Functional role and structure of the scalene: an accessory inspiratory muscle in hamster

1996 ◽  
Vol 81 (6) ◽  
pp. 2436-2444 ◽  
Author(s):  
Mario Fournier ◽  
Michael I. Lewis
Keyword(s):  
Functional Role ◽  
Respiratory Activity ◽  
Muscle Length ◽  
Muscle Spindles ◽  
Inspiratory Muscle ◽  
Emg Activity ◽  
Quiet Breathing ◽  
Scalene Muscle ◽  
Airway Occlusion ◽  
Resistive Loading

Fournier, Mario, and Michael I. Lewis. Functional role and structure of the scalene: an accessory inspiratory muscle in hamster. J. Appl. Physiol. 81(6): 2436–2444, 1996.—Although the scalene muscle (Sca) is a primary inspiratory muscle in humans, its respiratory function in other species is less clear. The electromyographic (EMG) activity of the Sca was studied during resting ventilation (eupnea) in both the awake and anesthetized hamster and after a variety of respiratory challenges in the anesthetized animal. The EMG activities of the medial Sca and the costal diaphragm were compared. The medial Sca, the major component of the Sca, originates from cervical transverse processes 2 to 5 and inserts primarily onto rib 4, with a small segment onto rib 3. In both the anesthetized and awake animal, the Sca was always silent during quiet breathing. With CO2-stimulated hyperpnea, the Sca was always recruited during inspiration in phase with the diaphragm. Active recruitment of the Sca was also observed after resistive loading and total airway occlusion. After ipsilateral phrenicotomy, the Sca was persistently recruited during eupnea. The specificity of the EMG signals was tested both by excluding cross contamination from other rib cage muscles and by selective denervation studies. Muscle spindles were identified in the medial Sca histochemically, suggesting that the respiratory activity of the Sca can also be modulated by changes in muscle length and/or load. These results indicate that the Sca functions as an accessory inspiratory muscle in the hamster and may play an important role in conditions of chronic load.

scholarly journals Neuromechanical matching of drive in the scalene muscle of the anesthetized rabbit

2009 ◽  
Vol 107 (3) ◽  
pp. 741-748 ◽  
Author(s):  
Alexandre Legrand ◽  
Melanie Majcher ◽  
Emma Joly ◽  
Adeline Bonaert ◽  
Pierre Alain Gevenois
Keyword(s):  
Muscle Length ◽  
Emg Activity ◽  
Quiet Breathing ◽  
Lung Inflation ◽  
Scalene Muscle ◽  
Resistive Loading ◽  
Before And After ◽  
Residual Capacity ◽  
The Mean ◽  
Effective Part

The scalene is a primary respiratory muscle in humans; however, in dogs, EMG activity recorded from this muscle during inspiration was reported to derive from underlying muscles. In the present studies, origin of the activity in the medial scalene was tested in rabbits, and its distribution was compared with the muscle mechanical advantage. We assessed in anesthetized rabbits the presence of EMG activity in the scalene, sternomastoid, and parasternal intercostal muscles during quiet breathing and under resistive loading, before and after denervation of the scalene and after its additional insulation. At rest, activity was always recorded in the parasternal muscle and in the scalene bundle inserting on the third rib (medial scalene). The majority of this activity disappeared after denervation. In the bundle inserting on the fifth rib (lateral scalene), the activity was inconsistent, and a high percentage of this activity persisted after denervation but disappeared after insulation from underlying muscle layers. The sternomastoid was always silent. The fractional change in muscle length during passive inflation was then measured. The mean shortening obtained for medial and lateral scalene and parasternal intercostal was 8.0 ± 0.7%, 5.5 ± 0.5%, and 9.6 ± 0.1%, respectively, of the length at functional residual capacity. Sternomastoid muscle length did not change significantly with lung inflation. We conclude that, similar to that shown in humans, respiratory activity arises from scalene muscles in rabbits. This activity is however not uniformly distributed, and a neuromechanical matching of drive is observed, so that the most effective part is also the most active.

