Muscular System Flashcards
Muscle tissue makes up ___% to ___% of body weight.
40
50
What enables the body to move about by pulling on underlying bones?
Muscle
What propels body contents such as air, blood, and food to move?
Muscle
What maintains the stability of joints, thereby contributing to the flexibility of the skeletal system?
Muscle
What contraction generates heat, thereby contributing significantly to body temperature?
Muscle
What contributes to the ability to communicate through speaking, writing, facial expressions, and other nonverbal means?
Muscle
What are the three muscle types?
Skeletal
Smooth
Cardiac
Which muscle type is generally attached to bone?
Skeletal
What is another name for skeletal muscle?
Voluntary
It is controlled by choice (choosing to move an arm).
Which muscle types cell’s are long, shaped like cylinders or tubes, and composed of proteins arranged to make the muscle appear striped or striated?
Skeletal
Which muscle type produces movement, maintains body posture, and stabilizes joints?
Skeletal
Which muscle type produces considerable heat and therefore helps maintain body temperature?
Skeletal
Which muscle type has limited capacity for regeneration if damaged?
Skeletal
Which muscle type is generally found in the walls of the viscera, such as the stomach?
Smooth
Visceral
Which muscle type is found in tubes and passageways such as the bronchioles (breathing passages) and blood vessels?
Smooth
What is smooth muscle also called?
Involuntary
It functions automatically.
What are smooth muscles refered to because they lack a striped apperance?
Nonstriated
Smooth muscle contraction is ___ and continues for a ___ period.
This characteristic allows for a continuous partial contraction of the smooth muscle, called smooth muscle ___.
slower
longer
tone
Which smooth muscle characteristic plays an important role physiologically?
Tone
Which smooth muscle characteristic in blood vessels helps maintain blood pressure?
Tone
If the muscle tone were to decrease, the person might experience a life-threatening decline in blood pressure.
Smooth muscle has a greater degree of ___ as compared with skeletal muscle.
stretchiness
Which smooth muscle characteristic allows the walls of organs such as the uterus, urinary bladder, and stomach to expand to store their contents temporarily?
Stretchiness
___ of the organ’s smooth muscle expels its content.
Contraction
Similarly, contraction of the smooth muscles of the stomach mixes solid food into a paste and then pushes it forward into the intestine.
Which muscle type has a decent capacity for regeneration if injured?
Smooth
Which muscle type is found only in the heart, where it functions to pump blood throughout the body?
Cardiac
Which muscle type’s cells are long branching cells that fit together tightly at junctions called intercalated discs?
Cardiac
Which disks promote rapid conduction of electrical signals throughout the heart?
Intercalated
Which muscle type is classified as striated and involuntary?
Cardiac
Which muscle type has no capacity for regeneration if damaged?
Cardiac
Three Types of Muscle
If you touch your anterior thigh, you will feel a large muscle.
What you are actually feeling are thousands of elongated muscle ___ (cells), ___ ___, and ___ that are packaged together by various layers of connective tissue.
fibers
blood vessels
nerves
What are the tough connective tissue layers surrounding the large skeletal muscle?
Fascia
What is the outer layer of fascia?
Epimysium
Which connective tissue layer surrounds smaller bundles of muscle fibers?
Perimysium
What are the bundles of muscle fibers?
Fascicles
What is the third connective tissue layer surrounding the individual muscle fibers found within the fascicles?
Endomysium
Which three tissue layers extend toward and attach to the bone as a tendon, a long cordlike structure?
Epimysium
Perimysium
Endomysium
What separates the muscles into isolated sections or compartments in the limbs?
Fascia
Muscles form attachments to other structures in three ways:
1) ___ attach the muscle to the bone.
2) ___ attach directly to a bone or soft tissue.
3) A flat sheetlike fascia called ___ connects muscle to muscle or muscle to bone.
tendons
muscles
aponeurosis
What is an elongated muscle fiber?
Muscle Cell
What long cylindrical structures compose each muscle fiber?
Myofibrils
What muscle membrane surrounds the muscle fiber?
Sarcolemma
What does the cell membrane sarcolemma form when penetrating deep into the interior muscle fiber at several points?
Transverse Tubules (T Tubules)
What is the specialized endoplasmic reticulum (ER) within the muscle fiber that surrounds the myofibrils?
Sarcoplasmic Reticulum (SR)
What envelope-like structure is the storage site of calcium (Ca2+) in the unstimulated muscle?
