injury injury an injury is any physiological damage to living tissue caused by immediate physical stress. an injury can occur intentionally or unintentionally and may be caused by blunt trauma, penetrating trauma, burning, toxic exposure, asphyxiation, or overexertion. injuries can occur in any part of the body, and different symptoms are associated with different injuries. injurycat scratches on an arm, a minor traumatic puncture wound to the skinspecialtyemergency medicine, traumatology complicationsinfection, shock, hemorrhaging, organ failuretypestraumatic, burn, toxic, overuse treatment of a major injury is typically carried out by a health professional and varies greatly depending on the nature of the injury. traffic collisions are the most common cause of accidental injury and injury-related death among humans. injuries are distinct from chronic conditions, psychological trauma, infections, or medical procedures, though injury can be a contributing factor to any of these. several major health organizations have established systems for the classification and description of human injuries. occurrence deaths from injuries per million persons in 2012 203-358 359-428 429-483 484-559 560-637 638-716 717-817 818-939 940-1,140 1,141-2,961 deaths from intentional injuries per million persons in 2012 14-65 66-89 90-114 115-137 138-171 172-193 194-226 227-291 292-379 380-2,730 injuries may be intentional or unintentional. intentional injuries may be acts of violence against others or self-harm against one's own person. accidental injuries may be unforeseeable or they may be caused by negligence the most common types of unintentional injuries in order are traffic accidents, falls, drowning, burns, and accidental poisoning. certain types of injuries are more common in developed countries or developing countries. traffic injuries are more likely to kill pedestrians than drivers in developing countries. scalding burns are more common in developed countries, while open-flame injuries are more common in developing countries. as of 2021, approximately 4.4 million people are killed due to injuries each year worldwide, constituting nearly 8% of all deaths. 3.16 million of these injuries are unintentional and 1.25 million are intentional. traffic accidents are the most common form of deadly injury, causing about one-third of injury-related deaths. one-sixth are caused by suicide, and one-tenth are caused by homicide. tens of millions of individuals require medical treatment for nonfatal injuries each year, and injuries are responsible for about 10% of all years lived with disability. men are twice as likely to be killed through injury than women. in 2013, 367,000 children under the age of five died from injuries, down from 766,000 in 1990. classification systems the world health organization (who) developed the international classification of external causes of injury (iceci). under this system, injuries are classified by mechanism of injury, objects/substances producing injury, place of occurrence, activity when injured, the role of human intent, and additional modules. these codes allow the identification of distributions of injuries in specific populations and case identification for more detailed research on causes and preventive efforts. the united states bureau of labor statistics developed the occupational injury and illness classification system (oiics). under this system injuries are classified by nature, part of body affected, source and secondary source, and event or exposure. the oiics was first published in 1992 and has been updated several times since. the orchard sports injury and illness classification system (osiics), previously osics, is used to classify injuries to enable research into specific sports injuries. the injury severity score (iss) is a medical score to assess trauma severity. it correlates with mortality, morbidity, and hospitalization time after trauma. it is used to define the term major trauma (polytrauma), recognized when the iss is greater than 15. the ais committee of the association for the advancement of automotive medicine designed and updates the scale. mechanisms trauma traumatic injury is caused by an external object making forceful contact with the body, resulting in a wound. major trauma is a severe traumatic injury that has the potential to cause disability or death. serious traumatic injury most often occurs as a result of traffic collisions. traumatic injury is the leading cause of death in people under the age of 45. blunt trauma injuries are caused by the forceful impact of an external object. injuries from blunt trauma may cause internal bleeding and bruising from ruptured capillaries beneath the skin, abrasion from scraping against the superficial epidermis, lacerated tears on the skin or internal organs, or bone fractures. crush injuries are a severe form of blunt trauma damage that apply large force to a large area over a longer period of time. penetrating trauma injuries are caused by external objects entering the tissue of the body through the skin. low-velocity penetration injuries are caused by sharp objects, such as stab wounds, while high-velocity penetration injuries are caused by ballistic projectiles, such as gunshot wounds or injuries caused by shell fragments. perforated injuries result in an entry wound and an exit wound, while puncture wounds result only in an entry wound. puncture injuries result in a cavity in the tissue. burns burns by severity burn injury is caused by contact with extreme temperature, chemicals, or radiation. the effects of burns vary depending on the depth and size. superficial or first-degree burns only affect the epidermis, causing pain for a short period of time. superficial partial-thickness burns cause weeping blisters and require dressing. deep partial-thickness burns are dry and less painful due to the burning away of the skin and require surgery. full-thickness or third-degree burns affect the entire dermis and is susceptible to infection. fourth-degree burns reach deep tissues such as muscles and bones, causing loss of the affected area. thermal burns are the most common type of burn, caused by contact with excessive heat, including contact with flame, contact with hot surfaces, or scalding burns caused by contact with hot water or steam. frostbite is a type of burn caused by contact with excessive cold, causing cellular injury and deep tissue damage through the crystallization of water in the tissue. friction burns are caused by friction with external objects, resulting in a burn and abrasion. radiation burns are caused by exposure to ionizing radiation. most radiation burns are sunburns caused by ultraviolet radiation or high exposure to radiation through medical treatments such