Human A&P Muscles

External Intercostals

The Muscles responsible for elevating the ribs during inspiration

Gluteus Medius

The hip muscle commonly used as a site for injections

Cholinesterase

Enzyme that breaks down acetylcholine

Synaptic Cleft

The Space between the presynaptic terminal and postsynaptic membrane

Sarcomere

The basic structural and functional unit of a muscle

Fascia

Connective tissue that separates muscles and surrounds the epiysium

Creatine Phosphate

High energy molecule that can be quickly used to produce ATP

Recruitment of Motor Units

The characteristic that allows muscles to have slow,smooth, sustained contractions.

Slow Twitch Muscle Fibers

Fatigue resistant muscle fibers

Fast Twitch Muscle Fibers

Fatigable muscle fibers

Contractibility

Ability to shorten with a force

Excitability

The capacity to respond to a stimulus

Extensibility

Ability to be stretched

Elasticity

Ability o recoil to original resting length after being stretched.

Epimysium

Connective tissue sheath that surrounds each skeletal muscle

Muscle Fasciculus

Muscle Bundle

Perimysium

Connective tissue that surrounds the muscle fasciculi

Muscle Fiber

Single muscle cell; makes up muscle fasciculi

Endomysium

Connective tissue that surrounds a muscle fiber

Muscle Twitch

Contraction of an entire muscle in response to a stimulus that causes an action potential in one or more muscle fibers

All-or-None response

Below a threshold stimulus a muscle fiber does not contract; a threshold or stronger stimulus causes the muscle fiber to contract maximally

Lag Phase

Time between application of stimulus and the beginning of contraction

Contraction Phase

Time during which a muscle shortens

tetanus

Condition where a muscle remains contracted without relaxing; results from rapid simulation of the muscle

Recruitment

The number of motor units being activated increases

ATP

Molecule used to provide energy for muscle contraction

Aerobic respiration

a type of respiration that requires oxygen and that produces most ATP molecules for each glucose molecule used.

Anaerobic Respiration

Type of respiration that produces lactic acid. Used during short period of intense exercise.

Oxygen Debt

Amount of oxygen needed to convert lactic acid to glucose

Muscle Fatigue

Results when ATP is used during muscle contraction faster than it can be produced in muscle cells, and lactic acid builds up faster than it can be removed.

Insertion

General term for the attachment of a muscle to a bone

Aponeurosis

A broad, sheetlike tendon

Origin

The most stationary end of a muscle; the head.

Tendon

End of the muscle attached to the bone undergoing the greatest movement

Belly

Part of the muscle between the origin and insertion

Synergists

Muscles that work together to accomplish movement

Antagonist

Muscle working in opposition to another muscle

Prime Mover

Muscle that plays the major role in accomplishing a particular movement

Fixator

Muscle that holds a bone in place

Occipitofrontales

Raises the eyebrow

Orbicularious oculi

Closes the eye

Oribcularis Oris

Only purses the mouth

Buccinator

Flattens the cheek

Zygomaticus

responsible for smiling

Levator Labii superioris

Accomplishes sneering

Depressor anguli oris

responsible for frowning