Muscular System

Muscular System

Goals
Content: Students will refresh over the
muscular system as well as learn how
muscles get their names (nomenclature).
The students will be able to categorize the
various muscles of the human body based
on their nomenclature.
Language: Students will learn and utilize
correct anatomical vocabulary to describe
and label the different muscle types of the
human body.

Muscle Functions
• Movement
• Protection
• Posture and Support
• Heat

Muscle
• Over 600 muscles
• 40 – 50 % of total body weight
• 215 pairs of muscles
– Aggregate muscle action

Muscle Nomenclature
• Appearance
• Location
• Function

Muscle Nomenclature
• Shape
– Deltoid
– rhomboid

Muscle Nomenclature
• Size
– Gluteus Maximus
– Teres Minor

Muscle Nomenclature
• Number of Divisions
– Biceps Brachii

Muscle Nomenclature
• Direction of fibers
– External Oblique

Muscle Nomenclature
• Location
– Rectus femoris
– Palmaris longus

Muscle Nomenclature
• Points of Attachement
– Coracobrachialis
– Flexor Digitorum Longus

Muscle Nomenclature
Action
– Erector spinae

Muscle Nomenclature
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
Shape
hamstrings
Number of Divisions
quadriceps
triceps

Muscle Nomenclature
Groups of muscles
Location
peroneals
abdominal
shoulder girdle
Action
hip flexors
rotator cuff

Myofilaments
• Actin – thin proteins
• Myosin – thick proteins

Myofilaments
Sarcomere
Contractile unit of a muscle fiber

What fiber joins muscles to bones?
Tendons

• Flexibility
• Strength
Muscle-tendon Functions
• Muscular power
Joints ROM
• Muscular endurance
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

Structural Damage
in Muscle Fibers
• The vertical lines are the “z -
lines” that define the
boundaries of the muscle
sarcomere
• Microscopic damage can
lead to disruption of the z-
lines and contribute to
soreness

Relative Strength
• The amount of weight lifted relative to the
person's body weight
• Measured as a ratio:
Relative Strength =
weight lifted (lb.)
body weight (lb.)

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

• Flat
– Thin and broad
• Fusiform
Parallel Structures
• Rectus abdominus
• External oblique
– Spindle shaped with a central belly that tapers to
tendons on the ends
• Strap
• Brachialis
• Brachioradialis
– 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
• Greater 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

• Scavenge the room.
Class Activity
• Find something that would be considered
fusiform.
• Find something that would be considered
pennate

Class Activity
• Classify the following items as:
fusiform
unipennate
bipennate
multipennate

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

• Synergistic Muscles – same function, work
together

Presentations
You may utilize the following website or any others you find
useful (do not use Wikipedia) to chose a muscle.
http://www.ptcentral.com/muscles/index.html
For the muscle use the internet or other resources to find
the following:
1. State the anatomical and if pertinent the “everyday”
name of the muscle.
2. Identify the muscle’s prime movement if possible
(ex. It is the agonist of flexing the upper arm)
3. State the muscle(s) that is(are) the antagonist(s) for the
muscle’s prime movement.
4. State if there are any synergists acting in conjunction
with the muscle for this action.

Presentations
5. State the muscle fiber arrangement type ( Ex. fusiform,
unipennate, bipennate, or multipennate)
6. State how the muscle received its name or classification.
7. Give an example of a movement that has this muscle
utilizing an isometric contraction.
8. Give an example a movement that has this muscle
utilizing both isotonic contractions (eccentric and
concentric).
9. Make a hypothesis regarding the fiber type this muscle
would most likely have. Also give logical reasoning as to
why you believe this to be so.
10.State a possible “lab” that you could perform to test your
hypothesis in #9.

11. Construct or draw (paint) a figure showing the muscle fiber
arrangement as well as it correct anatomical position.
12. Provide a table that distinguishes the 5 muscle properties
for the muscle by a picture-graph. You may forego the table
and create a slide for each property and picture-graph if
desired.
contractibility
( Ex. )
13. Find or create a video showing the muscle at work
(contracting/extending)