scholarly journals Geniohyoid muscle function in awake canines

2003 ◽  
Vol 95 (2) ◽  
pp. 810-817 ◽  
Author(s):  
M. Yokoba ◽  
H. G. Hawes ◽  
P. A. Easton
Keyword(s):  
Muscle Function ◽  
Breathing Pattern ◽  
Muscle Length ◽  
Upper Airway ◽  
Mechanical Action ◽  
Emg Activity ◽  
Airway Occlusion ◽  
Lateral Decubitus ◽  
The Right ◽  
Emg Electrodes

The geniohyoid (Genio) upper airway muscle shows phasic, inspiratory electrical activity in awake humans but no activity and lengthening in anesthetized cats. There is no information about the mechanical action of the Genio, including length and shortening, in any awake, nonanesthetized mammal during respiration (or swallowing). Therefore, we studied four canines, mean weight 28.8 kg, 1.5 days after Genio implantation with sonomicrometry transducers and bipolar electromyogram (EMG) electrodes. Awake recordings of breathing pattern, muscle length and shortening, and EMG activity were made with the animal in the right lateral decubitus position during quiet resting, CO2-stimulated breathing, inspiratory-resisted breathing (80 cmH2O · l-1 · s), and airway occlusion. Genio length and activity were also measured during swallowing, when it shortened, showing a 9.31% change from resting length, and its EMG activity increased 6.44 V. During resting breathing, there was no phasic Genio EMG activity at all, and Genio showed virtually no movement during inspiration. During CO2-stimulated breathing, Genio showed minimal lengthening of only 0.07% change from resting length, whereas phasic EMG activity was still absent. During inspiratory-resisted breathing and airway occlusion, Genio showed phasic EMG activity but still lengthened. We conclude that the Genio in awake, nonanesthetized canines shows active contraction and EMG activity only during swallowing. During quiet or stimulated breathing, Genio is electrically inactive with passive lengthening. Even against resistance, Genio is electrically active but still lengthens during inspiration.

Neuromuscular and mechanical responses to inspiratory resistive loading during sleep

1987 ◽  
Vol 63 (2) ◽  
pp. 603-608 ◽  
Author(s):  
D. W. Hudgel ◽  
M. Mulholland ◽  
C. Hendricks
Keyword(s):  
Tidal Volume ◽  
Chest Wall ◽  
Muscle Activity ◽  
Airway Resistance ◽  
Upper Airway ◽  
Inspiratory Muscle ◽  
Emg Activity ◽  
Resistive Load ◽  
Upper Airway Resistance ◽  
Resistive Loading

The purposes of this study were 1) to characterize the immediate inspiratory muscle and ventilation responses to inspiratory resistive loading during sleep in humans and 2) to determine whether upper airway caliber was compromised in the presence of a resistive load. Ventilation variables, chest wall, and upper airway inspiratory muscle electromyograms (EMG), and upper airway resistance were measured for two breaths immediately preceding and immediately following six applications of an inspiratory resistive load of 15 cmH2O.l–1 X s during wakefulness and stage 2 sleep. During wakefulness, chest wall inspiratory peak EMG activity increased 40 +/- 15% (SE), and inspiratory time increased 20 +/- 5%. Therefore, the rate of rise of chest wall EMG increased 14 +/- 10.9% (NS). Upper airway inspiratory muscle activity changed in an inconsistent fashion with application of the load. Tidal volume decreased 16 +/- 6%, and upper airway resistance increased 141 +/- 23% above pre-load levels. During sleep, there was no significant chest wall or upper airway inspiratory muscle or timing responses to loading. Tidal volume decreased 40 +/- 7% and upper airway resistance increased 188 +/- 52%, changes greater than those observed during wakefulness. We conclude that 1) the immediate inspiratory muscle and timing responses observed during inspiratory resistive loading in wakefulness were absent during sleep, 2) there was inadequate activation of upper airway inspiratory muscle activity to compensate for the increased upper airway inspiratory subatmospheric pressure present during loading, and 3) the alteration in upper airway mechanics during resistive loading was greater during sleep than wakefulness.

