A Guide To Your Muscles

Your muscles are hard at work every time you make a movement. Being able to identify both individual and groups of muscles accurately and understanding how they function is interesting and necessary if learning the art of massage.

Your body contains more than 600 skeletal muscles, enabling a wide range of movement. Each has its own role, although most actions occur through the combined effect of several muscles.

Skeletal muscles can be identified by:

  • Location – such as the intercostal muscles, located between the ribs.
  • Shape – for instance the trapezius is a trapezium, or parallelogram.
  • Size – such as the gluteus maximus and smaller gluteus medius.
  • Direction – for example, rectus abdominus (rectus means ‘straight).
  • Number of heads – if a muscle has more than one origin, or ‘head’, its name includes ‘ceps’, Greek for head.
  • Attachments – some names relate to the muscles’ body attachments.
  • Action – some are named for their effect on joints; for example, flexors bend and extensors straighten joints.

The most familiar muscles in your body are skeletal muscles, also known as striated, or voluntary muscles. They are under conscious control, but can contract in a reflex action, such as the knee jerk reaction. Muscles that contracts to move bone is called striated muscles due to its striped appearance under the microscope.

Each muscle fiber consists of long, thin strands, called myofibrils. These are made up of two kinds of tiny, overlapping protein filaments, which give the myofibril a banded appearance.

Most movable joints can flex (bend) and extend (straighten) like a hinge. Some can move in other directions, depending on the arrangement of bone ends and muscles that act across the joint. Flexion and extension are opposing actions, meaning that the muscles which flex the joint are relaxed when it is extended, while the muscles that extend the joint are relaxed when it is bent.

A muscle contracts when stimulated by a nerve impulse, which causes chemical changes to take place that shorten muscle fibers. Contraction of an opposing muscle, which is triggered by a chemical called acetylcholine, stretches the filaments of the original muscle.

When a muscle contracts it exerts a pulling force (load) on its bony attachments. The type of movement that results depends on the configuration of bones and joints that the muscle crosses.

The ability to rotate the forearm is peculiar to humans and apes. The actions used are pronation (palm facing downwards) and supination (palm facing upwards) and involve contraction of pronator and supinator muscles. The degree of joint movement possible is due to a combination of muscle strength, point mobility and the flexibility of support tissues such as ligaments. You’ll need to know a recipient’s full movement range in order to avoid putting stress on a joint during a massage session.

Muscles groups with opposing actions in the limbs are separated by tough, fibrous sheets of connective tissue call septa. These divisions help to maintain muscle alignment during joint movement. They also restrict available volume for each area of muscle. Therefore, if a muscle becomes swollen through injury or a build-up of lactic acid after exercise, compression may occur, compromising circulation to the muscle and causing pain.

Muscle fibers are bound together by connective tissue and divided into groups by a sheath. The muscle is attached to bone by a tough fibrous band, the muscle tendon. Muscles are generally attached at both ends to bone, either directly or via a tendon. In between is the belly, or fleshy part, which shortens during contraction, pulling on the most movable attachment. In most muscles the bone that moves least is the origin and the one that moves most, the insertion.

In any given task or joint action, muscles can be divided according to their functions:

  • Agonists – also called prime movers, these are responsible for the main effort in a task.
  • Antagonists – these oppose the agonist, relaxing while it contracts. Agonists and their antagonists are located on opposite sides of a joint.
  • Synergists – other muscles that help agonists, either directly, or by stabilizing an intervening joint.
  • Fixators – these are synergists that keep a bone still, or ‘fix’ it, so other muscles can pull against it.

Massage is a valuable tool for improving and maintaining muscle tone, especially if it is used in conjunction with essential oils that have muscle toning properties.

Techniques that are used in massage, such as stroking, rubbing and kneading, work in two ways; first they improve the circulation and ensure that the body’s tissues, including muscles, receive the oxygen and nutrients they need for optimum health; second, they work to break down the waste products that can become locked in the muscles.

The waste removal, in turn, gives the lymphatic system a boost, making the body increasingly efficient at eliminating the waste products that can become trapped within its systems, eventually creating problems that include poor muscle tone and cellulite.

All skeletal muscles tire easily and require periods of rest between contractions. Muscles that are constantly active such as the neck muscles are more prone to injury. Massage can help release this tension and improve the circulation of nutrients to these vital muscles.