Status Bar Clock UNCONSCIOUSNESS - THE FACTS

The movements and functions of the body and levels of responsiveness are governed by the nervous system.
Partial consciousness or unconsciousness in a casualty indicates that there is an interruption of the brains normal activity, and this can be pretensiously fatal. The disturbance mainly disturbs the Reticular Activating System, found at the base of the brain, and which is responsible for maintaining consciousness levels in the brain.

The aetiology of unconsciousness, includes fainting, head injuries etc.

However there are mneumonics of remembering the causes of unconsciousness, that you may already be familiar with e.g CHIEF SAP HEAD;
 
Cardiac conditions Shock Head injuries
Heart Attacks Asphyxia Extremes of temperature
Infantile Convulsions Poisons Apoplexy (stroke)
Epileptic fits   Diabetic Emergencies
Fainting    

 The central nervous system (CNS), comprises of the brain, spinal cords and nerves.

The brain (figure 1) is very delicate and most precious organ to us and is made up of about 1000 billion neurons. The brain is where sensation like pain are analysed and muscles are commanded to move e.g to raise your arm. The brain is enclosed in the skull, which is made up of twenty two bones, just inside the skull is the meninges, three layered membranes that cover and protect the brain and the spinal cord. The three layers are:- the dura mater, the arachnoid mater and the pia mater. The dura mater is the outermost layer and thus is the toughest of the three membranes. Situated beneath the dura mater is the arachnoid, so named because it resembles a spider's web. Next is a space termed the sub-arachnoid space, which is often inflamed in diseases such as Menigitis, due to the circulating fluids within the gap. Finally beneath the arachnoid mater and closest to the brain, is the pia mater, a transparent membrane that actually touches the brain and spinal cord. the brain is also surrounded by a clear fluid known as cerebrospinal fluid (CSF), which acts mainly as ashock absorber just like a shock absorber on a motor car.
Despite all this protection the brain is still at risk, bcause it is free to move in its house (skull) and hence violent movements can cause damage (imagine an egg in its shell, being shaken up.) Disorders may include hydrocephalus (water on the brain), oedema, concussion, compression etc.
It is worth detailing here that compression and concussion have very different signs and symptoms as the table below details:
 

Concussion

Compression
     
Pulse quick, feeble slow, full
     
Skin cold, clammy hot, dry
     
Colour pale flushed
     
Pupils equal contracted, react to light unequal dilated, no reaction to light

(dilated pupil is on the same side as injury to brain)
     
Breathing shallow, rapid, quiet deep, slow, noisy
     
Consciousness temporary loss deepening, possible hemiplegia
     
Onset sudden gradual
     
Recovery gradual with amnesia, nausea, possible vomiting condition deteriorates, possible vomiting
     
History giddiness, drowsiness headache, restlessness, twitching,

convulsions.
The spinal cord is an elongated cylindrical part of the CNS occupying the canal in the spinal column from the base of the skull to the level of the first lumbar vertebra. In an average adult it is about 45cm long and 1.25cm in diameter tapering towards its lower end, and is enclosed within three layers of membranes called the meniges. (figure 2)
It is composed almost entirely of nerve-tissue with a core of grey matter or nerve cells surrounded by white matter, (named because they are surrounded by the fatty substance myelin) consisting of nerve fibres which are disposed as 'tracts' conveying up or down its length.
At regular intervals there arise thirty-one pairs of spinal nerves each having and anterior and posterior root, the latter distinguished by an oval swelling or spinal ganglion containing nerve cells. These spinal nerves are bundles of both motor and sensory nerve fibres which respectively relay outward impulses to related muscles and carry incoming sensory stimuli. The motor fibres leave the cord by the anterior root and fibres carrying sensory impressions which enter by the posterior root. Within its membranes the cord, like the brain is also surrounded by CSF acting as a water-cussion for the support and protection.
Whats the possible clinical significance here ?
The nerves are encased between layers of bones called vertebra, which forms the spinal column, providing the main axis of the body. The vertebra are united to one another by intervertebral fibro-cartilaginous discs and ligaments. There are thirty three verterbra, named according to their region as; cervical (seven), thoracic (twelve), lumbar (five), sacral (five, and coccygeal (four) vertebra. In the first three groups, the twenty four vertebrae are each separately mobile allowing the column to be flexible, hence it can bend in all directions and rotate to a limited extent. However the sacral and coccygeal vertebrae are fused to form the sacrum and coccyx respectively.
The vertebrae each have an arch towards the back and these lye one above the other, forming the vertebral canal, in which the spinal cord lies.
A point to remember when positioning a patient on a spinal board.

Another important thing to think about here is that the C3, C4 and C5 verterbra keep the diaphragm alive, therefore what is the danger to a possible injured spinal patient ?

The peripheral nerves emerge in pairs containing motor (efferent) and sensory (afferent) nerves, from the brain and spinal cord, sensory nerves transport impressions received by the senses (e.g hearing, sight, touch, pressure, smell, and taste) to the brain. Then motor nerves then transport the "orders" given by the brain to the voluntary muscles, voluntary muscles get there name because they are under the control of will. The movement of these nerves is co-ordinated through the motor nerves which pass directly from the brain or via the spinal cord.
The CNS receives its information from the cranial nerves, of which there are 12 pairs, (e.g those serving the eyes and nose) and the spinal nerves (e.g those receiving "impulses" (action potentials) from the limbs.) The cranial and spinal nerves together constitute what is known as the peripheral nervous system (PNS) which is detailed above.
The autonomic nervous system (ANS), however coveys messages to the involuntary muscles and secreting glands, which is to say that it regulates functions not under the control of will, e.g heart rate, blushing, sweating, and control of digestion. The function of the autonomic system is divided into two parts the sympathetic nervous system (SNS), which is connected with the thoracic and upper lumbar spinal nerves, while the other division the, parasympathetic nervous system (PNS), is connected both with the vagus (tenth cranial nerve) and with the sacral nerve.
Activity of SNS mobilises the body to meet physical danger dilating the pupils, providing a sexual role and even raising the hair, which makes a frightening appearance. The widening of coranary and other major arteries is yet another attribute to increase the flow of blood to the muscles. The SNS also constricts the skin blood vessels, thus ensuring that less blood is lost from a superficial wound, increasing the force of the heart beat, again making more blood available to the muscles, as for dilating the bronchi and brochioles, the purpose to allow more air into the lungs. The SNS decreases the digestive organs. WHY ?
The SNS also stimulates the release of the hormone adrenalin, (note an injection of adrenalin as similar effects.) WHY ?
By contrast the PNS restores the functions of the body back to "normal" e.g slowing the heart beat down, allowing the spincters of the bladder and anus to relax and permit urination and defaecation.
It should also be understood that both of these systems are greatly influenced by ENDOCRINE GLANDS, which are largely influenced by emotions, such as stress, "road rage" and love. But thats another story !
A final point to mention is that within our body's there are also reflexes e.g when the body is subjected to a stimulus such as touching a hot kettle a "reflex action" will attempt to remove the affected part of the body from the stimulus as quickly as possible. However these pathways normally only involve the base of the spinal cord to save time when giving rise to a primary response. Given that "reflexes" are usually the first reponse to deplete in spinal injuries, could this be why they form a valuable clinical test in the field ?

References;

Here are some questions to challenge your learning.

1) Name the membrane that resembles a spider's web surrounding the brain ?

2) Name a disorder associated with this layer ?

3) Define the two divisions of the autonomic nervous system ?

4) What does the abbreviation GCS mean ?

5) What three cervical vertebra keep the diaphragm alive ?

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Last updated 11/05/97

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