Anatomy is the study of the structure of the body, physiology is the study of its organic functions.
The skeleton is composed of 206 bones, but our instruction will embrace only those parts of the body which are of direct interest to the corsetière, the spine, thorax and pelvis.
The spine, commonly called the back bone (Fig. 1. No. 3) is composed of twenty-six bones called vertebrae, which means "capable of turning." Between each vertebra is a padding of cartilage which serves as a cushion. The spine is a flexible column, supported entirely by muscles. Starting from the head down, the first twenty-four vertebrae are comparatively small and movable. They grow larger toward the bottom.
The first seven are called the cervical, and form the neck. The next twelve to which the ribs (Fig. 1, No. 1. are attached are the thoracic. The next five are the lumbar. They are situated in that part of the back known as the "small" of the back, or in medical terms, the lumbar region.
The ribs consist of 24 arches of bone, twelve on each side. They extend round the body from the twelve thoracic vertebrae, the upper seven being attached by cartilage to the sternum (breast bone) and known as true ribs, and the remaining five on each side being known as false ribs and not attached to the sternum. The first three of the false ribs are each attached to the rib above by cartilage, but the last two on each side have free ends.
The ribs serve the purpose of protecting the main organs of circulation and respiration enclosed within.
Next below the lumbar vertebrae is the sacrum (Fig. 1. No. 5) which, while solid in adults, at a very early age is five distinct bones.
Below the sacrum are four small bones known as the coccyx. (Fig. 1, No. 7.)
On either side of the sacrum and joined to it by the short, very strong sacro-iliac ligaments are the two hip bones or ilia. The upper portion of the hip bone at the back where it meets the sacrum (Fig. 1. No. 4.) and which can be felt when a person is not very fleshy, is the posterior superior spine of the ilia. That portion of the hip bone which is so prominent in the front near the abdomen (Fig. 1. No. 6) is called the anterior superior spine of the ilia. That part of the hip bone which is in the lower part of the back and supports the body when sitting (Fig. 1. No. 9) is the ischium.
The pelvic girdle is the heavy bony framework of the pelvis. It is made up of three bones, namely the sacrum behind and the hip or iliac bones at the sides which meet in front forming the pubis. (See Fig. 1. Nos. 5, 6, 4 and 8.) This is the heaviest and strongest bony structure in the body. Study this carefully as frequent reference is made to it.
There are four kinds of spinal weakness that we are called upon to treat--scoliosis, kyphosis, lordosis, Pott's disease.
Scoliosis is a lateral curvature of the spine, or in other words, the spine becomes twisted either toward the right or left side.
Kyphosis is commonly called "hunchback."
Lordosis is exactly the reverse of "hunchback." Sometimes it is known as "sway back."
Pott's disease is tuberculosis of the spine, which, if unchecked, will lead to kyphosis.
The sacrum is the foundation of the back bone and so carries the entire weight of the trunk of the body, just as the foundations of buildings carry the weight of everything above them.
As the sacrum is wedge-shaped, the weight of the body would tend to force it down between the two hip bones, were it not for the strong sacro-iliac ligaments which join it to the hip bones on each side. Under normal conditions these ligaments bind the hip bones to the sacrum so tightly that there is absolutely no movement between the two. If through an accident, or malnutrition, or other causes, these ligaments become stretched or weakened, we have what is termed the strained sacro-iliac joint. The pain may be felt at a place remote from the sacroiliac joint, but the treatment does not vary.
For instance, sometimes a case of supposed sciatic rheumatism, which causes a pain in the leg, is due to irritation of the sciatic nerve consequent upon a strained sacroiliac joint, and the remedy in such cases is a sacro-iliac support.
As previously described, this condition is caused by a strain of the ligaments which attach the sacrum to the hip bones, and when these ligaments are weakened, the weight of the trunk of the body tends to force the sacrum downward, and, so to speak, to pry apart the two hip bones, causing severe pain.
The treatment consists of squeezing the two hip bones firmly together, and pressing gently against the weakened joints in the back. Therefore, we provide a band inside the corset, which encircles the body, squeezing the two hip bones together, and a soft pad at the centre of the back which gives exactly the requisite amount of pressure to keep the sacrum in place, thus immobilising the sacro-iliac joints.
Lumbo-sacral strain is a weakness or strain of the joints of the lower lumbar vertebrae and the sacrum.