Interactive Ready for Review: Interactivities

The system is divided into two parts: the CNS and the peripheral nervous system.

The CNS consists of the brain and the spinal cord. The cables of nerve fibers linking nerve cells in the brain and spinal cord to the body's organs make up the peripheral nervous system.

In addition to the skull and spinal canal, the CNS is protected by the , which are three layers of tissue called the dura mater, arachnoid, and pia mater.

The peripheral nervous system consists of 31 pairs of spinal nerves, which conduct sensory impulses from the skin and other organs to the spinal cord and conduct motor impulses from the spinal cord to the muscles, and 12 pairs of cranial nerves, which transmit sensations relating to sight, smell, taste, and hearing directly to the brain. The three major types of peripheral nerves are sensory nerves, motor nerves, and connecting nerves.

The part of the nervous system that regulates our voluntary activities is called the or voluntary nervous system.

The much more primitive or involuntary nervous system regulates involuntary body functions. The %%4%% nervous system is composed of the sympathetic and parasympathetic nervous systems, which balance each other.

The skull is divided into two large bony structures that protect the brain: the cranium and the face.

The spinal column has 33 bones, called , in five sections: cervical, thoracic or dorsal, lumbar, sacral, and coccygeal.

The cervical, thoracic, and lumbar portions of the spine can be injured through compression resulting from a fall; through unnatural motions such as overextension caused by motor vehicle crashes and other types of trauma; and through distraction (pulling) along the length of the spine, as in hanging.

Start your assessment of a patient with a possible spinal injury by focusing on the ABCs and, if he or she is responsive, by asking five questions: Does your neck or back hurt? What happened? Where does it hurt? Can you move your hands and feet? Can you feel me touching your fingers and toes?

Look for contusions, punctures, or skull deformities; test for strength in the extremities; ask about pain; and check for numbness, weakness, or tingling in the extremities. Patients with severe spinal injury may lose sensation or be below the suspected injury.

Keep the head in a neutral, in-line position while you open and maintain the airway, assess respirations, and give supplemental oxygen. Provide manual immobilization until the patient is properly secured to a backboard.

A patient who is supine can be immobilized with a long backboard, using the .

With sitting patients, you should use a short immobilization device, then secure the short device to a long board.

If the patient is standing, immobilize him or her to a long backboard before starting your assessment; this requires three EMT-Is.

Common head injuries include skull wounds (scalp lacerations and skull fracture) and brain injuries (concussion, contusion, intracranial bleeding), typically caused by direct blows, car crashes, falls from heights, assault, and sports injuries.

Cerebral edema, seizures, vomiting, and leakage of CSF are common complications of open and closed head injuries.

Signs and symptoms of head injuries include lacerations, visible deformities of the skull, ecchymosis around the eyes or behind the ear, unequal pupil size and failure of the pupils to respond to light, loss of sensation and/or motor function, visual disturbances, irregular respirations and posturing.

The single most important observation that you can make in assessing a brain injury is of change in the . Use the AVPU scale or the Glasgow Coma Scale to assess consciousness immediately and every 15 minutes for a patient in stable condition and every 5 minutes for a patient in unstable condition, recording scores and times as you do so. Also monitor pupil size and reactions.

Patients with head injuries often have injuries to the cervical spine as well. Therefore, when treating a patient with a head injury, you must protect and stabilize the cervical spine at all times.

Three principles govern treatment of head injuries: airway, ventilation, and high-flow supplemental oxygen; bleeding and circulation; and assessing and monitoring the level of consciousness.

Immobilization devices include cervical collars, which must be the correct size; short backboards, including vest-type devices and rigid short boards; and long backboards.

A helmet that fits well prevents the patient's head from moving and should be left on, as long as it does not interfere with assessment and treatment of airway or ventilation problems and you can properly immobilize the spine. Remove a helmet if it makes assessing or managing airway problems difficult, prevents you from immobilizing the spine, or allows excessive head movement.

Never remove a helmet if doing so will further injure the patient. Always remove a helmet if the patient is in cardiac arrest.