To the respiratory physiologist or anatomist the diaphragm muscle is of course the prime mover of tidal air. However, gastrointestinal physiologists are becoming increasingly aware of the value of this muscle in helping to stop gastric contents from refluxing into the oesophagus. The diaphragm should be viewed as two distinct muscles, crural and costal, which act in synchrony throughout respiration. However, the activities of these two muscular regions can diverge during certain events such as swallowing and emesis. In addition, transient crural muscle relaxations herald the onset of spontaneous acid reflux episodes.
Studying the motor control of this muscular barrier may help elucidate the mechanism of these episodes. In the rat, the phrenic nerve divides into three branches before entering the diaphragm, and it is possible to sample single neuronal activity from the crural and costal branches.
This review will discuss our recent findings with regard to the type of motor axons running in the phrenic nerve of the rat. In addition, we will outline our ongoing search for homologous structures in basal vertebrate groups. In particular, the pipid frogs (e.g. the African clawed frog, Xenopus laevis) possess a muscular band around the oesophagus that appears to be homologous to the mammalian crural diaphragm. This structure does not appear to interact directly with the respiratory apparatus, and could suggest a role for this region of the diaphragm, which was not originally respiratory.
THE MECHANICS of a skeletal muscle is essentially determined by the anatomy of the muscle and the structures it displaces when it contracts. Given that the muscle fibers of the costal portion
of the diaphragm run cranially and dorsally from their insertion on the lower ribs, it would therefore be expected that isolated contraction of one hemidiaphragm would both lift these ribs
and pull them backward relative to the upper ribs.
In addition, even though the diaphragm is the main inspiratory muscle, it receives corticospinal inputs (e.g., Gandevia and Rothwell 1987; Murphy et al. 1990) and is involved in a range of nonrespiratory contractions, such as stabilization of the trunk prior to rapid arm movements (Hodges et al. 1997), flexion of the upper and lower extremities (Kolar et al. 2010), and trunk extension (in patients with complete cervical spinal cord injury, Sinderby et al. 1992; see also Hodges et al. 2001).
On these grounds, we hypothesized that the muscle would participate in ipsilateral rotation of the trunk. Thus the right hemidiaphragm would contract during rotation of the trunk to the
right to pull the lower rib cage on the right side dorsally relative to the spine, whereas it would remain silent during rotation of the trunk to the left (contralateral rotation). Conversely, the left hemidiaphragm would contract during rotation of the trunk to the left to pull the lower rib cage on the left side dorsally relative to the spine.
This chapter focuses on interventions with a psychological component, including emotional factors, the breaking of habits, details and implications of self-regulation, psychotherapeutic
techniques, and aspects of dealing with panic. As long as the mind and the intent are engaged, learning to breathe differently is a psychological process. This is especially true when disorders of
the breathing pattern are based in disordered thinking and feeling.
Changing such patterns is a bigger order than bringing about steadier breathing, and is not always necessary. Proceeding as if the breathing is simply excessive and trying to make it slower and less deep may be all that is needed. Because of the bidirectional relationship of body and mind, strictly physical or behavioral changes generally also have an impact on the emotional state. Theoretically, one person can come for improvement in the breathing pattern and end up feeling more psychologically stable, while another comes in for psychotherapy and ends up having more stable breathing.
The so-called respiratory muscles are those muscles that provide the motive power for the act of breathing. Thus, although many of these muscles are involved in a variety of activities, such as speech production, cough, vomiting, and trunk motion, their primary task is to displace the chest wall rhythmically to pump gas in and out of the lungs.
The present chapter, therefore, starts with a discussion of the basic mechanical structure of the chest wall in humans. Then, the action of each group of muscles is analyzed. For the sake of clarity, the functions of the diaphragm, the intercostal muscles, the muscles of the neck, and the muscles of the abdominal wall are analyzed sequentially. However, since all these muscles normally work together in a coordinated manner, the most critical aspects of their mechanical interactions are also emphasized.
MEASUREMENTS OF THORACOABDOMINAL motion in subjects with quadriplegia due to traumatic transection of the cervical cord have established that the diaphragm acting alone during breathing in humans produces an inward displacement of the upper portion of the rib cage and an expansion of the lower portion of the rib cage (4, 13, 17, 20, 21). Similarly, in dogs, isolated
contraction of the diaphragm during inspiration displaces the upper ribs in the caudal direction and the lower ribs in the cranial and outward direction (5, 6).
The expiratory action of the diaphragm on the upper rib cage is primarily caused by the fall in pleural pressure, and its inspiratory action on the lower rib cage is the result of two components of the force developed by the muscle (7). The first component, the so-called “insertional force,” is the direct cranial force applied by the muscle fibers of the costal portion of the diaphragm at the level of their insertions into the lower ribs. The second component, denoted the “appositional force,” is the lateral force due to the transmission of abdominal pressure on the lower rib cage through
the diaphragm in the zone of apposition (16). The magnitude of the rib cage displacements produced by the diaphragm in quadriplegic subjects, however, is affected by the elastance of the abdomen and by abdominal pressure. Specifically, when the abdomen in these subjects is given a passive mechanical support by a pneumatic cuff or an elastic binder, the expansion of the lower rib cage during inspiration is increased and the inward displacement of the upper rib cage is reduced (4, 20, 21).
This effect of abdominal support has traditionally been considered to be the result of an increase in the appositional force of the diaphragm. Indeed, because such a support produces an increase in abdominal pressure, the zone of apposition at end-expiration is increased. Moreover, abdominal support also causes an increase in the elastance of the abdomen. Consequently, the descent of the dome of the diaphragm in response to a given muscle activation is decreased, the zone of apposition is larger throughout inspiration, and the rise in abdominal pressure is greater. It would be expected, therefore, that the appositional force would be greater.
Seria a respiração um fluído, um ar vital emanado do Criador? Seria alento, fogo que mantém acesa a vida? Seria ela algo invisível, intangível, função destinada ao movimento de fole dos pulmões?
Sim a respiração pode ser assim percebida. Pode também ser traduzida em complicadas fórmulas físicas e matemáticas e avaliada em sofisticados equipamentos. Quando adoece, a respiração pode ser tratada com medicamentos de última geração e também com atitudes que melhorem a qualidade da vida.
Nós, fisioterapeutas respiratórios, que lidamos diariamente com pessoas portadoras de distúrbios respiratórios, precisamos literalmente tocar o problema da respiração. A respiração precisa se tornar real, tangível, palpável.
A respiração além da abrangência de fluxos, volumes, resistências, complascências, trabalho, pressões, capacidades e volumes é uma experiência corporificada. Isto significa que toda e qualquer equação relacionada à respiração se manifesta no corpo. Para alguns profissionais da área de saúde, sobretudo o Médico, é possível abordar os aspectos químicos da respiração, empregando medicamentos que possam auxiliar a retomada do funcionamento de parte do Sistema Respiratório. Ao Fisioterapeuta cabe a parte mecânica. Grande sorte para quem escolhe como profissão ser um terapeuta, alguém que acompanha e orienta a pessoa na busca de sua própria cura.
