Muscular System Vocab for Anatomy Quiz

A band

The ____________ is situated on either side of the H zone of a muscle sarcomere, that is the area where contraction and relaxation of the muscle occurs, where sarcomeres overlap during muscle movements.

Involuntary muscle

a muscle that contracts without conscious control. Examples include the smooth and cardiac muscles.

Transverse (T) tubule

are extensions of the cell membrane that penetrate into the center of skeletal and cardiac muscle cells

Fascicle

a group of muscle fibers is “bundled” as a unit within the whole muscle

Tropomyosin-troponin complex

regulates skeletal muscle by blocking the myosin binding site of actin in the absence of Ca2+

Acetylcholine

the chief neurotransmitter of the parasympathetic nervous system, the part of the autonomic nervous system.

can stimulate a response or block a response and thus can have excitatory or inhibitory effects

Isometric contraction

a muscle contraction without motion

used to stabilize a joint, such as when a weight is held at waist level neither raising nor lowering it.

Sarcolemma

the fine transparent tubular sheath which envelops the fibers of skeletal muscles.

acts as a barrier between the extracellular and intracellular compartments, defining the individual muscle fiber from its surroundings

Acetylcholine receptor

an integral membrane protein that responds to the binding of acetylcholine, a neurotransmitter

Isotonic contraction

maintains constant tension in the muscle as the muscle changes length

Sarcomere

the basic contractile unit of muscle fiber

each ___________ is composed of two main protein filaments - actin and myosin - which are the active structures responsible for muscular contraction.

Acetylcholinesterase

an enzyme found in the synapse between nerve cells and muscle cells.

It springs into action soon after a signal is passed, breaking down acetylcholine.

This effectively stops the signal, allowing the pieces to be recycled and rebuilt into new neurotransmitters for the next message.

Latent period

a short delay (1-2 msec) from the time when the action potential reaches the muscle until tension can be observed in the muscle.

Sarcoplasm

the cytoplasm of striated muscle cells

Actin

protein that is an important contributor to the contractile property of muscle and other cells.

Length-tension relationship

In general, as muscles shorten, they are able to generate greater amounts of tension.

However, shortening a muscle beyond a certain point will not longer generate any increases in tension.

Sarcoplasmic reticulum

specialized smooth endoplasmic reticulum that is important in transmitting the electrical impulse as well as in the storage of calcium ions

Aerobic metabolism

occurs when the body produces energy (in the form of ATP) using oxygen.

Fats and carbohydrates are the main fuels in aerobic metabolism

Motor end plate

a chemical synapse between the terminal part of the motor neuron and the target muscle.

Sliding filament theory

the explanation for how muscles contract to produce force.

The actin and myosin filaments within the sarcomeres of muscle fibers bind to create cross-bridges and slide past one another, creating a contraction.

Anaerobic metabolism

ATP production without oxygen (or in the absence of oxygen), occurs by direct phosphate transfer from molecules such as glycolytic intermediates or creatine phosphate (CrP), to ADP forming ATP.

Glucose is the only fuel for anaerobic metabolism.

Motor neuron

a neuron whose cell body is located in the motor cortex, brainstem or the spinal cord, and whose axon projects to the spinal cord or outside of the spinal cord to control muscles and glands.

Skeletal muscle

The functions of _____________ include producing movement, maintaining body posture, controlling body temperature, and stabilizing joints.

Aponeurosis

a thin sheath of connective tissue that helps connect your muscles to your bones.

__________ are similar to tendons, but is a thin sheet of connective tissue

Motor unit

The combination of an individual motor neuron and all of the muscle fibers that it innervates.

Spacial summation

signals coming from multiple simultaneous inputs

Asynchronous firing of motor units

one contracts and then a fraction of a second later another contracts before the first has time to relax and then another fires and so on.

This allows for smooth muscle contraction.

Multiunit smooth muscle

differs from single-unit in that each smooth-muscle cell receives its synaptic input.

This gives multi-unit smooth muscle much finer control.

It is found in the airways of the lungs, large arteries, and ciliary muscles of the eye.

Striations

repeating A and I bands of the proteins actin and myosin that are present along the length of myofibrils.

Muscle fiber

Each skeletal muscle fiber is a single cylindrical muscle cell.

