A&P Ch. 9

orbicularis oris

(kissing muscle) puckers the lips (draws lips together)

What causes fatigue and what occurs as a result?

If muscle fibers are stimulated repeatedly without adequate periods of rest, the strength of the muscle contraction decreases, resulting in fatigue. If repeated stimulation occurs, the strength of the contraction continues to decrease, and eventually the muscle loses its ability to contract.

Isotonic contractions: concentric and eccentric

-Concentric contraction: the muscle shortens-Eccentric contraction: the muscle lengthens but still provides work

Muscles of the trunk

-External oblique -Internal oblique -Transversus abdominis -Rectus abdominis -Diaphragm

Prime mover, synergist, and antagonist in bending of forearm

-Prime mover: biceps brachii the muscle that is mainly responsible for producing a particular movement -Synergists: brachialis the other muscles that help in producing the movement -Antagonists: Triceps brachii they produce a movement opposite to that of the prime movers and their synergist muscles.

Functions of skeletal muscle

1) Produces movement 2) Helps maintain a stable body position, or posture. 3) Helps produce heat and thus helps us maintain homeostatic balance.

Three types of muscle

1. Skeletal 2. Cardiac 3. Smooth

thin myofilaments made from?

Actin

Muscle hypertrophy

An increase in muscle size that may result from exercise.

Another term for muscle cell?

Muscle fiber

Muscular dystrophy

a group of genetic disease characterized by atrophy (wasting) of skeletal muscles tissues. Some forms can be fatal

Twitch contraction

a quick, jerky response to a stimulus. Play a minimal role in normal muscle activity.

deltoid

abducts upper arm

Effects of endurance training

aka aerobic training, doesn't usually result in muscle hypertrophy. It increases a muscle's ability to sustain moderate exercise over a long period, include running, bicycling, or other primary isotonic movements that increase the number of blood vessels in a muscle without significantly increasing the size. Also causes an increase in the number of mitochondria in muscle fibers.

Frontal muscle

allows you to raise your eyebrow in surprise and furrow the skin of your forehead into a frown

Inversion and Eversion

are also ankle movements. Inversion moves turn the ankle so that the bottom of the foot faces toward the midline of the body. Eversion turns the ankle in the opposite direction, so that the bottom of the foot faces toward the side of the body.

Antagonist

as the prime mover and synergist muscles at a joint contract, the antagonist just relaxes. When antagonists muscles actually contract, they produce a movement opposite to that of the prime movers and their synergist muscles.

Temporal

assist the masseter in closing the jaw

Contusion

bruise of the muscle

Thick myofilaments made from?

Myosin

Masseter

elevates the mandible - closes jaw

Tonic contraction

enables us to maintain body position, produces no movement of body parts (body posture)

Effects of strength training

enhances muscle hypertrophy, involves contracting muscles against heavy resistance. Examples include isometric exercises and weightlifting/ It increases the numbers of myofilaments in each muscle fiber.

diaphragm

expands thoracic cavity during inspiration. ( fibrous tissue, central tendon at center of diaphragm)

latissimus dorsi

extends and helps adduct upper arm

triceps brachii

extends elbow

Pectoralis major

flexes and helps adduct upper arm

biceps brachii

flexes elbow

Rectus abdominus

flexes trunk (pubis)

Cardiac

involuntary

Smooth

involuntary, unstriated

Flexion

is a movement that makes the angle between two bones at their joint smaller than it was at the beginning of the movement. "Bending"

Rotation

is movement around a longitudinal axis. You rotate your head and neck by moving your skull from side to side as shaking your head "no".

Body

main part of muscle, minus the ends

2 largest muscles of the group

masseter and temporal

Abduction

means moving a part of away from the midline of the body, such as moving your arm out to the side.

Adduction

means moving a part toward the midline, such as bringing your arms down to your sides from an elevated position.

