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The muscle fibres of the diaphragm radiate outward from the central tendon. While the diaphragm is one muscle, it is composed of two distinct muscle regions: the costal, which serves as the driver in the work of breathing, and crural diaphragm, which serves as an "anchor;" attaching the muscle to the lower ribs and lumbar vertebrae.
This phenomenon occurs because of the elastin in the elastic fibers in the connective tissue of the lungs, and because of the surface tension of the film of fluid that lines the alveoli. As water molecules pull together, they also pull on the alveolar walls causing the alveoli to recoil and become smaller.
There is no definitive list of accessory muscles, but the sternocleidomastoid and the scalenes (anterior, middle, and posterior) are typically included, as they assist in elevating the rib cage. [4] The involvement of these muscles seems to depend on the degree of respiratory effort.
The upper, horizontal fissure, separates the upper from the middle lobe. It begins in the lower oblique fissure near the posterior border of the lung, and, running horizontally forward, cuts the anterior border on a level with the sternal end of the fourth costal cartilage; on the mediastinal surface it may be traced back to the hilum. [1]
During inhalation, about twice as much oxygen is absorbed by the lung tissue as in a land mammal. As with all mammals, the oxygen is stored in the blood and the lungs, but in cetaceans, it is also stored in various tissues, mainly in the muscles. The muscle pigment, myoglobin, provides an effective bond. This additional oxygen storage is vital ...
The tissue has been characterized as viscoelastic, nonlinear, and anisotropic in the direction of the fibers. Young modulus values range from 585 Pa at the posterior free edge of the soft palate to 1409 Pa where the soft palate attaches to the maxilla. [ 3 ]
There are ten bronchopulmonary segments in the right lung: three in the superior lobe, two in the middle lobe, and five in the inferior lobe. Some of the segments may fuse in the left lung to form usually eight to nine segments (four to five in the upper lobe and four to five in the lower lobe.
Details of upper respiratory tract. The upper respiratory tract can refer to the parts of the respiratory system lying above the vocal folds, or above the cricoid cartilage. [4] [5] The larynx is sometimes included in both the upper and lower airways. [6] The larynx is also called the voice box and has the associated cartilage that produces sound.