Term | Definition |
Contractility | Shorten with force |
Excitability | Respond to a stimulus |
Extensibility | Stretched |
Epimysium | surrounded by a connective tissue sheath |
Fascia | located inside the epimysium. separates muscles |
Perimysium | a connective tissue sheet around the muscle fasciculi. |
Fibers | Fasciculi composed of single muscle cells. A single cylindrical cell |
Endomysium | fiber surrounded by a connective tissue sheath |
Myofibrils | threadlike structures |
actin myofilaments | thin;twisted pearls |
myosin myofilaments | thick;minute golf clubs |
sarcomeres | joined end to end to form myofibril
structural & functional unity of the muscle. |
resting membrane potential | outside - positively charged inside - negatively charged
The change difference across the membrane |
actin potential | stimulated the membrane characteristics change briefly.
The brief reversal back of the change |
Motor neurons | nerve cells |
Neuromusclular junction | |
Synapse | near the center of the cell |
Motor unit | many motor units form a single muscle |
Presynaptic terminal | enlarged nerve terminal |
synaptic cleft | space between the presynaptic terminal and the muscle cell |
postsynaptic terminal | muscle fibers |
synaptic vesicles | secrete a neurotransmitter |
acetylcholine | diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell |
acetylcholinesterase | |
sliding filament mechanism | muscle contraction |
muscle twitch | contraction of an entire muscle in response to a stimules |
threshold | point the muscle fiber 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 which the muscle relaxes |
tetany | where the muscle remains contracted without relaxing |
recruitment | increase in number of motor units being activated |
creatine phosphate | when at rest can't stockpile ATP but can restore an high energy molecule |
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 |
muscle fatigue | when ATP is used during muscle contraction faster than it can be produced in the muscle cells |
isometric | equal distance |
isotonic | equal tension |
muscle tone | constant tension |
fast-twitch fibers | contract quickly and fatigue quickly |
slow-twitch fibers | contract more slowly and are more resistant to fatigue |
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 the insertion |
synergists | muscles that work together to accomplish specific movements |
antagonists | muscles that work in opposition to one another |
prime mover | a group of synergists, if one muscle plays the major role in accomplishing the desired movement |
Erector spinae | group of muscles on each side of the back |
thoracic muscles | muscles that move the thorax |
external intercostals | elevate the ribs during inspiration |
internal intercostals | contract during forced expiration |
diaphragm | accomplishes quiet breathing |
dome | shaped muscles. aids in breathing |
linea alba | consists of white connective tissue rather than muscle |
rectus abdominis | on each side of the linea alba |
tendinous inscriptions | |
trapezius | rotates scapula |
serratus anterior | pulls scapula anteriorly |
pectoralis major and latissimus dorsi muscles | the arm is attached to the thorax |
pectoralis major | adducts and flexes the arm |
latissimus dorsi | medially rotates, adducts, and powerfully extends the arm. "swimmer muscles" |
deltoid | attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb |
triceps brachii | extends the forearm. |
biceps brachii | flexes the forearm |
brachialis | flexes forearm |
brachioradialis | flexes and supinates the forearm |
retinaculum (bracelet) | strong band of fibrous connective tissue that covers the flexor and extensor tendons and holds them in place around the wrist so they don't "bowstring" during muscle contraction |
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 within the hand |
interossi | located between the metacarpals, are responsible for abduction and adduction of the fingers |
gluteus maximus | buttocks |
gluteus medius | hip muscle and common injection site |
quadriceps femoris | extends the leg; anterior thigh muscles |
sartorius | "tailors muscles"; flexes the thigh |
hamstring muscles | posterior thigh muscles; flexes the leg and extends the thigh |
gastrocnemius and soleus | form the calf muscle |
calcaneal tendon | calf muscles helps join to form |
(Achilles tendons) | flex the foot and toes |
peroneus | lateral muscles of the leg. primarily everters (turning the lateral side of the foot outward) also aid in plantar flexion |
intrinsic foot | 20 muscles located within the foot. muscles flex extend, abduct, and adduct the toes |