Sequence of action of the diaphragm and quadratus lumborium during quiet breathing.код для вставкиСкачать
Sequence of Action of the Diaphragm a n d Quadratus Lumborium duri:ng Quiet Breathing ’ AND J. C. HAYNER Y e w Y o r k Medical College, Department of A n a t o m y , N e w Y o r k City, N . Y . UV. BOYD, H. BLINCOE ABSTRACT A smies of 15 rabbits had multiple intercostal clip electrodes implanted in the diaphragm and quadratus lumborum at open operation. Leads from the electrodes were passed to the back of the animals and soldered to a junction band. Simultaneous recordings of electromyographic activity and spirometry were made following recovery. The study revealed that the quadratus lumborum, acting simultaneously with the diaphragm, is an effective inspiratory muscle stabilizing the twelfth rib, converting i t into a fixed point from which the diaphragm acts. Very possibly the action of the quadratus pulls down the lower rib helping to increase the costo-diaphragmatic recess. Like the sternal, crural and costal portions of the diaphragm, the quadratus exerts a braking action to oypose the normal elastic recoil of the lungs during expiration. While investigating the activity of the diaphragm during normal quiet breathing, it became of interest to earn the sequence of action of this muscle and the quadratus lumborum, for the literature makes no reference to any electromyographic studies of this nature, or for that matter, to any studies of the behavior of the quadratus lumborum. Since there is a relatively small attachment of the quadratus to the thorax, it has been felt that it is unlikely to be of much importance in .he mechanics of breathing. The general opinion is that the quadratus lumborum acts as an inspiratory muscle which helps to fix the lower ribs and thus to convert them into fixed points from which the diaphragm can contract. In order to clarify these points, it was thought worth while 1 0 study the subject with precise electromyographic techniques. MATERIALS AND METHODS Experimental animals. Fifteen adult male rabbits, weighing 8-10 lbs, were the subjects. Equipment. The equipment centered on a Hathaway Type SC-16A recording C.R. oscillograph consisting of six identical but separate amplifers each of which is fitted with a 3” cathode-ray tube. The traces of the tubes were photographed by means of built-in chart drive system deANAT. REC., 151: 579-582. signed for recording transient or periodic phenomena. Although there is a constant sweep of the traces on the tubes, the beams of the recording tubes have no x-axis deflection; this is provided by the continuous movement of the film through the chart drive system. Independent Disa amplifiers, identical in construction, were used as pre-amplifiers. Each is a balanced four-stage a-c amplifier with an input circuit designed especially to accomplish a low noise level, a high input impedance, a wide frequency range, and a large inphase rejection ratio. Electrodes. A dual clip electrode of new design used to study intercostal activity was utilized in this investigation (fig. 1). It consists of two no. 0 “Petite” paper fasteners insulated with “Formvar” except for the tip of each jaw, soldered to the ends of no. 40 dual insulated stranded wire. Surgical procedure for implanting electrodes. Each rabbit was anaesthetized with pentobarbital (Nembutal 0 . 3 ml/lb body wt), and maintained with ether when necessary. With the animal supine on an adjustable operating table, a long horizontal incision through all muscle layers was made below the costal margin. ‘This study was supported by an N.1.H grant, NB 04771-01 to Dr. Boyd. 579 580 W. BOYD, H . BLINCOE AND J. C . HAYNER Fig. 1 Dual intercostal clip electrodes. x 20. The diaphragm was exposed by depressing the liver, and the quadratus lumborum was exposed by gently pushing aside the colon and the kidney. Electrodes 2 mm apart were clipped to the crus, sternal and costal slips of the diaphragm, and to the quadratus lumborum. With the aid of a large curved autopsy needle, the insulated stranded wires leading from the electrodes were drawn between the muscles of the lateral abdominal wall and the skin, around to the back of the animal. The free ends of the wire were brought out through puncture holes in the skin and soldered to a “junction band” which was then taped securely to the animal’s back. The incision was closed, sprayed with an antibiotic plastic dressing, and covered with sterile gauze held in place by elastic adhesive bandage. After several days of recovery, the animals underwent a series of tests which involved a simultaneous recording of electromyographic activity and spirometry. The small modified spirometer used for recording respiratory movements is discussed elsewhere (Boyd and Basmajian ’63). The experimental animals were tested on 3 or 4 occasions, and the data for study