Sarcoplasmic Reticulum (SR)
What contractile unit makes up each myofibril in series?
Sarcomeres
What extends from Z line to Z line and is formed by a unique arrangement of contractile proteins, referred to as thin and thick filament?
Sarcomeres
Which filaments extend toward the center of the sarcomere from the Z lines?
Thin
Which filament is composed of the proteins actin and troponin–tropomyosin complex?
Thin
What contains binding sites for the myosin?
Actin
Troponin–Tropomyosin
The ___ myosin filaments sit between the ___ filaments.
thick
thin
What structures extend from the thick myosin filaments?
Myosin Heads
The arrangement of the thin and thick filaments in each sarcomere gives skeletal and cardiac muscle their ___ appearances.
striated
The sliding filament mechanism describes how muscles ___.
To pull, muscles ___.
When muscles ___, they shorten.
contract x 3
Muscles shorten because the___ length shortens, and the ___ length shortens because the thin and thick filaments slide past each other.
sarcomere x 2
The following statements explain how the sarcomere shortens:
When the contractile apparatus is stimulated, the sarcomere is flooded with ___.
This enables the ___ ___ to make contact with special sites on the ___, forming temporary connections called ___-___.
calcium
myosin heads
actin
cross-bridges
Once the ___-___ are formed, the ___ ___ rotate, pulling the ___ toward the center of the sarcomere.
cross-bridges
myosin heads
actin
The rotation of the ___ ___ causes the thin filaments to slide past the thick filaments and sarcomere length ___.
myosin heads
shortens
What occurs in the muscle when the cross-bridges are broken, and the thin and thick filaments return to their original positions; the sarcomere lengthens?
Relaxation
Because of this sliding activity of the thin and thick filaments, muscle contraction is called the sliding ___ mechanism of muscle contraction.
filament
Sacromere length shortens not because the thin and thick filaments shrink or shrivel up, but because they ___ past one another.
slide
Muscle Structure
___ and ___ ___ (___) play important roles in the contraction and relaxation of muscle.
Calcium
Adenosine Triphosphate (ATP)
What is necessary for the formation of the actin-myosin connections called cross-bridges?
Calcium
What is stored in the sarcoplasmic reticulum (SR), away from the thin and thick filaments?
Calcium
What is released from the sarcoplasmic reticulum (SR) and floods the sarcomere when the muscle membrane is stimulated?
Calcium
What exposes a site on the actin that is necessary for the binding of the myosin heads, the formation of cross-bridges, and sarcomere shortening (muscle contraction)?
Calcium
What breaks and therefore causes muscles to relax when calcium is pumped back into the sarcoplasmic reticulum (SR)?
Cross-Bridges
The energy released by ___ ___ (___) is necessary for cross-bridges to both form and disengage.
adenosine triphosphate (ATP)
What occurs when the myosin heads bind to actin, thereby causing the thin and thick filaments to slide past one another?
Contraction
What only occurs in the presence of calcium?
Sliding
Which two proteins compose the thin filament?
Actin
Troponin - Tropomyosin
Troponin - Tropomyosin Complex
Which protein contains sites to which myosin heads bind?
Actin
In which muscle state are the myosin-binding sites on actin blocked by the troponin–tropomyosin complex?
Relaxed
What does not form when the muscles are relaxed?
Cross-Bridge
Relaxed State
Which site does calcium flood when it is released from the sarcoplasmic reticulum (SR)?
Troponin
What does the activation of troponin with calcium cause to move, thereby exposing the myosin-binding sites on actin?
Tropomyosin
What occurs in the muscle when the swiveling of the cross-bridges causes sliding movements of the thin and thick filaments?
Contraction
What do myosin heads form when they bind to actin?
Cross-Bridges
What is pumped back into the sarcoplasmic reticulum (SR) away from the troponin?
Calcium
What complex blocks the myosin-binding sites on actin when it moves back to its original position?
Troponin-Tropomyosin
What causes muscle relaxation when removed?
Calcium
What stimulates the skeletal muscle to contract?
Nerves
Which nerve type supplies the skeletal muscle?
Somatic Motor
What are the many cells that compose motor nerves?
Motor Neurons
Where do motor nerves emerge from to then travel to the skeletal muscle?
Spinal Cord
The interaction of the motor neuron and the muscle is described in terms of the ___ ___ and ___ ___.
motor unit
neuromuscular junction
What do motor neurons form as they approach skeletal muscle?
