Muscles as the Organs of Movement
Opposed to the passive nature of the skeletal structure is the active nature of the muscles.
These are the organs of movement and represent that part of the anatomical structure which makes possible, without outside force, the movements described in module 1. Muscles are divided into two classes:
- skeletal (striped) and
- visceral (unstriped).
- The skeletal structure is passive in nature.
- The muscular structure is active in nature.
- The muscles are the organs of movement which make possible the movements described in Mechanical Principles.
- Muscles divide themselves into two classes.
- Skeletal (striped).
- Visceral (unstriped).
- Skeletal muscles govern the bodily movement of rotation and translation. [1]
- Visceral muscles govern the activity of the internal organs such as the heart, lungs, and stomach.
- Our problem excludes the consideration of visceral muscles[2] .
Shape of Muscles
Each muscle is a combination of a great number of muscle fibers or muscle cells. Usually it is thickest at or near the middle of its length and tapers off at both ends into tendons attached to the bones. The fibers are grouped into bundles of various sizes and the entire muscle is enclosed in a sheath [3].
To this muscle-form, however, there are numerous exceptions. If the muscle divides at one end into two parts it gives the biceps form; a division into three parts gives the triceps form. Some muscles, whose function is range rather than power, are long and slender, others whose function is power, are short and thick. In some cases, the tendon at one end is missing, the belly forming the actual point of attachment. The muscle fiber of popular parlance [4] is something essentially different from the muscle-fiber of the anatomist. Since the muscle substance itself is quite soft, it is enclosed in a connective tissue, which, besides holding the muscle substance in place, transmits the pull of the fibers to the tendon and through this to the point of attachment, thus producing movement .
To this muscle-form, however, there are numerous exceptions. If the muscle divides at one end into two parts it gives the biceps form; a division into three parts gives the triceps form. Some muscles, whose function is range rather than power, are long and slender, others whose function is power, are short and thick. In some cases, the tendon at one end is missing, the belly forming the actual point of attachment. The muscle fiber of popular parlance [4] is something essentially different from the muscle-fiber of the anatomist. Since the muscle substance itself is quite soft, it is enclosed in a connective tissue, which, besides holding the muscle substance in place, transmits the pull of the fibers to the tendon and through this to the point of attachment, thus producing movement .
[1]translation: n. [ME. translacioun <MFr. translation <L. translatio ] 3. Mechanical motion in which every point of the moving object has simultaneously the same velocity and direction of motion. -translation adj.
[2]Visceral muscle:Visceral, or smooth, muscle is found inside organs such as the stomach and intestines, as well as in blood vessels. It is called a smooth muscle because, unlike skeletal muscle, it does not have the banded appearance of skeletal or cardiac muscle
[3]sheath :n. pl.sheaths [ME. schethe <OE. sceath, akin to German scheide <IE. base *skei-,
1. to cut, split, divide (whence L. scire, to know: cf SCIENCE: the earliest form of sheath was probably a split stick. 2. a covering or receptacle resembling this, as the membrane around a muscle, a leaf base enveloping a stem of grass, etc.
1. to cut, split, divide (whence L. scire, to know: cf SCIENCE: the earliest form of sheath was probably a split stick. 2. a covering or receptacle resembling this, as the membrane around a muscle, a leaf base enveloping a stem of grass, etc.
[4]parlance: language used by a particular group of people