Biomechanics of Traumatic Brain Injury

San Francisco Brain Injury Attorney

Traumatic brain injury (TBI), a closed-head injury, can occur in one of two ways. The first is when the head is violently subjected to an external impact, like when the head is struck, or if the head strikes an object. The second is when the head is subjected to a sudden acceleration and stop. This is commonly seen in rear-end vehicle collisions where a sudden acceleration and deceleration whips the head forward and back.

There are three major traumas which can contribute to a traumatic brain injury:

  • Impact of the brain against the skull
  • Shear between the layers of the brain (diffuse axonal injury)
  • Cavitation

Have you or a loved one suffered a catastrophic brain injury in San Francisco?

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Skull-Impact Brain Injury

Depending on the source of the impact or from what direction it occurred, the brain can slam against the inside of the skull if the head is hit hard enough. In situations such as rear-end accidents or other sources that cause the head to move back, the brain may resist movement, creating a pocket of space within the skull. As the force of the impact advances, a centrifugal force lifts the brain, creating a greater space. This force, coupled with inertia, causes the brain to impact with the skull. The inner contours of the skull are not smooth like the outside, and are characterized by sharp protuberances made of bone. When the brain collides with these protuberances, the brain may become torn and bruised, resulting in a serious brain injury.

Diffuse Axonal Injury

Different from the type of trauma that can occur after a direct impact, the brain may also sustain injury through a shear, often referred to as a diffuse axonal injury, which is based on rotational acceleration/ and deceleration. In the case of a shear, when the head is rapidly accelerated and decelerated, one layer of the brain can slide onto another. This is caused by the difference in the density of the layers. When this occurs, axons that cross junctions between different parts of the brain are stretched between areas of differing density. Two out of every three Diffuse Axonal Injury lesions occur in areas other brain where white and gray matter meet. In most cases, the damage of the axons is diffuse and the degeneration process occurs throughout various areas of the brain rather than in specific clusters. This type of diagnosis does not show up well on CT scans and usually requires an MRI scan to check for bleeds in the cerebral cortex or corpus callosum. For this reason, most diffuse axonal injuries are considered “mild” traumatic brain injuries.


When mass moves rapidly through a fluid, the pressure ahead of the mass is higher than the pressure behind it. In areas of low pressure, like the space behind the mass, vapor-filled bubbles can form. When the mass returns in the opposite direction, these bubbles can collapse, causing cavitation.

Often, these types of brain injuries are found on the opposite side of where the impact to the head occurred. Cavitation is the most commonly accepted way to explain this kind of injury, which is known as “countre-coup,” or “against the blow.”

Aggressive Representation for Victims & Families Affected by TBI

The San Francisco personal injury lawyers at Scarlett Law Group have fought for the rights of victims of TBI and other catastrophic injuries for almost 20 years. We have successfully recovered millions of dollars for our clients by providing high quality, knowledgeable, and fervent advocacy. We understand that when tragedy strikes, dealing with life in the aftermath of an injury can be overwhelming. That is why it is our goal to help victims and their families receive the compensation they deserve so to that they can put their lives back together.

We have what it takes to achieve success for your case. Contact us today to find out more about how we may be able to help.

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