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How Does a Traumatic Brain Injury Occur?

Brain damage can be a result of traumatic forces being applied to the brain or as a result of the brain being deprived of oxygen.

Traumatic Injuries to the Brain:

While there is no universally accepted definition of traumatic brain injury it is most often defined as a blow or jolt to the head or a penetrating injury that disrupts the function of the brain.

The skull provides poor protection to the brain from trauma

The interior surface of the human skull

While common belief is that the skull  provides a protective barrier around the brain providing adequate protection to the brain from outside forces, the very opposite is true. The brain is a soft gelatinous structure that floats in the skull in a sea of cerebrospinal fluid.

While the outside of the skull is strong and hard, the inside of the skull contains many sharp ridges and edges which can cause damage to the soft brain tissue. Much of the damage to the brain is related to the interior surface of the skull.

The brain is easily damaged when it moves within the skull cavity and is violently thrown up against these sharp areas. When the brain strikes the inside of the skull both the area that is struck can be injured as well as the opposite area of the brain.  When the brain is subjected to forces causing it to move forward or backward or rotate in the closed skull cavity, the brain is forcefully propelled against the sharp edges and protrusions in the interior of the skull causing bruising, bleeding and destruction of nerve cells.

You can’t judge a book by its cover

An object in motion stays in motion

The brain may be injured but the skull may be fine.

Think of shaking an egg.  Even if you shake the egg very hard, you will only  damage the yoke without ever breaking the skull.  The same principal applies to the movement of the head within the skull.  This is a concept well known in the “shaken baby syndrome.”

Coup and Contra Coup Brain Injury

Forces are transmitted to the brain after the skull and object makes contact causing damage and injury to the brain’s nerve fibers. The initial contact between the brain and skull is called a coup injury. The brain then rebounds after striking the skull and strikes the skull on the opposite side causing a secondary injury known as a contra coup injury.

Coup and Contra Coup

The well known principle learned in elementary physics, that a body in motion stays in motion can be used to understand how the brain is injured in an accident.  When a car stops short and the passenger is thrown forward and suddenly comes to a stop inside the vehicle or when a person falls and the head strikes an object and stops moving, the brain floating within the skull does not stop moving immediately, but continues until it strikes the interior ridges     of the forward aspects of the skull.

The brain can also be injured when a hard object strikes the skull (such as being hit by a baseball bat) causing movement of the brain within the skull cavity. The brain can also be injured when the head strikes a fixed object (such as when the back of the head hits the floor during a fall), again causing movement of the brain within the interior of the skull and striking the rough and hard surfaces.

When a moving object strikes the skull, the initial coup injury will be more substantial than the secondary, contra coup injury.  BUT, when the moving skull strikes a fixed object, the contra coup injury will be more significant than the initial coup injury.

Rotational injury to the brain

Brain Lobes

The four lobes of the human brain. Purple, Frontal Lobe; Green, Temporal Lobe; Blue, Parietal Lobe; Yellow, Occipital Lobe

In addition to direct trauma, the nerve fibers of the brain can be stretched, sheared or severed when the brain moves.  The entire brain does not move at the same rate of speed or velocity.  As a result, different forces are applied to different areas of the brain. Each different movement will produce it’s own type of brain injury.

The brain can be injured by the twisting or stretching of the nerve cells and nerve fibers, a process known as a shearing injury to the brain.  In car accidents the violent and sudden movement or turning of the head can cause damage to the nerve fibers and is called rotational injury

Each injury to the brain is different

Because each area of the brain controls different functions, depending upon the area that is damaged, different injury and consequences may result.

Injury to the brain lobes

Each side or hemisphere of the brain can be divided into four areas or lobes. These lobes are known as the frontal lobe, temporal lobe, parietal lobe and occipital lobe and control different important brain functions.

Injury to the frontal lobe

The area in the front of the brain in the region of the forehead is known as the frontal lobe.  This area controls motor functions (movement) and regulates our ability to think and problem solve.  The frontal lobe also controls our ability to regulate and control our behavior (self control).  Injury to this area of the brain often results in cognitive and behavioral problems.

Injury to the temporal lobe

The area on the side of the head known as the temporal lobe controls our memory and the processing of auditory information.  This area of the brain also plays an important role in the assembling and processing of information.  Injury to the temporal lobe often results in short term memory difficulties, losses of the sense of smell and taste and vestibular difficulties.  It also leads to impairments in executive functioning (the ability to perform multiple tasks at the same time)

Injury to the parietal lobe:

This area of the brain controls our sense of touch and plays an important role in our ability to read.

Injury to occipital lobe

The occipital lobe is the primary area of the brain involved in the processing of visual information.


The American Academy of Brain Injury Attorneys understands how and why the brain is injured and just as importantly, the effect that this injury has on the individual and his/her family.  We are available to assist you with your brain trauma legal case.