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Muscles &
Joints
Ch. 8
Movements of the body
• Flexion: >in angle of a jt. By bending it.
• Extension: < in angle of jt. By straightening it.
• Hyperextension: extension beyond the anatomical
position
• Abduction: moving away from midline
• Adduction: moving toward midline
movements
• Dorsi flexion: bending ankle so foot moves toward the
shin.
• Plantar flexion: bending ankle so foot points downward
• Inversion: moving foot so sole move inward( medially)
• Eversion: moving sole of foot outward( laterally)
movements
• Circumduction: circular movement along the
length of body part.
• Rotation: twisting around the axis of limb
internal rotation: moves medially
external rotation: moves laterally
• Elevation: raising body part
• Depression: lowering body part
movements
• Supination: turning hand palm up
• Pronation: turning hand palm down
• Protraction: moving part forward
• Retraction: moving part backward
joints
1. Form where bones meet
– Joints are functional
junctions between bones
2. Related terms
articulation: junction of 2 or more
bones
arthro: joint
arthology: study of joints
arthritis: inflammation of the joint
Arthroscopic: joint scope surgery
Joints
3. Functional vs. structural
Functional classification is based on:
Available movement
Structural classification is based on:
Materials that make up the joint
Joints
4. Functional classification
Synarthroidal= immovable
examples: sutures, coccyx-sacrum
Amphiarthroidal= slightly
moveable
examples: pubic symphysis, ribs,
vetebral disks, intervertebral jts.
Diarthroidal= freely moveable
examples: all synovial jts.
joints
5. Structural
classification
– Fibrous
– Cartilagenous
– synovial
Joints of the body
6.Fibrous Joints
– Syndesmoses (amphiarthroidal)
• Bones held together by connective
tissue(interoseous membrane)
• Tibia-fibula/Radius-Ulna
– Suture (synarthroidal)
• Between flat bones
– Gomphosis ( synarthroidal)
• Teeth to jaw
joints
7. Cartilagenous
– Temporary: Synchondrosis
(synarthroidal)
• (bone-cartilage-bone)
• Slightly movable: compression
• Example
– Epiphyseal plates
– 1st rib/manubrium
– Permanent: Symphasis
( amphiarthroidal)
• Example
– Pubis symphasis
– Intervertebral jts
Joints
8.Synovial
– Freely moveable
– All are diarthroidal
– Synovial membrane- secretes
synovial fluid
• Lubricates joint
– Joint capsule( fibrous tissueligament)
– Articular ( Hyaline) cartilage
( meniscus/menisci)
– Bursae: fluid filled sacs
• Reduce friction
Joints
8. Types of synovial joints
ball & socket
condyloid
gliding
hinge
pivot
saddle
joints
10. Ball & Socket
•
allows for greatest Range of Motion( ROM)
•
•
shoulder & hip
triaxial movement
flexion-extension-add/abduction- rotation
joints
• Condyloid ( ellipsoidal)
– Egg in spoon
– Flexion/extensionadd/abduction
– Wrist- MCP, MTP, IP, PIP,
DIP
• Gliding joint (plane)
– Articular ends nearly flat or
slightly curved.
– Inter (carpal/tarsal),
vertebrae, SI joint
Joints
– Hinge
• spool & cap
• Flexion/extension
– elbow, Knee, ankle
(talus-tib/fib)
– Pivot
– Cylinder within a ring
– Rotation
» Radio-humeral,
atlas-axis
Radius
Ulna
Joints
• Saddle
– Saddle on a horse
• Flexion/ext,
abd/adduction
• Carpometacarpal of
thumb
muscles
• 3 types
– Skeletal (striated, voluntary)
– Cardiac (striated, involuntary)
– Smooth ( involuntary)
• Characteristics
–
–
–
–
Irritability: ability to respond to stimuli
Contractility: ability to change length
Extensibility: ability to be stretched
Elasticity: ability to return to original
shape
Muscle facts
• Most common type of tissue in the body (over 600)
• Makes up 35-45% of body weight
• Muscles produce action only by pulling, they cannot
push
• Tendons connect bones to muscle
• One muscle may attach to another through an
aponeurosis (tendon)
• Each muscle is made up of many bundles of fibers
• Each fiber is an individual cell
• Cells are multinucleated
• They are thin, elongated cylinders
• Each cell may run the entire length of a muscle
Features of a muscle
•
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•
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Epimysium; muscle facia; outer covering of muscle
Perimysium: sheath that separates muscle cells into fascicles
Fasicle: bundle of muscle fibers
Endomysium: thin covering around each muscle fiber
Sarcolemma: membrane of the muscle cell
Sarcoplasm: cytoplasm of muscle cell
Muscle fiber: muscle cell composed of many myofibrils
Myofibril: threadlike structures within sarcoplasm essential for
contraction, made of myofilaments.
