Ch. 6 Muscles

Question Answer
contractility ability to shorten with force
excitability respond to a stimulus
extensibility ability to be stretched
elasticity ability to recoil
4 major functional characteristics contractility, excitability, extensibility, & elasticity
connective tissue located outside of epimysium, surrounds & separates muscle fascia
connective tissue sheath that surrounds skeletal muscle epimysium
a muscle is composed of numerous visible bundles called muscle fasciculi
fasciculi are surrounded by a loose connective tissue called endomysium
cytoplasm of each fiber is filled with myofibrils
2 major kinds of protein fibers from myofibrils actin myofilaments and myosin myofilaments
thin myofilament actin
thick myofilament myosin
highly ordered units formed by ac tin and myosin sarcomere
basic structural and functional unity of the muscle sarcomere
each sarcomere extends from… one z-line to another z-line
what causes banded appearance arrangement of actin and myosin
light area on each side of z-line I band
I band is made of actin
darker central region of sarcomere A band
light area in the center of each sarcomere H zone
dark staining band in center of sarcomere M line
the charge difference across the membrane resting membrane potential
brief reversal back of the charge action potential
nerve cells that carry action potentials to skeletal muscle fibers motor neurons
each branch that connects to the muscle forms neuromuscular junction
a single motor neuron motor unit
the enlarged nerve terminal presynaptic terminal
space between presynaptic terminal and muscle cell synaptic cleft
muscle fiber is the postsynaptic terminal
each presynaptic terminal contains synaptic vesicles
neurotransmitter acetylcholine
acetylcholine does what causes muscle to contract
the enzymatic breakdown ensures that one action potential yields only one action potential in the skeletal muscle acetylcholinesterase
the sliding of actin myofilaments past myosin myofilaments during contraction sliding filament mechanism
contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers muscle twitch
level at which point the muscle fiber will contract maximally threshold
time between application of stimulus to a motor neuron and beginning of a contraction lag phase
time of contraction contraction phase
time during which the muscle relaxes relaxation phase
where the muscle remains contracted without relaxing tetany
increase in number of motor units being activated recruitment
ATP (adenosine triphosphate) needed for energy for muscle contraction
ATP is produced in the mitochondria
ATP degenerates to the more stable ADP (adenosine diphosphate) plus phosphate
a high-energy molecule creatine phosphate
anaerobic respiration without oxygen
aerobic respiration with oxygen (more efficient)
oxygen debt the amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish the depleted stores of creatine phosphate stores in muscle cells.
results when ATP is used during muscle contraction faster than it can be made muscle fatigue
2 types of muscle contraction isometric and isotonic
isometric (equal distance) length doesn't change, but amount of tension increases during contraction
isotonic (equal tension) tension is constant, but the length changes
muscle tone refers to constant tension produced by muscles of the body for long periods of time.
fast-twitch fibers contract quickly and fatigue quickly. adapted to preform anaerobic metabolism.
slow-twitch fibers contract more slowly and are more resistant to fatigue. better suited for aerobic metabolism.
most stationary end of the muscle origin (head)
end of the muscle undergoing the greatest movement insertion
portion of the muscle between the origin and the insertion belly
can muscles have multiple origins yes
muscles that work together to accomplish specific movements synergists
muscles that work in opposition to one another antagonists
among a group of synergists, if one muscle plays the major role in accomplishing the desired movement it is the… prime mover
raises the eyebrow occipitofrontalis
closes the eyelids orbicularis oculi
puckers the lips orbicularis oris
flattens the cheeks buccinators
kissing muscles orbicularis oris and buccinators
smiling muscle zygomaticus
sneering levator labii superioris
frowning depressor anguli oris
chewing mastification
4 pairs of mastification muscles 2 pairs of pterygoids, temporalis, and masseter
change shape of the tongue intrinsic tongue muscles
move the tongue extrinsic tongue muscles
sternocleidomastoid lateral neck muscle and prime mover
group of muscles on each side of the back, responsible for keeping the back straight and the body erect. erector spinae
muscles that move the thorax thoracic muscles
most involved in breathing external intercostals and external intercostals
elevate the ribs during inspiration external intercostal
contract during forced expiration (dome shaped) internal instercostal
accomplishes quiet breathing diaphragm
tendinous area of the abdominal wall linea alba
on each side of the linea alba is the rectus abdominis
crosses the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled person to appear segmented tendinous inscriptions
rotates scapula trapezius
pulls scapula anteriorly serratus anterior
The arm is attached to the thorax by the pectoralis major and latissimus dorsi muscles
adducts and flexes the arm Pectoralis major
medially rotates, adducts, and powerfully extends the arm Latissimus dorsi
attaches the humerus to the scapula and clavicle, and is the major abductor of theupper limb Deltoid
extends the forearm Triceps brachii
flexes the forearm, Occupies the anterior compartment of the arm. Biceps brachii
flexes forearm Brachialis
flexes and supinates the forearm Brachioradialis
strong band of fibrous connective tissue that covers the flexor and extensor tendons and holds them in place Retinaculum (bracelet
flexes the wrist Flexor carpi
extends the wrist Extensor carpi
flexes the fingers Flexor digitorum
extends the fingers Extensor digitorum
19 hand musclesm located within the hand. intrinsic hand muscles
located between the metacarpals, are responsible for abduction and adduction of the fingers. Interossi
buttocks. Gluteus maximus
hip muscle and common injection site. Gluteus medius
extends the leg Quadriceps femoris
“tailors muscle”; flexes the thigh Sartorius
flexes the leg and extends the thigh Hamstring muscles
form the calf muscle (calcaneal tendon (Achilles tendon)) Gastrocnemius and soleus
lateral muscles of the leg peroneus muscles
20 muscles located within the foot that flex, extend, abduct, and adduct the toes. intrinsic foot muscles

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