Terminology

Origin: The beginning site, the more fixed attachment of the muscle. Can be considered as the anchoring point.

Insertion: The movable attachment of the distal end of the muscle.

Superior: Toward the upper part of the structure.

Inferior: Toward the lower part of the structure.

Anterior: Nearer to the front of the body.

Posterior: Nearer to or at the back of the body.

Medial: Near the midline of the body.

Lateral: Farther from the midline of the body.

Proximal: Near the point of attachment, center of the body.

Distal: Away from the trunk, from the center.

External: Towards the surface of the body.

Internal: Away from the surface of and within the body.

Plantar: Concerning the sole of the foot.

Dorsal: Concerning the back of the foot.

Unilaterally: Contracting on one side.

Bilaterally: Contracting on both sides.

Inversion: To turn inward.

Eversion: To turn outward.

Synergist: Cooperating and supporting.

Antagonist: That which counteracts, opposes.

Agonist: The muscle directly engaged in contraction.

Periosteum: The periosteum is a dense highly innervated membrane composed of fibrous connective tissue that closely wraps (invests) all bone, except that of the articulating surfaces in joints which are covered by a synovial membrane.

The periosteum is the most densely innervated, followed by bone marrow and cortex. It is important to recognize and respect the sensitivity of this membrane. It may well be the most sensitive component in the body.

For more information: Sensory Innervation of Human Bone

 "Peri-" is a prefix borrowed from the Greek meaning "around or about" and "-osteum" also comes from the Greek, from "osteon" meaning "bone", so periosteum literally means "around the bone."

Golgi Tendon Organ (GTO): A spindle-shaped structure near the muscular/tendinous junction. This structure is thought to function as a feedback system that monitors muscle tension, inhibits muscle contraction of the agonist, and facilitates contraction of the antagonistic muscle. The purpose of this mechanism is to prevent overuse and damage to the muscle and involved joint.