CHAPTER 6

Muscular Tissue; The Structure and Grouping of the Muscles

(Continued from p. 197.)

We come next to speak of the characteristics of muscular tissue, of all kinds, which enable it to perform the well-nigh endless movements of the body. These are (1) Irritability, (2) Contractility, (3) Extensibility, and (4) Elasticity.

Irritability, or sensitiveness, is the power of the muscular tissue to receive and respond to stimulation.

Contractility is the response of the muscle to the stimulation, and is shown in its change of form, becoming shorter and thicker.

Extensibility enables the muscle to be stretched, and Elasticity is the reverse action, enabling it to return to its original form. These last two characteristics are opposites, and normally serve to preserve the muscles in readiness for prompt and smooth movement. The slight tension of each muscle is held in that way by its elasticity. Looking upon each muscle as a figure of the individual, we see in these four characteristics the adaptation of each member of the body to respond to the impulses which reach him from the controlling spirit, shown by the change from the normal rest to a tension, more or less strong according to the nature of the impulse. This contraction may be likened to one's being drawn in upon himself, answering to the girding up of the loins (1 Pet. 1:13). The relaxation and ease gives place to a calling in, and corresponding bracing and enlarging of one's spiritual powers. They become more individual, and under the control of the stimulating force.

The opposite of this nerve tone is an undue relaxation, caused by a weakness and softness of the nerve control. This is hardly the place to enlarge upon the various affections of the nervous system, which will come before us later, and it must suffice here to point out the connection between neurasthenia and the general lassitude of the muscular tissue. Fatigue, exhaustion, disinclination for exertion, are the marked features of this.

It is easy to see the moral and spiritual significance of this. Lack of tonicity of soul is only too frequent. Instead of being "ready to every good work" (Tit. 3:1), we are prone to let the hands, hang down, the knees to be feeble, with the resulting devious ways and incomplete work. For the need of oft-repeated goading to action, followed by prolonged seasons of spiritual inertia, is not a mark of health and prosperity of soul (3 John 2).

By our physical structure the normal state of the muscles is slightly tense, and the same is true of the spiritual man. May we be recovered to an alertness of soul that will lead us to "press toward the mark" (Phil. 3:14).

There are three general classes of muscles:(1) the striped, or striated, which are attached to the bony structure, and are also called voluntary and skeletal. These are the muscles of voluntary motion, largely under the control of the will. (2) The plain, or non-striated, also called visceral and involuntary, indicating their detachment from the control of the will. (3) The cardiac, or tissue of the heart, which in a sense is intermediary between the other two kinds, but is involuntary, with marked characteristics of its own.

The striated, or voluntary, tissue is marked by each cell having a number of nuclei, so that we might call it a multiple cell. These cells are quite long and are composed of the contractile substance, the nuclei, and a kind of sheath or tube enclosing it. We might say that the muscles, which are composed of these cells, show the same general arrangement. They are enclosed in sheaths, making many bundles, all elongated, and abundantly supplied with blood-vessels and nerves.

The various muscles are themselves thus closely covered with sheets of fibrous tissue, which unite them together and form them into groups, or the large individual muscles. These latter vary in shape and size according to their use, some being short, others flat, and still others long.

This very brief summary must suffice for this part of our subject. Doubtless many more analogies would be found by a more detailed analysis. What stands out is- unity in multiplicity, abundant nutrition, and complete subjection to nerve control.

So it is with the powers of the spiritual man. There are "diversities of gifts (χαρίσμαια, what is bestowed), but the same Spirit; of administration (διακovίάι, services) but the same Lord; of operation (έvεργήμαπα, effects, workings), but the same God working all in all" (1 Cor. 12:4-6). In the passage quoted the reference is largely to the whole Body of Christ, the varied gifts and operations of the different members. But the same would apply to the varied elements composing the spiritual faculties and working of the individual. The forces working in us are the resultants of numbers of distinct features. Take for instance the action of preaching the Gospel-how many elements compose it. There is "knowing the terror of the Lord" (2 Cor. 5:11); the constraining love of Christ (ver. 14); the sense of responsibility (ver. 10); the desire to please the Lord (ver. 9); the yearning love for souls, "We pray you" (ver. 20)-all distinct, and yet bound together to effect the one purpose, "We persuade men."

