Short Wave Diathermy (SWD) Frequency (ƒ) 10 7 – 10 8 Hz Radio wavelength (λ) 3 -30 m Commonly used frequency (ƒ) is 27.12 MHz and wavelength 11 m. It this current two circuits are used. Machine circuit is coupled with the patient circuit leading to resonance phenomenon, in this way patient is treated. A. Machine circuit: The basic oscillator circuit consists of condenser, inductance, and the currents of different frequencies are obtained by selecting suitable condenser and inductance. It a current of very high frequency is required, the condenser and inductance are very small. While to produce a current of lower frequency a larger condenser and inductance is used. B. Patient circuit: When SWD is applied by the condenser field method, the electrodes in the patient tissues form a capacitor, the capacitance of which depends upon the size electrodes and distance material between them. When the oscillator and resonator cir...
Therapeutic Ultrasound Sound is the mechanical disturbance of an elastic medium such as air. Vibrations which travel through the air or another medium are called as sound. The frequency of hearing sound is 20Hz – 20,000Hz. Ultrasound means the above the frequency of sound or the sound waves which are produced above the 20,000 Hz. Production of Ultrasound: For a one mega Hz frequency machine vibrating source with a frequency of one million pulses/s (million cycles/s) is needed. This is achieved by using either quartz crystal or barium crystal. These crystals deformed when subjected to various potential differences (Piezoelectric effect). The basic components of Ultrasound apparatus are the following. o Source if high frequency current o Cable o Link electrodes o Barium or Quartz crystal o Metal plate Working: Source of high frequency current which is conveyed via co – axial cable to a ...
↵ Pain modulation Pain is unpleasant sensation of the body. The receptors of pain are called nociceptors. Nociceptors are present all over the body especially skin (subcutaneously). Any physical, thermal and mechanical pressure stimulates the nociceptors. The impulses are carried by two types of neuron; Primary or 1 st order neuron and Secondary or 2 nd order neuron. 1 st order neuron: Primary afferent fibers transmit impulses from the sensory receptors to dorsal horn of spinal cord. 2 nd order neuron: 2 nd order afferent fibers carry sensory impulses from the dorsal horn of the spinal cord to the brain. A α and A β are large diameter (myelinated) nerve fibers. A Δ and C fibers are the small diameter (unmyelinated) nerve fibers. The impulses from spinal cord to the brain are carried by Dorsal spinothalamic tract, spinoreticular tract and spinocephalic tract. Pain Gate Control Theory: This theory was suggested by Pat wall and Melazak i...
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