4.1 Joints and Muscles
• What would life be like without
Joints
Move a joint that you use often
How do different joints move
Essential Question
1. What role do joints play in the human body?
Joints are the places where two bones meet and
allow movement & flexibility and provides
support to the human skeleton.
2. How are joints classified by both structure and
function?
Functionally, joints are classified by how much
motion they allow. Structurally, joints are
classified as fibrous, cartilaginous, or synovial.
Joint Classification
• Immovable/Fibrous
– Do not move—EX: joints in dome of skull and
between teeth and jawbone
• Partially Moveable/Cartilaginous
– Move little—linked by cartilage—EX: vertebrae
in spine
Immovable joints and slightly movable joints
are restricted mainly to the axial skeleton
where protection and stability are key
Joint Classification
• Freely Moveable/Synovial
– Move in many directions— found at the hip,
shoulders, elbows, knees, wrists, and ankles
—filled with synovial fluid (acts as lubricant)—
these joints have synovial cavities
Freely movable joints are found on the
appendicular skeleton and permit flexibility
in the limbs.
Activity 4.1.1 Bones, Joints, Action!
• Obtain a body system graphic
organizer (skeletal view)
• Research the six main types of synovial
joints
• Complete activity through question 6
Essential Question
3. What are the different types of synovial
joints?
– Pivot joint
– Ball-and-Socket joint
– Saddle joint
– Condyloid (Ellipsoidal) joint
– Hinge joint
– Plane (Planar or Gliding) joint
Types of Synovial Joints
Types of Synovial Joints
Activity 4.1.1 Bones, Joints, Action!
• http://www.youtube.com/watch?v=9fZk
ne0GE9g- cow elbow dissection
• Create groups of 3 or 4
• Obtain Gloves, Goggles and Cow
Elbow
• Look for the movement of the joint,
cartilage, tendons and ligaments
• Complete the rest of Activity 4.1.1 and
Conclusion Questions
Dissected Cow Elbow
Activity 4.1.1 Bones, Joints, Action!
• How are cow elbows and human
elbows similar and different?
– In the cow joint, the ulna and the radius
are fused; whereas in the human, they are
two separate bones
– Human elbow joint allows for rotation and
overall dexterity (not needed by the cow)
• What type of synovial joint was
modeled by cow elbow?
Connective Tissue
• Connective tissue protects, supports, and binds together
other body tissues.
• Connective tissue is made up of different types of cells in
varying amounts of a nonliving substance around the
cells, called the matrix.
• Fibrous connective tissue which is found in tendons and
ligaments. Fibrous connective tissue is composed of
large amounts of closely packed collagenous fibers.
• Cartilage is a form of fibrous connective tissue that is
composed of closely packed collagenous
fibers in a rubbery gelatinous substance
called chondrin.
Essential Question
• 4. What role do cartilage, tendons, and
ligaments play at a joint?
 Cartilage - Cushions/protects bones where they
meet and rub against each other. The cartilage
found in joints is hyaline cartilage—the same kind
found in a fetal skeleton & it’s referred to as
articular cartilage where it attaches to articular
bone surfaces.
 Tendons - Fibrous tissue that connects muscles to
bones
 Ligaments -Fibrous straps that fasten bones to
other bones
Motion with the Cow Elbow
• How did your cow elbow move?
– Think about the type of synovial joint
• How do human elbows move?
Flexibility
What makes our bodies flexible?
Joints
Joints
 Joints with a large range of motion has limited
stability
 Joint with limited mobility, such as the sutures in the
skull, have great stability
 Move your hip and shoulder and describe the range
of motion of each joint
 Joints make up for a lack of stability by the addition
of muscle
 Joints that are very stable and produce little
movement are assisted by limited amounts of muscle
 Joints that are very flexible, but offer little stability are
surrounded by large amounts of muscle
Describing Motion
• How do we describe the motions of a
joint ?
