NAMING MUSCLES: Tips
• 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.
Naming Skeletal Muscles
1 – Location of the muscle
2 – Shape of the muscle
3 – Size of the muscle
4 – Direction/Orientation of the muscle
fibers/cells
5 – Number of Origins
6 – Location of the Attachments
7 – Action of the muscle
Location:
•
•
•
•
•
•
•
____________________ (chest)
____________________ (buttock)
____________________ (arm)
______________________(above)
______________________ (below)
_____________________(under or beneath)
_______________________ (lateral).
Shape:
• deltoid (_______________)
• rhomboid (like a rhombus
with equal and parallel sides)
• latissimus (____________)
• teres (__________)
• trapezius (like a trapezoid, a four-sided figure
with two sides parallel).
Size:
•
•
•
•
•
____________ (huge)
_______________ (large)
__________________(long)
____________ (small)
__________________(short)
Direction of fibers:
•
•
•
•
____________ (straight)
_____________ (across)
___________(diagonally)
______________(circular)
Number of origins:
• biceps (two heads)
• triceps (three heads)
• quadriceps (four heads)
Triceps
Brachii
Origin
long head: infraglenoid tubercle of scapula
lateral head: upper half of the posterior surface of humerus
medial head: distal two thirds of the posterior surface of
humerus
Origin and insertion:
• sternocleidomastoid (origin on the sternum
and clavicle, insertion on the mastoid process)
• brachioradialis (origin on the brachium or
arm, insertion on the distal end of radius at
the styloid process)
Action:
•
•
•
•
•
____________(to abduct a structure)
_____________(to adduct a structure)
______________(to flex a structure)
_____________ (to extend a structure)
_____________ (to lift or elevate a structure)
How Muscles Attach to Bone
• Indirect Attachment – ___________________
• the _______________________ (sheath of
connective tissue that surrounds the exterior
of the muscle fibre) extends past the muscle
as a ____________________ and then
attaches to
____________________________.
How Muscles Attach to Bone
• Direct Attachment – the epimysium adheres
to and fuses with the periosteum
Review:
• What is origin?
• What is Insertion?
Try to Remember…
• The origin usually stays fixed and the insertion
moves closer to it
Origin
Insertion
3 Basic Types of Muscle Contractions
Concentric
– ________________________________
– Ex. biceps shorten when lifting an object
Eccentric
– ___________________________________
– Ex. biceps lengthen as the same weight is
placed back on the ground
Isometric (static)
– _________________________________________
– Ex. trying to lift an immovable object.
Push or Pull???
• Muscles _____________ by contracting and
relaxing, muscles _________________
• They work in pairs to create smooth
movement, they are called
_________________________(opposing
pairs).
Agonist vs Antagonist?
• Agonist–
• Antagonist -
Example:
• In elbow flexion, the biceps brachii will
concentrically contract while the triceps
brachii will eccentrically contract.
Fixators/Stabilizer
• Muscles that are active isometrically (muscle
does not shorten or lengthen) in order to
fixate an area when the agonist contracts
• Fixators/ Stabilizers -
Fixators/Stablizer
• Example: When performing a push-up, the
serratus anterior stabilizes the shoulder girdle
during the downward stage in order to
prevent adduction
Examples of opposing muscles and muscle groups
Elbow flexion
Shoulder abduction
Medial shoulder
rotation
Knee extension
Wrist flexion
Dorsi flexion
Trunk flexion
Hip flexion
AGONIST
(Prime Mover)
Biceps brachii
ANTAGONIST
Triceps brachii