By Dr. Luca Franzon
Breathing and Diaphragm
The respiratory system is composed of the lungs, which represent the site of gas exchange, and of the pump that serves to ventilate the lungs themselves. The pump consists of the rib cage, the respiratory muscles that move it and the nerve centers that control its movements. The pump work is regulated by the respiratory centers located in the medulla oblongata. The affected muscles are the diaphragm and the external and internal intercostal muscles, the intercondral parasternal, the scalenes, and the sternocleidomastoid.
The diaphragm consists of three parts:
the rib portion, consisting of the muscle fibers that are attached to the ribs around the bottom of the rib cage;
the crural portion, made from the fibers that are attached to the ligaments along the vertebrae;
the tendon center, in which the rib and crural fibers are inserted. The latter, passing on each side of the esophagus, can compress it when they contract. The tendon center is also the lower part of the pericardium. The costal and crural portions are innervated by different parts of the phrenic nerve and can contract separately. For example, during vomiting and belching, intra-abdominal pressure is increased by the contraction of the rib fibers, but the crural fibers remain released, allowing the material to pass from the stomach into the esophagus.
In addition to the diaphragm, the other main inspiratory muscles are the external intercostals, which run obliquely downward and forward from each coast to the next. The ribs rotate pivoting posteriorly on the cost-vertebral joint, and when the intercostal muscles contract, they, which are inclined downwards and forwards, are raised to a more horizontal position; the sternum is then pushed forward, and the anteroposterior diameter of the thorax increases. The transverse diameter also increases, but to a lesser extent. Both the diaphragm and the external intercostal muscles can, on their own, maintain adequate ventilation in resting conditions. The section of the spinal cord above the 3rd cervical segment is fatal if no intervention is made with artificial respiration, while a section below the origin of the phrenic nerves (cervical segments 3-5) is not. on the other hand, in patients with bilateral phrenic paralysis, but with intact innervation of the intercostal muscles, breathing is a bit tiring but sufficient. Scalenes and sternocleidomastoids are accessory inspiratory muscles that help to lift the rib cage in deep and tiring breathing.
When the expiratory muscles contract, the intrathoracic volume and forced expiration decrease. The internal intercostals have this action because they run obliquely downward and posteriorly, from a coast to the one below, so they pull down the rib cage when they contract. Also the contractions of the muscles of the anterior abdominal wall help expiration, both because they pull the rib cage down and inside, and because they increase intra-abdominal pressure, which pushes up the diaphragm.
Inspiration
It consists in the dilation of the thoracic cage which, due to the pleural system, involves the dilation of the lungs and the recall of air in the bronchial tree and in the alveoli. In normal breathing the activity is almost exclusively dependent on the diaphragm. With an intense inspiratory effort, the intra pleural pressure can drop to -30 mmHg, producing an expansion (inflation) of the lungs much greater than the norm. When ventilation increases, the emptying (deflation) of the lungs also increases, due to the entry into activity of the expiratory muscles which reduce the intra-thoracic volume.
expiration
The flow of air coming out of the lungs is determined by the decrease in chest volume. It is largely a passive phenomenon due to the elastic nature of the cartilaginous tissues, the lungs themselves and the abdominal walls. This allows reduction without muscle intervention. Only forced expiration requires considerable muscular effort. Ventilation maintains the normal concentration of O2 and CO2 in the alveolar blood, through a passage of these gases from the alveoli to the blood capillaries by diffusion. The perfusion corresponds to the pulmonary blood flow which is given by the heart rate for the systolic volume of the right atrium. The relationship between ventilation and perfusion should be the same throughout the lung. The difference between the partial pressures of respiratory gases in exhaled gas and in systemic arterial blood is a measure of the efficiency of lung function.
Breathing Exercises
Most of the exercises described below should be performed in a sufficiently heated and quiet place and require the use of one or more sand bags weighing 3 kg.
DIAFRAMATIC GYMNASTICS
Supine position with knees bent, place hands on abdomen at diaphragm. Inhale deeply inflating the abdomen, hold the breath for a few seconds, then exhale completely compressing the abdomen with your hands. Repeat the exercise slowly 20 times.
Supine position bent legs, place the sand bag on the abdomen. Inhale deeply lifting the bag with the abdomen, hold the breath for a few seconds, then exhale completely lowering the bag. Repeat 30 times.
Position sitting hands on the abdomen, inhaling inflating the abdomen, keeping the position a few seconds then exhaling deeply compressing the abdomen with the hands. Repeat 30 times.
Standing upright hands placed on the abdomen, inhale deeply inflating the abdomen, hold the position for 10 seconds then exhale compressing the abdomen with your hands. Repeat the exercise 30 times.
On the right lateral decubitus position, the right leg is bent, the hands placed on the abdomen inhale inflating the abdominal cavity; hold the breath a few seconds then exhale compressing the abdomen with your hands. Repeat the exercise 25 times on each side.
Exercise similar to the previous one with the addition of a sandbag on the abdomen Repeat the exercise 30 times per side.
COSTAL GYMNASTICS
Supine legs bent, hands placed on the chest, inhale raising the chest as much as possible; hold the breath a few seconds, then exhale compressing the chest with your hands. Repeat 30 times.
Exercise similar to the previous one with the addition of a sand bag on the chest. Repeat 30 times.
Variant to the previous exercise by adding the movement of the arms that are carried towards the back in the inspiratory phase, in the expiratory phase they return along the sides. Repeat the exercise 25 times.
On the right side with the bag on the same side, inhale bringing the left arm back and lifting the sandbag; hold the breath for a few seconds then exhale, lowering the upper limb and the bag. Repeat the exercise 20 times on each side.