• Bending
• Flexing
• Scientists and medical professionals
use precise terms to describe the
direction of motion as well as the
relationship of one body part to another
• Depression and Elevation (Make this
Motion)
Elevation and Depression
Movement
Elevation
Depression
Activity 4.1.2: Range of Motion
• In groups of 3 research the following Terms and
Document on your Body Organizers (Complete
Steps 1 & 2)
–
–
–
–
–
Depression and elevation
Rotation and circumduction
Flexion and extension (and hyperextension)
Abduction and adduction
Plantar flexion and dorsiflexion
• When you know all the Motion as a group
demonstrate them to your teacher
Essential Question
• 5. What terms describe the path of movement
at a joint?
Essential Question
• 6. What is range of motion?
– Range of motion is the range through
which a joint can be moved & can be
measured using a goniometer to
determine angles.
Essential Question
• 7. How do you measure the range of
motion of a particular joint movement?
– Each specific joint has a normal range of motion that is
expressed in degrees.
– Devices to measure range of motion in the joints of the body
include the goniometer and inclinometer which use a
stationary arm, protractor, fulcrum, and movement arm to
measure angle from axis of the joint.
– As measurement results will vary by the degree
of resistance, two levels of range of motion
results are recorded in most cases.
Normal ROM for Joints in Adults
Joint
Movement
Normal Range of
Motion (°)
Elbow
Flexion
0 - 140
Shoulder
Flexion
0 - 165
Extension
0 - 60
Medial Rotation
0 - 70
Lateral Rotation
0 - 90
Abduction
0 - 180
Knee
Flexion
0 - 145
Ankle
Dorsiflexion
0 - 20
Plantar Flexion
0 - 50
Hip
Flexion
Extension
0 - 120
0 - 20
Finish Activity 4.1.2: Range of
Motion
• You will need
– Activity 4.1.2 Range of Motion
– Activity 4.1.2 Student Resource Sheet - ROM
– ROM Schematics
– Goniometer
• http://www.youtube.com/watch?feature=pl
ayer_embedded&v=ZUF7tpkVAIY- or
http://www.youtube.com/watch?v=J_RigYFj98&feature=player_embedded
Instructions on how to use a goniometer
Key Terms
Abduction
Adduction
Articular cartilage
Articulation
Ball-and-socket
joint
Cartilage
Circumduction
Dorsiflexion
Extension
Flexion
Goniometer
Movement away from the midline of the body
Movement toward the midline off the body
Hyaline cartilage attached to articular bone surfaces
The action or manner in which the parts come together at a
joint
An articulation (as the hip joint) in which the rounded head of
one bone fits into a cuplike cavity of the other and admits
movement in any direction
A usually translucent somewhat elastic tissue that composes
most of the skeleton of vertebrate embryos and except for a
small number of structures (as some joints, respiratory
passages, and the external ear) is replaced by bone during
ossification in the higher vertebrates.
A movement at a synovial joint in which the distal end of the
bone moves in a circle while the proximal end remains
relatively stable
Bending the foot in the direction of the dorsum (upper surface)
An unbending movement around a joint in a limb (as the knee
or elbow) that increases the angle between the bones of the
limb at the joint
A bending movement around a joint in a limb (as the knee or
elbow) that decreases the angle between the bones of the limb
at the joint
An instrument for measuring angles (as of a joint or the skull)
Hinge joint
Hyaline cartilage
Joint
Ligament
Plantar flexion
Range of Motion
Rotation
Synovial cavity
Synovial fluid
Synovial joint
Tendon
Joint between bones (as at the elbow or knee) that permits
motion in only one plane
Translucent bluish white cartilage consisting of cells
embedded in an apparently homogeneous matrix, present in
joints and respiratory passages, and forming most of the fetal
skeleton
The point of contact between elements of an animal skeleton
whether movable or rigidly fixed together with the surrounding
and supporting parts (as membranes, tendons, or ligaments)
Dense regular connective tissue that attaches bone to bone
Bending the foot in the direction of the plantar surface (sole)
The range through which a joint can be moved
Moving a bone around its own axis, with no other movement
The space between the articulating bones of a synovial joint,
filled with synovial fluid. Also called a joint cavity.
