Muscular System Flashcards
myocyte
muscle cells “muscle fibers”
Contraction
how muscle generates force to move bones
Relaxation
muscle goes back to original shape and size
Smooth Muscle
- non-striated
- mono nucleated
- tapered at each end
- muscle contractions happes slowly relaxation happen slowly
- muscle contractions occur in waves in response to nerve impulses, hormonal stimulation and stretching
- Location: walls of hallow organs, gi tract, resp. tract,blood vessels, iris of the eye
Cardiac Muscle
- Muscle tissue of the heart
- striated
- involuntary
- branched, mono-nucleated, intercalated disc(allow quick nerve impulse transmission)
- impulses that initiate cardiac muscle contraction start within the muscle itself. rate of contraction can be modified by the nervous system
Skeletal Muscle
- striated, voluntary
- striated because of arrangement of the protein fibers(actin and myosin)
- cylindrical and have multiple nuclei
- most abundant type of muscle cell
- Functional unit/contractile unit of a skeletal muscle cell sarcomeres.
Function of Skeletal Muscle
1) Movement
2) Maintaing Posture
3) Generation of Heat: most metabolic active tissue
Characteristics of Muscles
1) Irritability(excitability): ability to respond to certain stimuli by producing electrical signals
2) Contractility: ability to become shorter and thicker, slide across each other
3) Extensibility: ability to become longer
4) Elasticity: ability to return to original shape
Mycocytes
- individual muscle fibers
- wrapped in connective tissue called endomysium
Endomysium
wraps muscle fibers/myocytes
Perimysium
wraps muscle fibers into bundles (anywhere between 10 to 100 or more) or fascicles.
Epimysium
- wraps entire muscle
- layer of connective tissue, which ensheaths the entire muscle.[1] It is composed of dense irregular connective tissue. It is continuous with fascia and other connective tissue wrappings of muscle including the endomysium, and perimysium. It is also continuous with tendons where it becomes thicker and collagenous. The epimysium also protects muscles from friction against other muscles and bones.
Tendon
- connect muscle to bone
- Endo + Peri + Epimysium = TENDON
Sarcomere
contains filaments of the proteins actin and myosin
Motor Unit
motor nerve and all of the muscle fibers it innervates
Neuromuscular Junction
-point at which motor nerve meet muscle
ACH(Acetylcholine
-neurotransmitter that travel across synapse
Summary of Muscle Contraction
- Sliding filament mechanism
- all or none response: each muscle fiber must receive a certain amount of stimulation before it will generate an action potential.
- amount of stimulation needed is called a threshold
- Each muscle requires a different threshold
- When ACH binds to the cell membrane of the muscle fibers it causes the cell membrane of the muscle fiber to generate an electrical impulse called an action potential
- Action potential causes CA ions to be released in the muscle fiber
- sliding filaments mechanism
- CA ions + ATP will cause the filaments of actin and myosin slide across each other which makes the muscle fiber(muscle contraction)
All or none response
each muscle fiber must receive a certain amount of stimulation before it will generate an action potential
threshold
amount of stimulation needed
Energy
- muscle contraction/ relaxation require energy
- form of energy used by a cell is ATP
- ATP is produced by oxidation of nutrients in the presence of oxygen(cellular respiration)
- some ATP can be produced in the absence of 02
- Lactic Acid is produced burn and muscle fatigue
- muscle failure/ fatigue=Lactic acid
Muscle tone
-state of partial contraction of muscles responsible for posture, contractures, flaccidity
Isotonic Contraction
-tone of muscle remains the same but the muscle as a whole gets shorter in length. This produces flexion results in movement you can see
Isometric Contraction
tone of the muscle increases but the length of the muscle remains the same, no movement occurs
Effects of Exercise
1) Changes in muscles(local effect)
- increase in blood supply
- increase in protein filaments
- changes lead to hypertrophy of the muscle(gets bigger)
2) Vasodilation(systemic effect)
- allows greater bloodflow w/ reduced resistance = overall drop in BP
3) Strengthening of the Heart(systemic effect)
- increase in the volume of the blood returning to the heart which strengthens the myocardium=greater efficiency=lower resting heart rate
4) improvement in respiration
5) Oxygen dept=burn fuel without oxygen owe muscle oxygen
Action of Muscles
skeletal muscle causes movement because it is attached to two bones. when the muscle contracts across a joint one bone is pulled towards another one.
