+ Site Statistics
+ Search Articles
+ Subscribe to Site Feeds
EurekaMag Most Shared ContentMost Shared
EurekaMag PDF Full Text ContentPDF Full Text
+ PDF Full Text
Request PDF Full TextRequest PDF Full Text
+ Follow Us
Follow on FacebookFollow on Facebook
Follow on TwitterFollow on Twitter
Follow on Google+Follow on Google+
Follow on LinkedInFollow on LinkedIn

+ Translate

Triangularis sterni: a primary muscle of breathing in the dog

Triangularis sterni: a primary muscle of breathing in the dog

Journal of Applied Physiology 60(1): 14-21

The isolated action, pattern of neural activation, and mechanical contribution to eupnea of the triangularis sterni (transversus thoracis) muscle were studied in supine anesthetized dogs. Linear displacement transducers were used to measure the axial displacements of the ribs and sternum. Tetanic stimulation of the triangularis sterni in the apneic animal caused a marked caudal displacement of the ribs, a moderate cranial displacement of the sternum, and a decrease in lung volume. During quiet breathing, there was invariably a rhythmic activation of the muscle in phase with expiration that was independent of the presence or absence of activity in the abdominal and internal interosseous intercostal muscles. This phasic expiratory activity in the triangularis sterni was of large amplitude and caused the ribs to be more caudal and the sternum to be more cranial during the spontaneous expiratory pause than during relaxation. Additional studies on awake animals showed that rhythmic activation of the triangularis sterni occurs in all body positions and is not caused by anesthesia. These findings indicate that expiration in the dog is not a passive process and that the end-expiratory volume of the rib cage is not determined by an equilibrium of static forces alone. Rather, it is actively determined and maintained below its relaxation volume by contraction of the triangularis sterni throughout expiration. The use of this muscle is likely to facilitate inspiration by increasing the length of the parasternal intercostals and taking on a portion of their work.

(PDF 0-2 workdays service: $29.90)

Accession: 006840714

Download citation: RISBibTeXText

PMID: 3944024

Related references

Effect of posture on triangularis sterni muscle use during breathing in man. FASEB Journal 2(5): ABSTRACT 6991, 1988

The triangularis sterni a primary muscle of inspiration in the dog. Federation Proceedings 44(4): 1003, 1985

Coupling between triangularis sterni and parasternals during breathing in dogs. Journal of Applied Physiology 61(2): 539-544, 1986

Triangularis sterni muscle use in supine humans. Journal of Applied Physiology 62(3): 919-925, 1987

Role of the triangularis sterni muscle during coughing in dogs. Clinical Research 36(3): 508A, 1988

Contractile and endurance properties of feline triangularis sterni muscle. Respiration Physiology 85(3): 279-288, 1991

Triangularis sterni muscle use during eupnea in humans effect of posture. Respiration Physiology 74(2): 151-162, 1988

Advantages of the triangularis sterni muscle of the mouse for investigations of synaptic phenomena. Journal of Neuroscience Methods 4(2): 109-116, 1981

Extrajunctional resting Ca2+ influx is not increased in a severely dystrophic expiratory muscle (triangularis sterni) of the mdx mouse. Neurobiology of Disease 14(2): 229-239, 2003

Elimination of synapses in triangularis sterni muscle of neonatal Wld-s mice does not occur by nerve terminal degeneration. Acta Anatomica 152(4): 323-324, 1995

Size-related differences in the branching pattern of the motor nerve terminals in triangularis sterni muscle of the mouse. Biology of the Cell 65(3): 271-280, 1989

Mechanical advantage of the canine triangularis sterni. Journal of Applied Physiology 84(2): 562-568, 1998

Mechanism of triangularis sterni shortening during expiration in dogs. Journal of Applied Physiology 66(5): 2287-2292, 1989

Role of triangularis sterni during coughing and sneezing in dogs. Journal of Applied Physiology 65(6): 2440-2445, 1988

Diaphragm, genioglossus, and triangularis sterni responses to poikilocapnic hypoxia. Journal of Applied Physiology 67(6): 2303-2310, 1989