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Ch. 6 Muscles

Contractility shorten with force
Excitability respond to a stimulus
Extensibility ability to be stretched
Elasticity ability to recoil
Epimysium connective tissue sheath that surrounds skeletal muscle
Faschia connective tissue located outside the epimysium that surrounds and separates muscles
Fasciculi (fascicle) numerous visible bundles that make up a muscle
Perimysium loose connective tissue that surrounds fasciculi
Muscle cells Muscle Fibers
Endomysium connective tissue sheath that surrounds fibers
Myofibrils threadlike structure that extends from one end of the fiber to the other
Actin Myofilaments thin myofilaments (resemble strands of pearls)
Myosin Myofilaments thick myofilaments (resemble bundles of golf clubs)
Sacromeres unit of measurement from one z line to the next z line
Z Line attachment site for actin
I Band consists of actin
A Band extends the length of the myosin
H Zone center of each sarcomere, consists of only myosin
M Line dark staining band
Resting Membrane Potential The charge difference across the membrane
Action Potential The brief reversal back of the charge when a muscle cell is stimulated the membrane characteristics change briefly
Motor Neurons nerve cells that carry action potentials to skeletal muscle fibers
Neuromuscular Junctions (synapse) Each branch that connects to the muscle
Motor Unit A single motor neuron and all the skeletal muscle fibers it innervates
Presynaptic Terminal The enlarged nerve terminal
Ssynaptic Cleft The space between the presynaptic terminal and the muscle cell
Postsynaptic Terminal the muscle fiber
Synaptic Vesicles Contained be each presynaptic terminal and secrete a neurotransmitter called acetylcholine
Acetylcholine a neurotransmitter.. It diffuses across the synaptic cleft and binds to the postsynaptic terminal causing a change in the postsynaptic cell.
Acetylcholinesterase Enzyme that breaks down acetylchlorine
Sliding Filament Mechanism The sliding of actin myofilaments past myosin myofilaments during contraction
Threshold a level at which point the muscle fiber will contract maximally
All-Or-None Response When a stimuli reaches the threshold
Lag Phase The 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
Muscle Twitch a contraction of an entire muscle in response to a stimulus
Recruitment increase in number of motor units being activated
ATP Adenosine triphosphate
ADP Adenosine diphosphate
Creatine Phosphate 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 when ATP is used during muscle contraction faster than it can be produced
isometric equal distance, tension increases
isotonic equal tension, length changes
Muscle tone constant tension produced by muscles
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 muscle that plays the major role in movement
Occipitofrontalis raises the eyebrows
Orbicularis oculi closes the eyelids
Orbicularis oris puckers the lips
Buccinator Trumpeter’s muscle. Flattens the cheeks
Orbicularis oris and buccinator kissing muscles
Zygomaticus smiling muscle
Levator labii superioris sneering
Depressor anguli oris frowning
Mastication chewing
4 pairs of mastication muscles 2 pair of pterygoids, temporalis, and masseter
Intrinsic Tongue Muscles change the shape of the tongue
Extrinsic Tongue Muscles move the tongue
Sternocleidomastoid neck muscle
Erector spinae Trunk muscle. Keeps back straight
Thoracic Muscles External intercostals, internal intercostals, diaphragm
Diaphragm accomplishes quiet breathing
External intercostals Elevate the ribs during inspiration
Internal intercostals contract during forced expiration
linea alba abdominal muscle that consists of white connective tissue rather than muscle
rectus abdominis on each side of the linea alba
Tendinous inscriptions crosses the rectus abdominis
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. “Swimmer muscles”
Deltoid attaches the humerus to the scapula and clavicle, and is the major abductor of the upper limb
Triceps brachii extends 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 that they do not “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
Interossi muscles responsible for abduction and adduction of the fingers
Gluteus maximus buttocks
Gluteus medius Hip muscle
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. They join to form the calcaneal tendon (Achilles tendon)
peroneus muscles lateral muscles of the leg
intrinsic foot muscles 20 bones in the foot that flex extend, abduct, and adduct the toes
Created by: kimmie3711