonance (indicating air in the abdominal cavity) or dullness (indicating a buildup of blood). The abdomen may be distended or tender, signs which indicate an urgent need for surgery. The standard management of penetrating abdominal trauma was for many years mandatory laparotomy . A greater understanding of mechanisms of injury, outcomes from surgery, improved imaging and interventional radiology has led to more conservative operative strategies being adopted. Assessment can be difficult because much of

1196-425: The chest cavity outside of the lung), pneumothorax (an accumulation of air in the chest cavity) and hemopneumothorax (accumulation of both blood and air). Sucking chest wounds and tension pneumothorax may result. Penetrating trauma can also cause injuries to the heart and circulatory system. When the heart is punctured, it may bleed profusely into the chest cavity if the membrane around it (the pericardium )

1242-446: The clinical presentation and any laboratory data. The introduction of cutaneous ultrasound has allowed the detection of cutaneous tumors, inflammatory processes, and skin diseases. The skin weighs an average of 4 kg (8.8 lb), covers an area of about 2 m (22 sq ft), and is made of three distinct layers: the epidermis , dermis , and subcutaneous tissue . The two main types of human skin are glabrous skin ,

1288-598: The damage is often internal and not visible. The patient is thoroughly examined. X-ray and CT scanning may be used to identify the type and location of potentially lethal injuries. Sometimes before an X-ray is performed on a person with penetrating trauma from a projectile, a paper clip is taped over entry and exit wounds to show their location on the film. The patient is given intravenous fluids to replace lost blood. Surgery may be required; impaled objects are secured into place so that they do not move and cause further injury, and they are removed in an operating room . If

1334-514: The dermis and subcutaneous tissues. The epidermis is the most superficial layer of skin, a squamous epithelium with several strata : the stratum corneum , stratum lucidum , stratum granulosum , stratum spinosum , and stratum basale . Nourishment is provided to these layers via diffusion from the dermis, since the epidermis is without direct blood supply. The epidermis contains four cell types: keratinocytes , melanocytes , Langerhans cells , and Merkel cells . Of these, keratinocytes are

1380-440: The dermis is fourfold: to supply nutrition, to regulate temperature, to modulate inflammation, and to participate in wound healing. The subcutaneous tissue is a layer of fat between the dermis and underlying fascia . This tissue may be further divided into two components, the actual fatty layer, or panniculus adiposus , and a deeper vestigial layer of muscle, the panniculus carnosus . The main cellular component of this tissue

1426-476: The diagnosis of any particular skin condition begins by gathering pertinent information of the presenting skin lesion(s), including: location (e.g. arms, head, legs); symptoms ( pruritus , pain); duration (acute or chronic); arrangement (solitary, generalized, annular , linear); morphology ( macules , papules , vesicles ); and color (red, yellow, etc.). Some diagnoses may also require a skin biopsy which yields histologic information that can be correlated with

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1472-432: The diseases of the skin'). It is considered the first scientific work dedicated to dermatology . The physical examination of the skin and its appendages, as well as the mucous membranes, forms the cornerstone of an accurate diagnosis of cutaneous conditions. Most of these conditions present with cutaneous surface changes termed "lesions," which have more or less distinct characteristics. Often proper examination will lead

1518-521: The globe of the eye to rupture or vitreous humor to leak from it, and presents a serious threat to eyesight. Most penetrating injuries are chest wounds and have a mortality rate (death rate) of under 10%. Penetrating chest trauma can injure vital organs such as the heart and lungs and can interfere with breathing and circulation. Lung injuries that can be caused by penetrating trauma include pulmonary laceration (a cut or tear) pulmonary contusion (a bruise), hemothorax (an accumulation of blood in

1564-644: The hands and the skeletal section. Infections are a result of bacteria from the mouth spread to another human and are the third common types of bites that require a hospital visit. Biting in children is common however, it may be prevented by methods including redirection, change in the environment and responding to biting by talking about appropriate ways to express anger and frustration. School-age children, those older than 30 months, who habitually bite may require professional intervention. Some discussion of human biting appears in The Kinsey Report on Sexual Behavior in

1610-495: The location of the injury is not obvious, a surgical operation called an exploratory laparotomy may be required to look for internal damage to the organs in the abdomen . Foreign bodies such as bullets may be removed, but they may also be left in place if the surgery necessary to get them out would cause more damage than would leaving them. Wounds are debrided to remove tissue that cannot survive and other material that presents risk for infection. Negative pressure wound therapy

