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Muscular System Ezequiel Herrera Period 4 Yang (Disorders associated…
Muscular System
Ezequiel Herrera
Period 4
Yang
Major Functions of the muscular System
Produce movement
Blood courses rhythmically beating cardiac muscle of your heart and the smooth muscle in the walls of your blood vessels, which helps maintain blood pressure.
Skeletal muscles are responsible for all locomotion and manipulation
Smooth muscle in organs of the digestive, urinary, and reproductive tracts propels substances
Maintain posture and body position
muscles function almost continuously
make tiny adjustments after another to counteract the never-ending downward pull of gravity
Stabilize joints
they strengthen and stabilize the joints of the skeleton
Generate heat
Muscles generate heat as they contract
maintains normal body temperature
Names of all the muscles
Anterior
Muscles at the Head
orbicularis oculi
closes the eye
temporalis
move the mandible up, back, and side-to-side
frontalis
raises eyebrows
masseter
closes the jaw
orbicularis oris
closes lips
Buccinator
muscle for sucking in your cheek
Zygomaticus
muscle involved in smiling
Pelvis
iliopsoas
flex the thigh at the hip joint.
Thigh
gracilis
adducts the thigh and flexes the leg
rectus femoris
helps to extend or raise the knee
sartorius
move the hip joint and the knee joint
vastus lateralis
extend the lower leg
vastus medialis
knee extension
Muscles of the neck region
Sternocleidomastoid
both sides together: flexes neck forward
one side contraction: laterally flexes neck, rotates head to opposite side;
Levator scapulae
raises the scapula
Platysma
pulls down the mandible and pulls the corners of the lips
Trapezius
extends or straightens and hyper extends the neck.
Elevates the shoulders
Chest Region
Pectoralis Major
involved in raising arm forward
serratus anterior
accessory respiratory muscle; raises ribcage
Deltoid
abduct, flex, extend and rotate the arm
Arm
Brachioradialis
flexes and supinates the forearm at the elbow
Flexor carpi radialis
flexes and abducts the wrist
tricep brachii
extends forearm at the elbow
bicep brachii
helps control the motion of two different joints, the shoulder and the elbow
Leg
extensor digitorum
longus
extend your toes and dorsiflex your feet
fibularis longus
flexes the ankle
tibialis anterior
dorsiflexion and inversion of foot
soleus
two muscles that allows standing on tip toes
gastrocnemius
Posterior
Muscles at the head
Occipitalis
moves the scalp back
Arm
tricep brachii
extends forearm at the elbow
Back
latissimus dorsi
extends, adducts, and medially rotates the shoulder
infraspinatus
externally rotate the humerus and stabilize the shoulder joint
teres major
medial rotator and adductor of the humerus
Thigh
semitendinosus
flex the knee and extend the hip
semitendinosus
flex the knee and extend the hip
bicep femoris
extending the thigh, bending the knee, and rotating the knee
extensor digitorum
extends the fingers
flexor carpi ulnaris
flexes and abducts the wrist
extensor carpi radialis
wrist extensors
Muscle Tissue
Smooth Muscle
Characteristics
found in the walls of hollow visceral organs
elongated cells
nonstriated
involuntary
Function
forms valves to regulate the passage of substances through internal body openings
forms the arrector pili muscles attached to hair follicles
dilates and constricts the pupils of your eyes
Cardiac Muscle
Characteristics
striated
not voluntary
occurs only in the heart
Function
contracts at a fairly steady rate set by the heart’s pacemaker
constitutes the bulk of the heart walls
Skeletal Muscle
longest muscle cells
voluntary muscle
have stripes called striations
Function:
overall body movement
can exert tremendous power
Common Characteristics
Excitability
respond to a stimulus
Contractility
ability to shorten
Extensibility
ability to extend or stretch
Elasticity
recoil and resume its resting length after stretching
Body Movements
Abduction
moving parts away from the midline
Extension
straighten or increase angle at a joint
Pronation
palm is downward
Flexion
bending a joint, decreasing the angle
Supination
palm is upward
Plantar flexion
bending foot downward or pointing toes down
Eversion
moving foot outward
More Body Movements
Adduction
moving parts towards the midline
Hyperextension
moving parts beyond the 180 degrees
Dorsiflexion
flexing foot at ankle/toes up off the ground
Inversion
moving foot inward
Circumduction
one end stays same position and the other end moves in circular motion
Supination
movement need to turn a door knob
Extension
movement needed to kick a ball
