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Ch. 6 Muscles
For Anatomy
| Question | Answer |
|---|---|
| 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 they have been stretched. |
| Epimysium | connective tissue sheath surrounding entire muscle |
| fascia | a band or sheet of fibrous connective tissue that covers, supports, and separates muscle, above epimysium |
| muscle | made up of muscle fascicle, muscle fibers |
| perimysium | surrounds fascicles |
| fasciculi | bundles of muscle fibers |
| Endomysium | bundles of muscle fibers |
| Myofibrils | protein structures that make up muscle fibers, threadlike structures that extend from one end of the fiber to the other |
| Actin myofilaments | thin filaments |
| Myosin myofilaments | thick filaments |
| sarcomeres | the space from one z line to another z line, structural and functional unit of muscle |
| Z line | A dark thin protein band to which actin filaments are attached in a striated muscle fiber, marking the boundaries between adjacent sarcomeres. |
| I Band | area on each side of z band made up of actin |
| A Band | entire length of thick filament (myosin), darker central region of sarcomere |
| H zone | light area within the center of a sarcomere made up of myosin |
| M line | middle of sarcomere, where myosin is anchored |
| resting membrane potential | charge difference across the membrane, outside is positive inside is negative |
| action potential | nerve impulse, when a muscle cell is simulated the membrane characteristics change and the reversal of the charge is called action potential |
| motor neurons | nerve cells that carry action potentials to skeletal muscle fibers |
| Axon | The extension of a neuron through which neural impulses are sent |
| neuromuscular junction | each branch of an axon that connects to a muscle |
| Synapse | A junction where information is transmitted from one neuron to the next. |
| motor unit | A motor neuron and all of the muscle fibers it innervates |
| presynaptic terminal | enlarged nerve terminal |
| synaptic cleft | space between the presynaptic terminal and muscle cell |
| postsynaptic terminal | the muscle fiber that receives impulses |
| synaptic vesicles | saclike structures found inside the presynaptic terminal which secrete acetylcholine |
| Acetylcholine | enables muscle action, learning, and memory which diffuses across the synaptic cleft and binds to the postsynaptic terminal |
| Acetylcholinesterase | the enzyme that breaks down acetylcholine in the synaptic cleft |
| sliding filament mechanism | muscle contraction during which the H and I bands shorten but the A bands remain the same length |
| muscle twitch | contraction of an entire muscle in response to a stimulus that causes an action potential in one or more muscle fibers |
| all-or-none response | a neuron's reaction of either firing (with a full-strength response) or not firing. |
| lag phase | Time between application of a stimulus and the beginning of contraction |
| contraction phase | muscle contraction |
| relaxation phase | muscle relaxes |
| tetany | constant muscle contraction |
| recruitment | increase in the number of motor units activated |
| ATP (adenosine triphosphate) | needed for muscle contraction, produced in mitochondria, degrades into ADP plus phosphate |
| Creatine phosphate | high energy molecule used to produce ATP in times of activity. |
| anaerobic respiration | without oxygen |
| aerobic respiration | with oxygen |
| oxygen debt | amount of oxygen needed in chemical reactions to convert lactic acid to glucose and to replenish creatine phosphate in muscle cells |
| muscle fatigue | ATP is used in muscle contraction faster than it can be made |
| isometric (equal distance) contraction | the length of the muscle does not change, but the amount of tension increases |
| isotonic (equal tension) contraction | amount of tension produced says the same, 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 resistant to fatigue |
| origin (head) | most stationary end of muscle |
| insertion | end of muscle undergoing 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 | the muscle that plays a major role in a group of synergists |
| Occipitofrontalis | raises eyebrows |
| Orbicularis oculi | closes eyelids |
| orbicularis oris | puckers lips |
| buccinator | flattens cheeks |
| zygomatics | smiling muscle |
| Levator labii superioris | sneering |
| Depressor anguli oris | frowning |
| 4 pairs of mastication muscles | 2 pair of pterygoids, temporalis, and masseter |
| intrinsic tongue muscles | change shape of tongue |
| Extrinsic tongue muscles | move the tongue |
| Sternocleidomastoid | lateral neck muscle and prime mover; rotates and abducts the head |
| Erector spinae | group of muscles on each side of the back, keeps back straight and body erect |
| external intercostals | elevates the ribs during inhalation |
| internal intercostals | contract during forced exhalation |
| diaphragm | accomplishes quite breathing, dome shaped muscle, lays at bottom of lungs |
| linea alba | vertical linear indentation extending from sternum to the pubic, consists of white connective tissue |
| rectus abdominis | either side of linea alba |
| tendinous inscriptions | what causes abs |
| layers of muscle lateral to rectus abdominis | (superficial to deep) external abdominal oblique, internal abdominal oblique, transverses abdominis muscles |
| trapezius | rotates scapula |
| serratus anterior | pulls scapula anteriorly |
| pectoralis major and latissimus dorsi muscles | attaches arm to the thorax |
| pectoralis major | adducts and flexes the arm |
| latissimus dorsi | medially rotates, adducts, and powerfully extends the arm |
| deltoid | attaches the humerus to the scapula and clavicle, major abductor of the upper limb |
| triceps brachii | extends the forearm |
| flexes the forearm | flexes forearm (occupies anterior compartment of arm) |
| brachialis | flexes forearm |
| brachioradialis | flexes and supinates the forearm |
| retinaculum (bracelet) | strong band of fibrous conective tissue that covers the flexor and extensor tendons and holds them in place during contractions |
| flexor carpi | flexes wrist |
| extensor carpi | extends the wrist |
| flexor digitorum | flexes the fingers |
| extensor digitorum | extends fingers |
| intrinsic hand muscles | 19 hand muscles in the hand |
| interossi muscles | located between the metacarpals, responsible for abduction and adduction of the fingers |
| gluteus medius | hip muscle and common injection site |
| quadriceps femoris | extends the leg, anterior thigh muscles |
| sartorius | "tailors muscle", flexes the thigh |
| hamstring muscles | posterior thigh muscles, flexes the leg and extends the thigh |
| gastrocnemius and soleus | form the calf muscle |
| calcaneal tendon | flexes foot and toes, both gastrocnemius and soleus together |
| peroneus muscles | everters, turn the lateral side of the foot outward, aid in plantar flexion |
| intrinsic foot muscles | flex, extend, abduct, and adduct the toes |
Created by:
KaylaJP
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