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Chapter 6 Anatomy

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
Epimysium surrounds the entire skeletal muscle
Fascia located outside the epimysium; surrounds and separates muscles
Perimysium surrounds muscle fascicle
Endomysium surrounds each muscle fiber
Myofibrils the cytoplasm each fiber is filled with; extends from one end of the fiber to the other
Myofibrils consist of 2 major kinds of protein fibers Actin and Myosin
Actin thin myofilaments; resemble 2 minute strands of pearls twisted together
Myosin thick filaments; resemble bundles of minute golf clubs
Sarcomere the basic structural and functional unity of the muscle
Each sarcomere extends from one ____________ to another __________. Each _______________ is an attachment site for _____________. Z line; Actin
What gives a sarcomere its banded appearance? The arrangemnt of actin and myosin
On each side of the Z line is a light area called an ______________. It consists of _____________. I band; actin
The ____________ extends the length of the myosin. It is the darker central region in each sarcomere. A band
What's in the center of each sarcomere? What does it consist of? light area called H zone; myosin
What is the dark staining band in the center of the sarcomere? M line
Resting Membrane Potential The charge difference across the membrane (outside is positive, inside is negative)
Action Potential The brief reversal back of the charge
Motor neurons nerve cells that carry action potentials to skeletal muscle fibers
Neuromuscular junction synapse; formed by an enlarged nerve terminal resting in an identation of the muscle cell membrane
Motor unit a single motor neuron and all the skeletal muscle fibers it innervates
Enlarged nerve terminal Presynaptic terminal; contains synaptic vesicles that secrete a neurotransmitter called acetycholine
Sliding filament mechanism the sliding of actin myofilaments past myosin myofilaments during sontraction; H and I bands shorten, but A bands do not change in length
Muscle twitch a contraction of an entire muscle in response to a stimulus that causes the action potential in one or more muscle fibers
Threshold the level a stimulus needs to reach for a muscle fiber to respond
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
The increase in number of of motor units being activated is called recruitment
_____________ is needed for energy for muscle contraction ATP: produced in mitochondria
ATP is short lived; It degenerates to ADP plus phosphate
ATP adenosine triphosphate
ADP adenosine diphosphate
Anaerobic respiration without oxygen
Aerobic respiration with oxygen (more efficient)
Why does muscle fatigue occur? when ATP is used during muscle contraction faster than it can be produced
isometric (equal distance) the length of the muscle does not change but the amount of tension increases during the contraction process
Muscle tone refers to constant tension produced by muscles of the body for long periods of time. Keeps head up and back straight
Fast-twitch fibers contract quickly and fatigue quickly. Well adapted to perform anaerobic metabolism. Ex. white meat of a chicken's breast
Slow-twitch fibers contact more slowly and are more resistant to fatigue. They are better suited for aerobic metabolism. Ex, dark meat of a duck's breast or the legs of a chicken
Origin (head) the most stationary end of the muscle; some muscles can have multiple heads
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 a muscle among a group of synergists that play a major role in accomplishing a 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. Trumpeter's muscle
Zygomaticus smiling muscle
Levator labii superioris sneering
Depressor anguli oris frowning
Mastification Chewing; 4 pairs of mastification muscles- 2 pair of pterygoids, temporalis, and masseter
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
Thoracic muscles most involved in breathing external and internal intercostals
External intercostals elevate the ribs during inspiration
Internal intercostals contract during forced expiration
Diaphragm accomplishes quiet breathing. Dome-shaped muscle. Aids in breathing
Muscles of the anterior abdominal wall flex and rotate the vertebral column, compress the abdominal cavity, and hold in the abdominal viscera
Linea Alba tendinous area of the abdominal wall that consists of white connective tissue rather than muscle
On each side of the Linea Alba Rectus Abdominis
Tendinous inscriptions cross the rectus abdominis at three or more locations, causing the adominal wall of a well-muscled person to appear segmented
Scapula movements trapezius Serratus anterior
The arm is attached to the thorax by the pectoralis major and latissimus dorsi muscles
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
Forearm movements Triceps brachii Biceps brachii Brachialis Brachioradialis
Trapezius rotates scapula
Serratus anterior pulls scapula anteriorly
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
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
Wrist and finger movements flexor carpi extensor carpi flexor digitorum extensor digitorum
Flexor Carpi flexes the wrist
Extensor Carpi extends the wrist
Flexor Digitorum flexes the fingers
Extensor digitorum Extends the fingers
The 19 hand muscles located within the hand intrinsic hand muscles
The muscles located between the metacarpals that are responsible for adduction and abduction of the fingers. interossi muscles
Gluteus maximus buttocks; contributes most of the mass of the buttocks
Gluteus medius hip muscle and common injection site
Leg movements Quadriceps Femoris Sartorius
Quadriceps Femoris extends the leg; anterior thigh muscles
Sartorius "tailor's muscle";flexes the thigh
Hamstring muscles posterior thigh muscles; flexes the leg and extends the thigh
Gastrocnemius and Soleus form the calf muscle
The gastrocnemius and soleus join to form the calcaneal tendon (Achilles tendon); flex the foot and toes
The lateral muscles of the leg that are primarily everters of the foot, but also aid in plantar flexion. Peroneus muscles
20 muscles located within the foot that flex, extend, abduct, and adduct the toes. Insintric muscles
Created by: alpaccaalex



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