G, of the front of the neck.
]

76. Important Muscles. There are scores of tiny muscles about the
head, face, and eyes, which, by their alternate contractions and
relaxations, impart to the countenance those expressions which reflect the
feelings and passions of the individual. Two important muscles, the
temporal, near the temples, and the masseter, or chewing muscle,
are the chief agents in moving the lower jaw. They are very large in the
lion, tiger, and other flesh-eating animals. On the inner side of each
cheek is the buccinator, or trumpeter's muscle, which is largely
developed in those who play on wind instruments. Easily seen and felt
under the skin in thin persons, on turning the head to one side, is the
sterno-cleido-mastoid muscle, which passes obliquely down on each
side of the neck to the collar bone--prominent in sculpture and painting.

The chest is supplied with numerous muscles which move the ribs up and
down in the act of breathing. A great, fan-shaped muscle, called the
pectoralis major, lies on the chest. It extends from the chest to the
arm and helps draw the arm inward and forward. The arm is raised from the
side by a large triangular muscle on the shoulder, the deltoid, so
called from its resemblance to the Greek letter delta, [Greek: D]. The
biceps, or two-headed muscle, forms a large part of the fleshy mass
in front of the arm. Its use is to bend the forearm on the arm, an act
familiarly known as "trying your muscle." Its direct antagonist is the
three-headed muscle called the triceps. It forms the fleshy mass on
the back of the arm, its use being to draw the flexed forearm into a right
line.

On the back and outside of the forearm are the extensors, which