Secretion of synovial membranes that lubricates joints and
nourishes articular cartilage
A fully moveable joint in which the synovial (joint) cavity is
present between the two articulating bones
A white fibrous cord of dense regular connective tissue that
attaches muscle to bone
Essential Question
• 8. How do bones, muscles and joints
work together to enable movement and
locomotion for the human body?
– Our bones provide support and give our
bodies shape, but cannot move on their
own. The muscles provide the movement.
The joints help attach bones to one
another to provide flexibility & allow the
muscles to help give the bones a way to
move.
Lesson 4.2 Muscles
Essential Question
• 1. How do muscles assist with movement
of the body and of substances around the
body?
– Our muscles are what allow all movement of our
bodies (and within our bodies). They help us
involuntarily by helping food move down the
esophagus and into the stomach (peristalsis) and
helping blood move through our bodies (the heart is a
muscle). They also help us move our bodies
voluntarily from place to place (the muscles in our
limbs). Our bodies each have about 650 muscles &
are ~ 50% muscle by weight!
ACTIVITY 4.2.1 MUSCLE RULES
PART 1
With a partner research the following 3 muscle tissues
skeletal muscle
smooth muscle
cardiac muscle
Create this table in your Journal
View prepared slides
Complete Part 1 only
Essential Question
• 2. How do the structure and function of the
three types of muscle tissue compare?
Cardiac - They are striated muscle fibers form the wall of the
heart & function involuntarily.
Skeletal -They are attached to bone, mostly in the legs, arms,
abdomen, chest, neck and face. They are striated muscle
fibers (lined under microscope) & attach to bone by a tendon.
They hold the skeleton together and give the body shape.
They are voluntary (we control them) and contract quickly and
powerfully), but they tire easily.
Smooth -They are smooth (not striated) & are controlled
automatically by our nervous system. They are also called
―involuntary‖ muscles. They make up the walls of the
stomach and intestine to help break down and move food.
They also line the walls of blood vessels. They take longer to
contract than skeletal muscles, but also don’t tire as easily.
Skeletal Muscle
• Voluntary – we control the movement
• Striated – looks like long fibers
• Linked to bones by tendons
• Function – to help us move / move our bones
Smooth Muscle
• Involuntary Action –
controlled by our CNS
• Non-striated
• Found in arteries, veins, intestines, etc.
• Function : Maintain organ dimensions –
stretch and recoil
Cardiac Muscle
• Involuntary
• Striated – but, may be branched which is
unlike skeletal muscle.
• Found in walls of the heart
• Function : To pump the heart!
– Highly resistant to fatigue
w/lots of mitochondria
Activity 4.2.1 Muscle Rules
Part 2
Let’s Start By Building a Muscle from Spaghetti
• Pick up one piece of spaghetti.
• Each piece of spaghetti will represent one
skeletal muscle cell or fiber
• Each muscle fiber is enclosed by a delicate
membrane called the endomysium. (For the
purposes of this activity, the yellow outer coating of the
spaghetti represents this membrane.)
Spaghetti Muscle Cont’d
• Pick up a handful of spaghetti. This bundle of fibers
represents a fascicle.
• Each fascicle, however, is covered by a membrane called
the perimysium.
• Place the bunch of spaghetti on the end of a piece of plastic
wrap.
• Roll the spaghetti up in the plastic used to represent the
perimysium.
• Hold up the completed fascicle.
• Pull the ends taut, and notice that this tissue has little to no
bumps.
• These ends represent dense regular connective tissue.
Spaghetti Muscle Cont’d
• Fascicles group together to form a skeletal muscle.
• Combine your fascicle w/ three other pairs’ to form a whole
muscle.
• These fascicles are bound together by an even tougher outer
membrane called the epimysium.
• Wrap the combined fascicles in another piece of plastic wrap.
– This layer of wrap will represent the epimysium.
• Twist the plastic wrap on each end of the completed muscle.
• At the ends of the muscle, the epimysia blend together to form
tendons, cordlike structures that attach muscle to bone,
cartilage or other connective tissue.
Essential Question
3. How are muscle fibers and membranes
organized to form a whole skeletal muscle?
•
•
•
•
The epimysium (“upon muscle”) is the
outermost layer of connective tissue.
