Word List/Vocabulary Ch. 6 Muscular System
Definition terms
Actin
Atrophy
Myosin
Tetanus
Myofibril
Striated
Sarcomere
Contraction
Tendon
Flexion
Extension
Rotation
Functions of the Muscular System
1. Movement of skeleton and other substances in the body
2. Generate Heat
3. Stabilize joints
All muscle tissue can contract on demand of the nerves that supply them.
Muscle contraction then provides movement of bones, blood and food
through the digestive system. There are three types of muscles depending on
their location and function
1. Skeletal Muscle- is striated (striped), voluntary, has multiple nuclei
and is of course attached to skeletal bone. skeletal cells are long and
slender
2. Cardiac Muscle- is also striated, involuntary, has extra mitochondria
and is found only in the heart. These cells are shorter and branched.
3. Smooth Muscle- is non-striated, involuntary and has a slow
contraction speed. Found in the digestive system, blood vessels and in
the bladder. Cells are flat with large nuclei when compared to other
muscle cells.
Do not attempt to
copy th ese
diagrams
Microscopic Muscle Anatomy:
Myofibril- The long slender muscle cellSarcomere- The individual contracting units of a muscle cell
Actin- the thin protein filaments of a Sarcomere
Myosin- the thick protein filaments of a Sarcomere
Z-disc- The ends of the Sarcomere
Cross Bridges- the connections on myosin and attach to the actin
H-zone- the distance between the ends of the actin in a sarcomere.
Do not attempt to
copy th ese
diagrams
Sliding Filament Theory of Muscle Contraction
Under muscle stimulation, the Actin filaments are pulled by the Cross Bridges of the
myosin filaments. This shortening process draws the ends of the sarcomere closer
together and the combined efforts of thousands of sarcomeres in a muscle fiber bring the
insertion of the muscle towards the origin. With w skeletal joint between the origin and
insertion there can be substantial amount of movement!
5 Golden Rules of Muscle Activity
1. A muscle must cross at least one joint.
2. The bulk of a muscle lies proximal to the joint
3. Muscles have both and origin and an insertion
4. Muscles can only pull, they cannot push.
5. During muscle contraction, the Insertion moves toward the origin.
As best you can please copy and label this diagram
Origin
Insertion
Elbow
STOP>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>HERE
Types of Muscle Movement with skeleton
1. Flexion2. Extension3. Rotation4. Abduction5. Adduction6. Circumduction-
Antagonistic Muscles- Muscles that move in opposition to each other. Ex. Biceps Brachii
and Triceps Brachii bend the elbow in opposite directions.
Muscle Names- Most names are in Latin but each reflects some important clue about
them.
1. Muscle Direction- ex. Rectus= straight, Oblique=slanted, Sphincter=circular.
2. Muscle size- ex maximus, minimus, major, minor, longus.
3. Location- ex. Frontialis, Temporialis, Femoris.
4. Number of Origins- Biceps (2), Triceps (3), Quadriceps (4).
5. Location of origin/insertion- ex. Sternocleidomastoid.
6. Muscle Shape- ex. Deltoid, Trapezius.
7. Muscle activity- ex. Abductor, Flexor, Extensor.
There are over 600 Muscles of the Human body. The following are ones to know for this
class.
Head and Neck
MasseterSternocleidomastoidObicularis oculi
Obicularis orisFrontialisTemporialisZygomaticusPlatysma-
Trunk
Pectorialis Major
IntercostalAbdominal Girdle-
Rectus abdominis (six pack)
External oblique
Internal oblique
Transverse abdominis
TrapeziusLatissimus dorsiErector spinae-
Shoulder and Arm
DeltoidBiceps brachiiTriceps brachiiBrachioradialisFlexor digitorum
Extensor digitorum-
Hip and Leg
Gluteus maximusHamstring group-
GastrocnemiousSoleusQuadriceps group-
Biceps femoris
Semitendinosus
Semimembranosus
Rectus femoris
Vastus lateralis
Vastus medialis
SartoriusAdductor muscleTibialis anterior-
Diseases and Disorders of the Muscular system.
 Muscular Dystrophy- genetic factors that causes muscles to lose
contact with nerve impulses. Gradual loss of muscle function. There
are dozens of different types of MD.
 Myasthenia Gravis- neurotransmitters no longer function causing
muscle weakness.
 Tetanus- bacteria infection which causes the muscles to all contract
simultaneously.
 Nerve Damage atrophy- muscle waste away due to nerve damage like
spinal cord injury.
 Hernia- a tear in abdominal muscle wall causing the internal organs to
protrude through the gap.
 Tendonitis- inflammation of a tendon causing pain in a joint.
 Ruptured tendon- tendon is torn so that muscle can no longer move
bone.
 Aging- gradual loss of muscle tone, strength and bulk is 50% by age
70.
 Cramps- muscles contract involuntarily due to overuse, lack of
sodium/potassium or limited of blood flow as well as dehydration.
 Fibromyalgia- unexplained muscle pain thought to be associated with
nerve hyperactivity. Usually occurs with females more than males.