During respiratory exercise, the chest is enlarged and contracted due to the contraction and relaxation of respiratory muscles. This physiological process is difficult for students to understand in teaching, especially the lateral expansion and contraction of the thorax, which is a major difficulty in teaching. The model in the laboratory is an integrated model, and the thorax can only swing back and forth, the size is the same, and the intercostal muscle does not move, which will give students a wrong understanding. Therefore, the author wants to make a model, which can show the thoracic changes caused by intercostal muscle movement during human breathing to help teaching.
2 Research process
2. 1 First production
A rib movement model consists of four boards, nails and elastic bands (Figure 1). The teacher demonstrated that students can see the contraction and relaxation of the external intercostal muscle, which drives the movement of ribs and sternum, so that the anterior and posterior diameter of the thorax is enlarged and reduced.
Disadvantages: there is no name label, so it is difficult to distinguish parts; When pulling the external intercostal muscle, both ends of the intermediate contraction relax, resulting in illusion; No intercostal muscle; The shade is very big.
2.2 improve the process
The improved scheme of the rib motion model is shown in Figure 2, and the comparison of the three improved schemes is shown in Table 1.
2.3 Making process of the final model (Figure 4)
(1) Manufacture of backboard: Select an aluminum-plastic board with a height of 100 cm and a width of 70 cm, surround it with an aluminum alloy frame, and press the bracket on the back to manufacture the backboard.
(2) making intercostal muscle: cut two white elastic belt, both of which are 50cm； long; Draw a line segment every 9 cm on the elastic band with a red marker to mark the external and internal intercostal muscles; Cut the plastic pipe into 6 cm long sections, and sew the plastic pipe on the back of elastic belt every 3 cm with a sewing needle; Put a pull rope in the plastic pipe.
(3) Thoracic production: saw the white trunk into four sections, the lengths of which are 43cm (two ribs), 40 cm (one spine) and 29 cm (one sternum) respectively, and affix the names; Separate the gap in the middle of each trunking, drill a small hole as shown in the figure at the intersection (half face of trunking), and the size of the hole is similar to the thickness of the screw. Place the end of intercostal muscle and the starting point of the drawstring between the overlapping part of spine and ribs, spine and sternum, then tighten it through the hole, and finally tighten the other face of each trunking.
(4) Assembly: fix the upper and lower ends of the thoracic vertebra on the left side of the backboard with screws, drill two holes in the backboard near the intersection of two ribs and the spine, and pass the drawstring through the holes, and the rib motion model is completed.
3 Use verification
When using, the teacher first introduces to the students which structure each part represents. Then, by pulling the strap on the back of the external intercostal muscle, the red line spacing on the external intercostal muscle becomes shorter and the red line spacing on the internal intercostal muscle becomes longer, indicating that the external intercostal muscle contracts, the internal intercostal muscle relaxes, the ribs move upward and outward, and the sternum moves forward, which increases the anterior and posterior diameter of the thorax. Then loosen the hand of the rope, and the observed phenomenon is just the opposite. Through several rounds of teaching, the model intuitively reflects the changes of thoracic transverse size caused by intercostal muscle contraction and relaxation, which is convenient for students to understand the principle of respiratory movement, break through difficulties and achieve good teaching results.
4 innovation
(1) The intercostal muscle has a red line on the front and a short plastic tube and a pull-down rope on the back. During the demonstration, the intercostal muscles contract evenly, and the whole model is presented to the students completely, with clear observation and good effect.
(2) The contraction and relaxation of the external intercostal muscle and the internal intercostal muscle alternate at the same time, which can drive the sternum and ribs to move at the same time.
(3) There is a backboard and a bracket, which is very stable during the demonstration.