Myofilaments: protein strands actin (thin) and myosin (thick). Give
striped appearance to muscle.
Sarcomere: functional unit of muscle contraction between Z-lines of
each myofibril.
Myosin filament: Thick dark filament, make up A bands of
sarcomere, contains cross-bridges that connect them to the thin
filaments.
Actin Filaments: Thin, light colored filaments, make up I bands
connected together at Z lines, move with a muscle contraction.
Muscle fiber
fasicle
Actin & myosin
filaments
Muscle cell diagram
I-band
A-Band
I-band
actin
myosin
Cross
bridge
Sarcomere
Z line –Z line
Z-line
Z-line
H- band
sarcomere
•
•
•
•
•
•
•
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Sarcomere contractile unit of muscle
Actin: thin myofilament, troponin & tropomyosin
Myosin: thick myofilament, has crossbridges.
Z-line: connects ends of actin together, move toward
each other during contraction
A band: full length of myosin fiber within a
sarcomere, between I bands
I band: end of myosin in one sarcomere to the
myosin in the next sarcomere.
H- band: in the middle of the sarcomere between
ends of actin gets smaller with contractions.
Crossbridge: functional unit of myosin that attach to
troponin/tropomyosin heads on actin filament to
cause contraction
Muscle contraction
8.3-8.4
Muscle contraction
Lets watch a sarcomere shortening
• http://highered.mcgrawhill.com/sites/0072437316/student_view0/
chapter42/animations.html#
• Now let’s discover how this process
occurs
Muscle contraction (sliding filament theory)
1. Nerve impulse travels down a motor neuron to muscle
unit.
2. The motor neuron terminal releases neurotransmitter
acetylcholine (ACh)
3. ACh binds to ACh receptors (nicotinic receptor) on
muscle
Motor end unit
http://glencoe.mcgrawhill.com/sites/0015081981/student_view0/chapter8/function_of_the_neuromuscular_j
unction_.html
Muscle contraction (sliding filament theory)
4.The sarcolemma is
stimulated and the muscle
impulse travels over the
surface of the muscle fiber
into the transverse tubules.
5. The impulse reaches the
sarcoplasmic reticulum
and Ca+ channels open
6. Ca+ ions diffuse from the
sarcoplamic reticulum into
the sarcoplasm and bind to
troponin molecules.
4.
5
6.
Ca+ and it’s role in muscle
contraction
• http://www.youtube.com/watch?v=vv6WBe
qw2Nc
Muscle contraction (sliding filament theory)
• Thin filaments slide past the
thick filaments and the
sarcomere shortens.
• Myosin molecule has a head
and a tail
– Tail is a hinge allowing head to
attach to actin
– Head has a power stroke to pull
actin molecule.
• Myosin uses ATP to contract ( head has binding site for
actin & ATP)
• Actin molecule has 2 proteins: troponin & tropomyosin
– Tropomyosin covers binding site so myosin cannot bind
( prevents contraction)
– Troponin exposed binding sites ( w/Ca+)
7. Ca+ ions released by
action potential of nerve
causes tropomyosin to
move off of binding site.
8. Cross-bridge flexes and
binds to actin molecule.
9. Head flexes (power
stroke) and pulls the
actin, thus shortening the
sarcomere
( muscle contraction)
Sliding filament in action
Myofilament Contraction
Sarcomere shortening
• http://glencoe.mcgrawhill.com/sites/0015081981/student_view0/
chapter8/action_potentials_and_muscle_c
ontraction.html
Muscle relaxation
1. Acetylcholinesterase(enzyme) decomposes
ACh, and the muscle fiber membrane is no
longer stimulated (no ATP)
2. CA+ ions are actively transported back into
sarcoplasmic reticulum.
