Following penetrating trauma, spinal motion restriction is associated with worse outcomes and therefore it should not be done routinely. Mechanism
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 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 the ruptured blood vessels and escape of blood and fluid and other injuries that interrupt the circulation. Cavitation
Permanent
Low-velocity items, such as knives and swords, are usually propelled by a persons 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. Temporary
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.
Endemic goiter is a type of goitre that is associated with dietary iodine deficiency. Cause
Some inland areas where soil and water lacks in iodine compounds and consumption of marine foods is low are known for higher incidence of goitre. In such areas goitre is said to be "endemic". Prevention
This type of goiter is easily preventable. In most developed countries regulations have been put into force by health policy institutions requiring salt, flour or water to be fortified with iodine. Treatment
Treatment of endemic goiter is medical with iodine and thyroxine preparations. Surgery is only necessary in cases where complicated by significant compression of nearby structures. References


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