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Chapter 6 Anatomy
| Question | Answer |
|---|---|
| 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 |
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