The perimysium (“around muscle”) is
made of connective tissue and forms
casings for bundles of muscle fibers.
The endomysium (“within muscle‖) is
connective tissue surrounding each
individual muscle fiber.
Each fascicle is a small cluster of muscle
fibers, with endomysium between the
individual fibers. Blood vessels run
between the fascicles, bringing the tissue
nutrients & removing waste. Nerves also
run throughout, controlling the movement
of the muscles. Together, the network of
nerves and blood vessels are referred to
as the plexus
Activity 4.2.1 Muscle Rules
Part 3
• Will need your
– Manikins
– Clay
– Lab Journals
• We will create a muscle together
Step 1
• Locate the ventral side and use a pencil
to place a dot on the lateral and medial
side of the radial groove (about halfway
up the humerus).
Step 2
• Locate the ulna just below the fold of
the elbow. Help the students see the
hollowed out area in the antecubital
region. Place a pencil dot above this
area.
Step 2 Cont’d - Rule 1
• These dots each represent an attachment
point for a muscle.
• Note that there are at least two
attachments (in this case three) and the
muscle will cross a joint at the elbow.
• This leads us to Muscle Rule #1:
Muscles must have at least two
attachments and must cross at least
one joint.
Step 3 – Brachialis Muscle
• Using terra cotta clay, form two balls about the
diameter of a nickel.
• Rolling the clay between the tabletop and a
palm, roll each ball into a long carrot. The total
length of the carrots should stretch from the
humeral attachment to the ulnar attachment.
• Bring the fat part of the carrots together,
leaving the tops free
(rabbit ears).
Step 4 – Rule 2
• Using your left thumb to represent the humeral
attachments and your left middle finger to
represent the ulnar attachment, place the left hand
on the right arm where the attachments would be.
• Make sure to cross the joint.
• Pull your forearm towards your heart and watch
the position of your fingers.
• You should notice that your index finger and
thumb are closer together than when you started.
• This lead to rule 2:
Muscles always “pull” and get shorter.
Step 5 – Rule 3
• Repeat the motion and identify which attachment is
“pulling” or moving closer to the other attachment.
• The attachment that moves is known as the insertion of
the muscle.
– The insertion is usually the distal attachment.
– The attachment that does not move and pulls the other
attachment toward it is referred to as the origin.
– The origin is usually the proximal attachment.
• This leads to Rule 3:
The attachment that moves is known as the insertion
and the attachment that remains stationary is
known as the origin.
Step 6
• Extend your arms out in front of their bodies.
Notice this angle is 180°.
• Show the movement again of the muscle you
have just built.
• This time pay attention to what happens to
this angle when the muscle shortens.
• Notice that the angle decreases.
• Do you remember what we call motion at a
joint that decreases the angle between
articulating bones?
• Flexion and thus a muscle such as this is
referred to as a flexor.
Step 7 – Rule 4
• Flex your arms one more time, but stop at the end
of the movement.
• If muscles only pull, then how can the arm be
straightened?
• What do we call motion at a joint that increases
the angle between articulating bones?
• Extension and thus a muscle that controls this
movement is referred to as an extensor.
Muscles that decrease the angle between ventral
surfaces of the body are known as flexors.
Muscles that increase the angle between
ventral surfaces of the body are known as
extensors
Step 8
• Place a pencil dot halfway up the dorsal
side of the humerus.
• Place another dot just distal of the
elbow onto the ulna
Step 9 –triceps medial head
• Using terra cotta clay, form a ball the
diameter of a nickel. Roll the ball into an even
tube.
• Attach the ends of the clay tube to dots on
the humerus and on the ulna.
• Since the back of the humerus is flat, the
muscle shapes to the bone and is also flat.
• Use your thumbs to flatten
the clay.
• Remove any clay that
makes its way to the
ventral side.
Step 9 Cont’d
• Act out the action of this muscle. With the
right arm in the flexed position, place the left
thumb on the back of the humerus and the
left index finger on the back of the elbow.
• “Pull” with your index fingers and the angle
should increase to 180°.
