About You - Central Chiropractic Clinic

Dermatome

A dermatome is an area of skin that is mainly supplied by a single spinal nerve. There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves and five sacral nerves. Each of these nerves relays sensation (including pain) from a particular region of skin to the brain.

Along the thorax and abdomen the dermatomes are like a stack of discs forming a human, each supplied by a different spinal nerve. Along the arms and the legs, the pattern is different: the dermatomes run longitudinally along the limbs. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints.

A similar area innervated by peripheral nerves is called a peripheral nerve field.

Clinical significance

Dermatomes are useful in neurology for finding the site of damage to the spine. Because painful dermatomes are symptoms, not causes, of the underlying problem, surgery should never be determined by a pain. Aching in a dermatomic area indicates a lack of oxygen to the nerve as occurs in inflammation somewhere along the path of the nerve. Pain in a dermatomic area (that is not accompanied by heat, as would occur in infection) is indicative of a referral pattern from some other source. This "other source" will not be painful until it is palpated and is usually found (according to Head) on the left side of the vertebral column at the level or one level above or below the dermatomal region of the experienced pain. This information is important in the clinical relevance of dermatomes in that dermatomes are not good measures of dysfunction (that is, non-pathological states as experienced by most people in chronic pain). A compressed spinal nerve, for example, will show as a loss of motor function (i.e. as loss of muscle mass in a proscribed area and/or as an inability to use the muscle against gravity elsewhere on the body) but may or may not exhibit symptoms in the dermatomic area covered by the compressed nerve.

Viruses that infect spinal nerves such as Herpes zoster infections (shingles), can reveal their origin by showing up as a painful dermatomic area. Herpes zoster, a virus that is dormant in the dorsal root ganglion, migrates along the spinal nerve to affect only the area of skin served by that nerve. Symptoms are usually unilateral but in the immune suppressed, they are more likely to become bilateral and symmetrical, meaning that the virus is present in both ganglia of a dorsal root ganglion pair.

Dermatome A dermatome is an area of skin that is mainly supplied by a single spinal nerve. There are eight cervical nerves, twelve thoracic nerves, five lumbar nerves and five sacral nerves. Each of these nerves relays sensation (including pain) from a particular region of skin to the brain. Along the thorax and abdomen the dermatomes are like a stack of discs forming a human, each supplied by a different spinal nerve. Along the arms and the legs, the pattern is different: the dermatomes run longitudinally along the limbs. Although the general pattern is similar in all people, the precise areas of innervation are as unique to an individual as fingerprints. A similar area innervated by peripheral nerves is called a peripheral nerve field. Clinical significance Dermatomes are useful in neurology for finding the site of damage to the spine. Because painful dermatomes are symptoms, not causes, of the underlying problem, surgery should never be determined by a pain. Aching in a dermatomic area indicates a lack of oxygen to the nerve as occurs in inflammation somewhere along the path of the nerve. Pain in a dermatomic area (that is not accompanied by heat, as would occur in infection) is indicative of a referral pattern from some other source. This "other source" will not be painful until it is palpated and is usually found (according to Head) on the left side of the vertebral column at the level or one level above or below the dermatomal region of the experienced pain. This information is important in the clinical relevance of dermatomes in that dermatomes are not good measures of dysfunction (that is, non-pathological states as experienced by most people in chronic pain). A compressed spinal nerve, for example, will show as a loss of motor function (i.e. as loss of muscle mass in a proscribed area and/or as an inability to use the muscle against gravity elsewhere on the body) but may or may not exhibit symptoms in the dermatomic area covered by the compressed nerve. Viruses that infect spinal nerves such as Herpes zoster infections (shingles), can reveal their origin by showing up as a painful dermatomic area. Herpes zoster, a virus that is dormant in the dorsal root ganglion, migrates along the spinal nerve to affect only the area of skin served by that nerve. Symptoms are usually unilateral but in the immune suppressed, they are more likely to become bilateral and symmetrical, meaning that the virus is present in both ganglia of a dorsal root ganglion pair.

The nervous system and organs

The main organs of the nervous system are the brain and the spinal cord. The nervous system controls the actions and feelings of all parts of your body. It helps you have thoughts, feelings, and memory.

The nervous system is an organ system containing a network of specialized cells called neurons that coordinate the actions of an animal and transmit signals between different parts of its body. In most animals the nervous system consists of two parts, central and peripheral. The central nervous system of vertebrates (such as humans) contains the brain, spinal cord, and retina. The peripheral nervous system consists of sensory neurons, clusters of neurons called ganglia, and nerves connecting them to each other and to the central nervous system. These regions are all interconnected by means of complex neural pathways. The enteric nervous system, a subsystem of the peripheral nervous system, has the capacity, even when severed from the rest of the nervous system through its primary connection by the vagus nerve, to function independently in controlling the gastrointestinal system.

Neurons send signals to other cells as electrochemical waves travelling along thin fibers called axons, which cause chemicals called neurotransmitters to be released at junctions called synapses. A cell that receives a synaptic signal may be excited, inhibited, or otherwise modulated. Sensory neurons are activated by physical stimuli impinging on them, and send signals that inform the central nervous system of the state of the body and the external environment. Motor neurons, situated either in the central nervous system or in peripheral ganglia, connect the nervous system to muscles or other effector organs. Central neurons, which in vertebrates greatly outnumber the other types, make all of their input and output connections with other neurons. The interactions of all these types of neurons form neural circuits that generate an organism's perception of the world and determine its behavior. Along with neurons, the nervous system contains other specialized cells called glial cells (or simply glia), which provide structural and metabolic support.

Nervous systems are found in most multicellular animals, but vary greatly in complexity. Sponges have no nervous system, although they have homologs of many genes that play crucial roles in nervous system function, and are capable of several whole-body responses, including a primitive form of locomotion. Placozoans and mesozoans other simple animals that are not classified as part of the subkingdom Eumetazoa also have no nervous system. In Radiata (radially symmetric animals such as jellyfish) the nervous system consists of a simple nerve net. Bilateria, which include the great majority of vertebrates and invertebrates, all have a nervous system containing a brain, one central cord (or two running in parallel), and peripheral nerves. The size of the bilaterian nervous system ranges from a few hundred cells in the simplest worms, to on the order of 100 billion cells in humans. Neuroscience is the study of the nervous system.