Question | Answer |
Contractility | The ability of skeletal muscle to shorten with force. |
Excitability | The capacity of skeletal muscle to respond to a stimilus. |
Extensibility | The ability to be strected. |
Elasticity | The ability to recoil to their original resting length after they have been stretched. |
Epimysium | A connective tissue sheath upon the skeletal. |
Fascia | Connective tissue located outside the epimysium. |
Muscle Fasciculi | Composed of numerous visible bundles. |
Perimysium | Loose connective tissue. |
Fibers | The fasciculi are composed single muscle cells. |
Myofibrils | A threadlike structure tha extends from one end of the fiber to the other. |
Four major functional Characteristics | contractility, excitability, extensibility, and elasticity. |
Myofibers consist of 2 major kinds of protein fibers | actin myofilaments and myosin myofilaments |
Actin myofilaments | thin myofilaments; resemble 2 minute strands of pearls twisted together. |
Myosin myofilaments | thick myofilaments; resemble bundles of minute golf clubs |
Sarcomeres | Actin and myosin myofilaments form highly ordered units |
Sacomere | is the 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 | branch that connects to the muscle near the center of the cells |
Synapse | neuromusclular junction |
Motor Unit | single motor neuron and all the skeletal muscle fibers it inntervates |
Presynaptic terminal | enlarged nerve terminal |
Synaptic cleft | the space between the presynaptic terminal and the muscle cell |
Postsynaptic terminal | muscle fibers |
Each presynaptic terminal contains | synaptic vesicles |
neurotansmitter | acetylcholine |
Muscle twitch | a contraction of an entire muscle in response to a stimulus that causes that action potential in one or more muscle fibers. |
A muscle fiber will not respond to stimulus until that stimulus reaches this level | threshold |
tetany | where the muscle remains contracted without relaxing |
ATP | adenosine triphosphate |
ADP | adenosine diphosphate |
Isometric | equal distance; the length of muscle does not change |
Isontonic | equal tension; the amount of tenison is constant during contraction |
Fast-twitch fibers | contract and fatigue quickly |
Slow-twitch fibers | contract more slowly and are more resistant to fatigue |
Orgin | head of muscle |
Insertion | undergoing the greatest movement |
Belly | between the orgin and the insertion |
How are muscles named? | location, size, orientation of fibers, shape, origin, insertion,and function |
Synergists | work together to accomplish specific movements |
Antagonists | muscles that work againist one another |
Sternocleidomastoid | moving neck |
Frontalis | raises the eyebrows |
Orbicularis Oculi | closes the eyelid |
Orbicularis Oris | puckers the lips |
Buccinator | flattens the checks |
zygomatious | smiling :) |
Levator labii superioris | sneering |
Depressor anguli oris | frowning :( |
mastication | chewing |
extrinsic tongue muscle | moves tongue |
Intrinsic tongue muscle | changes shape |
Erector spinae | muscles on each side of the back; responible for keeping straight and body erect |
External intercostals | elevate the ribs during inspiration |
Internal intercostals | contract during forced expiration |
Diaphragm | quiet breathing |
Trapezius | rotates scapula |
Serratus anterior | pulls scapula anteriorly |
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 |
Triceps brachii | extends forearm |
Biceps brachii | flexes the forearm |
Brachioradialis | flexes and supinates the forearm |
Flextor carpi | flexes the wrist |
Flexor digitorum | flexes the fingers |
Extensor carpi | extends the wrist |
Flexor digitorum | flexes the fingers |
Extensor digitorum | extends the fingers |
Glueteus maximus | buttocks |
Gluteus medius | hip muscle |
Quadriceps femoris | extends leg; thigh muscle |
Satorius | flexes thigh |
Hamstring | posterior thigh muscle; flexes the leg and extends the thigh |
Gastrocenmius and soleus | form the calf muscle |
Calcaneal tendon (Achilles tendon) | flexes the foot and toes |