What is the largest muscle in the human body?

According to most online sources, the gluteus maximus or
buttock muscle is the biggest of the 639 named muscles in the human
body.

The longest muscle in the human body is the sartorius. This
narrow muscle of the thigh passes obliquely across the front of the thigh and helps
rotate the leg to the position assumed in sitting
cross-legged.

The strongest muscle depends on how
you measure strength. A good case could be made for the
heart!

Information from
ehow.com:

In terms of absolute force, the strongest muscle
in the body is the masseter, the prime mover of the jaw for chewing. It can create force
of 55 lbs. on the incisors or 200 lbs. on the molars.

The
hardest-working muscle in the body is the heart. It pumps 2 oz. blood at every
heartbeat, at least 2,500 gallons daily.

The muscle that
can pull with the greatest force is the soleus, underneath the calf muscle. It is this
muscle that keeps us from falling backward while standing up, and it is essential to
running, walking and dancing.

The largest muscle in the
body is also one of the strongest--the gluteus maximus. This large muscle in the
buttocks keeps us standing upright and fights against gravity when we walk up
stairs.

The most flexible muscle is the tongue, which can
take many shapes and also is always moving, even in
sleep.

The most active of muscles is the eye muscles.
Muscles of the eye are constantly moving. In an hour's worth of reading, they can move
10,000 times. Unlike the heart, however, eye muscles can get fatigued
easily.