Muscles of Breathing: Development, Function, and Patterns of Activation

Abstract

This review is a comprehensive description of all muscles that assist lung inflation or deflation in any way. The developmental origin, anatomical orientation, mechanical action, innervation, and pattern of activation are described for each respiratory muscle fulfilling this broad definition. In addition, the circumstances in which each muscle is called upon to assist ventilation are discussed. The number of “respiratory” muscles is large, and the coordination of respiratory muscles with “nonrespiratory” muscles and in nonrespiratory activities is complex—commensurate with the diversity of activities that humans pursue, including sleep (8.27). The capacity for speech and adoption of the bipedal posture in human evolution has resulted in patterns of respiratory muscle activation that differ significantly from most other animals. A disproportionate number of respiratory muscles affect the nose, mouth, pharynx, and larynx, reflecting the vital importance of coordinated muscle activity to control upper airway patency during both wakefulness and sleep. The upright posture has freed the hands from locomotor functions, but the evolutionary history and ontogeny of forelimb muscles pervades the patterns of activation and the forces generated by these muscles during breathing. The distinction between respiratory and nonrespiratory muscles is artificial, as many “nonrespiratory” muscles can augment breathing under conditions of high ventilator demand. Understanding the ontogeny, innervation, activation patterns, and functions of respiratory muscles is clinically useful, particularly in sleep medicine. Detailed explorations of how the nervous system controls the multiple muscles required for successful completion of respiratory behaviors will continue to be a fruitful area of investigation. © 2019 American Physiological Society. Compr Physiol 9:1025‐1080, 2019.

Ultrasound measurements of abdominal muscle thickness are associated with postmenstrual age at full oral feedings in preterm infants: A preliminary study

“…Similarly, a study by Rehan et al found that thickness of the diaphragm, another abdominal muscle, was positively correlated with PMA at measurement and infant weight and length but not nutrition intake (calories) 19 . Respiration during oral feeding in preterm infants involves both effective inspiration and expiration; the diaphragm is primarily involved in the inspiration phase of the respiratory cycle, whereas the rectus abdominis is involved in both expiration and early inspiration 20,21 . The coordination and rhythm of respiration to swallow is a complex process that requires the infant to have a paucity of respiration to allow for swallow (deglutition) 22 .…”

Mouth breathing impairs the development of temporomandibular joint at a very early stage

“…In the same process of stretching, skeletal muscles may play a more critical role, because they provide the force required for the process of mouth breathing (Pilarski et al, 2019). Through trichrome staining, we found that the skeletal muscles undergo significant alteration in the proliferation of collagen due to the stretching effect.…”

“…For example, patients who suffer from TMD always have sleep‐apnea‐related problem, while patients who complain about sleep disorders tend to be at risks from TMD (Sanders et al., 2013; Yamada, Tanne, Miyamoto, & Yamauchi, 1997). Considering that hypoxia and mouth breathing are the two main clinical manifestations of pediatric OSA, and that their impacts and outcomes are not yet fully understood, it becomes imperative to determine the mechanisms and effects of hypoxia and mouth breathing on early facial development (Huang & Guilleminault, 2017; Sato et al., 2018; Pilarski et al, 2019). This is the case particularly because if mouth breathing, rather than hypoxia, plays a greater role in affecting the development of the TMJ in children, then these children need to receive treatment as early as possible.…”

Gene delivery to the hypoglossal motor system: preclinical studies and translational potential

“…Extrinsic muscle contraction can protrude or retract the tongue as well as depress the tongue base. Table 1 summarizes the innervation and mechanical actions of the tongue muscles based on prior publications [7][8][9][10].…”