An individual skeletal muscle may be made up of hundreds, or even thousands, of muscle fibers bundled together and wrapped in a connective tissue covering.

Synaptic cleft

a small gap between the axon terminal of the presynaptic neuron and the membrane of the postsynaptic cell.

Cardiac muscle

makes up the thick middle layer of the heart.

It is one of three types of muscle in the body, along the skeletal and smooth muscle.

Muscle tone (tonus)

the natural and continuous slight contraction of a muscle that gives resistance to passive stretching during relaxation.

Synaptic knob

A “synaptic knob” (also called a bouton) is a relay point at the tip of a transmitting neuron in the brain.

Glycogen

the stored form of glucose that’s made up of many connected glucose molecules.

Twitch contraction

the contractile response of a single muscle fiber to a single stimulus from a motor neuron.

Glycogen-lactic acid system

uses glucose stored in the muscles as glycogen during anaerobic metabolism to produce energy quickly.

Lactic acid is produced as an end product.

Visceral (single-unit) smooth muscle

produces slow, steady contractions that allow substances, such as food in the digestive tract, to move through the body.

I Band

it is called the light band that contains only the thin filament (actin)

Recruitment

a measure of how many motor neurons are activated in a particular muscle.

The higher the recruitment, the stronger the muscle contraction will be.

Voluntary muscle

skeletal muscles of the body that attach to the bones and control movement of the limbs, head, neck, and body under conscious control.

Incomplete tetany

when the muscle fibers do not completely relax before the next stimulus because they are being stimulated at a fast rate; however there is a partial relaxation of the muscle fibers between the twitches.

Innervation

The distribution or supply of nerves to a part

Refractory period

a state of recovery that occurs after a neuron has fired an action potential.

During this period, another action potential cannot be easily produced.

Wave summation

occurs when stimulations are delivered to a muscle fiber faster than it is able to completely relax.

Intercalated discs

gap junctions that link adjacent cardiac muscles so that electrical impulses can travel between cells and causes to contract almost simulatanenously.

Relaxation phase Z line

The Z-lines are closer during contraction because actin and myosin interaction generates cross-bridges, which slide the myofilaments over each other.

During relaxation, myosin and actin detach and the Z-lines slide back apart.

Agonist (prime mover)

These muscles cause the movement to occur.

______________ are also referred to as prime overs since they are the muscles that are primarily responsible for generating the movement

Gracilis

a slender superficial muscle of the inner thigh

Semimembranosus

a muscle within the posterior compartment of the thigh

Antagonist

These muscles act in opposition to the movement generated by the agonists and are responsible for returning a limb to its initial position

Hamstrings

any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris)

Semitendinosus

one of the three muscles that make up the hamstrings muscle group, and it is located at the posterior and medial aspect of the thigh.

The _____________ is so named due to it having a long tendon of insertion

Belly

The widest part of a muscle

Insertion

The place where one end of a muscle is attached to the freely moving bone of its joint.

Serratus anterior

very thin and covers the side of the ribcage.

Also called the “boxer” muscle

Biceps brachii

commonly known as the biceps, is a large, thick muscle on the ventral portion of the upper arm.

Latissimus dorsi

a broad, flat muscle occupying most of the lower posterior thorax.

The muscle’s primary function is to move the upper extremity, but it is also considered an accessory muscle of respiration.

Sternocleidomastoids

each of a pair of long muscles that connect the sternum, clavicle, and mastoid process of the temporal bone and serve to turn and nod the head

Biceps femoris

a muscle of the posterior compartment of the thigh, and lies in the posterolateral aspect.

Complete tetany

The stimulus frequency is so high that the relaxation phase disappears completely, contractions become continuous

Myocyte

a muscle cell

Synaptic vesicle

small, electron-lucent vesicles that are clustered at presynaptic terminals.

They store neurotransmitters and release them by calcium-triggered exocytosis.

Conductivity

ability to cross space in between neurons

Myofibril

a cylindrical bundle of contractile filaments within the skeletal muscle cell.

The _________ are composed of individual contractile proteins called myofilaments

Temporal summation

the effects of impulses received at the same place can add up if the impulses are received in close temporal succession

Contractility

the ability of muscle cells to forcefully shorten

Myofilament

threadlike structures that comprise the myofibril inside the muscle cell.

