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Chapter 6 Muscles

TermDefinition
contractility ability of skeletal muscle to shorten with force
excitability capacity of skeletal muscle to respond to a stimulus
extensibility ability to be stretched
elasticity ability to recoil to their original resting length after being stretched
epimysium each skeletal muscle is surrounded by a connective tissue sheath
fascia another connective tissue located outside the epimysium surrounds and separates muscles
muscle fasciculi numerous visible bundles
perimysium muscle fascicle surrounded by loose connective tissue
fibers muscle cells
endomysium connective tissue sheath
myofibrils threadlike structure that extends from one end of the fiber to the other
actin myofilaments thin
myosin myofilaments thick
sarcomeres basic structural and functional unity of the muscle
resting membrane potential charge difference across the membrane
action potential brief reversal back of the charge
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
neuromusclular junction synapse
motor unit single motor neuron
presynaptic terminal enlarged nerve terminal
synaptic cleft the space between the presynaptic terminal and the muscle cell
postsynaptic terminal muscle fiber
synaptic vesicles secrete a neurotransmitter
acetylcholine neurotransmitter that diffuses across the synaptic cleft
sliding filament mechanism sliding of actin myofilaments past myosin myofilaments during contraction
muscle twitch a contraction of an entire muscle in response to a stimulus that causes the actin potential in one or more muscle fibers
threshold at which point the muscle fibers will contract maximally
all-or-none response phenomenon
lag phase time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase time of contraction
relaxation phase time during the muscle relaxes
tetany where the muscle remains contracted without relaxing
recruitment increase number of motor units being activated
ATP adenosine triphospahte
ADP adenosine diphosphate
creatine phosphate high energy molecule
anaerobic respiration without oxygen
aerobic respiration with oxygen
oxygen debt amount of oxygen needed in chemical reactions to convert lactic acid to glucose
muscle fatigue results in ATP is used during muscle contraction faster than it can be produced
isometric (equal distance) length of muscle doesn't change, but amount of tension increases
isotonic (equal tension) amount of tension produced by the muscle is constant, length of 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 better suited for anaerobic metabolism
slow-twitch fibers contract more slowly and are more resistant to fatigue better suited for aerobic metabolism
origin head; most stationary end of the muscle
insertion end of the muscle undergoing the greatest movement
belly portion of the muscle between the origin and insertion
synergists muscles that work together to accomplish specific movement
antagonists muscles that work in opposition to one another
prime mover among a group of synergists, one muscle plays the major role in accomplishing the desired movement
occipitofrontalis raises the eyebrows
orbicularis oculi closes the eyelids
orbicularis oris puckers the lips
buccinator flattens the cheeks
zygomaticus smiling muscles
levator labii superioris sneering
depressor anguli oris frowning
mastication chewing
intrinsic tongue muscles changes the shape
extrinsic tongue muscles move the tongue
sternocleidomastoid rotates and abducts the head
platysma pulls down the corners of the mouth
erector spinae group of muscles on each side of the back
external intercostals elevate the ribs during inspiration
internal intercostals contract during forced expiration
diaphragm dome-shaped muscle that aids in breathing and accomplishes quiet breathing
linea alba tendinous area of abdominal wall that consists of connective tissue
rectus abdominis each side of the linea alba
tendinous inscriptions cross the rectus adominis at three or more locations
trapezius rotates the scapula
serratus anterior pulls the scapula anteriorly
pectoralis major adducts and flexes the arm
latissimus dorsi medially rotates, adducts, and powerfully extends the arm
triceps brachii extends the forearm
biceps brachii flexes the forearm
brachialis flexes the forearm
brachioradialis flexes and supinates the forearm
flexor carpi flexes the wrist
extensor carpi extends the wrist
flexor digitorum flexes the fingers
extensor digitorum extends the fingers
intrinsic hand muscles 19 hand muscles located in the hand
interossi muscles located between the metacarpals
gluteus maximus buttocks
gluteus medius hip muscles
quadriceps femoris extends the leg: anterior thigh muscles
sartorius "tailors muscle" ;flexes the thigh n
hamstring posterior thigh muscles; flexes the leg and extends the thigh
gastrocnemius and soleus form the calf muscles
calcaneal tendon flex the foot and toes
peroneus lateral muscles of the leg
intrinsic foot muscles flex, extend, abduct, and adduct the toes ; 20 muscles located on the foot.
Created by: oliviabarrett