• Repeat the motion and think of Rules 2, 3
and 4.
• Since the angle in this motion increases, the
muscle is an extensor.
The Triceps
• Origin = proximal half of dorsal
humerus
• Insertion = distal of elbow on the ulna
• Action = extends elbow
Flexors and Extensors
• Flexors are on the ventral side of the body
and extensors are located dorsally.
• “For smooth movements to occur, can
both extensors and flexors be contracting
at the same time?”
• When the flexors are pulling, the extensors
are relaxing.
• This brings us to Rule #5:
Muscles work in opposing pairs.
Rule # 6
Muscle striations point to
the attachments and
show the direction of
pull.
Naming Muscles
Each muscle is given a Latin name based on one or
more of its features
Take a look at the following muscle names and
brainstorm what you can tell about these muscles
simply by their names
–
–
–
–
–
–
–
Trapezius and Rhomboid minor
Gluteus maximus and Gluteus minimus
Frontalis and Temporalis
Orbicularis Oculi and Transverse abdominis
Flexor Carpi Ulnaris and Extensor digitorum longus
SternoCleidomastoid and Brachioradialis
Biceps Brachii and Triceps Brachii
Essential Question
• 4. What do skeletal
muscle structure
and attachment to
bones tell you
about function?
Muscles each have an insertion, where they attach
to the moveable bone and an origin, where they
attach to the stationary bone.
Essential Question
• 5. How are muscles named?
– Several factors are considered when naming a muscle, including
– 1) Location (EX: tibialis anterior is on the front of the tibia)
– 2) Shape (EX: deltoid ―resembles‖ (- oid ) a ―triangle‖ ( delt ))
– 3) Points of attachment (EX: sternocleidomastoid—the muscle attaches to
the sternum and the tendons attach to the mastoid process of the skull.)
– 4) Relative size (EX: gluteal or ―rump‖ region – the gluteus maximus is
bigger and the gluteus minimus smaller).
– 5) Number of muscle ―heads‖ or divisions (EX: Biceps means ―twoheaded‖ and has two divisions)
– 6) Direction of muscle fibers (EX: the rectus abdominis muscle is located in
the front of the abdomen and its fibers are oriented in a ―straight‖ (rect),
vertical direction).
– 7): Association with characters (EX: sartorius means ―presence of‖ (-us) a
―tailor‖ (sartori )! Tailors used to sit cross-legged upon the ground. The
sartorius is actually located along the inner aspect of each thigh. Thus,
when it contracts, it flexes (bends) the lower leg like an ancient tailor.
Activity 4.2.2: Building a Better
Body
HBS - A.4.2.2
How to Build a Better Body
Please grab your maniken and
a tool kit and sit with your
partner!
Use the wrench to take the arm off
your Maniken.
DO NOT LOSE THE SCREWS!
Muscle #1: Intercostals
• We will build the external intercostals of the
chest. These muscles are found in between
the ribs and extend from the front of the ribs,
around back and past the bend in the bones.
• Describe the function of the muscles that are found between
the ribs.
– These muscles help move air in and out of the chest.
– When you eat ribs, you are actually eating the intercostal
muscles between the bones, not the ribs themselves.
• Place a strand of spaghetti between each rib, starting at the
back of the rib where it attaches to the vertebral column, all
the way around to the rib’s attachment at the sternum.
• Use your thumb or one of the clay tools to flatten down these
strands. The intercostal muscles do not stick out of the chest.
Muscle #2 – Serratus Anterior
• Attach the stand-off to the torso. The
indentation in the stand-off should face the
midline of the model. Do not yet tighten
the screws completely.
• The Maniken® displays vertical dashes
midway around the ribs to indicate where
the bone becomes cartilage.
– Origin = lateral surface of ribs 1-8 (bone only)
– Insertion = medial border of the scapula
Muscle #2 – Serratus Anterior
• Take small pieces of spaghetti and attach these
strands from the medial side of each rib (where the
dashes are shown) to the stand-off on the arm.
– Attach one strand from each of ribs 1-8 to form a
saw-like structure – a “serrated” edge.
