MUSCLES TO KNOW
Muscle Name
Action
Muscles of Facial Expression
Occipitalis
Frontalis
Orbicularis oculi
Orbicularis oris
Buccinator
Zygomaticus
Platysma
Muscles of Mastication (Eating)
Temporalis
Masseter
Neck Muscles
Sternocleidomastoid
Trapezius
Muscles that move the Shoulder and Arm
Latissimus Dorsi
Deltoid
Pectoralis Major
Rotator Cuff
Muscles that move the Vertebral Column
Erector spinae
Muscles of the Thoracic Wall
External intercostals
Internal intercostals
Diaphragm
Muscles of the Abdominal Wall
Rectus abdominus
External oblique
Internal oblique
Transverse abdominus
Muscles that move the Forearm and Hand
Biceps brachii
Triceps brachii
Brachialis
Brachioradialis
Flexor carpi ulnaris
Flexor carpi radialis
Extensor carpi radialis
Extensor carpi ulnaris
Flexor digitorum
Extensor digitorum
Muscles that move the Thigh
Gluteus maximus
Gluteus medius
Rectus femoris
Vastus lateralis
Vastus medialis
Fourth member of quadriceps…
Sartorius
Adductor Muscles
Muscles that move the Leg
Biceps femoris
Semimembranosus
Semitendinosus
Muscles that move the Ankle and Foot
Tibialis anterior
Gastrocnemius
Soleus
Fibularis longus
Extensor digitorum
longus
Unit 4 Notes: Movement of the Muscles
1. Let’s review… using the picture,
tell what type of connective tissue
surrounds the following:
a. Muscle surrounded by a
____________________
b. Fascicle surrounded by a
____________________
c. Muscle Fiber (Cell)
surrounded by a
___________________
What we’re going to look at now are the
individual muscle fibers (cells) and the
characteristics that they have which
contribute to the movement of the
muscle.
2. The following picture shows an individual
muscle fiber (cell) from the picture
above. Let’s fill in the blanks.
Note: The _________________ (cell membrane) is surrounded by
__________________ (connective tissue).
3. The following picture shows an individual
myofibril from the picture above.
Let’s fill in
the blanks.
4.
Fill in the blanks about a MYOFIBRIL:
a. The light band is also called the ____ band, and has a dark midline interruption called
the ____ disc. The ____ disc marks the end of the _________________ and is
formed by a disc-like membrane.
b. The dark band is also called the ____ band, and has a lighter central area called the
____ zone (which contains the M line). The ____ zone lacks
__________________________, so it looks a bit lighter than the rest of the A band.
c. Striations in skeletal muscle are formed by the locations of ____________ and
____________ filaments.
5. Within each myofibril there are millions of contriactile units called
sarcomeres.
The bands of a muscle are actually formed by many myofilaments packed together.
There are two types of myofilaments:
__________________________________ & _________________________________
1.
Myofilament type #1: THICK FILAMENTS
a.
Contain which type of protein?
b. What are the purpose of the ATPase enzymes that thick filaments contain?
c.
Which “band” do the thick filaments form?
d. What are some other names for the small projections off of the thick filaments?
e.
What is the purpose for these projections?
2. Myofilament type #2: THIN FILAMENTS
a.
Contain which type of protein?
b. Also contain…
c.
What are the thin filaments anchored to?
d. Thin filaments extend throughout the I band, and through part of the A band.
What is the name of the zone where thin filaments do not exist?
Let’s Review a Few Definitions…
a.
Sarcolemma:
b. Myofibrils:
c.
Sarcomeres:
d. Myofilaments:
e.
Sarcoplasmic Reticulum:
f.
There are also multiple nuclei and mitochondria scattered throughout the muscle
fiber, surrounding the myofibrils.
So, in summary, as you work
your way smaller in a muscle….
•
_______________ –
surrounded by epimysium
•
______________ –
surrounded by perimysium
•
______________–
surrounded by
endomysium/sarcolemma
•
______________ –
sections called
sarcomeres, surrounded by
sarcoplasmic reticulum,
mitochondria, and nuclei
•
__________________ –
2 types are actin & myosin
LET’S NOW ANSWER THE QUESTION… HOW/WHY DOES A MUSCLE CONTRACT???