There are two main types of myofilaments: thin filaments and thick filaments.

In skeletal muscle, the myofilaments are arranged in a repeating pattern of light and dark bands.

Tendon

a flexible but inelastic cord of strong fibrous collagen tissue attaching a muscle to a bone

Contraction phase

A single muscle twitch has a latent period, a contraction phase when tension increases and a relaxation phase when tension decreases.

Myoglobin

a protein that’s found in striated muscles, which includes skeletal muscles and heart muscle.

Its main function is to supply oxygen to myocytes.

Elasticity

the ability to recoil or bounce back to the muscle’s original length after being stretched

Myosin

a fibrous protein that forms (together with actin) the contractile filaments of muscle cells and is also involved in motion in other types of cells

Endomysium

the key element that separates single muscle fibers from one another.

It allows their autonomous gliding during muscle contraction.

Myosin ATPase

An enzyme that causes ATP hydrolysis which provides energy for actomyosin production

Epimysium

a sheath of fibrous elastic tissue surrounding a muscle

Neuromuscular junction

a synaptic connection between the terminal end of a motor nerve and a muscle (skeletal/smooth/cardiac)

Threshold stimulus

The minimum strength required for the stimulus to initiate the response of muscle contraction

Oxygen debt

The difference between the amount of oxygen needed by the muscles and the actual amount present

Titin

a molecular spring in muscle cells
_______ binds calcium at specific sites, thereby increasing its stiffness

Extensibility

the ability of a muscle to be stretched

Masseter

a muscle which runs through the rear part of the cheek from the temporal bone to the lower jaw on each side and closes the jaw in chewing

Synergist

assists the agonist muscle or “primary mover” for a specific action at a joint.

This muscle is not the main muscle involved in the action but works in synergy with the primary muscle.

Deltoid

a large triangular-shaped muscle that lies over the glenohumeral joint and which gives the shoulder its rounded contour

Origin (head)

the proximal site that stays more stable and relatively fixed during muscle contraction.

The ___________ is a portion at the end of the origin muscle where its fixes to the bone

Temporalis

a fan-shaped muscle which runs from the side of the skull to the back of the lower jaw and is involved in closing the mouth and chewing

External abdominal oblique

a muscle of the anterior abdominal wall.

It is the largest and most superficial of the flat abdominal wall muscles.

Attachments: Originates from ribs 5-12 and inserts onto the iliac crest and pubic tubercle.

Pectoralis major

It is a thick, fan-shaped muscle that lies underneath the breast tissue and forms the anterior wall of the axilla

Tensor fascia lata

a muscle of the proximal anterolateral thigh that lies between the superficial and deep fibers of the iliotibial (IT) band

Fixator

A muscle which acts as the stabilizer and helps the agonist work effectively of one part of the body during movement of another part.

Quadriceps femoris

the most voluminous muscle of the human body.

The _____________ is a hip flexor and a knee extensor

Tibialis anterior

the largest of four muscles in the anterior compartment of the leg.

Its thick muscle belly arises from its proximal attachment at the lateral tibia

Gastrocnemius

the chief muscle of the calf of the leg, which flexes the knee and foot. It runs to the Achilles tendon from two heads attached to the femur

Rectus abdominis

each of a pair of long flat muscles at the front of the abdomen, joining the sternum to the pubis and acting to bend the whole body forward or sideways

Triceps brachii

a large, thick muscle on the dorsal part of the upper arm.

It often appears as the shape of a horseshoe

Gluteus maximus

the main extensor muscle of the hip in humans. It is the largest and outermost of the three gluteal muscles

Rectus femoris

flexes the hip along with the sartorius and iliopsoas and extends the lower leg at the knee, working in conjunction with the other three quadriceps muscles.

The _____________ antagonizes the hamstring muscles at the knee and the hip

Vastus medius

one of the four muscles that make up the quadriceps group of muscles

Vastus lateralis

a muscle located on the lateral, or outside, part of your thigh.

The muscle is one of the four quadriceps muscles and is the largest muscle of that group

Perimysium

the sheath of connective tissue surrounding a bundle of muscle fibers