• This muscle helps move the scapula forward and is
often used at the end of big
movements such as a bench press, a
baseball pitch, or a swimming stroke.
• Attach the arm of your Maniken®.
• The screws should thread in as easily as
they unthreaded on removal.
Muscle #3- Pectoralis Minor
• Where are the origin and insertion of the pectoralis minor?
– Origin = anterior surface of ribs 3 – 5 (just past the origins
of the serratus anterior)
– Insertion = coracoid process of the scapula (piece of the
scapula visible on the front)
• Use spaghetti strands to form the pectoralis minor. Place one
small strand at the origin of each rib and run these three
strands together as they attach at the scapula. The
muscle is built in a manner similar to the serratus
anterior.
• Act out the movement of this muscle.
• This muscle works to rotate the shoulder
forward.
Muscle #4 – Pectoralis Major
• Even though this muscle only has one name, there are actually
three different “heads” or pieces to this muscle.
• Each part will be built separately and will be formed from a carrotshaped tube that has been rolled flat.
• Keep these muscles thick and striate each muscle as it is built.
• Have students first construct the abdominal head of the pectoralis
major.
• Given the name only, ask students where they think this muscle
might attach.
• What are the origin and insertion of the abdominal head of the
pectoralis major?
– Origin = ribs 5-7 (actually attaches to fascia of abdominal
muscles)
– Insertion = lateral edge of the most proximal part of the humerus
• Make a long carrot out of terra cotta clay. Flatten the carrot slightly
to make a tongue.
Muscle #4 – Pectoralis Major
• Gently lay the muscle across the chest of the Maniken®
from the origin to the insertion.
• The long end of the carrot should point towards the
shoulder and the wide end should run down towards
the 5th through 7th rib. The muscle will have a teardrop shape. Keep
the insertion very narrow and the origin much wider. Do not worry
about perfect shape at this point. You will trim the muscle to fit the
Maniken®.
• Use the wire tool or a pencil to carefully outline the shape of the
muscle and trim off any jagged edges.
• Take the muscle off the model and use the knife to trim the edges
you have marked with your tool or pencil. Gently roll out the muscle
if you need to stretch it a bit to fit from the origin to the attachment.
• Attach the muscle to the model. Ask students to striate the muscle.
Remember that the striations of the muscle indicate the direction the
muscle moves.
Pectoralis Major
• Act out the motion of this portion of the pectoralis
major.
• Which sports or exercises utilize this muscle?
– Tennis serve or a volleyball spike.
• We will now create the largest portion of the muscle – the
sternal or sternocostalis head.
– Where do you think this muscle might attach.
– Origin = ribs 1-5 on the lateral edge of the sternum (no
clay should be on the sternum)
– Insertion = lateral edge of the humerus, inferior to the
insertion of the abdominal head.
• Make a short, fat carrot out of terra cotta clay. Flatten the
carrot slightly to make a thick triangle. Do not worry about
perfect shape at this point. You will trim the muscle to fit the
Maniken®.
Pectoralis Major
• Gently lay the muscle across the chest of the model from the origin
to the insertion.
– The long end of the carrot should point towards the humerus and
the wide end should run along the lateral edge of the sternum.
– The origin of this muscle will overlap the origin of the abdominal
head.
• Use the wire tool or a pencil to carefully outline the shape of the
muscle.
• Take the muscle off of the model and use the knife to trim the edges
you have marked with your tool or pencil. Gently roll out the muscle
if you need to stretch it a bit to fit from the origin to the attachment.
Make sure no clay extends over the sternum.
• Attach the muscle to the Maniken®. Ask students to striate the
muscle. Remember that the striations of the muscle indicate the
direction it moves.
Pectoralis Major
• Ask students to act out the motion of this portion of the
pectoralis major.
• Which sports or exercises utilize this muscle?
– This muscle adducts the arm across the chest and is at the
route of a tennis forehand shot.
– The butterfly machine in the gym allows a person to isolate
and train this portion of the muscle.
• Create the smallest portion of the muscle – the clavicular head.
• What are the origin and insertion of the clavicular head of the
pectoralis major?