The same might be said of the pastoral care for souls- there is the love of the lambs and sheep, the obligation to the Lord, the sympathetic interest, the firmness and the discretion. Not one fibril is lacking in the spiritual structure, none should be wanting in carrying out the behests of the Master-"Lovest thou Me; feed my lambs, shepherd my sheep" (John 21:15-17).

What full provision is made for the nourishment and energizing of each element in all this service! None of us can plead insufficient supply or of power; "According to the power that worketh in us" (Eph. 3:20); "I can do all things through Christ which strengthened me" (Phil. 4:13).

Returning to the entire Body of Christ, we find the same great truth of diversity in unity, the same merciful and complete provision for "the effectual working in the measure of every part" (Eph. 4:16). We discern the varied gifts, but they are closely bound together in harmonious unity. Some are more closely linked to one another in service than to others. There are groups of those engaged in the same service. The disciples were sent out two and two; Peter and John were both engaged in their work of healing and of testimony (Acts 3); Paul ever craved the presence and help of one or more helpers. He could speak of "those women who labored with me in the gospel" (Phil. 4:3). Here we have the various individual "cells" bound together in common activity. But many as they are, provision is made for the direct nutrition and stimulation for each one separately.

In all this we have been speaking of the significance of the striated, or voluntary, muscles. The same truth is seen in the involuntary, non-striated ones, forming the mobile walls of the viscera. The thought here is not so much outward service connected with the bony framework of testimony, but of the vital processes connected with the upbuilding of the "inner man." In the same twofold way we may apply this to the individual or to the body corporate. All the processes of nutrition, assimilation, and elimination are controlled by these involuntary, we might almost say automatic, muscles. In the cell here there is but one nucleus, emphasizing the unity of each portion of the inner man. Communion with God seems to be the prominent thought here. "If there be any consolation in Christ, if any comfort of love, if any fellowship of the Spirit, if any bowels and mercies"- σπλάγχvα the viscera, composed of the unstriated, involuntary muscles (Phil. 2:1). Communion with God is not exactly the same as activity, though they are not contradictory thoughts. The nourishment and the vital processes which give us strength to serve are not exactly secured by effort. It is the "abiding" of which our Lord speaks (John IS) which produces fruit. There is a hidden, an inner, life in which we drink in under the Spirit's direct control the abundant consolations and nourishment of Christ. There is motion, but it is under His control. The two kinds of muscle might be illustrated by Mary and Martha, in their proper spheres. The Cardiac tissue is found only in the heart. The cells, like those of the viscera are involuntary, though not unstriated. They are shorter than the cells of the voluntary, or of the visceral muscles, without the enveloping tube or sarcolemma; they contain but one nucleus, and are grouped in bundles which are held together by fine fibrils uniting the whole into one organ.

The outstanding feature of the cardiac muscle is not only its involuntary or automatic action, but its rhythmicity. This is inherent in the tissue, as well as controlled by the nerves. Throughout the day and night, from birth to the close of life, this wondrous mechanism continues its work, without effort on the part of the one whose life depends upon its unfailing action.

We speak of it here simply in connection with the nature of its muscular tissue. In its proper place we trust to go into it in some detail. The entire circulatory system is one of the marvels of the structure, "fearfully and wonderfully made."

The heart! It is the man, in a physical as in a spiritual sense. "As he thinketh in his heart, so is he." "Keep thine heart with all diligence, for out of it are the issues of life" (Prov. 4:23). And yet it is, in a very real sense, beyond man's control. And how good that this is so! Suppose we had to watch over and produce the pulsations of our hearts! Its aloofness and yet its nearness, its absolute necessity for our life, and yet we cannot lay a hand upon it! It seems thus to emphasize that which is in the hands of God. "Create in me a clean heart, O God" (Ps. 51:10). "Ye must be born again" (John 3:7). Absolute necessity, yet entire dependence upon God. May not the striated and yet involuntary character of cardiac muscle teach us the close connection with the voluntary muscle, and yet distinction from it? As in the third chapter of John we have the necessity for new birth which emphasizes man's powerlessness, yet hi the faith which beholds the uplifted Son of God may we not have the antitype of the striated tissue? "With the heart man believeth unto righteousness" (Rom. 10:9). Thus God meets man where his utter helplessness is most manifest. S. R.

(To be continued, D. V.)