Muscle
• Over 600 muscles
• 40 – 50 % of total body weight
• 215 pairs of muscles
– Aggregate muscle action
Action and Shape
Pronator quadratus
Action and Size
Adductor magnus
Shape and Location
Serratus anterior
Muscle Nomenclature
Location and Attachment
Brachioradioalis
Location and Number of Divisions
Biceps femoris
Muscle Nomenclature
Groups of muscles
Location
peroneals
abdominal
shoulder girdle
Action
hip flexors
rotator cuff
Muscle Nomenclature
Muscle-tendon Functions
• Flexibility
• Strength
• Muscular power
• Muscular endurance
Joints ROM
Maximum force on a unit
Rate of muscular force applied
to move a load
Ability of a muscle to exert a
force repeatedly or constantly
Muscle fatigue, soreness, pain – build-up of lactic acid in the muscles
Fibers and Shape
• Determine a muscle’s ability to exert force
– Cross section diameter
• Greater = greater
• Determine range through which it can exert force onto the bone it is attached
– Ability to shorten
• Longer muscles shorten through a greater range = more effective moving joints through large ranges of motion
Classification by Fiber Arrangement
• Parallel
run longitudinally or somewhat parallel with the muscle’s long axis
• Pennate
(feather-like) tendons run down the muscle’s long axis, and fibers run obliquely to the tendon
Parallel Structures
• Fibers are longer
• Run parallel to the length of the muscle
• Pull bones through a greater ROM
Parallel Structures• Flat
– Thin and broad
• Rectus abdominus
• External oblique
• Fusiform
– Spindle shaped with a central belly that tapers to tendons on the ends
• Brachialis
• Brachioradialis
• Strap
– More uniform
• Sartorius
Parallel Structures• Radiate (triangular or fan-shaped)
– Combo of flat and fusiform
• Pectoralis major
• Trapezius
• Sphincter (circular)
– Endless strap around openings
• Orbicularis oris
• Orbicularis oculi
Pennate Structures
• Shorter fibers run oblique to tendons
• Gearter cross section = greater force
• Most muscles in the body
• To provide more force than fusiform, but less ROM
Example: sit-ups
Pennate Structures
• Types
– Unipennate . . . Biceps femoris
– Bipennate . . . Rectus femoris
– Multipennate . . . Deltoid
Class Activity
• Scavenge the room.
• Find something that would be considered fusiform.
• Find something that would be considered pennate
Skeletal Muscle Tissue Properties
• Irritability or Excitability
• Conductivity
• Contractility
• Distensibility or Extensibility
• Elasticity
responds to nervous stimuli
wave of excitement
pulling ends together
stretched
recoil from a stretch
Reciprocal Inhibition or Innervation
• Agonists
muscles that cause or help cause motion
• Antagonists
perform opposite to the movement being
done
Example: hip flexors & hip extensors
Powerpoint PresentationsUtilize the following website to chose 5 muscles (the may
be random or close together):
http://www.ptcentral.com/muscles/index.html
For each of the muscles use the internet or other resources
to find the following:
1. Identify a movement (ex. flexing the upper arm)
2. State the muscle that is the agonist for the movement
3. State if there are any synergists acting in conjunction
with the agonist for this action
4. State the antagonist of the agonist for the movement
5. For the agonist only state the muscle fiber arrangement
type ( Ex. fusiform, unipennate, bipennate, or
multipennate)
For the remaining points, chose 1 of the 5 only to provide the following:
6. Construct or draw (paint) a figure showing the muscle fiber arrangement as well as it correct anatomical position.
7. Provide a table that distinguishes the muscle properties for the muscle in #6 by a picture-graph. You may cut the table and create a slide for each property and picture-graph if desired.
( Ex. )
8. Find or create a video showing the same muscle ( in #6) at work (contracting/extending)
contractibility
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