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muscle notes

TermDefinition
contractility the ability of skeletal muscle to shorten with force
excitability capacity of skeletal muscle to respond to a stimulus
extensibility the ability to be stretched
elasticity ability to recoil to their original resting length after they have been stretched
epimysium skeletal muscle is surrounded by a connective tissue sheath
fascia another connective tissue located outside the epimysium
perimysium a muscle is composed of numerous visible bundles called muscle fasciculi, which are surrounded by loose connective tissue
fibers fasciculi are composed of single muscle cells
endomysium each fiber is surrounded by a connective tissue sheath
myofibers a threadlike structure that extends from one end of the fiber to the other
actin myofilaments thin myofilaments, they resemble 2 minute strands of pearls twisted together
myosin myofilaments thick myofilaments, they have resemble bundles of minute golf clubs
sarcomeres actin myosin myofilaments form highly ordered units
resting membrane potential the change difference across the membrane
action potential when a muscle cell i stimulated the membrane characteristics change briefly
motor neurons nerve cells that carry action potentials to skeletal muscle fibers
neuromuscluar junction or synapse near the center of the cell
motor joint a single motor neuron and all the skeletal muscle fibers innervates
presynaptic terminal the enlarged nerve terminal
synaptic cleft the space between the presynaptic terminal
postsynaptic terminal the muscle fiber
acetylcholine the secrete a neurotransmitter
synaptic vesicles what each presynaptic terminal contains
acetylcholinesterase the acetylcholine released into the synaptic cleft between the neuron and muscle cell is rapidly broken down by this enzyme
sliding filament mechanism the sliding of actin myofilaments past myosin myofilaments during contraction
muscle twitch a contraction of an entire muscle is response to a stimulus that causes the action potential in one or more muscle fibers
threshold the point to which the muscle fibers will contract maximally
all- or- none response the phenomenon
lag phase the time between application of a stimulus to a motor neuron and the beginning of a contraction
contraction phase the time of a contraction
relaxation phase the time during which the muscle relaxes
tetany where the muscle remains contracted without relaxing
recruitment the increase in number of motor units being activated
creatine phosphate when at rest they cant stockpile atp but they can store another high-energy molecule
anaerobic respiration without oxygen
aerobic respiration with oxygen
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
muscle fatigue results when atp is used during muscle contraction faster than it can be produced in the muscle cells
isometric the length of the muscle does not change, but the amount of tension increases during the contraction process
isotonic the amount of tension produced by the muscle is constant during contraction, but the length of the muscle changes
muscle tone muscle tone refers to constant tension produced by muscle of the body for long periods of time
fast-twitch fibers contract quickly and fatigue guickly
slow-twitch fibers contract more slowly and are more resistant to fatigue
origin (head) is the most stationary end of the muscle
insertion the end of the muscle undergoing the greatest movement
belly the 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 if one muscle plays the major role in accomplishing the desired movement
Occipitofrontalis raises the eyebrows
Orbicularis oculi closes the eyelids and causes “crows feet” wrinkles in the skin at the lateral corners of the eye
Orbicularis oris puckers the lips
buccinator flattens the cheeks
Zygomaticus smiling muscle
Levator labii superioris sneering
Depressor anguli oris frowning
Intrinsic Tongue Muscles change the shape of the 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. Responsible for keeping the back straight and the body erect
External intercostals elevate the ribs during inspiration
Internal intercostals contract during forced expiration
Diaphragm accomplishes quiet breathing. Dome-shaped muscle. Aids in breathing.
linea alba The tendinous area of the abdominal wall
rectus abdominis it is on each side of the linea alba
Tendinous inscriptions cross the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled person to appear segmented.
Trapezius rotates scapula
Serratus anterior pulls scapula anteriorly
pectoralis major and latissimus dorsi muscles how 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. Occupies the posterior compartment of the arm
Biceps brachii flexes the forearm. Occupies the anterior compartment of the arm
Brachialis flexes forearm
Brachioradialis flexes and supinates the forearm
Created by: Bnbevin2