3. ATP breaks linkages between actin & myosin
filaments
4. Tropomyosin slides back over myosin binding
sites
5. Muscle is relaxed and ready for next
contraction
Energy source is ATP
- We use creatine phosphate to re charge the
ATP molecule
- Has High energy phosphate bonds
- 4-6x more abundant in muscle than ATP
- Active muscle uses Creatine Phosphate rapidly.uses cellular respiration after creatine is gone.
- Krebs cycle in aerobic environments
- lactic acid fermentation in anaerobic
Figure 08.10
Figure 08.11
Oxygen supply
- Myoglobin (like hemoglobin) helps provide muscle with extra
oxygen during respiration.
- Oxygen Debt
- During strenuous muscle use, anaerobic path ways are used to
obtain energy (1-2 mins)
- the amount of Oxygen the liver needs to covert lactic acid to
glucose + the amount of oxygen required to restore ATP/creatine
phosphate back to original concentrations) VERY SLOW process
- Can train to increase aerobic capacity
- Fatigue is usually caused from a build up of lactic acid.
- Lowers pH so muscle cells no longer respond to stimuli
Muscle control
• All-or-nothing response
– Threshold: weakest stimuli to elicit a response
- muscle fibers have different thresholds. must have
threshold for muscle to contract (twitch)
- Frequency fibers are stimulated & how many are
stimulated determine contractile force
- Recruitment of fibers occurs with larger stimuli
Muscle parts
• 3 main parts
– Origin= proximal; usually
immovable
belly
• 2 origins= biceps
• 3 origins= triceps
• 4 origins= quadriceps
– Insertion= distal attachment,
usually movable
– Belly= “body” of muscle, between
O&I
Muscle names
• Named for their
– Action ( flexor, extensor)
– Location (carpi, tibialis)
– Shape and size ( deltoid, maximus, longus)
– Number of attachments ( bi, tri..)
– Point of attachment ( sternocleidomastoid)
– Direction of their fibers ( transverse, oblique)
Muscle work in groups
• Prime mover (agonist) Muscle
primarily responsible for movement
– Ex. Deltoid-abducting arm/biceps-arm
flexion
biceps
• Synergist assist prime mover
– Make movements more smooth and
efficient
– Ex. Rotator cuff deltoid in arm Abduction
Brachialis
(under biceps)
triceps
• Antagonist performs opposite of
agonist
– Ex. Triceps/biceps; quad/hamstrings
Muscles of the face
• Muscles of facial expression(6)
–
–
–
–
–
–
Epicranius:
Orbicularis oris
Orbicularis oculi
Buccinator
Zygomaticus
Platysma
• Muscles of mastication(2)
– Masseter
– Temporalis
1. epicranius: lifts eye brows
“flirting:
frontalis+ occiptalis
2. Orbicularis oculi: closes eye
5.
“winking”
3. Orbicularis oris: close mouth
“kissing”
4. Buccinator: compress cheeks in
“whistle”
5. zygomaticus: raises corner of
mouth
“smile”
4.
6. platysma: draws angle of
mouth downward
“pout”
7. Sternocleidomastoid:
Turns head to side, pulls
head to chest, raises
sternum
6.
7.