Prime Mover(agonist)
- main muscle invovled in producing movement
- when muscle is acting as prime mover it contracts
Antagonist
- muscle that opposes the movement of the prime movers
- located at the opposite side of the bone/body from prime mover
- prime move, contracts the antagonist must relaxin order for movement to occur
Synergist
muscle or muscles that assist the prime mover
Fixator
specialized synergist that helps to fix(stabilize) the position of the bone that is being moved. fixator serves as an anchor
Naming of Muscles
Size
Direction of fiber
Location
Action
- Size: vastus, maximus, minimus
- Direction of fibers:
Rectus(Vertical, top/bottom)
Oblique(on angle)
Transverse(horizontal)
Circularis(circle) - Location: in the body or proximity to the bone
- Action:
Adductor(Towards)
Abductor(Away)
Levator(bring up)
Sphincter(controlling an opening)
Naming of Muscles(continued)
Origin/Insertion
- Origin/Insertion
Origin: part of muscle that attaches to the less moveable bone(proximal)
Insertion: part of muscle attached to moveable bone(distal)
Naming of Muscles(continued)
Number of Heads
Sphincter
- Number of origins(heads)
Biceps Brachii
Triceps Brachii
Quadriceps Femorus - Sphincter
cardiac sphincter: controls entrance into the stomach
pyloric sphincter: controls exit out of the stomach
Anal sphincter:
Urethra sphincter:
Muscles of the Head
1) Massater: found at the angle of the lower jaw(mandible). functions to raise mandible
2) Oribicularis Oris:
- circular(sphincter) muscle around the mouth
- closing the mouth, puckering of the lips
3) Orbicularis Oculi:
- circular muscle around the eye
- winking,blinking,squinting
Muscles of the Neck
1) Sternocleidomastoid
- along the side of the neck
- flexes and rotates the head
2) Trapezius
- broad muscle on the posterior surface of the neck and shoulder
- extends the head, elevates the shoulder and pulls them back
Movement of Shoulder and Arm
1) Latissimus Dorsi
- large broad muscle on mid and lower back
- ADDUCTS AND ROTATES the arm behind the back
2) Pectoralis Major
- Large muscle that covers the upper anterior chest
- ADDUCTS and FLEXES the upper arm across the chest and pulls shoulder forward and downward.
3) Deltoid
- Large triangular muscle which covers the shoulder
- abducts the arm
- site for IM injection
Rotator cuff muscles
- 4 muscles that attach humerous to the -scapula
- tendons forms a cuff over proximal end of humerus
- rotate arm@shoulder
Muscles of Forearm and Hand
1) Biceps Brachii
- major muscles on anterior surface of the upper arm
- flexes and supinates the forearm
Triceps Brachii
- Major muscle on the posterior surface of the upper arm
- extends the forearm
Muscles of the Trunk
Muscles of Respiration:
1. intercostal muscles: connects ribs with each other
external intercostal-inhalation-synergist with diaphragm
internal intercostal-exhalation
- Diaphragm: Synergistic with external intercostal muscles
- large dome shaped muscle
- major muscle of respiration
- attached to the xphoid process, the costal
- cartilage and lumbar vertebrae
- contraction of diaphragm causes the thoracic cavity to expand(inhalation)
Muscles of the Back/Posture
- Erector Spinae
- deep vertical muscles that run parallel to the spinal column, errect posture
Muscles of Abdomen and Pelvis
