Picture - Cosmic Polymath

NEW VIEW OF THE MECHANISM OF RESPIRATION 295
Professor Flint has given expression to the views of the majority of physiologists of the present day, and is in no
way to be held responsible for popular beUefs however incorrect.
For these and other reasons already stated, I hold that the inspiratory and expiratory muscular movements are
both vital in their nature, and that the abdominal muscles of expiration are correlated to, and act in concert with,
the thoracic muscles of inspiration.
The inspiratory and expiratory movements are produced by spontaneous self-acting muscles ;
quite a subordinate part in both movements, but being most pronounced in expiration.
elasticity playing
As regards the subject of elasticity it may be well to point out that the elastic properties of living muscles and
elastic bodies generally, such as steel, caoutchouc, and other springs, are not identical, and give quite different
results. The elasticity of muscle acts slowly and is more or less under control—that of mechanical springs acts
quickly and is, in no sense, under guidance.
While I do not attach the same importance to elasticity in muscular action as some of my confreres do, I
am far from denying its existence or ignoring its power in animal physics.
in expiration and in wing and other movements.
It certainly does perform a" useful function
The one-sided view of the opening and closing of the chest, whereby the opening is ascribed to vital action
inhering in the muscles, and the closing to elastic recoil, is due to the almost universal belief that muscle is endowed
with only one power, namely, that of shortening or contracting. A compensating force in that case becomes a
necessity, and elasticity is made to do duty in and out of season when a difficulty arises. For reasons already
stated, I maintain that muscles are endowed with a double power, namely, a centripetal power of contracting
or shortening, and a centrifugal power of relaxing or elongating ; these movements being both vital in their
nature. An analysis of the movements of muscle (voluntary and involuntary) is given in Sections 54 and 55 of the
present work.
According to my views, muscles never oppose and contend against each other as rivals. On the contrary,
they work harmoniously together ;
of their movements.
elasticity helping them over their dead points and contributing to the continuity
Hitherto I have confined my observations to the movements of the respiratory muscles m calm or normal
breathing, and before leaving the subject, and in order to emphasise my findings on an avowedly difficult and important
matter, I append a table in which not only the muscles engaged are enumerated, but also their attachments set forth.
The nmscles connected with violent or forced breathing are given further on. They are usually designated extra-
ordinary muscles of respiration.
TABLE OF MUSCLES ENGAGED IN RESPIRATION ACCORDING
TO THE AUTHOR
Inspiratory Muscles Engaged in Ordinary Calm Breathing
Aitarhiiiimfx.
(a) The external and internal intercostal The external intercostal muscles are attached to the outer borders of
muscles. the ribs ; the internal intercostal muscles (sturnal portions) to the
borders of tlic costal cartilages.
(6) The pectorales minor muscles.' These muscles are attached to the coracoid process of the scapula and
the anterior surfaces and upper margins of the third, foiu'th, and fifth
riljs near the cartilages.
(c) The soaleni muscles (anticus, medius, and The scalenus anticus muscle is attached to the third, fourth, and fifth
posticus). ribs of the c('r\-ical vertebrse and the tubercle of the tii'.st rib ; the
scalenus medius to the transverse processes of the lower six cevvii.'al
vc'T'tebviE and the upper surface of the first rib ; the scalenus posticus
to the transverse processes of the lower tliree cervical vertebrse and the
outer surface of the second rib.
(d) The twelve levatores costarum muscles. The levatores costarum muscles are attached to the transverse processes
of the dorsal vertebrse and the ribs liet ween the tubercles and angles.
(e) The diaphragm, at once inspiratory and ex.- The diaphragm is attached to the bodies of several of the upper lumbar
piratory. vertebrfe, the ligamenlum ai'cuata, the ensiform cartilage, and the carti-
lages of the sixth lower rilis.
' These muscles are said to net in forced or deep inspiration.