Inspiratory muscles . They take part in the movement that is used to introduce air into the lungs . Inspiration also causes an acceleration of the venous circulation back to the heart . Being an important and excellent filling element for the heart and for the good arrival of venous blood to the lungs in contact with the fresh air that has just entered it.
Summary
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- 1 Main muscles
- 2 Main facilitating muscles of the inspiratory phase
- 3 Accessory muscles of inspiration
- 4 See also
- 5 Sources
Main muscles
- The diaphragm is the main respiratory muscle and represents the plane of separation of the rib cage and abdomen . It is striated, the fibers of which are oriented radially from its tendon central zone to the bony structures of the periphery and which, when compared with peripheral muscles, shows greater tolerance to fatigue , greater blood flow, greater capillary density and greater oxidative capacity. Its contraction produces a decrease in its dome which leads to an increase in the anteroposterior and transverse diameters of the rib cage.
- The external intercostal muscles are thin muscles that are located in the most superficial plane of the intercostal spaces. Its fibers are oriented obliquely towards the anterior midline. Its inspiratory action is based on the ability to pull the immediately inferior rib caudo-cephalad and thus increase the diameter of the chest.
- The para-sternal intercostal muscles correspond to the bilateral chondro-sternal portion of the internal intercostal muscles. Their active participation during the inspiratory phase has been verified electromyographically. Its contraction contributes to the shortening of the intercostal spaces and the elevation of the ribs.
Main facilitating muscles of the inspiratory phase
Under normal inspiration conditions, a series of extra thoracic muscles intervene that generate three facilitating effects of the inspiratory phase:
- Vomer
- Ethmoid
- Septal cartilage
- Hard palate
- Soft palate
- Patellar Veil Tightening
- Palate Veil Elevator
- Pharyngeal tonsil
- Palatopharyngeal
- Palatine tonsil
- Palatoglossus
- Geniogloss
- Genihyoid
- Mylohyoid
- Arytenoepiglottic fold
- Cartilage aritenoides BOCA
Accessory muscles of inspiration
Most of the muscles in the neck region, shoulder girdle and upper chest region participate in inspiration during special circumstances (forced inspiration). Among them the following stand out.
- The scalene muscles are three: anterior, middle, and posterior, extending from the transverse processes of the last five cervical vertebrae to the anterior surface of the first and second ribs. Its contraction collaborates with the ascension of the upper ribs and is evidenced as the retraction of the neck and supraclavicular space during forced inspiration. As an additional function, they fix the gossip during an intense cough to avoid herniation of the pulmonary vertices, this function can be attributed to it during expiration.
- The sternocleidomastoid muscle extends from the mastoid process to the front of the chest, inserting into the clavicle and sternum . Its contraction also helps to elevate the upper rib cage. Considered the most important accessories. The action of the muscle is to produce lateral tilt movements or head rotation. For its inspiratory action to take place, the head and neck need to remain stable. By a combined action of the neck flexors and extensors. In such a way that the insertion point remains fixed and the contraction on the points of origin produces the movement of elevation of the sternum and clavicle with the consequent enlargement of the anteroposterior diameter of the thorax.
- The latissimus dorsi muscle extends from the external aspect of the last four ribs, the iliac crest and the spinous processes of the last dorsal and lumbar vertebrae to the bicipital slider of the humerus . If it is fixed in this place, its contraction collaborates with the elevation of the ribs helping in inspiration.
- Pectoralis major: It is a large fan-shaped muscle. It intervenes in deep inspiration. For your activity to be possible it is necessary to keep your shoulders and arms fixed. So that the movement takes place taking the insertion as a fixed point and the origin as the moving point.
The accessory muscles of second-order inspiration are those that intervene in situations of extreme need to increase the volume of the rib cage. The main muscles are the minor pecs accompanied by others such as: the trapezius and serratus.
- Pectoralis minor: it is a muscle originating from the rib cage and insertion into the scapula. In order for it to act as accessories for inspiration, the fixed insertion point must be maintained to project the ribs anteriorly and superiorly.
- Traps and serrates: accessory muscles of the second phase. During the inspiratory phase they depend on two factors: on the inversion of the points of origin and insertion, a situation in which the point of insertion is fixed and the point of mobile origin and, on the other hand, the fixation of thoracic and non-thoracic structures to help The inspiration. The upper trapezius extends and fixes the cervical spine to facilitate the action of the sternocleidomastoid and by raising the shoulder it facilitates the action of the pectorals. The serratus major acts on forced inspiration if the scapula is adducted by the rhomboids.