1656-412: The macroscopic morphology, configuration, and distribution of skin lesions, which are listed below. "Configuration" refers to how lesions are locally grouped ("organized"), which contrasts with how they are distributed (see next section). "Distribution" refers to how lesions are localized. They may be confined to a single area (a patch) or may be in several places. Some distributions correlate with

1702-414: The major component, constituting roughly 95% of the epidermis. This stratified squamous epithelium is maintained by cell division within the stratum basale, in which differentiating cells slowly displace outwards through the stratum spinosum to the stratum corneum, where cells are continually shed from the surface. In normal skin, the rate of production equals the rate of loss; about two weeks are needed for

1748-411: The means by which a given area becomes affected. For example, contact dermatitis correlates with locations where allergen has elicited an allergic immune response. Varicella zoster virus is known to recur (after its initial presentation as chicken pox ) as herpes zoster ("shingles"). Chicken pox appears nearly everywhere on the body, but herpes zoster tends to follow one or two dermatomes; for example,

1794-416: The nonhairy skin on the palms and soles (also referred to as the "palmoplantar" surfaces), and hair-bearing skin. Within the latter type, hairs in structures called pilosebaceous units have a hair follicle , sebaceous gland , and associated arrector pili muscle. In the embryo , the epidermis, hair, and glands are from the ectoderm , which is chemically influenced by the underlying mesoderm that forms

1840-418: The object that enters the body, penetrating injuries may be associated with secondary injuries, due for example to a blast injury . The path of a projectile can be estimated by imagining a line from the entrance wound to the exit wound, but the actual trajectory may vary due to ricochet or differences in tissue density. In a cut, the discolouration and the swelling of the skin from a blow happens because of

1886-408: The physician to obtain appropriate historical information and/or laboratory tests that are able to confirm the diagnosis. Upon examination, the important clinical observations are the (1) morphology, (2) configuration, and (3) distribution of the lesion(s). With regard to morphology, the initial lesion that characterizes a condition is known as the "primary lesion", and identification of such a lesions

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1932-682: The projectile that accelerate material away from its path. The characteristics of the tissue injured also help determine the severity of the injury; for example, the denser the tissue, the greater the amount of energy transmitted to it. Skin, muscles, and intestines absorb energy and so are resistant to the development of temporary cavitation, while organs such as the liver, spleen, kidney, and brain, which have relatively low tensile strength, are likely to split or shatter because of temporary cavitation. Flexible elastic soft tissues, such as muscle, intestine, skin, and blood vessels, are good energy absorbers and are resistant to tissue stretch. If enough energy

1978-715: The ruptured blood vessels and escape of blood and fluid and other injuries that interrupt the circulation. Low-velocity items, such as knives and swords, are usually propelled by a person's hand, and usually do damage only to the area that is directly contacted by the object. The space left by tissue that is destroyed by the penetrating object as it passes through forms a cavity; this is called permanent cavitation . High-velocity objects are usually projectiles such as bullets from high-powered rifles, such as assault rifles or sniper rifles . Bullets classed as medium-velocity projectiles include those from handguns , shotguns , and submachine guns . In addition to causing damage to

2024-469: The tissues they contact, medium- and high-velocity projectiles cause a secondary cavitation injury: as the object enters the body, it creates a pressure wave which forces tissue out of the way, creating a cavity which can be much larger than the object itself; this is called "temporary cavitation". The temporary cavity is the radial stretching of tissue around the bullet's wound track, which momentarily leaves an empty space caused by high pressures surrounding

2070-518: The two layers interact through the basement membrane zone. Structural components of the dermis are collagen , elastic fibers , and ground substance also called extra fibrillar matrix. Within these components are the pilosebaceous units, arrector pili muscles, and the eccrine and apocrine glands . The dermis contains two vascular networks that run parallel to the skin surface—one superficial and one deep plexus—which are connected by vertical communicating vessels. The function of blood vessels within

2116-610: Was used during surgery to reduce pain and allow more time for operations. Due in part to the lack of sterile technique in hospitals, infection was the leading cause of death for wounded soldiers. In World War I , doctors began replacing patients' lost fluid with salt solutions. With World War II came the idea of blood banking , having quantities of donated blood available to replace lost fluids. The use of antibiotics also came into practice in World War II. Wheals A skin condition , also known as cutaneous condition ,

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