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Origin
The attachment of a muscle’s tendon to the STAIONARY bone (usually PROXIMAL)
Insertion
The attachment of the muscle’s other tendon to the MOVABLE bone (usually DISTAL)
How do muscles produce movement?
Most skeletal muscles produce movement by exerting a force on tendons, which then pull bones or other structures
Most muscles cross one joint (sometimes 2; 2 joint muscles) and they can create movement at joints they cross
Agonist (Prime mover)
Contracts to cause an action
Antagonist
Stretches and yields to the effects of the agonist
What is an example of Agonist & Antagonist?
When flexing the elbow, the biceps is the agonist and the triceps is the antagonist.
Name the muscles of the RESPIRATION/BREATHING group
Diaphragm, internal & external intercostals
Name the muscles of the ABDOMINAL group
Rectus abdominis, Transverse abdominis, external obliques, and internal obliques
Name the muscles of the ROTATOR CUFF group
Supraspinatus, infraspinatus, teres minor, and Suprascapularis
Name the muscles of the HIP ADDUCTORS group
Gracilis, adductors longus, adductor magnus, and pectineus
Name the muscles of the GLUTEAL group
Gluteaus maximus, gluteus medius, and gluteus minimus
Name the muscles of the QUADRICEPS
Rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius
Name the muscles of the HAMSTRINGS
Bicep femoris, semitendinosus, and semimembranous
Masseter
One of the strongest muscles in the body
Describe the ACTION of the MASSETER
Elevates and protracts the mandible; closes the mouth
What is the ORIGIN of the STERNOCLEIMASTOID?
Manubrium and sternal end of clavicle
What is the INSERTION of the STERNOCLEIMASTOID?
mastoid process (temporal bone)
Describe the ACTION of the STERNOCLEIMASTOID
Bilateral contraction - Flexes the neck
Unilateral contraction - Lateral flexion to its own side and rotation of the opposite side
What does the diaphragm separate?
Thoracic and abdominal cavities
Describe the ACTION of the DIAPHRAGM
Contracts during inspiration and relaxes during expiration
What is the ACTION of the RECTUS ABDOMINIS?
Trunk flexion and compression of abdomen
What is the deepest abdominal muscle?
Transverse abdominis
What is the ACTION of the EXTERNAL OBLIQUES?
Bilateral trunk flexion and unilateral lateral flexion and rotation of the trunk (to opposite side)
What is the ACTION of the INTERNAL OBLIQUES?
Bilateral trunk flexion and unilateral lateral flexion and rotation of trunk to same side
What is the ACTION of the TRAPEZIUS?
Elevation and depression of scapula; rotation & retraction of head
What is the ACTION of the LATISSIMUS DORSI?
Extension, adduction, and medial rotation of shoulder
What is the ORIGIN of the PECTORALIS MAJOR?
Medial clavicle, sternum, and ribs
What is the INSERTION of the PECTORALIS MAJOR?
Intertubercle groove of humerus
What is the ACTION of the PECTRAOLIS MAJOR?
Adduction, flexion, and medial rotation of shoulder
What is the ACTION of the DELTOID?
Adduction, flexion, and rotation of the shoulder
What is the ACTION of the SUPRASPINATUS?
Abduction of the shoulder
What is the ACTION of the INFRASPINATUS?
Lateral rotation of the shoulder
What is the ACTION of the TERES MINOR?
Adducts and laterally rotates shoulder
What is the ACTION of the SUBSCAPULARIS?
Medial rotation of the shoulder
What is the ACTION of the BICEPS BRACHII?
Flexion and supination of elbow/forearm
What is the ACTION of the TRICEPS BRACHII?
Extension of elbow/forearm; extension and adduction of the shoulder
What is the ACTION of the SARTORIUS?
Flexes hip and knee; laterally rotates hip
What is the ACTION of the INNER THIGH MUSCLES?
Adduction of thigh
What is the ACTION of the GLUTEAL MUSCLES?
Responsible for hip extension
What is the ACTION of the RECTUS FEMORIS?
Flexion of hip and extension of knee
What is the ACTION of the VASTUS LATERALIS, MEDIALIS, and INTERMEDIUS?
Extension of knee
What is the ACTION of the HAMSTRINGS?
Flexion of knee and extension of hip
What is the ACTION of the GASTROCNEMIUS?
Plantarflexion of ankle (and flexion of knee)
What is the ACTION of the TIBIALIS ANTERIOR?
Dorsiflexion of foot
What muscles are 2 jointed?
Biceps brachii, triceps brachii, sartorius, rectus femoris, biceps femoris, and gastrocnemius
What are the functions of the muscular system?
Producing body movement
Stabilizing body positions
Protection & support
Storing/moving substances within the body
Generate heat
What are the properties of muscular tissue?
Electrical excitability & conductivity
Contractility
Extensibility
Elasticity
Why is elasticity so important of muscular tissue?
It helps the muscle to return to original length and shape after contraction or extension
What are the different types of muscle tissue?
Skeletal, cardiac, and smooth
What are the characteristics of the skeletal muscle?
Striated
Light and dark protein bands
Multinucleated
Voluntary
What are the characteristics of the cardiac muscle?
Striated
Light and dark protein bands
Single nucleus
Involuntary
What are the characteristics of the smooth muscle?
Found in the walls of internal hollow structures such as blood vessels
Non-striated
Single nucleus
Involuntary
What 3 connective tissue layers are present in muscle tissue?
