A contribution to the study of the mechanism of respiration : with especial reference to the action of the vertebral column and diaphragm / by J.F. Halls Dally ; communicated by T. Clifford Allbutt.

  • Dally, John Frederick Halls, 1877-1944.
Date:
[1908]
Catalogue details

Licence: In copyright

Credit: A contribution to the study of the mechanism of respiration : with especial reference to the action of the vertebral column and diaphragm / by J.F. Halls Dally ; communicated by T. Clifford Allbutt. Source: Wellcome Collection.

Provider: This material has been provided by The Royal College of Surgeons of England. The original may be consulted at The Royal College of Surgeons of England.

    5/10 (page 184)
    examinations of healthy adults, in deep inspiration, the average antero- posterior range of movement was as follows:— At upper aperture of thorax opposite 1st thoracic vertebra, 6 mm. Midway between upper aperture of thorax and level of diaphragm opposite 5th thoracic vertebra, 7'5 mm. At level of posterior part of diaphragm opposite 10th thoracic vertebra, 9 mm. These measurements show that on the average the spinal column is most displaced towards the lower part of the thoracic curvature, and that rectifica- tion lessens from below upwards. Individual differences, however, are not infrequent. This straightening, which occurs especially in that segment of the spine which articulates with the 6th, 7th, 8th, and 9th ribs, happens as a consequence of the backward push of the sternal ribs when the sternum is raised upwards and forwards by contraction of the cervical and thoracic muscles, thus bringing a larger costal arc into the place previously occupied by a smaller one, and so increasing the antero-posterior diameter of the thorax. Upon the ribs assuming a position of less obliquity, the spinal column, being far more limited in its possible range of movement than the sternum, on account of its multiple attachments can only execute a fraction of the sternal movement. Towards the end of inspiration, as the movement of the sternum reaches its dynamic limit, the remainder of the force of the respiratory cycle is spent upon the spine, which accordingly, during the latter half of inspiration, shows progressive mobility. In the lateral oblique position the apparent movement of the vertebral column is 6 to 9 mm.; the real movement may be readily calculated by means of a mathematical formula. Importance of the Spinal Movement.—The antero-posterior enlargement of the thoracic cavity produced by simultaneous extension of the thoracic vertebrae in deep breathing lias an important influence upon the aeration of the apices of the lungs, the forward and upward movement of the thorax, together with backward movement of the spine, being of far greater value than the lateral movement in promoting free access of air. III. Anatomical Dissimilarity of the Two Halves of the Diaphragm. Anatomically the two halves of the diaphragm differ in size and shape, the right half being the larger and the more powerful, the reason being that this half has to overcome the resistance of the mass of the liver, whereas the stomach is much more easily compressed by the left half. Functionally, although the two halves of the diaphragm are of unequal size and strength, yet, owing to the difference in resistance on the two sides, their range of b 2