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Chapter 6 Muscles
| Term | Definition |
|---|---|
| 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
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