Naming Muscles
Muscles causing movement…

Skeletal Muscle – an organ made of
several different types of tissue including
muscle tissue, vascular tissue and
nervous tissue

Tendon – attaches the skeletal muscle to
bone and pulls on bone when the muscle
contracts
Joints

Skeletal muscles usually cross one or more
joints. When a muscle contracts it pulls
one bone closer to another

One bone stays in place while the other
moves
Parts of a skeletal muscle



Origin – the attachment of a muscle on a
stationary bone
Insertion – the attachment of a muscle on
the movable bone
Belly – the fleshy portion of muscle
between the origin and insertion
Group Actions

Most movements occur because groups of
muscles work together, generally grouped
in opposing pairs


Ex – abductors and adductors
Ex – extensors and flexors



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Agonist – muscle that produces the desired
movement
Antagonist – muscle that relaxes when the
agonist contracts
Synergists – another skeletal muscle that moves
in the same general direction as the agonist
increasing the force
Fixators – stabilize the origin and hold other
joints still so the agonist can work more
efficiently
Principle Skeletal Muscles

With over 700 skeletal muscles in the
body, it will be easier to first learn the
naming system and then learn specific
muscles region by region
Naming Skeletal Muscles

Muscles are named according to the
direction the fibers run, the size of the
muscle, the shape of the muscle, the
action the muscle produces, the number
of origins the muscle has and/or the
location of the muscle
Directions

The following terms refer to the direction
the muscle fibers run in relation to the
midline.
Rectus

Parallel to the midline
Transverse

Perpendicular to the midline
Oblique

Diagonal to the midline
Size

Relative to other muscles in that group
Maximus

Largest
Minimus

Smallest
Longus or Longissimus

Longest
Latissimus

Widest
Magnus

Large
Major

Larger
Minor

smaller
Vastus

great
Shape

General shape of the muscle
Deltoid

Triangle
Trapezius

Trapezoid
Serratus

Saw-toothed
Rhomboid

Diamond Shaped
Orbicularis

Circular
Pectinate

Comb-like
Piriformis

Pear shaped
Platys

Flat
Quadratus

square
Gracilis

slender
Action

Based on the action the muscle performs
Flexor/Extensor


Flexor – decreases the angle between bones
Extensor – increases the angle between
bones
Abductor/Adductor


Abductor – moves a bone away from the
midline
Adductor – moves a bone toward the
midline
Levator/Depressor


Levator – elevates body part
Depressor – lowers body part
Supinator/Pronator


Supinator – turns palms up
Pronator – turns palms down
Sphincter

Decreases the size of an opening
Tensor

Makes a body part rigid
Number of Origins

Biceps – 2 heads

Triceps – 3 heads

Quadriceps – 4 heads
Location

Muscles named for the
structures that they are
by. Examples include the
sternocleidomastoid
muscle (runs from the
sternum across the
clavicle to the mastoid
process) and the
temporalis (near the
temporal bone)