Muscle Groups
There are more than 600 muscles in the body, which together
account for about 40 percent of a person's weight. Most skeletal muscles have names that describe some feature
of the muscle. Often several criteria are combined into one
name. Associating the muscle's characteristics with its name
will help you learn and remember them. The following are some
terms relating to muscle features that are used in naming
muscles. - Size: vastus (huge); maximus (large); longus (long); minimus
(small); brevis (short).
- Shape: deltoid (triangular); rhomboid (like a rhombus
with equal and parallel sides); latissimus (wide); teres
(round); trapezius (like a trapezoid, a four-sided figure
with two sides parallel).
- Direction of fibers: rectus (straight); transverse (across);
oblique (diagonally); orbicularis (circular).
- Location: pectoralis (chest); gluteus (buttock or rump);
brachii (arm); supra- (above); infra- (below); sub- (under
or beneath); lateralis (lateral).
- Number of origins: biceps (two heads); triceps (three
heads); quadriceps (four heads).
- Origin and insertion: sternocleidomastoideus (origin on
the sternum and clavicle, insertion on the mastoid process);
brachioradialis (origin on the brachium or arm, insertion
on the radius).
- Action: abductor (to abduct a structure); adductor (to
adduct a structure); flexor (to flex a structure); extensor
(to extend a structure); levator (to lift or elevate a structure);
masseter (a chewer).
Listed below are some significant and obvious muscles arranged
in groups according to location and/or function. Click one
of the hyper-links to explore a specific muscle group listed
below. - Muscles
of the Head and Neck
- Muscles of
the Trunk
- Muscles
of the Upper Extremity
- Muscles
of the Lower Extremity
| 