as repeated radiography or radiation therapy. electrical burns are caused by contact with electricity as it enters and passes through the body. they are often deeper than other burns, affecting lower tissues as electricity penetrates the skin, and the full extent of electrical burns are often obscured. they will also cause extensive destruction of tissue at the entry and exit points. electrical injuries in the home are often minor, while high tension power cables cause serious electrical injuries in the workplace. lightning strikes can also cause severe electrical injuries. fatal electrical injuries are often caused by tetanic spasm inducing respiratory arrest or interference with the heart causing cardiac arrest. chemical burns are caused by contact with corrosive substances such as acid or alkali. chemical burns are rarer than most other burns, though there are many chemicals that can damage tissue. the most common chemical-related injuries are those caused by carbon monoxide, ammonia, chlorine, hydrochloric acid, and sulfuric acid. some chemical weapons induce chemical burns, such as white phosphorus. most chemical burns are treated with extensive application of water to remove the chemical contaminant, though some burn-inducing chemicals react with water to create more severe injuries. the ingestion of corrosive substances can cause chemical burns to the larynx and stomach. other mechanisms toxic injury is caused by the ingestion, inhalation, injection, or absorption of a toxin. this may occur through an interaction caused by a drug or the ingestion of a poison. different toxins may cause different types of injuries, and many will cause injury to specific organs. toxins in gases, dusts, aerosols, and smoke can be inhaled, potentially causing respiratory failure. respiratory toxins can be released by structural fires, industrial accidents, domestic mishaps, or through chemical weapons. some toxicants may affect other parts of the body after inhalation, such as carbon monoxide. asphyxia causes injury to the body from a lack of oxygen. it can be caused by drowning, inhalation of certain substances, strangulation, blockage of the airway, traumatic injury to the airway, apnea, and other means. the most immediate injury caused by asphyxia is hypoxia, which can in turn cause acute lung injury or acute respiratory distress syndrome as well as damage to the circulatory system. the most severe injury associated with asphyxiation is cerebral hypoxia and ischemia, in which the brain receives insufficient oxygen or blood, resulting in neurological damage or death. specific injuries are associated with water inhalation, including alveolar collapse, atelectasis, intrapulmonary shunting, and ventilation perfusion mismatch. simple asphyxia is caused by a lack of external oxygen supply. systemic asphyxia is caused by exposure to a compound that prevents oxygen from being transported or used by the body. this can be caused by azides, carbon monoxide, cyanide, smoke inhalation, hydrogen sulfide, methemoglobinemia-inducing substances, opioids, or other systemic asphyxiants. ventilation and oxygenation are necessary for treatment of asphyxiation, and some asphyxiants can be treated with antidotes. injuries of overuse or overexertion can occur when the body is strained through use, affecting the bones, muscles, ligaments, or tendons. sports injuries are often overuse injuries such as tendinopathy. over-extension of the ligaments and tendons can result in sprains and strains, respectively. repetitive sedentary behaviors such as extended use of a computer or a physically repetitive occupation may cause a repetitive strain injury. extended use of brightly lit screens may also cause eye strain. locations abdomen abdominal trauma includes injuries to the stomach, intestines, liver, pancreas, kidneys, gallbladder, and spleen. abdominal injuries are typically caused by traffic accidents, assaults, falls, and work-related injuries, and physical examination is often unreliable in diagnosing blunt abdominal trauma. splenic injury can cause low blood volume or blood in the peritoneal cavity. the treatment and prognosis of splenic injuries are dependent on cardiovascular stability. the gallbladder is rarely injured in blunt trauma, occurring in about 2% of blunt abdominal trauma cases. injuries to the gallbladder are typically associated with injuries to other abdominal organs. the intestines are susceptible to injury following blunt abdominal trauma. the kidneys are protected by other structures in the abdomen, and most injuries to the kidney are a result of blunt trauma. kidney injuries typically cause blood in the urine. due to its location in the body, pancreatic injury is relatively uncommon but more difficult to diagnose. most injuries to the pancreas are caused by penetrative trauma, such as gunshot wounds and stab wounds. pancreatic injuries occur in under 5% of blunt abdominal trauma cases. the severity of pancreatic injury depends primarily on the amount of harm caused to the pancreatic duct. the stomach is also well protected from injury due to its heavy layering, its extensive blood supply, and its position relative to the rib cage. as with pancreatic injuries, most traumatic stomach injuries are caused by penetrative trauma, and most civilian weapons do not cause long-term tissue damage to the stomach. blunt trauma injuries to the stomach are typically caused by traffic accidents. ingestion of corrosive substances can cause chemical burns to the stomach. liver injury is the most common type of organ damage in cases of abdominal trauma. the liver's size and location in the body makes injury relatively common compared to other abdominal organs, and blunt trauma injury to the liver is typically treated with nonoperative management. liver injuries are rarely serious, though most injuries to the liver are concomitant with other injuries, particularly to the spleen, ribs, pelvis, or spinal cord. the liver is also susceptible to toxic injury, with overdose of paracetamol being a common cause of liver failure. face a black eye, a common facial injury. facial trauma may affect the eyes, nose, ears, or mouth. nasal trauma is a common injury and the most common type of facial injury. oral injuries are typically caused by traffic accidents or alcohol-related violence, though falls are a more common cause in young children. the primary concerns regarding oral injuries are that the airway is clear and that there are no concurrent injuries to other parts of the head or neck. oral injuries may occur in the soft tissue of the face, the hard tissue of the mandible, or as dental trauma. the ear is susceptible to trauma in head injuries due to its prominent location and exposed structure. ear injuries