1.
These are the special functional properties of muscles that enable them to perform their
duties…
a.
Irritability:
b. Contractility:
c.
Conductility:
d. Elasticity:
2. Define “Motor Unit”:
Pictured to the left is a motor unit. We looked at
motor units when we identified nervous tissue.
What you are seeing in the picture are muscle fibers
running across, with the nerve fibers, or axons (the
“branches”) branching into the muscle. On the end of
the axons are the axon terminals (the “berries”) forming junctions with different muscle
fibers.
Something important to realize… nerve endings (axon terminals) and muscle fibers don’t
physically touch! They are REEEEAAAAALLLLY close to each other….
3.
Define Neuromuscular Junction:
4. Define Synaptic Cleft:
How does our neurons stimulate muscle contraction!?
5. What steps occur to stimulate muscle movement???
a.
b.
c.
d.
e.
f.
g.
How does the muscles create movement?? Sliding Filament Theory
Now, it’s great to know that the muscle contractions are
stimulated by the influx of sodium ions creating an action
potential. But we still need to look at how the muscle
contraction itself occurs. To understand this concept, we
must look at the Sliding Filament Theory.
When muscle fibers are activated by the nervous system due
to an action potential being released, Calcium ions happen to
be released by the sarcoplasmic reticulum. The release of
Ca+2 allows troposin & tropomyosin to stop blocking the
binding sites on the actin… which allows the heads (crossbridges) on the thick filaments to attach to the binding sites
on the thin filaments. This attachment allows the sliding to
begin.
Energized by energy from ATP, each cross-bridge attaches
and detaches from the thin filaments several times in a
single contraction. Each time, the cross-bridges work like an
oar to keep moving the thin filaments closer and closer
together. They attach, pull, detach. Attach, pull, detach.
As this process is happening in every sarcomere throughout
the muscle, the muscle itself is contracting. The whole
series of events takes just a few thousandths of a second!!!
6.
Changes that occur within the sarcomere…
a.
b.
c.
Where’s all this energy coming from?
As a reminder, energy comes from
ATP because of breaking one of the phosphate bonds.
Breaking a bond releases energy, which your body can use. When this energy is used by your body,
heat is also usually released – which is why we say that your muscular system can help control your
body temperature.
However, where are your cross-bridges (heads) of your thick filaments getting all of this ATP from,
so they can move back and forth? Muscles only store very limited supplies of ATP – only 4 to 6
seconds’ worth. Since ATP is the only energy source that can be used to move the cross-bridges
back and forth (which contract the muscle), ATP must be regenerated continuously if contraction is
to continue.
7.
The three sources of ATP Regeneration…
a.
Direct Phosphorylation of ADP by Creatine Phosphate
b.
Aerobic Respiration
c.
Anaerobic Glycolysis and Lactic Acid Formation
8. Which of the three pathways for ATP regeneration is the main source of ATP, producing
some 95% of ATP used in muscle activity?
C6H12O6 (aq) + 6O2 (g) → 6CO2 (g) + 6H2O + 36 ATP
9. Shown above is the overall equation for aerobic (cellular) respiration. Using this reaction as
a basis for reasoning, explain why proper blood circulation (as well as proper breathing)
would be important for your muscles.
MUSCLE FATIGUE
10. When can you tell that your muscle is fatigued?
11. What are some things that can happen in your muscles if they lack oxygen?
TYPES OF MUSCLE CONTRACTIONS
12. What are isotonic contractions? Give examples.
13. What are isometric contractions? Give an example.
MUSCLE TONE / EFFECT OF EXERCISE ON MUSCLES
14. What is muscle tone?
15. What can muscle inactivity lead to?
16. What are some examples of aerobic exercise?
17. What impact do aerobic exercises have on muscles?
18. What are some examples of resistance exercises?
19. What impact do resistance exercises have on muscles?