- Rectus Abdominis
- compresses the abdomen - External Oblique
- compresses the abdomen
- bends the vertebral column laterally
- rotates the vertebral column - Internal Oblique
- compresses the abdomen
- bends the vertebral column laterally
- rotates the vertebral column - Transverses Abdominis
- compresses the abdomen
- deepest part of the abdominal muscle
Muscles of the Lower Extremities
- Gluteus Maximus
- largest and most superficial gluteal muscle
- forms buttock
- extends the thigh - Gluteus Medius
- found partly deeper and superior to gluteus maximus
- abducts and rotates the thigh - Quadriceps Femoris
- group of four muscles on the anterior and lateral surface of the thigh
- extends the lower leg - Hamstring Group
- three muscles located on the posterior surface of the thigh
- flex the lower leg
- extend the thigh
(side bar
- flexer for forearm is anterior
- flexer for legs posterior)
Muscles of the lower leg that move the foot
- Gastrocenemius
- large muscle that forms the calf
- posterior muscle of the lower leg
- gastrocenemius attached by the achilles tendon
- plantar flexion - Soleus
- posterior surface of the lower leg
- plantar flexion - Tibialis Anterior
- anterior leg
- dorsiflexes foot
- inverts foot
Effects of Aging on Muscles
- loss of muscle mass
- smaller weaker muscles
- weakness and feeling cold
- loss of muscle tone=posture change
- slower muscle responses= increased response to time
- decrease in elasticity of tendons and ligaments=Loss of ROM
Muscular Disorders
Atrophy: wasting of muscle
Dystrophy: death of muscle
Spasm: sudden painful contraction of a muscle(cramps)
Strains: injury of overuse
Sprains: injury
Rest, Ice, Compress, Elevate-increase bloodflow back
Sternocleidomastoid
along lateral neck, to mastoid process
- FLEXES HEAD
- ROTATES HEAD TOWARD OPPOSITE SIDE FROM MUSCLE
Masseter
at angle of the jaw
-CLOSES JAW
Temporalis
above ear
-CLOSES JAW
Trapezius
Posterior neck and upper back to clavicle and scapula
- RAISES SHOULDER AND PULLS BACK
- EXTENDS AND ROTATES NECK
Latissimus Dorsi
Middle and Lower back to humerus
-EXTENDS AND ADDUCTS ARM BEHIND BACK
Pectoralis Major
Superior, anterior chest to humerus
-FLEXES AND ADDUCTS ARM ACROSS CHEST, PULLS SHOULDER FORWARD AND DOWNWARD
Deltoid
covers shoulder joint
ABDUCTS THE ARM
FLEXES AND EXTENDS ARMS AT SHOULDER
Biceps Brachii (Anterior arm along humerus, to radius)
FLEXES FOREARM AT ELBOW
SUPINATES THE FOREARM AND HAND
Triceps Brachii
Posterior arm to ulna
EXTENDS FOREARM TO STRAIGHTEN UPPER EXTREMITY
Diaphragm
Dome-shaped partition btw thoracic and abdominal cavity
Dome descends to enlarge thoracic cavity from top to bottom
Intercostals (BTW RIBS)
ELEVATE RIBS AND ENLARGE THORACIC CAVITY
Erector spinae(deep) (group of deep verical muscles btw sacrum and skull)
EXTENDS VERTEBRAL COLUMN TO PRODUCE ECRECT POSTURE
Gluteus Maximus
Superfical buttock to femur
EXTENDS THIGH
Gluteus Medius
Deep buttock, to femur
ABDUCTS THIGH
Quadriceps Femoris
Anterior thigh to tibia
EXTENDS THE LEG
Hamstring Group
Posterior thigh
FLEXES LEG AT KNEE, EXTENDS AND ROTATES THIGH AT HIP
Gastrocnemius
Posterior leg, Inserts into Achillies tendon
plantar flex foot
Soleus (posterior leg)
plantar flex foot
Tibialis Anterior (anterior and lateral to led to foot)
Dorsiflex foot