Branches
What does each branch individually innervate?
Muscle Fiber
What consists of a single motor neuron and the muscle fibers that are supplied by the motor neuron?
Motor Unit
What is each muscle innervated by, thereby forming many motor units?
Motor Neurons
What does muscle contraction strength depend on?
Motor Units
What is the consequence of activation of additional motor units?
Recruitment
What is the area where the motor neuron meets the muscle?
Neuromuscular Junction (NMJ)
What includes the membrane at the end of the neuron, the space between the neuron and the muscle, and the receptors on the muscle membrane?
Neuromuscular Junction (NMJ)
What is stimulated that causes an electrical signal or nerve impulse to move toward its end?
Neuron
Step 1
What are the chemical substances stored within the full nerve ending’s vesicles or membranous pouches?
Neurotransmitters
Step 1
What is the neurotransmitter at the neuromuscular junction (NMJ)?
Acetylcholine (ACh)
Step 1
What causes the vesicles to move toward and fuse with the membrane at the end of the neuron?
Nerve Impulse
Step 2
What is released from the vesicles into the space between the neuron and the muscle membrane?
Acetylcholine (ACh)
Step 2
What diffuses across the space and binds to the receptor sites on the muscle membrane?
Acetylcholine (ACh)
Step 3
What does acetylcholine (ACh) stimulate to cause an electrical signal to develop along the muscle membrane?
Receptors
Step 4
What is found within the neuromuscular junction (NMJ) (near the muscle membrane) that immediately destroys acetylcholine (ACh) when it unbinds the receptor site?
Enzyme
Step 4
What enzyme destroys acetylcholine (ACh)?
Acetylcholinesterase or Cholinesterase
Step 4
Innervation of a Skeletal Muscle
A) Motor Unit
B) The Four Steps in the Transmission of the Signal at the Neuromuscular Junction (NMJ)
Steps in the Electrical Stimulation of Skeletal Muscle and Its Contractile Response
Muscle responses include those that characterize a single ___ ___ and responses of whole muscles (many ___ ___ bundled together).
muscle fiber
muscle fibers
Which response is a single electrical stimulus delivered to a muscle fiber where the fiber contracts and then fully relaxes?
Twitch
Which response is not useful physiologically?
Twitch
What is sustained muscle contraction?
Tetanus
Which response includes the contraction of many muscle fibers to help maintain posture?
Tetanus
Which response is characteristic of the whole muscle and additional motor units increasing the contractile force of a muscle?
Recruitment
What refers to a normal, continuous state of partial muscle contraction?
Tone
Which response is caused by the contraction of different groups of muscle fibers within a whole muscle?
Tone
Which response is maintained by one group of muscle fibers contracting first and as these fibers begin to relax, a second group contracting?
Tone
Which response includes the skeletal muscles in the back of the neck preventing the head from falling forward?
Tone
Which muscle group is layered so that the fibers of each four muscles run in four different directions?
Abdominal
Which muscle group’s contraction causes flexion and rotation of the vertebral column?
Abdominal
Which muscle group compresses its organs during urination, defecation, and childbirth?
Abdominal
What are the four abdominal muscles?
Transversus Abdominis
Internal Oblique
Rectus Abdominis
External Oblique
TIRE
Which abdominal muscle’s fibers run in an up and down, or longitudinal, direction?
Rectus Abdominis
Which abdominal muscles extend from the sternum to the pubic bone?
Rectus Abdominis
Which abdominal muscle flexes the vertebral column when contracted?
Rectus Abdominis
Which two abdominal muscle makes up the lateral walls of the abdomen?
Internal Oblique
External Oblique
Which two abdominal muscles’ fibers run slanted?
External Oblique
Internal Oblique
Oblique = Slanted
Which abdominal muscle adds to the strength provided by the external oblique muscle?
Internal Oblique
Which two abdominal muscles’ fibres form a crisscross pattern?
External Oblique
Internal Oblique
Which muscles form the innermost layer of the abdominal muscles?
Transversus Abdominis
Which abdominal muscles’ fibers run horizontally across the abdomen?
Transversus Abdominis
Which muscle is located along the anterior surface of the humerus; its two heads attach to the scapula (origin), and the distal end inserts on the radius of the forearm?
Biceps Brachii
Which muscle acts synergistically with the brachialis and brachioradialis to flex the forearm?
