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Chapter 6 Muscles

Contractility the ability of skeletal muscle to shorten with force.
Excitability the 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.
Each skeletal muscle is surrounded by a connective tissue sheath called the _________ Epimysium
_______ is another connective tissue located outside the epimysium. It surrounds and separates muscles. Fascia
The fasciculi are composed of single muscle cells called ______. Fibers
Each fiber is surrounded by a connective tissue sheath called the _______. Endomysium
Cytoplasm of each fiber is filled with. Myofibrils
2 Major Kinds of Protein Fibers Actin Myofilaments and Myosin Myofilaments
Sarcomere basic structural and functional unit of the muscle.
An A Band extends length of _______. myosin
Is Myosin thick or thin? thick
Resting Membrane Potential The outside of most cell membranes is positively charged compared to the inside of the cell membrane, which is negatively charged. The charge difference across the membrane
Motor Neurons nerve cells that carry action potentials to skeletal muscle fibers.
Motor Unit A single motor neuron and all the skeletal muscle fibers it innervates
Presynaptic Terminal enlarged nerve terminal
Synaptic Cleft space between the presynaptic terminal and the muscle cell
Postsynaptic Terminal the muscle fiber
Muscle Twitch contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers.
Contraction Phase The time of contraction
Relaxation Phase The time during which the muscle relaxes
Threshold A muscle fiber will not respond to stimulus until that stimulus reaches a level
Lag Phase The time between application of a stimulus to a motor neuron and the beginning of a contraction
Tetany Where the muscle remains contracted without relaxing.
Recruitment The increase in number of motor units being activated
ATP needed for energy for muscle contraction and produced in mitochondria.
Anaerobic Respiration without oxygen
Aerobic Respiration with oxygen (more efficient)
Muscle Fatigue results when ATP is used during muscle contraction faster than it can be produced in the muscle cells.
2 types of muscle contractions Isometric and Isotonic
Muscle Tone Muscle tone refers to constant tension produced by muscles of the body for long periods of time.
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 better suited for aerobic metabolism.
Origin (head) 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 Among a group of synergists, if one muscle plays the major role in accomplishing the desired movement
Occipitofrontal 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.
Depressor Anguli Oris frowning.
Mastication chewing
Intrinsic Tongue Muscles change the shape of the tongue.
Extrinsic Tongue Muscles move the tongue.
Sternocleidomastoid lateral neck muscle and prime mover.
Trapezius rotates scapula.
Serratus Anterior pulls scapula anteriorly.
Pectoralis adducts and flexes the arm
Latissimus Dorsi medially rotates, adducts, and powerfully extends the arm.
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.
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.
Quadriceps Femoris extends the leg; anterior thigh muscles
Satorius “tailors muscle”; flexes the thigh
Hamstring Muscle posterior thigh muscles; flexes the leg and extends the thigh.
Linea Alba This tendinous area of the abdominal wall
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.
4 pairs of mastication muscles 2 pair of pterygoids, temporalis, and masseter.
Gluteus maximus buttocks.
Gluteus medius hip muscle and common injection site.
Tendinous Inscriptions cross the rectus abdominis at three or more locations, causing the abdominal wall of a well-muscled person to appear segmented.
Rectus Abdominis On each side of the linea alba
Diaphragm accomplishes quiet breathing
Created by: jmnicho8



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