– Origin = medial half of inferior edge of the clavicle
– Insertion = lateral edge of the proximal humerus, inferior to
the insertion of the sternal head
Pectoralis Major
• Make a small carrot out of terra cotta clay.
Flatten the carrot slightly to make a shape
similar to an isosceles triangle. Do not worry
about perfect shape at this point. You will trim the
muscle to fit the Maniken®.
• Gently lay the muscle across the chest of the model from
the origin to the insertion. The long end of the carrot
should point towards the humerus and the slightly wider
end should run up against the bottom of the clavicle. The
insertion of this muscle will cross over the insertion of the
other two muscles on its way to the humeral attachment.
Pectoralis Major
• Use the wire tool or a pencil to carefully
outline the shape of the muscle.
• Take the muscle off the model and use
the knife to trim the edges you have
marked with your tool or pencil. Gently roll
out the muscle if you need to stretch it a
bit to fit from the origin to the attachment.
• Attach the muscle to the Maniken®. Striate
the muscle. Remember that the striations
of the muscle indicate the direction it
moves.
Building Muscles
• Thinking about the muscles we built,
why would one exercise not tone all of
the muscles.
Essential Question
• 6. What are the requirements for muscle
contraction?
• Calcium and ATP are cofactors required for the contraction of
muscle cells.
• ATP supplies the energy
• Calcium is required by two proteins that regulate muscle
contraction by blocking the binding of myosin to filamentous
actin
– Troponin
– Tropomyosin
• In a resting sarcomere, tropomyosin blocks the binding of
myosin to actin
Essential Question
7. What role do calcium and ATP play in
muscle contraction?
• 1) Calcium ions cause troponin and tropomyosin to
shift, exposing myosin binding sites
• 2) Myosin heads connect with actin binding sites &
move the thin filament, contracting the muscle
• 3) The ADP & P that caused the myosin heads to cock
back are left behind during the power stroke
• 4) Introduction of ATP causes myosin heads to
release the actin
• 5) ATP is broken down into ADP & P, causing myosin
heads to cock back and prepare for another power
stroke
Muscle Contraction
• http://www.youtube.com/watch?v=hqyn
Csign8E- Video discussing muscle
contraction
Activity 4.2.4 Laws of Contraction
• Pair up
• You will need:
–
–
–
–
5 Test tubes
5 Micorscopic slides
Salt solution, no ATP
0.25% ATP in distilled
water
– 0.25% ATP in salt
solution
– 0.10% ATP in salt
solution
– 0.05% ATP in salt
solution
– Disposable transfer
pipettes (1ml)
– Laboratory journal
– Teasing needles
(from dissection kits)
or straight pins
– Forceps or tweezers
– Millimeter ruler
– Microscope
– Frog Muscle
Essential Question
8. What is a sarcomere?
– The contractile unit of a myofibril;
sarcomeres are repeating structural units
of striated muscle fibrils, delimited by the Z
bands along the length of the myofibril.
9. How does a sarcomere contract and
lengthen to cause muscle contraction?
Muscle Contraction-Sacomere
Molecular Muscle Movement
• Muscle filaments are called myofibrils.
Myofibrils are made up of two kinds of
filament:
– Thin filaments made of actin protein
– Thick filaments made of myosin protein.
• Actin and myosin filaments work
together to make muscles contract.
These fibers are located between
protein sheets called Z-discs
Muscle Contraction
Actin and myosin are layered. Myosin filaments
have hooked parts that will stretch and pull
themselves along the actin filaments when ATP
attaches to them.
Muscle Filament Contraction
Muscle Filament Relaxation
Calcium (Ca2+) must be
removed for the
muscle fibers to relax
Moving (Ca2+) back into the
sarcoplasmic reticulum is
ACTIVE TRANSPORT
(requires ATP)
If the muscle cannot
remove the (Ca2+) the
muscle cannot relax and
will stay contracted.
Rigor Mortis
Rigor Mortis
• How is the condition rigor mortis related
to muscle contraction?
– After death actin and myosin shorten muscle fibers.
– ATP is needed to release the myosin heads from the actin
fibers and allow muscles to relax, but ATP reserves are
quickly depleted, causing muscles to remain contracted.