Respiratory patterns during progressive asphyxia in newborn rabbits

1977 ◽  
Vol 43 (3) ◽  
pp. 468-474 ◽  
Author(s):  
E. E. Lawson ◽  
B. T. Thach
Keyword(s):  
Respiratory Activity ◽  
Emg Activity ◽  
Electromyographic Activity ◽  
Airway Occlusion ◽  
Activity Frequency ◽  
Relaxation Loss ◽  
Tracheal Pressure ◽  
Residual Capacity ◽  
Electrocorticogram Ecog ◽  
Muscle Groups

During acute progressive asphyxia an abrupt transition occurs from regular respiratory efforts to primary apnea and gasping. To study this transition we measured inspiratory duration (TI), expiratory duration (TE), maximal inspiratory tracheal pressure (Pmax), electromyographic activity (EMG) of different muscle groups, and the electrocorticogram (ECoG) of 3- to 5-day-old rabbits following airway occlusion at functional residual capacity (FRC). The onset of primary apnea was associated with other central nervous system events as indicated by decerebrate posture and maximal EMG activity which were followed by relaxation, loss of EMG activity, and an isoelectric ECoG. Indices of inspiratory drive (Pmax and Pmax/TI) were preserved or accentuated following primary apnea despite a reduction of overall respiratory activity (frequency X Pmax). The onset of primary apnea appears to be due to interruption of the respiratory cycling controls rather than failure of the respiratory center which regulates inspiratory force. Gasping appears to be linked with progressive changes in respiratory patterns which are observed prior to primary apnea. These findings do not support the concept of a “gasping” center.

Role of the Superior Pharyngeal Constrictor Muscle in Forced Breathing in Dogs

2000 ◽  
Vol 37 (2) ◽  
pp. 197-204 ◽  
Author(s):  
Zekai Yaman ◽  
Mikihiko Kogo ◽  
Hitomi Senoo ◽  
Seiji Iida ◽  
Shoichirou Ishii ◽  
...  
Keyword(s):  
Respiratory Activity ◽  
Upper Airway ◽  
Emg Activity ◽  
Sodium Pentobarbital ◽  
Tracheotomy Tube ◽  
Quiet Breathing ◽  
Airway Patency ◽  
Pharyngeal Airway ◽  
Nasal Tube ◽  
Forced Breathing

Objective Respiratory-related electromyographic (EMG) activity of the superior pharyngeal constrictor (SPC) muscle was analyzed during the early stage of forced breathing. Design Four adult dogs anesthetized with sodium pentobarbital were used. In the first part of the study, oral and nasal breathing tubes were placed into the respective cavities, and a tracheotomy tube was placed in the second part of the study. Two conditions, the presence (oral-nasal tube breathing) and absence (tracheotomy breathing) of airflow in the upper airway, were achieved in each dog. Following quiet breathing, animals were connected to a closed breathing system, first by an oral-nasal tube and then by a tracheotomy tube. We proposed to induce a forced breathing condition mechanically by using this system for 1 minute. We increased resistance to airflow during forced breathing by means of connecting tubes and a bag. Our aim was not to produce chemical drive but to produce a forced respiration by increasing the resistance to airflow. Tidal volume, breathing frequency, minute volume, chest wall movement, and EMG activity of the SPC muscle were measured and analyzed. Results During quiet breathing through an oral-nasal or tracheotomy tube, low-amplitude EMG activity of the SPC muscle corresponding to the expiratory cycle of the respiration was observed. In both study conditions, phasic expiratory EMG activity increased immediately after the advent of the breathing from the closed system. Tidal volumes and frequencies also increased rapidly during forced breathing. Conclusions An increase in the resistance to airflow increased the activity of the SPC muscle. This augmented respiratory activity probably assists the patency of the upper airway. The augmented respiratory activity was independent of the local reflex pathways. Respiratory-related activity of the SPC muscle may help dilate and stiffen the pharyngeal airway, promoting airway patency.