Flexion
movement for bending at the wais
Opposition
movement of thumb to touch the tips of other fingers of the same hand
Opposition
movement of the fingers to make the "ok" sign
Rotation
spinning on a an imaginary axis
Muscle Organization
1) Muscle
Consists of thousands of muscle cells, connective tissue wrapping, blood vessels, and nerve fibers
Covered by epimsyium
2) Fasicle
Discrete bundle of muscle cells
Separated by perimysium
3) Myofibril
Complex organelle composed of bundles of filament
Composed of sacomeres arranged end to end
Bands of adjacent myofibrils are aligned
4) Sarcomere
Composed of myofilaments made up of contractile proteins
The contractile unit
Extends from one Z disc to the next
5) Myofilament
Thick Filaments
H zone
Thick filaments only
M line
thick filaments linked by accessory proteins
bundled myosin molecules
Thin filaments
Contain actin molecules
tropomyosin
a rod-shaped protein, spiral about the actin core and help stiffen and stabilize it
Sliding of the thin filaments past thick filaments produces muscle shortening
I Band only
Troponin
subunit attaches troponin to actin
Physiology of Muscles
Rapidly changing membrane potential in requires the opening and closing of membrane channels
Chemically gated ion channels
opened by chemical messengers
Two classes of ion channels are important for excitation and contraction of skeletal muscle
Voltage-gated ion channels
open or close in response to changes in membrane potential
1) Events at the neuromuscular junction
The motor neuron releases ACh that stimulates the skeletal muscle fiber
causes local depolarization (EPP)
2) Muscle fiber excitation
action potential travels across the entire sarcolemma
3) Excitation-contraction coupling
AP in the sarcolemma propagates along the T tubules and causes release of Ca2+
Ca2+ binds to troponin and this causes the myosin-binding sites on actin to be exposed so that myosin heads can bind to actin
4) Cross bridge cycling
muscle contracts as a result of a repeating cycle of steps that cause myofilaments to slide relative to each other
MORE DETAILS
1) Cross Bridge formation
Energized myosin head attatches to actin filament, forming a cross bridge
2) Power Stroke
ADP and Pi is released
Myosin heads twist and pivot
1 more item...
3) Cross bridge detatchment
2 more items...
Essential Vocab for muscle contraction :warning:
Action potential
large change in membrane potential that spreads rapidly over long distances within a cell
acetylcholine
Chem. transmitter substance
myofibrils
long filaments that run parallel to each other to form muscle fibers
Repolarization
Restoring sarcolemna to initial polarized state
sarcolemma
plasma membrane of a muscle
Disorders associated with the
Muscular system.
Any disease of muscle
Spasm
sudden, involuntary twitch in muscle ranging from merely irritating to very painful
Myopathy
Strain
excessive stretching and possible tearing of a muscle due to muscle overuse or abuse
Myofascial pain syndrome
Pain caused by a tightened band of muscle fibers
Tetanus
An acute infectious disease caused by the anaerobic bacterium Clostridium tetani
persistent painful spasms of some skeletal muscles
Hernia
Protrusion of an organ through its body cavity wall
disuse atrophy
Immobilization due to enforced bed rest or loss of neural stimulation
muscle strength can decline at the rate of 5% per day
Myalgia
Muscle pain resulting from any muscle disorder
muscular dystrophy
refers to a group of inherited muscle-destroying diseases that generally appear during childhood.
most common and serious form is Duchenne muscular dystrophy (DMD)
boys become clumsy and fall frequently as their skeletal muscles weaken
progresses upward, finally affecting the head and chest muscles, and cardiac muscle
Fibromyalgia
group of conditions involving chronic inflammation of muscles, their connective tissue coverings and tendons, and capsules of nearby joints
tenderness, fatigue and frequent awakening from sleep
More Disorders
Electromyography
Recording and interpretation of the electrical activity of contracting muscles
Ruptured calcaneal tendon
rupture is accompanied by abrupt pain. A gap may be seen just above the heel,
Charley horse
Painful muscle spasm
Can result from stretching or tearing muscle, muscle strain, or contusion
Shin splints
painful inflammation of the muscles, tendons, and connective tissue surounding the tibia.
Tennis elbow
Tenderness due to overuse of the tendon of origin of the forearm extensor muscles at the lateral epicondyle of the humerus
Torticollis
A condition in which the neck stays rotated to one side