was obtained from these recordings. The EMG activity was rated from 0 to 3+. One plus ( 1 + ) indicates slight activity, two plus ( 2 + ) moderate activity, and three plus ( 3 + ) great activity. OBSERVATIONS The quadratus lumborum. Since the diaphragm in the rabbit has been considered elsewhere (Boyd and Basmajian, ’ 6 3 ) , it is necessary only to describe the quadratus lumborum. The quadratus lumborum, broader below than above, takes origin from the ilio-lumbar ligament and from the iliac crest. As it passes upwards, it gives several fibers to the transverse processes of the lumbar vertebrae, and eventually reaches its insertion on the medial three Fig. 2 Typical recording of activity during quiet breathing from the quadratus lumborum ( B ) , and from the crus of the diaphragm ( A ) . The numbers below the spirometric tracing refer to the phases in the respiratory cycle. Pre-inspiration (phase l), inspiration (phase 2), terminal phase of inspiration (phase 3), pre-expiration (phase 4 ) , expiration (phase 5 ) . CIAPHRAGM AND QUADRATUS LUMBORUM fourths of the last rib by passing behind the diaphragm. Its ~ppennost part is therefore covered with pleura. The respiratory cycle. The spirometric tracings show the same phasic tendency seen in other studies o n respiratory muscles, and are described elsewhere (Boyd and Basmajian, '63). T h e recordings. Surveys of the recordings (fig. 2), revealed that both the diaphragm and the quadratus lumborum were slightly active 1(1+) during preinspiration (phase l ) , but activity in both muscles showed signs of change at the onset of inspiration (phase 2). In the diaphragm, s:ight activity ( l + ) was recorded for the first 60-70msec of inspiratory phase 2, fctllowed by a sharp increase to moderate 2 ctivity for another 60-70 msec of the phxse. Great activity ( 3 f ) followed for the next 70-80 msec, which quickly returned to moderate activity (2+) for the last 10-20msec of inspiratory phase 2. The slight activity recorded during the 10-15msec of inspiratory phase 3, abruptly terminated at the onset of preexpiration. In most instances, just noticeable to slight activivi ( 1 + ) continued throughout pre-expirat ion and expiration. In the typical recordings presented in figure 2, the clip was on the crus, which was electrically silent throughout preexpiration and expiration. In all other parts of the diaphragm, slight activity ( 1+ ) was always re1:orded during preexpiration and expiration. In contrast to diaphragmatic activity, the quadratus showed only slight activity during the first 110-120 msec of inspiration. This, in fact, was throughout nearly the entire first half of inspiratory phase 2. Moderate activity (:I+) recorded at the onset of the second half of phase 2 lasted 60-70 msec but quickly increased to great activity ( 3 + ) for the next 70-80 msec, returning to moderat68 activity (2+) for the last 10-15msec of this phase. Although the diaphragm showed slight activity during inspiratory phase 3, the quadratus was electrically silent through- 58 1 out this phase and the pre-expiratory phase as well. The slight activity ( I f ) recorded from the quadratus muscle throughout expiration was identical to that recorded from the sternal and costal parts of the diaphragm. DISCUSSION The recordings reveal that the force of diaphragmatic contraction increases gradually during the early stages (first half) of inspiration. It is very likely that this gradual increase is proportional to the amount of resistance to stretch in the tissues of the lungs, mediastinum and thoraco-abdominal parietes. During the latter part of inspiration (second half) the expenditure of energy by the diaphragm is considerably increased, and it is maintained at a higher level throughout all but the last few milliseconds of the phase. The effect of diaphragmatic contraction with no opposing muscle action would tend to elevate the twelfth rib, thus causing a less effective lowering of the dome of the diaphragm and impairing somewhat the efficiency of inspiration. Any ascent of the twelfth rib is partially prevented by the action of the quadratus lumborum. During the early stage of diaphragmatic contraction, the quadratus lumborum is only partially utilized to stabilize the lower rib, for it is possible that other more passive structures such as fascia and ligaments act as sufficient stabilizers at this time. However, during the later more energetic phase of diaphragmatic contraction, the quadratus lumborum rapidly and progressively becomes more active in resisting stretch in order to bring about a greater stability of the rib. In addition, it is possible that the quadratus somewhat depresses the rib, thus helping to increase the costo-diaphragmatic recess. LITERATURE CITED Boyd, W. H., and J. Basmajian 1963 Electromyography of the diaphragm in rabbits. Am. J. Physiol., 204: 943-948.