Читать книгу Reflexology: The Definitive Practitioner's Manual: Recommended by the International Therapy Examination Council for Students and Practitoners - Beryl Crane - Страница 23

The nervous system is divided into a number of parts. First, there is the division into the central nervous system (the brain and spinal cord) and the peripheral nervous system. The peripheral nervous system distributes to the skin or peripheral parts of the body. The spinal nerves emerge from the spinal cord; the cranial nerves emerge directly from the brain. (See figure 2.5.) There is a functional division between the somatic nervous system, supplying the skeletal muscles, and the autonomic nervous system, supplying the glands, cardiac muscle, and smooth muscle of the internal organs. Reflexology contacts the autonomic nervous system, more than any other therapy, balancing the parasympathetic nervous system and the sympathetic nervous system. These are the two subdivisions of the autonomic nervous system. They exert opposite effects on the end organs, so that homeostasis is maintained. Sympathetic impulses tend to stimulate, and parasympathetic impulses inhibit; for instance, the first increase the heart rate, while the second slow it down. (See figures 2.4 and 2.5)

The spinal cord gives off 31 pairs of nerves in its course from the base of the skull to the lumbar region, each of these nerves arises by two roots, an anterior and a posterior root, one being sensory, the other being motor; these unite prior to leaving the spinal canal, forming a mixed nerve that then separates, supplying the front and back of the body respectively. The nerves that form plexuses are from the top and the bottom of the spinal cord; out of these plexuses a number of branches arise to supply the arms and legs with a network of sensory and motor nerve fibres. These are the cervical, brachial, lumbar and sacral plexuses; the thoracic nerves from T2 do not form plexuses, but supply the skin and muscles in the corresponding area. The eight cervical nerves are divided into two. First there is the cervical plexus, formed from the upper four nerves (1–4); these also communicate with cranial nerves X, XI and XII. They have cutaneous sensory branches and penetrating muscular branches. The lower four (5–8) unite with the first dorsal nerves to form the brachial plexus.

Figure 2.4 Functions of the autonomic nervous system

Figure 2.5 Sympathetic and parasympathetic innervation of the spinal cord

The cranial nerves include the vagus nerve, which contains parasympathetic fibres that help the function of the viscera of the thorax and abdomen, motor nerve fibres to the muscles of larynx, sensory or somatic stimuli to the auditory canal, and also sensory (visceral afferent) stimuli of the thorax and abdomen. These cranial nerves comprise some motor nerves and some mixed nerves. There is also the trigeminal nerve, which has three branches; the ophthalmic nerve, passing through the superior orbital fissure (affecting the areas around the orbits and certain parts of the nasal cavities), the maxillary branch (affecting sensation below the orbits down to the upper jaw and teeth) and the mandibular nerve (again sensory to lower part of face, lower jaw and teeth, and the motor nucleus of this nerve serving the muscles of mastication). These nerves are attached to the brain stem at different levels. The major nerves all originate from nuclei inside the brain.

Note. It is important that the practitioner is aware of the cranial nerves at all times. There is a simple way of remembering these. I think of a very dear friend of mine from the early days – this lady’s name was OOOTTA FAGVSH. The letters of this name correspond to all the cranial nerves. The cranial nerves are given roman numerals, I—XII. We only have three sensory nerves (S), five motor (M), and four mixed (MX) both sensory and motor. Of these cranial nerves, four are parasympathetic nerves (P/S/N) – these are nerves III, VII, IX and X. The nerves are as follows:

I	Olfaction – the sense of smell (S)
II	Optic – the sense of vision (S)
III	Oculomotor – the muscles of the eye (M. P/S/N)
IV	Trochlear – the muscles of the eye (M)
V	Trigeminal – the forehead, cheek sensations, and lower jaw (MX)
VI	Abducent – the muscles of the eye (M)
VII	Facial – impulses of taste and facial expression (MX. P/S/N)
VIII	Auditory – the sense of hearing (S)
IX	Glossopharyngeal – sensations from the tongue and to the pharynx (MX. P/S/N)
X	Vagus – the larynx, trachea, oesophagus, heart, respiratory, all digestive organs, the small intestine, spleen, ascending colon, kidneys and the blood vessels (MX. P/S/N)
XI	Spinal accessory – the muscles of the neck, the sternocleidomastoid and trapezius muscles (M)
XII	Hypoglossal – the hyoid region and the muscles of the tongue (M).

By remembering the above name you will always ensure you never miss out on a brain region as it is so important.

The functioning of the autonomic nervous system is closely linked to the pituitary, the adrenal gland and many other specialized nerve cells that secrete their hormones at the nerve endings. Our sensory system makes us aware of changes; these elaborate sense organs receive stimuli from outside of our body. These are then transmitted to our brain. An enormous amount of information is fed into our nervous system; all this sensory information allows the organism to change and correct the internal environment. Interpretation by the brain depends on the connections through the many nerve pathways. If these connections are not co-ordinated the parts of our body fail to respond.

The autonomic nervous system (see figure 2.4) depends on the co-ordinated and opposing regulatory functions of the sympathetic and parasympathetic divisions of the nervous system. Each of the organs of the body is supplied with a dual set of nerves from each of these branches; the overall commander of the autonomic nervous system is the hypothalamus, which ensures the interdependence and co-ordination of functions within this system. We do not need to think consciously of which branch of the autonomic nervous system we need to stimulate during treatment, because the brain centre decides which section of it will be dominant when the system is stimulated. If the person is tired, lethargic or sluggish the sympathetic stimulation results in an improvement to all activities, with the person having more energy and sparkle. The body has remarkable powers to protect and heal itself. If the need is for the body to be calmed down, then the parasympathetic branch comes to the fore, slowing the heartbeat, inducing deep physical relaxation, promoting the digestion and increasing the tone and motility of the whole gastrointestinal tract and its eliminating process. If there is also a depletion or loss of energy, the parasympathetic division will help to conserve and restore the energy we need while we sleep. It is only when we are physically or emotionally stressed that the sympathetic nervous system may override the parasympathetic nervous system. This action may inhibit many functions, and the whole gastrointestinal tract may slow down, often decreasing motility and tone – hence the many digestive disorders that are evident in people who are extremely stressed.

The overseer of this dual innervation is the hypothalamus, which lies at the back of the forebrain in the floor of the third ventricle (see figure 2.23). This small portion of the brain controls the vital processes, acting as a regulatory centre of thirst, hunger and temperature, thus moderating the water and food intake. It also regulates the emotions and our sleep patterns and it governs the pituitary body, the major endocrine gland that releases many regulatory hormones directly into the bloodstream. If there is an imbalance in these hormones there can be a decline in the state of health. Ill-health can take many forms, from the simple headache to a complete breakdown in many of the functions of the body.

When the body is totally relaxed, its healing mechanism is given a chance to right itself as blood flow and nerve transmission are allowed to occur unimpeded. The benefits of reflexology are therefore manifold; all parts of the body can be reached through precise stimulation of the reflexes through the feet and hands. A return to homeostasis can be achieved after approximately 40 minutes of such stimulation.

The autonomic nervous system is not separate from the central nervous system; there are many interconnections. It was once thought that we have no control over the autonomic nervous system as most of its responses are involuntary. However, the Hindu system of yoga exercises appears to develop some degree of control and influence over it. Also the Chinese exercises of Tai Chi and Qigong (Chi Kung), popularly practised for health and relaxation, demonstrate that relaxation of the mind improves the natural flow of energy, which in turn stimulates all the internal organs. It seems that the health benefits are considerable when the body is relaxed, and many disorders benefit from the reduction of anxiety or stress.