Diaphragm function from a developmental perspective 

Definition of an ideal respiratory pattern from a developmental perspective 

Posture and postural function of the diaphragm 

Pathological respiratory postural pattern 

Visceral and sphincter functions of the diaphragm 

References

Diaphragm function from a developmental perspective

In a human embryo, the origin of the diaphragm is concentrated in the cervical region, possibly as an extension of the rectus abdominis muscle (or the ‘cervical portion’ of the rectus cervicis muscle). During development, the diaphragm descends caudally and tilts forward. This development continues after birth and the diaphragm attains its definite position in an almost transverse plane between 4–6 months.

The muscular portion of the diaphragm has two main parts with different embryonic origins: costal and crural (Pickering & Jones 2002). They are formed by different types of fibres and have specific influence on the ribcage and purposeful movement; e.g. during vomiting or belching, the costal fibres are active while the crural fibres around the esophagus are inactive (Abe et?al.1993). The dorsal mesesophagus and mesogastrium partially contribute to the development of the crural portion, which plays an important role in the sphincter function of the diaphragm (Langman 1981).

During ontogenetic development, the diaphragm initially participates in respiration (Murphy & Woodrum 1998). With completion of the neonatal developmental stage (the first 28 days of life), the diaphragm begins to contribute in both postural and sphincter functions. The non-respiratory functions of the diaphragm emerge as the postural anti-gravity role develops – the infant begins to prop up onto forearms and lifts the head when prone or in supine lifts the lower extremities (LE) above the mat (Hermsen-van Wanrooy 2006, Vojta 2004, Vojta & Schweizer 2009). This combined postural-respiratory function of the diaphragm is an important prerequisite for trunk stabilization followed by locomotor movement of the upper and lower extremities (Hemborg et?al. 1985, Hodges & Gandevia 2000a, Hodges & Gandevia 2000b, Kolar et?al. 2010).

The diaphragm of a healthy newborn is flat and positioned cranially (Devlieger et?al 1991); the thorax short and cone-shaped (Openshaw et?al. 1984). The posterior rib angles are ventral to the spinous processes, and neither the spinous nor the transverse processes have a definitive shape. The transverse processes exhibit a progressive posterior and inferior angulation with age and move down the thoracic spine. The facet joints angulate accordingly (Lord et?al. 1995). The distances between the jugular fossa and the xyphoid process and between the xyphoid process and the pubic symphysis differ from an adult. The newborn has a ‘short’ thorax and a ‘long’ stomach. The thoracic cavity of the newborn is limited by the thymus and diaphragm excursion is limited by the large liver. Only breathing movements are realized by the activity of the diaphragm; it does not yet participate in postural and sphincter functions (Murphy & Woodrum 1998).

With CNS maturation, muscle co-activation develops when the neonatal stage is completed. Simultaneous and balanced activity of the agonists and the antagonists allows for active body posture within the gravitational field. An infant no longer only passively lies on the mat, but begins to lift the head and the extremities above the mat and stabilization, support and equilibrium functions develop (Hermsen-van Wanrooy 2006, Vojta 2004, Vojta & Schweizer 2009).

Simultaneous and symmetrical co-activation of the diaphragm, abdominal, back and pelvic muscles allows for the interconnection between breathing pattern and stabilization function (Hodges et?al. 2007, Hodges & Gandevia 2000a, Kolar et?al. 2009). This combined muscle function is relatively challenging and is only possible in a healthy CNS, which allows for perfect motor control (Assaiante et?al. 2005, Hodges & Gandevia 2000a). A disturbance in CNS control causes not only a deficit in movement patterns, including the breathing pattern, but also structural deformities (Koman et?al. 2004). A child with a developmental CNS dysfunction will never demonstrate an ideal skeletal anatomy.

Central motor programmes coordinate muscles that significantly influence growth plates. If muscle function is balanced and ensures a symmetrical pull in the area of the growth plates, it is very likely that the anatomical development will be correct. Muscle imbalance during ontogenesis results in less than ideal skeletal development. In extreme cases (e.g. cerebral palsy), various deformities can be observed in extremity joints (e.g. coxa valga antetorta neurogenes) and the thorax (Koman et?al. 2004). Respiratory function will then be modified not only as a result of less than ideal CNS control but also as a result of an abnormal shape and position of the spine, ribs, clavicles and other structures.

In a physiologically normal situation, at 3 months the stabilization quality of muscle synergies increases, the cervical and thoracic spine straightens and development of lower costal breathing begins. At 4½ months, when the differentiation of extremity function occurs in the form of support and stepping (grasping) movements, the differentiation function of the muscles of the trunk and the abdominal cavity continues. A child begins to use one upper extremity (UE) and one lower extremity for support and the opposite UE and LE for stepping. This differentiated function allows for...