Physiology Of The Vocal Organ
The body of vertebrates, of which man is the nest form, has as its basic structure the form of a double tube. These two tubes are closely connected with each other for their entire length. They are parallel to on another and stand in an upright position (vertical).
The front tube (A). Fig. 33, surrounds the so-called vegetative organs (lungs, viscera, heart, etc.); the second tube (B), behind the other, Fig 33, forms the head and spinal column, containing the brain and marrow and nervous system. This second tube distinguishes animal from vegetable life; hence, it is called the animal tube, while the first is called the vegetable tube, showing that the human body belong both to the vegetable and animal kingdoms.
The upper parts of the tubes are considerably extended and widened. The animal tube lies above the vegetable tube. The enlargement of the animal tube forms the brain part of the head. It is called the cranium (Cr.) The enlargement of the vegetable tube forms the face (F). Both together constitute the head. Below the head there is a considerable narrowing of the tubes to form the throat (c). These two tubes are called the trunk of the body (Tr.). In man, as well as in most animals, there are continuations of the trunk for the purpose of motion. These are called the extremities (legs, feet, etc.).
When we examine more closely the two tubes which form the body, we shall see that they serve different objects.
Fig. 34 is a horizontal section of the body.
The trunk is surrounded by bones (O) which are connected by means of muscles. Bones and muscles are the organs which give the body the means of motion. They also support the vegetable tube (V).
The chest – thorax- Fig. 35, consists of the spinal column, the breast bone and eleven ribs:
The head (cranium), the shell which forms the upper extremity of the trunk, consists of two main sections.
The upper section contains the brain, eyes, nose and ears; the lower constitutes the jaw (Fig. 36).
Between the jaw and the head parts proper are the palate and tongue. At the base of the tongue, and inside the jaw, is located the hyoid bone (Fig. 37).
Hyoid Bone – It has the shape of a horseshoe.
It’s main parts are the body ( c ), the large horns (Cmj) and the small horns (Cm).
All the bones of the body are surrounded by muscles which in the main are what we call the flesh. Muscles consist chiefly of substance which can be contracted. Contraction is caused by the irritation originating in the nerves. In the course of contraction muscles become shorter and thicker; on relaxation they resume their natural shape. As muscles are attached at both ends to bones they move these bones toward each other when they contract. The muscles of the trunk belong to what are called “striped muscles”. All striped muscles are voluntary muscles; in other words, we can contract any one or all of the striped muscles voluntarily through the power of the will. Because of this fact, any one of the striped muscles can be isolated and developed by itself, a fact which is best illustrated by the pianist’s fingers. Most muscles are supplied with distinct nerves. The great variety and power of muscles can be seen by an examination of Fig. 38
Most of these muscles support and move the head.
The diaphragm is shown in the shaded portion of Fig. 35. It is a broad sheet of muscles which divides the trunk or body into two parts – the upper, or chest, and the lower, or abdomen. It has the shape of a dome, of which the apex reaches far upward into the chest. It starts from the spine and in circular form follows and is attached to the ribs, thus forming a complete partition between the chest and the abdomen.
Above the diaphragm (shaded portion) and within the chest are the lungs on the right and left side; also the heart, liver, esophagus, and spleen.
The chest is completely surrounded by muscles. The ribs are connected with the spine by means of very strong, but flexible, tendons, not unlike the manner in which a door is fastened to a post by means of hinges. The ribs are fastened in front in the same way to the breastbone. These flexible connections of the ribs with the spine and breastbone make it possible to raise and lower the ribs somewhat as a bird raises and lowers its wings. The raising of the ribs enlarges the cavity of the chest and allows the lungs to expand. The muscles of the chest are employed in raising and lowering the ribs or, as it is called, in “expansion” and “contraction”.
These muscles arise out of the chest, the breastbone and shoulder blades.(Fig. 39 and 40)
The Latin name for ribs is “costales.” Hence, the muscles which connect the ribs with each other are called the intercostal muscles. The chest muscles are on the outside of the ribs, and the intercostal muscles are between the ribs, somewhat like the web feet of a duck; that is, the space between the ribs is lined, and this lining consists of muscles which separate and contract the ribs. Rheumatism of the chest is usually an inflammation of these intercostal muscles.
It was said that the two tubes which form the basis of the body curve inward and become narrow at the upper end. This narrowing process forms the throat. The spine here bends strongly inward at the middle line, and just opposite to this bend of the spine is the hyoid bone, with the body or thick part in front, just under the skin of the neck, and the long horns stretching towards the spine. Between the hyoid bone and the spine is the air tube, and behind it the food pipe. The air tube arises out of the lungs. It is called the trachea or windpipe, and its purpose is to supply the lungs with air and to set the vocal chords in vibration for the purpose of producing sound.
The tube behind this one is the esophagus or food pipe.
It extends into the stomach. So food passes from the mouth into the food pipe and from there into the stomach.