Muscles Muscles for anatomy chapter 6

Question Answer
Contractility ability of skeletal muscle to shorten with force
Excitability respond to a stimulus
Extensibility ability to be stretched
Elasticity ability to recoil to original resting length after being stretched
Epimysium Muscle surrounded by connective tissue sheath
Fascia surrounds and separates muscles
Perimysium bundles of muscle
Fibers single cylindrical muscle cell
Endomysium surrounds each fiber
Myofibrils threadlike structure that extends from one end to another of a fiber
Actin Myofilaments 2 minute strands of pearls twisted together (Protein Fibers)
Myosin Myofilaments Resemble golf clubs (thick)
Sarcomeres joint end to end to form myofibril. (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
Neuromuscular Junctions Each branch that connect to the center of a cell
Synapse near center of the cell.
Motor Unit single motor and all skeletal muscle fibers it innervates
Presynaptic Terminal enlarged nerve terminal
Synaptic Cleft space between synaptic terminal and the muscle cell
Postsynaptic Terminal the muscle fiber
Synaptic Vesicles each presynaptic terminal has one
Acetylcholine secrete neurotransmitter
Acetylcholinesterase atc in the synaptic cleft between the neuron and the muscle that is rapidly broken down.
Sliding Filament Mechanism sliding of the actin myofilaments past myosin myofilaments during contractions
Muscle Twitch contraction of an entire muscle
Threshold muscle fiber that does not respond to stimulus until that stimulus reaches a certain level
All-or-none Response the threshold at which the point of the muscle fiber will contract maximally
Lag Phase the time between application of a stimulus to a motor neuron and the beginning of a contraction
Contraction Phase Time of the contraction
Relaxation Phase time in which the muscle relaxes
Tetany muscle remains contracted without relaxation
Recruitment Increase in the number of motor units being activated
Creatine Phosphate rest can't stockpile ATP but they can store another high-energy molecule
Anaerobic Respiration without oxygen
Aerobic Respiration With Oxygen
Oxygen Debt amount of oxygen needed in chemical reactions to convert lactic to glucose and to replenish the depleted stores of the 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 (equal distance) Length of a muscle doesn't change but the amount of tension increases during contraction process
Isotonic Amount of tension produced by the muscle is constant during contraction 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 Quickly and fatigue quickly (contracting)
Slow-twitch fibers Contract slowly and are more resistant to fatigue
Origin head – most stationary end of the muscle
Insertion End of muscle undergoing most amount of movement
Belly Portion of muscle between the origin and insertion
Synergists Muscles that work together to cause a specific movement
Antagonist Muscles that work against eachother
Prime Mover One muscle that plays the major rule in accomplishing desired movements
Occipitofrontalis raises eyebrows
Obicularis Oris puckers lips
Obicularis occuli closes eyelids
Buccinator flattens cheeks
Mastication chewing
Zygomaticus smiling
Levator Labii Superioris (Mekenna Muscle) Sneering (Makenna Muscle)
Depressor Anguli Oris frowning
Intrinsic Tongue Muscles Changes Shape
Extrinsic Tongue Muscles moves the tongue
Sternocleidomastoid lateral neck muscle and prime mover. rotates and abduct the head
Platysma sheetlike muscle that covers the anterolateral neck. Action is to pull the corners of the mouth inferiorly, producing a downward sag of the mouth.
Erector Spine keeps spine erect
Thoracic Muscles muscles that move the thorax
External intercostals elevate the ribs during inspiration
Internal Intercostals Contract during forced expiration
Diaphragm accomplishes quiet breathing
Linea Alba Sternum to the navel and pubis
Rectus Abdominis each side of the Linea Alba
Tendinous Inscriptions crosses the R.A causing abdominal wall of a well-muscled person to appear segmented
Trapezius Rotates Scapula
Serratus Superior pulls scapula anteriorly
Pectoralis Major abducts and flexes arm
Latissimus Dorsi medially rotates, adducts, and powerfully extends the arm
Deltoid Attaches humerus to scapula and clavicle and is the major abductor of the upper limb
Triceps Brachii extends forearm occupies exterior part of arm
Biceps Brachii flexes forearm Occupies anterior part of arm
Brachialis flexes forearm
Brachioradialis flexes and supinates the forearm
Retinaculum Strong band of fiberous connective tissue that covers the flexor and extensor tendons and hols them in place around the wrist so they don't bowstring during muscle contraction
Flexor Carpi flexes wrist
Extensor Carpi extends wrist
Flexor digitorum flexes fingers
Extensor digitorum extends fingers
Intrinsic hand muscles all 19 hand muscles located within the hand
Interossi muscles responsible for abduction and adduction of the fingers
Gluteus Maximus Butt
Gluteus Medius hip muscles
Quadriceps Femoris Extends leg anterior thigh muscle
Sartorius flexes thigh "tailors muscle"
Hamstring flexes leg and extends the thigh
Gastrocnemius and Soleus Forms calf muscle
Calcaneal Tendon "Achilles Tendon" Flexes the foot and toes
Peroneus lateral leg muscles are primarily everters of the foot but also aid in plantar flexion
Intrinsic Foot Muscles muscles that flex extend, abduct, and adduct the toes.

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