– It can take 10 minutes to hours to occur, with maximum
stiffness 12-24 hours after death.
– Eventually tissue decays and lysosomal enzymes leak and
cause muscles to relax.
Essential Question
11. How do nerves interact with muscles?
– In order for muscles to contract (shorten and thicken), they
must receive a message from the CNS to do so. The
messages come through efferent neurons (nerves that
move away from the CNS).
– Afferent neurons send messages back from muscles to the
CNS.
– If there are problems with nerves, it can lead to issues with
muscle function (i.e. Carpal Tunnel Syndrome)
Activity 4.2.6: You’ve Got Nerve
• Building Nerves
– Part 1 Brachial Plexus and Radial Nerve
Activity 4.2.6: You’ve Got Nerve
• Part 2 Carpal Tunnel
– Carpal tunnel syndrome is related to
pinching of the medial nerve.
– How can repetitive movement cause
damage.
• Complete Part 2
Essential Question
• 12. How can we assess muscle
function?
– Heart rate can help assess cardiac muscle
function. Strength tests can help assess
function of voluntary muscles.
• What equipment and testing have we
used that could be used on muscles.
Labview
EMG data
Key Terms
• Actin -A contractile protein that is part of the thin
filaments in muscle fibers
• Afferent neurons-Nerve cells that carry impulses
towards the central nervous system
• Cardiac muscle- Striated muscle fibers (cells) that
form the wall of the heart; stimulated by the intrinsic
conduction system and autonomic motor neurons
• Carpal tunnel syndrome-A condition caused by
compression of the median nerve in the carpal tunnel
and characterized especially by weakness, pain, and
disturbances of sensation in the hand and fingers
• Contract -To shorten and thicken
Key Terms
Efferent neurons- Nerve cells that conduct impulses away
from the central nervous system
Endomysium - The delicate connective tissue surrounding the
individual muscular fibers within the smallest bundles
Epimysium - The external connective-tissue sheath of a
muscle
Fascicle - A small bundle or cluster, especially of nerve or
muscle fibers
Insertion - The attachment of a muscle tendon to a moveable
bone or the end opposite the origin
Muscle - An organ composed of one of the three types of
muscular tissue (skeletal, cardiac, and smooth), specialized for
contraction to produce voluntary and involuntary movements of
parts of the body
Key Terms
Myofibril - A threadlike structure, extending longitudinally
through a muscle fiber (cell) consisting mainly of think
filaments (myosin) and thin filaments (actin, troponin, and
tropomyosin)
Myosin- The contractile protein that makes up the thick
filaments of muscle fibers
Nerve- A cordlike bundle of neuronal axons and/or
dendrites and associated connective tissue coursing
together outside the central nervous system
Origin - The attachment of a muscle tendon to a stationary
bone or the end opposite the insertion
Perimysium-The connective-tissue sheath that surrounds
a muscle and forms sheaths for the bundles of muscle
fibers
Key Terms
Plexus- Network of interlacing blood vessels or nerves
Rigor mortis-Temporary rigidity of muscles occurring after death
Sarcomere- Any of the repeating structural units of striated
muscle fibrils
Skeletal muscle- An organ specialized for contraction, composed
of striated muscle fibers (cells), supported by connective tissue,
attached to bone by a tendon or aponeurosis, and stimulated by
somatic motor neurons
Sliding filament mechanism-The explanation of how thick and
thin filaments slide relative to one another during striated muscle
contraction to decrease sarcomere length
Smooth muscle- A tissue specialized for contraction, composed
of smooth muscle fibers (cells), located in the walls of hollow
internal organs, and innervated by the autonomic motor neurons
Key Terms
Striation- Any of the alternate dark and light cross bands of a
myofibril of striated muscle
Tropomyosin - A protein of muscle that forms a complex with
troponin regulating the interaction of actin and myosin in
muscular contraction
Troponin - A protein of muscle that together with tropomyosin
forms a regulatory protein complex controlling the interaction
of actin and myosin and that when combined with calcium ions
permits muscular contraction