Tetanic contraction

more sustained and steady response than a twitch. It is produced by a series of stimuli bombarding the muscle in rapid succession.

Prime mover

of all muscles contracting simultaneously, the one that is mainly responsible for producing a particular movement.

Myalgia

over-stretching of tearing of muscle fibers

Cramps

painful muscle spasms, can be a symptom of any irritation or an ion and water imbalance

Supination and pronation

refer to hand positions that result from rotation of the forearm. The term prone refers to the body as a whole lying face down. Supine means lying face up.

poliomyelitis

viral infection of the nerves that control skeletal muscle movement. Often causes paralysis that may progress to death

Isometric contraction

when the muscle contracts and no movement results. The muscle's length during contraction and during relaxation is about equal.

zygomaticus

(smiling muscle) elevates the corners of the mouth and lips

Sliding filament model

During contraction, the thick and thin myofilaments in a muscle fiber first attach to one another by forming crossbridges that then act as levers to ratchet or pull the myofilaments past each other

Responsibility of hamstring muscle group

Flexing the knee Extending the hip

Intercalated disks

Found in cardiac muscle, unique dark bands where the plasma membranes of adjacent cardiac fibers come in contact with each other

Mechanisms of muscle contraction

Sliding filament model: thick and thin myofilaments slide past each other as a muscle contracts. Contraction requires calcium and energy-rich ATP molecules. -Thick myofilaments (containing the protein myosin) -Thin myofilaments (composed of actin) Nerve impulse travels to a muscle fiber through a motor neuron, triggering an electrical impulse that travels along the muscle fiber membrane The impulse triggers the release of calcium ions from the endoplasmic reticulum and into the cytoplasm The Calcium ions bind to thin filaments and permit actin to react with myosin. Myocin heads form ratcheting crossbridges with actin, which pull the thin filaments toward the middle of the sarcomere, thus producing a contraction.

bursae

Small sacs that lie between some tendons and the bones beneath them. These are made of connective tissue and are lined with synovial membrane.

Sarcomere

The basic functional, or contractile, unit of skeletal muscle. Separated from each other by Z lines. (The muscle fiber)

Oxygen debt

The continued increased metabolism that must occur in a cell to remove excess lactic acid that accumulates during prolonged exercise. Oxygen debt mechanism is a good example of homeostasis at work.

Threshold stimulus

The minimal level of stimulation required to cause a fiber to contract

Tonic contraction responsibility

We are able to maintain our body position because of a specific type of skeletal muscle contraction called muscle tone or tonic contraction.

orbicularis oculi

closes eye

External oblique

compresses abdomen (lower thoracic cage)

internal oblique

compresses abdomen (pelvis)

transversus abdominus

compresses abdomen (ribs, vertebrae, and pelvis)

Duchenne muscular dystrophy (DMD)

most common form of muscular dystrophy. Also called pseudohypertrophy which means false muscle growth. The atrophy of muscle is masked by excessive replacement of muscle by fat and fibrous tissue. DMD is caused by a missing gene in the X chromosome. It occurs primarily in boys because they don't have two X chromosomes

Extension

movements are the opposite of flexions. They make the angles between two bones at their joint larger than it was at the beginning of the movement. "Straightening"

Origin

muscle attachment to more stationary bone (doesn't move)

Insertion

muscle attachment to the more movable bone (movable)

dorsiflextion and plantar flexion

refers to ankle movements. To dorsiflex the ankle, the dorsum or top of foot is elevated with the toes pointing upward. Plantar flex the ankle, the bottom of the foot is directed downward so that you are in effect standing on your toes.

Muscles of mastification

responsible for closing the mouth and chewing movements. As a group they are among the strongest muscles in the body

Skeletal muscle

striated, voluntary,

Synergists

the other muscle that helps produce the movement

Isotonic contraction

this type of muscle produces movement at a joint, the muscle changes length and the insertion end moves relative to the point of origin. 2 types of isotonic contraction (concentric and eccentic)