Twitch Tension, Spike Amplitude and Recruitment Order of Masseter Muscle Single Motor Units

1978 ◽  
pp. 78-90 ◽  
Author(s):  
Louis J. Goldberg
Keyword(s):  
Masseter Muscle ◽  
Motor Units ◽  
Single Motor ◽  
Spike Amplitude ◽  
Single Motor Units ◽  
Recruitment Order

Modulation of stretch-evoked reflexes in single motor units in human masseter muscle by experimental pain

2000 ◽  
Vol 132 (1) ◽  
pp. 65-71 ◽  
Author(s):  
Peter Svensson ◽  
Timothy S. Miles ◽  
Thomas Graven-Nielsen ◽  
Lars Arendt-Nielsen
Keyword(s):  
Masseter Muscle ◽  
Experimental Pain ◽  
Motor Units ◽  
Single Motor ◽  
Single Motor Units

Voluntary hyperventilation changes recruitment order of parasternal intercostal motor units

1987 ◽  
Vol 62 (1) ◽  
pp. 187-193 ◽  
Author(s):  
T. W. Watson ◽  
W. A. Whitelaw
Keyword(s):  
Human Subjects ◽  
Motor Units ◽  
Quiet Breathing ◽  
Rib Cage ◽  
Voluntary Hyperventilation ◽  
Single Motor ◽  
Intercostal Muscles ◽  
Single Motor Units ◽  
Normal Human ◽  
Recruitment Order

The order of recruitment of single-motor units in parasternal intercostal muscles during inspiration was studied in normal human subjects during quiet breathing and voluntary hyperventilation. Electromyograms were recorded from the second and third intercostal spaces by means of bipolar fine wire electrodes. Flow at the mouth, volume, end-expired CO2, and rib cage and abdominal anterior-posterior diameters were monitored. Single-motor units were identified using criteria of amplitude and shape, and the time of first appearance of each unit in each inspiration was noted. Hyperventilation was performed with visual feedback of the display of rib cage and abdomen excursions, keeping the ratio of rib cage to abdominal expansion. Subjects were normocapnic in quiet breathing and developed hypocapnia during hyperventilation. Recruitment order was stable in quiet breathing, but in some cases was altered during voluntary hyperventilation. Some low threshold units that fired early in the breath in quiet breathing fired earlier at the beginning of a period of voluntary hyperventilation but progressively later in the breath as hyperventilation went on, whereas later firing units moved progressively toward the early part of inspiration. This suggests that different groups of motoneurons in the pool supplying parasternal intercostal muscles receive different patterns of synaptic input.

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