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chapter 6 muscles

skeletal attached to bones or, for some facial muscles, to skin
cardiac walls of the heart
smooth mostly in walls of hallow visceral organs (other than the heart)
contractility the ability of skeletal muscle to shorten with force
excitability the capacity of skeletal muscle to respond to a stimulus
elasticity ability to recoil to their original resting length after they have been stretched
epimysium connective tissue sheath that surrounds each skeletal muscle
fascia connective tissue located outside of the epimysium- surrounds and separates muscles.
perimysium loose connective tissue that surrounds fasciculi
fibers single muscle cells that compose the fasciculi
endomysium connective tissue sheath that surrounds fibers
myofibrils fills the cytoplasm of each fiber. A threadlike structure that extends from one end of the fiber to the other,
2 major protein fibers actin and myosin
actin myofilaments thin
mysosin myofilaments thick
sarcomere the basic structural and functional unit of the muscle
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
motor unit a single motor neuron and all the skeletal muscle fibers it innervates
presynaptic terminal enlarged nerve terminal
synaptic cleft the space between the presynaptic terminal
postsynaptic terminal muscle fiber
presynaptic terminal is filled with synaptic vesicles
acetylcholine neurotransmitter
sliding filament mechanism the sliding of actin myofilaments past past myosin myofilaments during contraction. the H and I bands shorten, but the A bands do not change in length.
muscle twitch a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers
lag phase the time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase the time of contraction
relaxation phase the muscle is relaxed
tetany the muscle remains contracted without relaxing
recruitment the increase in number of motor units being activated
ATP Adenosine triphosphate needed for energy for muscle contraction, produced in the mitochondria, short lived and unstable,
ADP Adenosine Diphosphate
anaerobic respiration without oxygen
aerobic respiration with oxygen
2 types of muscle contractions isometric and isotonic
isometric equal distance- the length of the muscle does not change, but the amount of tension increases during the contraction process
isotonic equal tension- the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes
muscle tone constant tension produced by muscles of the body for long periods of time
fast twitch fibers contract quickly and fatigue quickly
slow twitch fibers contract more slowly and are more resistant to fatigue
origin head- the most stationary end of the muscle
insertion the end of the muscle undergoing the greatest movement
belly the portion of the muscle between the origin and the insertion
synergist muscles that work together to accomplish specific movements
antagonists muscles that work in opposition to one another
prime mover one muscle that plays the major role in movement
how are muscles named? location, size, orientation of fibers, shape, origin, insertion, and function. most have names that are descriptive
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids
buccinator flattens the cheeks
zygomaticus smiling muscle
lavator labii superioris sneering
depressor anguli oris frowning
mastication chewing
4 pairs of mastication muscles 2 pairs of pterygoids, temporalis, and massester
sternocleidomastoid neck muscle
intrinsic tongue muscles changes the shape of the tongue
extrinsic tongue muscles moves the tongue
erector spinae group of muscles on each side of the back, keeps the straight and body erect
muscles that move the thorax thoracic muscles
external intercostals elevate the ribs during inspiration
internal intercostals contract during forced expiration
diaphragm dome shaped muscle- accomplishes quiet breathing
rotates scapula trapezius
pulls scapula anteriorly serratus anterior
adducts and flexes the arm pectoralis major
medially rotates, adducts, and powerfully extents the arm latissimus dorsi
attaches the humerus to the scapula and the clavicle, the major abductor of the upper limb deltoid
extends the forearm triceps brachii
flexes the forearm biceps brachii
flexes forearm brachialis
flexes and supinates the forearm brachioradialis
flexor carpi flexes the wrist
extensor carpi extends the wrist
flexor digitorum flexes the fingers
extensor digitorum extends the fingers
gluteus maximus buttocks
quadriceps femoris extends the leg; anterior thigh muscles
Sartorius flexes the thigh
hamstring muscles posterior thigh muscles; flexes the leg and extends the thigh
gastrocnemius and soleus form the calf muscle
Created by: kaleigh.khaos