Epimysium, perimysium, and endomysium
Epimysium
Outermost layer of dense irregular CT that encircles entire muscle
Perimysium
Surrounds groups of muscle fibers/bundles called fascicles (dense irregular CT)
Endomysium
Separates and surrounds individual muscle fibers (thin sheath of areolar CT)
Somatic motor neurons
Neurons that penetrate a skeletal muscle
What characteristics are unique to SKELETAL MUSCLES?
Multinucleated
Cannot undergo cell division
Multinucleated
Each mature skeletal muscle fiber has a hundred or more nuclei (groups of embryonic myoblasts fuse to form single skeletal muscle fibers)
What are the components of the Skeletal muscle fiber?
Sarcolemma (transverse tubules)
Sarcoplasm
Myofibrils (sarcoplasmic reticulum)
Myofilaments (actin & myosin)
Sarcomere
Sarcolemma
Plasma membrane of a muscle cell
Transverse tubules
Ensures that action potentials excite all parts of muscle fiber at the same instant
Sarcoplasm
Contains myoglobin (protein found only in muscle that releases oxygen needed by the mitochondria for ATP production)
Myofibrils
Contractile organelles of skeletal muscle
80% of the contents of each muscle fiber
Sarcoplasmic reticulum
Store calcium ions that when released, trigger a muscle contraction
Myofilaments
Smaller muscle protein structures within myofibrils
Thick filaments
Formed from bundles of hundreds of myosin protein molecules
Thin filaments
Composed of 2 strands of the actin protein
Sarcomere
Myofilaments within the myofibril are arranged in repeating units/compartments called sarcomeres (basic functional units of the myofibril)
What are the components of the sarcomere
Z-discs
A-band
I-band
H-zone
M-line
Z-discs
Narrow regions of dense material that separate one sarcomere from the next
A-band
Dark, middle part of sarcomere that extends the length of the thick filaments and parts of thin filaments that overlap with thick filaments
I-band
Lighter area of sarcomere that contains rest of the thin filaments, but no thick filaments
H-zone
Narrow region in center of each A band that contains thick, but no thin filaments
M-line
Region in center of H zone that contains proteins at center of the sarcomere
Tropomyosin
When skeletal muscle is relaxed, it prevents myosin from binding to actin (covers the myosin binding sites on the actin)
Troponin
Allows myosin to bind to actin, enabling a muscle contraction
What’s the difference between tropomyosin & troponin?
tropomyosin relaxes muscle, troponin contracts muscle
What is the muscle hierachy?
Myosin & actin protein molecules > myofilaments > sarcomere > myofibrils > muscle fiber > fascicle > muscle
What are the components of the neuromuscular junction?
Synaptic knob
Motor plate
Synaptic cleft
Synaptic knob
End of motor neuron and contains synaptic vesicles filled with acetylcholine (neurotransmitter)
Motor end plate
Region of the sarcolemma of a muscle fiber that contains acetylcholine receptors
Motor unit
Consists of a somatic motor neuron plus all of the skeletal muscle fibers that stimulates/control
Resting membrane potential
The relative difference in charge across the plasma membrane of a cell
What is the steps for excitation of skeletal muscle fiber?
Propagation of nerve signal
Release of acetylcholine
Binding of acetylcholine
Propagation of nerve signal
Triggers calcium to move down its concentration gradient into the synaptic knob and bind to the synaptic vesicles
Release of acetylcholine
When calcium binds to synaptic vesicles, this triggers the release of acetylcholine into the synaptic cleft
Binding of acetylcholine
Acetylcholine diffuses across the synaptic cleft and binds to the receptors in the motor end plate > causes excitation of a muscle fiber
How is the end plate developed at the motor end plate?
Acetylcholine (Ach) binds to the Ach receptors in the motor end plate of a skeletal muscle fibers > sodium diffuses into the skeletal muscle fiber & potassium diffuses out
How does depolarization happen in muscle tissue?
Sodium channels open in the sarcolemma
Sodium moves into the muscle fiber
The side of the muscle fiber becomes positive
How does repolarization happen in muscle tissue?
In response to the opening of the sodium channels, potassium channels open
Potassium moves out of the muscle fiber
The negative resting membrane potential is restored
What does the sarcoplasmic reticulum release?
Calcium into the sarcoplasm
What are the steps to calcium binding?
Calcium that is released from the sarcoplasmic reticulum binds to troponin
Changes shape
Tropomyosin is moved and the myosin binding sites of the actin are exposed
What are the steps of crossbridge cycling?
Crossbridge formation
Power stroke
Release of the myosin head
Reset of the myosin head
Crossbridge formation
Myosin head attaches to actin
Crossbridge forms between the thick and thin filaments
Power stroke
Thin filaments pull past the thick filaments toward the center of the sarcomere
Sliding filament theory
When the thick and thin filaments slide past one another (no not shorten)
What are the steps of the sliding filament theory?
H zone disappears
I band narrows and may disappear
Z discs move closer together
The sarcomere shortens
What are the steps of muscular contraction?
Action potential travels down motor neuron
Calcium binds to synaptic vesicles (in neuron)
Triggers release of acetylcholine
Acetylcholine binds to motor end plate (of muscle fiber)
Sodium moves in and potassium moves out of muscle fiber
Action potential travels along sarcolemma (T-tubules)
Ca released from sarcoplasmic reticulum into sarcoplasm
Ca binds to troponin
Myosin attaches to actin
Thin filaments slides past thick filament
Sarcomere shortens (contraction)
What are 3 ways muscle fibers can produce ATP
Phosphagen system
Anaerobic cellular respiration
Aerobic cellular respiration