This article provides a concise overview, at the structural and functional level, of those changes evoked by traumatic brain injury across the spectrum of the disease. Using data derived from animals and humans, the pathogenesis of focal versus diffuse brain damage is presented for consideration of its overall implications for morbidity. Emphasis is placed on contusion and its potential expansion in concert with diffuse changes primarily assessed at the axonal level. Concomitant involvement of neuroexcitation and its role in global and focal metabolic changes is considered. Lastly, the influence of premorbid factors including age, genetics, and socioeconomic background is discussed.