Influence of submaximal isometric contractions of the hamstrings on electromyography activity and force while functioning as hip extensors

2020 ◽  
pp. 1-8
Author(s):  
Dasom Oh ◽  
Wootaek Lim
Keyword(s):  
Prone Position ◽  
Supine Position ◽  
Isometric Contraction ◽  
Muscle Length ◽  
Biceps Femoris ◽  
Emg Activity ◽  
Isometric Contractions ◽  
Significant Difference ◽  
Extension Force ◽  
Long Head

BACKGROUND: Although the medial and lateral hamstrings are clearly distinct anatomically and have different functions in the transverse plane, they are often considered as one muscle during rehabilitation. OBJECTIVE: The purpose of the study was to compare the electromyographic (EMG) activity between the prone position and the supine position during maximal isometric contraction and to additionally confirm the effect of submaximal isometric contractions on EMG activity of medial and lateral hamstrings, and force. METHODS: In the prone position, EMG activities of the long head of biceps femoris (BFLH) and semitendinosus (ST) were measured during the maximal isometric contraction. In the supine position, hip extension force with EMG activity were measured during the maximal and the submaximal isometric contractions. RESULTS: EMG activity in the prone position was significantly decreased in the supine position. In the supine position, there was a significant difference between the BFLH and ST during the maximal isometric contraction, but not during the submaximal isometric contractions. CONCLUSIONS: The dependence on the hamstrings could be relatively lower during hip extensions. When the medial and lateral hamstrings are considered separately, the lateral hamstrings may show a more active response, with increased muscle length, in clinical practice.

Muscle dynamics in skipjack tuna: timing of red muscle shortening in relation to activation and body curvature during steady swimming

1999 ◽  
Vol 202 (16) ◽  
pp. 2139-2150 ◽  
Author(s):  
R.E. Shadwick ◽  
S.L. Katz ◽  
K.E. Korsmeyer ◽  
T. Knower ◽  
J.W. Covell
Keyword(s):  
Fork Length ◽  
Muscle Length ◽  
The Body ◽  
Emg Activity ◽  
Skipjack Tuna ◽  
Force Transmission ◽  
Muscle Strain ◽  
Muscle Shortening ◽  
Red Muscle ◽  
Length Changes

Cyclic length changes in the internal red muscle of skipjack tuna (Katsuwonus pelamis) were measured using sonomicrometry while the fish swam in a water tunnel at steady speeds of 1.1-2.3 L s(−)(1), where L is fork length. These data were coupled with simultaneous electromyographic (EMG) recordings. The onset of EMG activity occurred at virtually the same phase of the strain cycle for muscle at axial locations between approximately 0.4L and 0.74L, where the majority of the internal red muscle is located. Furthermore, EMG activity always began during muscle lengthening, 40–50 prior to peak length, suggesting that force enhancement by stretching and net positive work probably occur in red muscle all along the body. Our results support the idea that positive contractile power is derived from all the aerobic swimming muscle in tunas, while force transmission is provided primarily by connective tissue structures, such as skin and tendons, rather than by muscles performing negative work. We also compared measured muscle length changes with midline curvature (as a potential index of muscle strain) calculated from synchronised video image analysis. Unlike contraction of the superficial red muscle in other fish, the shortening of internal red muscle in skipjack tuna substantially lags behind changes in the local midline curvature. The temporal separation of red muscle shortening and local curvature is so pronounced that, in the mid-body region, muscle shortening at each location is synchronous with midline curvature at locations that are 7–8 cm (i.e. 8–10 vertebral segments) more posterior. These results suggest that contraction of the internal red muscle causes deformation of the body at more posterior locations, rather than locally. This situation represents a unique departure from the model of a homogeneous bending beam, which describes red muscle strain in other fish during steady swimming, but is consistent with the idea that tunas produce thrust by motion of the caudal fin rather than by undulation of segments along the body.

Mechanics of the parasternal intercostals in prone dogs: statics and dynamics

1993 ◽  
Vol 74 (6) ◽  
pp. 2757-2762 ◽  
Author(s):  
A. De Troyer ◽  
G. Farkas
Keyword(s):  
Mechanical Behavior ◽  
Inspiratory Muscle ◽  
Emg Activity ◽  
Relaxation Length ◽  
Intercostal Muscles ◽  
Muscle Shortening ◽  
Statics And Dynamics ◽  
Tension Curve ◽  
Spontaneously Breathing ◽  
Prone Posture

