Question

identify and describe the primary and accessory muscle of respiratory.?

Answer 1

The muscles of respiration are those muscles that contribute to inhalation and exhalation, by aiding in the expansion and contraction of the thoracic cavity. The diaphragm and, to a lesser extent, the intercostal muscles drive respiration during quiet breathing. Additional 'accessory muscles of respiration' are typically only used under conditions of high metabolic demand (e.g. exercise) or respiratory dysfunction (e.g. an asthma attack). However, in instances where these accessory muscles become stiff and hard, expansion of the rib cage can be restricted. Maintenance of the elasticity of these muscles is crucial to the health of the respiratory system and to maximize its functional capabilities . .The processes of inspiration (breathing in) and expiration (breathing out) are vital for providing oxygen to tissues and removing carbon dioxide from the body. Inspiration occurs via active contraction of muscles – such as the diaphragm – whereas expiration tends to be passive, unless it is forced.

Process of Passive Expiration

Expiration is the phase of ventilation in which air is expelled from the lungs. It is initiated by relaxation of the inspiratory muscles:

• Diaphragm – relaxes to return to its resting position, reducing the superior/inferior dimension of the thoracic cavity.
• External intercostal muscles – relax to depress the ribs and sternum, reducing the anterior/posterior dimension of the thoracic cavity.

The relaxation of the inspiratory muscles results in a decrease in the volume of the thoracic cavity. The elastic recoil of the previously expanded lung tissue allows them to return to their original size.

The processes of inspiration (breathing in) and expiration (breathing out) are vital for providing oxygen to tissues and removing carbon dioxide from the body. Inspiration occurs via active contraction of muscles – such as the diaphragm – whereas expiration tends to be passive, unless it is forced

The Lungs and Breathing

The space between the outer surface of the lungs and inner thoracic wall is known as the pleural space. This is usually filled with pleural fluid, forming a seal which holds the lungs against the thoracic wall by the force of surface tension. This seal ensures that when the thoracic cavity expands or reduces, the lungs undergo expansion or reduction in size accordingly.

During breathing, the contraction and relaxation of muscles acts to change the volume of the thoracic cavity.

• When the volume of the thoracic cavity increases – the volume of the lungs increases and the pressure within the lungs decreases.
• When the volume of the thoracic cavity decreases – the volume of the lungs decreases and the pressure within the lungs increases.

Process of Inspiration

Inspiration is the phase of ventilation in which air enters the lungs. It is initiated by contraction of the inspiratory muscles:

• Diaphragm – flattens, extending the superior/inferior dimension of the thoracic cavity.
• External intercostal muscles – elevates the ribs and sternum, extending the anterior/posterior dimension of the thoracic cavity.

The action of the inspiratory muscles results in an increase in the volume of the thoracic cavity. As the lungs are held against the inner thoracic wall by the pleural seal, they also undergo an increase in volume.

Process of Passive Expiration

Expiration is the phase of ventilation in which air is expelled from the lungs. It is initiated by relaxation of the inspiratory muscles:

• Diaphragm – relaxes to return to its resting position, reducing the superior/inferior dimension of the thoracic cavity.
• External intercostal muscles – relax to depress the ribs and sternum, reducing the anterior/posterior dimension of the thoracic cavity.

The relaxation of the inspiratory muscles results in a decrease in the volume of the thoracic cavity. The elastic recoil of the previously expanded lung tissue allows them to return to their original size.

Forced Breathing

Forced breathing is an active mode of breathing which utilises additional muscles to rapidly expand and contract the thoracic cavity volume. It most commonly occurs during exercise.

Active Inspiration

Active inspiration involves the contraction of the accessory muscles of breathing (in addition to those of quiet inspiration, the diaphragm and external intercostals). All of these muscles act to increase the volume of the thoracic cavity:

• Scalenes – elevates the upper ribs.
• Sternocleidomastoid – elevates the sternum.
• Pectoralis major and minor – pulls ribs outwards.
• Serratus anterior – elevates the ribs (when the scapulae are fixed).
• Latissimus dorsi – elevates the lower ribs.

Active Expiration

Active expiration utilises the contraction of several thoracic and abdominal muscles. These muscles act to decrease the volume of the thoracic cavity:

• Anterolateral abdominal wall – increases the intra-abdominal pressure, pushing the diaphragm further upwards into the thoracic cavity.

  Primary muscle..

  The primary muscles of inspiration are the diaphragm, the upper and more lateral external intercostals, and the parasternal portion of the internal intercostal muscles. Both the external intercostal muscles and the parasternal portion of the internal intercos- tal muscles elevate the ribs.

• Internal intercostal – depresses the ribs.
• Innermost intercostal – depresses the ribs Accessory muscles of ventilation include the scalene, the sternocleidomastoid, the pectoralis major, the trapezius, and the external intercostals. Smooth muscle is found in the trachea and in the pulmonary arteries and smaller vessels. Use of accessory muscles.....
  
  Stand behind patient and place your hands behind the sternomastoid and feel the scalene muscles during quiet respiration. If the muscle contraction is palpable during quiet tidal breathing, the accessory muscles are in use. These muscles contract normally during an attempt at deep inspiration.