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Chapter 6 Muscles

Contractility to shorten with force
Excitability to respond to a stimulus
Extensibility the ability to be stretched
Elasticity ability to recoil
Epimysium surrounds each skeletal muscle
Fascia connective tissue located outside the epimysium
Perimysium loose connective tissue that surrounds fasciculi or fascicle
Fibers single muscle cells that fasciculi is made up of
Endomysium connective tissue sheath that surrounds each fiber
Myofibrils this threadlike like structure fills the cytoplasm of each fiber
Actin myofilaments thin myofilaments that resemble 2 minute strands of pearls
Myosin myofilaments thick myofilaments that resemble bundles of minute golf clubs
Sarcomeres joined end to end to form the myofibril
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 junction branch that connects to the muscle
Synapse near the center of the cell
Motor unit single motor neuron that innervates muscle fibers
Presynaptic terminal enlarged nerve terminal
Synaptic cleft space between presynaptic terminal and the muscle cell
Post synaptic terminal the muscle fiber
Synaptic vesicles secrete a neurotransmitter
Acetylcholine neurotransmitter that is secreted
Acetylcholinesterase enzymatic breakdown
Sliding filament mechanism sliding of actin myofilaments during contraction
Muscle twitch contraction of an entire muscle in response to a stimulus
Threshold when the muscle fiber will contract maximally
All-or-none response the 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 when the muscle relaxes
Tetany where the muscle stays contracted without relaxing
Recruitment increase in the number of motor units being activated
Creatine phosphate high- energy molecule
Anaerobic respiration without oxygen
Aerobic respiration with oxygen
Oxygen debt amount of oxygen needed in chemical reactions to convert lactic acid
Muscle fatigue results when ATP is used during muscle contraction faster than it can be produced
Isometric the length of the muscle does not change, but the amount tension increases during the contraction process
Isotonic the amount of tension produced by the muscle is constant during by the muscle is constant during contraction, but the length of the muscle changes.
Muscle tone refers to constant tension produced by the muscles of the body
Fast-twitch fibers contract quickly and fatigue quickly, well adapted to perform anaerobic metabolism.
Slow-twitch fibers contract more slowly and are more resistant to fatigue, they are more suited for aerobic metabolism.
Origin (head) the most stationary end of the muscle
Insertion the 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 against eachother
Prime mover among a group of synergists, one muscle plays a major role in accomplishing the desired movement
Occipitofrontalis raise the eyebrows
Orbicularis oculi closes the eyelids and cause "crows feet" wrinkles in the skin
Orbicularis oris puckers the lips
Buccinator flattens the cheeks, also known as the trumpeter's muscle
Zygomaticus smiling muscle
Levator labii superioris sneering
Depressor anguli oris frowning
Mastication chewing, 2 pair of pterygoids, temporalis, and masseter
Intrinsic Tongue Muscles changes the shape of the tongue
Extrinsic Tongue Muscles move the tongue
Sternocleidomastoid lateral neck muscle and prim mover
Platysma sheetlike muscle that covers the anterolateral neck
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
Abdominal wall muscles the muscles of the anterior abdominal wall flex and rotate the vertebral column
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 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
Flexor carpi flexes the wrist
Extensor carpi extends the wrist
Flexor digitorum flexes the fingers
Extensor digitorum extends the fingers
Gluteus maximus buttocks, contributes most of the mass of the buttocks
Gluteus medius hip muscle and common injection site
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
Created by: bmay726