It is well established that the parasternal intercostal muscles in supine dogs play a major role in causing the inspiratory elevation of the ribs. This posture, however, is not physiological in the dog. In the present study, we measured the electromyographic (EMG) activity and the respiratory changes in length of these muscles in the prone (standing) and supine postures in seven anesthetized spontaneously breathing dogs. With a change from the supine to the prone posture, the parasternal intercostals showed a 3.2% reduction in their relaxation length (Lr), but their mechanical behavior was essentially unchanged. Thus, the muscles continued to shorten below Lr during inspiration and to lengthen beyond Lr during expiration. With the adoption of the prone posture, the amount of parasternal inspiratory EMG activity and the amount of inspiratory muscle shortening each increased by 30–35%. Furthermore, when the parasternal intercostal in a single interspace was selectively denervated, the shortening of the muscle during inspiration in both postures was virtually eliminated. These observations indicate that in the dog the parasternal intercostals still play a major role in causing the inspiratory elevation of the ribs in the prone posture. These observations also suggest that these muscles in prone animals continue to operate on the descending limb of their length-tension curve.

Coordination between rib cage muscles and diaphragm during quiet breathing in humans

1984 ◽  
Vol 57 (3) ◽  
pp. 899-906 ◽  
Author(s):  
A. De Troyer ◽  
M. Estenne
Keyword(s):  
Tidal Volume ◽  
Marked Reduction ◽  
Emg Activity ◽  
Quiet Breathing ◽  
Rib Cage ◽  
Intercostal Muscles ◽  
Inspiratory Activity ◽  
Normal Humans ◽  
Volume Range

The pattern of activation of the scalenes and the parasternal intercostal muscles was studied in relation to the pattern of rib cage and abdominal motion during various respiratory maneuvers in the tidal volume range in five normal humans. Electromyograms (EMG) of the scalenes and parasternal intercostals were recorded with bipolar needle electrodes, and changes in abdominal and rib cage displacement were measured using linearized magnetometers. The scalenes and parasternal intercostals were always active during quiet breathing, and their pattern of activation was identical; in both muscles the EMG activity usually started together with the beginning of inspiration, increased in intensity as inspiration proceeded, and persisted into the early part of expiration. In addition, like the parasternal activity the scalene inspiratory activity persisted until the tidal volume was trivial, increased during tidal inspirations performed with the rib cage alone, and was nearly abolished during diaphragmatic isovolume maneuvers. However, attempts to perform tidal inspiration with the diaphragm alone, while causing an increase in parasternal EMG activity, were associated with a marked reduction or a suppression of scalene EMG activity and a reduced substantially distorted rib cage expansion. In particular, the upper rib cage was then moving paradoxically.(ABSTRACT TRUNCATED AT 250 WORDS)

Chest wall and trunk muscle activity during inspiratory loading

1992 ◽  
Vol 73 (6) ◽  
pp. 2373-2381 ◽  
Author(s):  
S. J. Cala ◽  
J. Edyvean ◽  
L. A. Engel
Keyword(s):  
Chest Wall ◽  
Lung Volume ◽  
Normal Subjects ◽  
Systematic Difference ◽  
Erector Spinae ◽  
Inspiratory Pressure ◽  
Emg Activity ◽  
Consistent Difference ◽  
Lung Volumes ◽  
Resistive Loading

We measured the electromyographic (EMG) activity in four chest wall and trunk (CWT) muscles, the erector spinae, latissimus dorsi, pectoralis major, and trapezius, together with the parasternal, in four normal subjects during graded inspiratory efforts against an occlusion in both upright and seated postures. We also measured CWT EMGs in six seated subjects during inspiratory resistive loading at high and low tidal volumes [1,280 +/- 80 (SE) and 920 +/- 60 ml, respectively]. With one exception, CWT EMG increased as a function of inspiratory pressure generated (Pmus) at all lung volumes in both postures, with no systematic difference in recruitment between CWT and parasternal muscles as a function of Pmus. At any given lung volume there was no consistent difference in CWT EMG at a given Pmus between the two postures (P > 0.09). However, at a given Pmus during both graded inspiratory efforts and inspiratory resistive loading, EMGs of all muscles increased with lung volume, with greater volume dependence in the upright posture (P < 0.02). The results suggest that during inspiratory efforts, CWT muscles contribute to the generation of inspiratory pressure. The CWT muscles may act as fixators opposing deflationary forces transmitted to the vertebral column by rib cage articulations, a function that may be less effective at high lung volumes if the direction of the muscular insertions is altered disadvantageously.

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