Information compiled by Mr. Paul Riley: Naginata Shugyo; Aurora, CO

Know your body, Know your limitations,
Then dare to stretch your horizons...
Note: The following material has been compiled and presented without markers and footnotes. A material source can be found on the sidebar.

Classification
The 700 or more muscles of the body are grouped in various ways. For example, they can be divided into dynamic (fast) and postural (slow) muscles, depending on how each muscle is used. Even the metabolic character of the muscle fibers is different in these muscles, although in humans there are no exclusively fast or slow muscles, as there are in many other organisms.
Muscles may also be sub-divided regionally into axial muscles (trunk, head and neck) and limb muscles (upper and lower). The limb muscles may be further divided into flexors (benders) and extensors of the various joints. In some joints movements also occur in a crosswise direction; hence, abductors are muscles that move the bone away from the mid-line axis of the body; adductors act in the opposite direction. In the upper limbs, flexors are generally stronger than extensors; in the lower limbs the reverse is true, because standing, walking, running, etc., depend on extensors thrusting at the joints both to maintain posture and to lift the body upward against gravity.
Most muscles have Latin names that refer to their primary function, location, shape, or size. Thus flexor digitorum profundus means the "deep bender of the fingers", and the adductor magnus of the hip joint is the "big (muscle) that pulls (the thigh) toward (midline)".

Supplementary Structures
  • SHEATHS
    Muscles are surrounded and supported by essential structures. Each muscle is enveloped within a fibrous-tissue sheath, and regional groups of muscles are further wrapped in a fibrous connective tissue (deep fascia). Some muscles even gain extra origin or insertion to such fibous tissue, which is made of the same tough, inert material as tendons.
  • RETINACULA
    Deep fascia often becomes specialized in certain areas in order to hold down tendons and prevent them from bowstringing. For example, the flexor running to the last joints in the fingers are held down by fibrous-tissue loops and tunnels at the front of the wrist, palm, and fingers. The function of these fibrous retinacula (singular, retinaculum) is revealed in their names; they retain the tendons.
  • SYNOVIAL BURSAE
    An anti-friction device develops in the connective tissues wherever a tendon rubs hard against a bone or a similiar hard structure (such as another tendon). This bursa (Latin, "purse") is like a collapsed thin, cellophane bag, lubricated inside by synovial fluid, which is also found inside the joints. When the friction is too great or the tendon is injured or inflamed, the bursa gets inflamed, producing a condition called BURSITIS.
  • SYNOVIAL SHEATHS
    Because many tendons run through retinacula, they experience friction all around them. Hence, tubular synovial sheaths surround and protect the tendons. They are particularly important in the wrist, hand and fingers and in the ankle region. They also may suffer from Bursitis.

Major Muscles and Muscle Groups
  • FACIAL MUSCLES
    The muscles used in facial expression are unique in that they are attached to various parts of the facial skin. They surround and radiate from the vital orifices of the face: the mouth, nostrils, eyes, and ears. Some muscles open these orifices wide; others narrow or close them. Human facial muscles consist of many wisps and bundles, all with Latin names that indicate their location or function; for example, levator anguli oris means the "elevator of the angle of the mouth". All the muscles of the face are supplied by branches of two main nerves, the right and left facial nerves, which arise from the brain stem. When one of those nerves is injured or inflamed, half of the face is paralyzed in a condition (usually temporary) known as Bell's Palsy.
  • MUSCLES OF MASTICATION
    A group of four large muscles on each side moves the jaw for chewing and biting. The temporalis (in the temple) and the masseter (on the side of the jaw) can be felt when a person bites forcibly. The other muscles help provide the motions needed for grinding food between the molars.
  • TONGUE, SWALLOWING, AND SPEECH MUSCLES
    The tongue, like the heart, is almost all muscle; unlike the routine and repetative cardiac contractions, though, the tongue is capable of very precise, complicated and elaborate movements. In eating, the tongue moves food around; in swallowing, it pushes food into the throat; and in talking, it articulates the sounds coming from the larynx. Many bundles of fibers running in various directions produce all these complex movements. Once food enters the pharynx (throat) it is moved down into the esophagus by waves of muscle contraction. Humans can swallow water standing on their heads. Special sets of muscle guard the larynx. Others alter the tension and position of the vocal cords, which are able to produce sound when the lungs force air between them.
  • RESPIRATORY MUSCLES
    Deep in the neck and between the ribs are repiratory muscles that lift and regulate the ribs during inspiration; they relax completly during expiration (a passive "collapse" of the bellows). Even more important to breathing is a dome-shaped, horizontal partition (the diaphram) below the lungs and above the abdominal cavity. Its contraction greatly enlarges the chest and draws air into the lungs with each inspiration.
  • ABDOMINAL WALLS
    Layers of muscle surround the abdominal cavity; they enclose and can greatly compress the contents of the abdomen. This forceful compression is required to expel urine from the bladder, the contents of the colon and rectum during bowel movements, and the baby from a woman's uterus.In each of these cases, smooth muscles in the walls of the hollow organs also take part in the expulsion of the contents. Further, each of the outlets is guarded by a ring of striated (voluntary) muscle that can be trained to prevent uncontrolled expulsions.
  • BACK MUSCLES
    The vertebral column has a great number of muscle bundles that help to position and move it. When caught off guard, these muscles can be strained, causing spasms and pain.
  • SHOULDER AND HIP MUSCLES
    The Scapula (shoulder blade) must be kept constantly in a proper position so that the upper limb and hand may be used. Large muscles radiate from it to the chest wall, spinal column, and skull. The shoulder joint is capable of many movements, because it has flexors, extensors, abductors, adductors, and rotators.The hip bones are much less mobile; the huge muscles at the hip are mostly concered with moving and stabilizing the hip joint. This joint also requires a complete complement of muscles, the largest of which is the gluteus maximus ("biggest in the buttock"), which is important in running and climbing.
  • MUSCLES OF THE ARM, FOREARM, THIGH, AND LEG
    The emphasis in these areas is on opposing groups of flexor and extensor muscles on the front and back of each limb. Almost all the muscles act on the joints just below them; some go on into the hand or foot to act as flwors and extensors of the digits.
  • INTRINSIC MUSCLES OF THE HAND AND FOOT
    In addition to the long muscles that come from above and provide force, the digits have many small local muscles that produce fine movements. The combined functions of the two groups of muscles provide both power to grip and precision manipulation in the hand.The human foot lost most of these functions when it became highly specialized for bi-pedal posture and walking, which are actually much more human traits than manipulation. Although apes can manipulate with their feet as well as their hands, they have some difficulty standing upright, a task that the human foot performs superbly and with a great economy of muscle power.


Exercise Part 1
Exercise Part 3
Exercise Part 4

 Aurora, CO 80041
Naginata Shugyo
P.O. Box 32212