those of the eyelids and lips, often radiate like the spokes of a wheel.

Muscles are named according to their shape, position, division of origin
or insertion, and their function. Thus we have the _recti_ (straight), and
the _deltoid_ ([Greek: D], delta), the _brachial_ (arm), _pectoral_
(breast), and the _intercostals_ (between the ribs), so named from their
position. Again, we have the _biceps_ (two-headed), _triceps_
(three-headed), and many others with similar names, so called from the
points of origin and insertion. We find other groups named after their
special use. The muscles which bend the limbs are called _flexors_ while
those which straighten them are known as _extensors_.

After a bone has been moved by the contraction of a muscle, it is brought
back to its position by the contraction of another muscle on the opposite
side, the former muscle meanwhile being relaxed. Muscles thus acting in
opposition to each other are called antagonistic. Thus the biceps serves
as one of the antagonists to the triceps, and the various flexors and
extensors of the limbs are antagonistic to one another.

71. The Tendons. The muscles which move the bones by their
contraction taper for the most part, as before mentioned, into
tendons. These are commonly very strong cords, like belts or straps,
made up of white, fibrous tissue.

Tendons are most numerous about the larger joints, where they permit free
action and yet occupy but little space. Large and prominent muscles in
these places would be clumsy and inconvenient. If we bend the arm or leg
forcibly, and grasp the inside of the elbow or knee joint, we can feel the
tendons beneath the skin. The numerous tendons in the palm or on the back
of the hand contribute to its marvelous dexterity and flexibility. The