Head injuries cause approximately 50% of deaths resulting from trauma and are the commonest cause of subsequent life-long disability. Over 1 million patients attend A&E departments each year in the UK; fortunately less than 10% are serious.
Primary brain damage occurs directly as a result of the trauma done to the brain at the time of the injury. This is instantaneous and irreversible. Secondary brain damage occurs as the result of subsequent events such as hypoxia and raised intracranial pressure (ICP). Secondary brain damage is potentially preventable appropriate treatment.
GENERAL ANATOMY OF THE HEAD
The head contains the most important organ in the body, the brain, and receptors for the five major senses, sight, sound, smell, taste and touch. The brain is protected by several layers both outside (extracranial) and inside (intracranial) the skull.
The outermost of the protective layers is the SCALP. This word provides a useful mnemonic for remembering the extracranial layers. Proceeding from the outside inwards these are;
• Skin, with hair • Subcutaneous tissue, which is very vascular Galea Aponeurotica; a tough, tendinous layer Loose connective tissue, this is the layer of separation in 'scalping' injuries.
Collections of blood in this layer, subgaleal hematoma, can occur as the result of blunt trauma and can be mistaken for depressed skull fractures • Periosteum, the outer bone layer of the skull The skull is a composite of several bones. They form the facial skeleton and the vault which houses the brain. The joints between these bones are called sutures
The base of the vault is complex and has several small openings or foramina to allow passage of the cranial nerves. The largest of these is the foramen magnum.
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