8. masseter: elevates mandible
“chew”
9.Temporalis: elevates mandible
“chew”
Figure 08.17b
11. Extends head, bends to
one side, rotates head
10.Rotates head, bends head
to one side, brings head to
upright position
Muscles of pectoral girdle
1. Trapezius:
A. upper: rotate/raise
scapula
B. Middle: adduct scapula
C. Lower: depress
scapula/shoulder
2. Deltoid
A. anterior: flex shoulder
B. Lateral: abduct
shoulder
C. Posterior: extend
shoulder
3. Rhomboid: major& minor
a. raise & Adduct shoulder
4. Levator scapulae: “IDK”
a. elevate & adduct
shoulder
b. flex head to side
Muscle that move shoulder girdle
5. Serratus Anterior
a. Abducts scapula &
rotates
Serratus
anterior
6. Pectoralis Minor
a. Draws scapula forward &
downward
b. elevates ribs
Pectoralis
minor
Muscles that move Arm
7. Pectoralis Major
a. flex, adduct & medially
rotate arm
8. Latissimus Dorsi (Lats)
a. extend arm
b. adduct medially rotate
arm
c. pulls shoulder down &
back
“Rotator Cuff”
9. Teres Major:
extends, adducts &
medially rotates arm
10. Teres Minor*:
Rotates arm laterally w/
infraspinatus
11. Infra spinatus:
rotates arm laterally
12. Supraspinatus:
abducts arm
13. Subscapularis*:
medially rotates arm
Muscles that move forearm
1. Biceps brachii:
a. Flexes forearm
b. Supinates hand
2.Brachialis
a. flex forearm
3. Brachioradialis
a. flex forearm
Muscles that move forearm
4.Triceps brachii
– A. extend forearm
supinator
5. Supinator*
a. supinates hand
6. Pronator teres*
a. pronates hand
7. Pronator quadratus*
a. pronates hand
Superficial muscles that move hand/wrist
1. Flexor carpi radialis*
a. Flex abduct wrist
2. Flexor carpi ulnaris*
a. Flex adduct wrist
3. Palmeris longus*
a. Flex wrist
4. Flexor Digitorium
1. Flexes distal
phalanges (digits)
Superficial muscle that move wrist/hand
5. Extensor carpi radialis*
longus & brevis
a. extend wrist, abduct hand
6. Extensor carpi ulnaris*
a. extend adduct wrist
7. Extensor digitorum*
a. extends fingers
Muscles of Abdominal Wall
•
Rectus abdominis
–
–
•
External oblique
–
–
–
•
both side together compress
abdomen
one side, aids back in rotation
one side aids in trunk flexion
internal oblique
–
–
–
•
flex trunk,
compress abdomen
both side together compress
abdomen
one side, aids back in rotation
one side aids in trunk flexion
transverse abdominis
–
–
–
both side together compress
abdomen
one side, aids back in rotation
one side aids in trunk flexion
Muscles of Abdominal
Wall
5. intercostal muscles
a. depress & elevate ribs
for breathing
6. erector spinae
extends back
Intercostals
Muscles that move the Thigh
1. Tensor facia latae
a. abducts,
b. flexes
c. medially rotates thigh
2. Gluteus maximus
a. Extends thigh
3. gluteus medius
a. abducts
b. medially rotates thigh
4. adductor longus
a. adducts,
b. flexes,
c. laterally rotates thigh
5. adductor magnus
a. adducts
b. anterior portion flexes
c. posterior portion extends
6. gracilis
a. adducts
b. flexes
c. medial rotation
Muscle that move the thigh
5. adductor magnus
a. adducts
b. anterior portion flexes
c. posterior portion extends
6. gracilis
a. adducts
b. flexes
c. medial rotation
7. iliopsoas
a. Flexes( primary hip flexor)
b. Medial rotation
Muscles that move hip/leg
1. Sartorius (basket weaver)
a. flex leg & thigh
b. abducts & laterally rotates thigh
c. rotates leg medially
Quadriceps femoris group
1. Rectus femoris*:
a. extends knee
b. flex hip
2. Vastus lateralis:
a. extend knee
3. Vastus medialis:
a. extend knee
4. Vastus intermedius*:
a. extend knee
IT band
Muscles that move the leg
Hamstring group*
1. Biceps femoris*:
a. flex knee
b. extend thigh
c. rotates knee laterally
2. Semitendonosis:
a. flex knee
b. extends thigh
c. more superficial w/ long
tendon
3. Semimenbranosis:
a. flex knee
b. extends thigh
c. deep to semitendonosis
d. broad tendon
Muscles that Move the Foot and
Toes
1. Anterior
a. Tibialis anterior
a. Dorsi flex
b. Inversion
b. Extensor digitorum longus
a. Dorsi flexion
b. eversion
2. Posterior
a. gastrocnemius* 2 joint muscle
a. plantar flex foot
b. flexion of knee
b. soleus
a. plantar flex foot
c. flexor digitorum longus
a. curl toes 2-5
b. plantar flexion
c. inversion foot
Muscles that Move the Foot and
Toes
1. Lateral
a. peroneus longus
a. plantar flexion
b. eversion foot
c. support arch
b. peroneus brevis
a. plantar flexion
b. eversion foot
c. peronius tertius
a. dorsi flexion
b. eversion foot