Biceps Brachii
The ___ ___ and brachialis are the prime movers for flexion of the forearm.
biceps brachii
When someone is asked to “make a muscle,” the biceps brachii becomes most visible.
Which muscle forms the rounded portion of the shoulder and forms the shoulder pad?
Deltoid
Which muscle extends from its origins on the clavicle and scapula to its insertion on the humerus?
Deltoid
Which muscle abducts the arm, raising it to a horizontal position (the scarecrow position)?
Deltoid
Which muscle flexes, extends, and rotates the arm at the shoulder joint?
Deltoid
What is the dome-shaped muscle that separates the thoracic cavity from the abdominal cavity?
Diaphragm
What is the chief muscle of inhalation or the breathing-in phase of respiration?
Diaphragm
Which muscle has its origins on the ilium (coxal bone) and sacrum and inserts on the femur?
Gluteus Maximus
Which muscle rotates the thigh laterally and extends the thigh at the hip, as in climbing stairs or walking?
Gluteus Maximus
Which muscle produces the backswing of the leg while walking?
Gluteus Maximus
Which muscle is the largest muscle in the body, forming the area of the buttocks and is the muscle on which you sit?
Gluteus Maximus
Posterior Surface
Which muscle group is located on the posterior surface of the thigh?
Hamstrings
Which muscle group extends from the ischium (coxal bone) to the tibia?
Hamstrings
Which muscle group flexes the leg at the knee and are therefore antagonistic to the quadriceps femoris?
Hamstrings
Which muscle group spans the hip joint and therefore extends the thigh?
Hamstrings
The strong tendons of these muscles can be felt behind the knee.
The tendons form the pit behind the knee called the popliteal fossa.
Which muscles are located between the ribs?
Intercostal
Which muscles have their origin and insertion on the ribs and are responsible for raising and lowering the rib cage during breathing?
Intercostal
What is the large broad muscle located in the middle and lower back region?
Latissimus Dorsi
Which muscle’s origin is on the lower thoracic vertebrae, lumbar vertebrae, sacrum, and lower ribs; it inserts on the posterior humerus?
Latissimus Dorsi
Which muscle lowers the shoulder and brings the arm back when contracted, as if pointing to an object behind?
Latissimus Dorsi
This same backward movement occurs in swimming and rowing.
Which two muscles attach the humerus to the axial skeleton?
Pectoralis Major
Latissimus Dorsi
What is the large broad muscle that helps form the anterior chest wall?
Pectoralis Major
What muscle connects the humerus (arm) with the clavicle (collarbone) and structures of the axial skeleton (ribs and sternum)?
Pectoralis Major
Which muscle moves the arm across the front of the chest when contracted, as if pointing to an object in front of the body?
Pectoralis Major
Which muscle flexes and extends the arm at the shoulder joint?
Pectoralis Major
Many gym exercises are designed to hypertrophy the “pecs.”
Which two muscle groups move the thigh?
Quadriceps Femoris
Hamstring
The ___ ___ flexes the thigh at the hip, whereas the ___ extend the thigh at the hip.
quadriceps femoris
hamstrings
Which group of four muscles attach the humerus (insertion) to the scapula (origin)?
Rotator Cuff
What are the two main rotator cuff muscles?
Infraspinatus
Teres Minor
SITS
Supraspinatus
Subscapularis
Which muscle group’s tendons form a cap, or a cuff, over the proximal humerus, thus stabilizing the joint capsule?
Rotator Cuff
Which muscle group helps rotate the arm at the shoulder joint?
Rotator Cuff
Which muscle extends from the sternum and clavicle to the mastoid process of the temporal bone in the skull?
Sternocleidomastoid
Which muscles, on either side of the neck, causes flexion of the head when contracted?
Sternocleidomastoid
It is known as the praying muscle.
Which muscles cause the head to flex and rotate toward the opposite direction when one is contracted?
Sternocleidomastoid
Which muscle has its origins at the base of the occipital bone of the cranium and on the spines of C7 to T12 of the upper vertebral column?
Trapezius
Which muscle inserts on both the scapula and clavicle?
Trapezius
Which muscle allows the head to tilt back (hyperextension) so that the face looks at the sky when contracted?
Trapezius
Which muscle works antagonistically with the sternocleidomastoid muscle, which flexes and bows the head?
Trapezius
Which muscle causes lateral flexion of the head and shrugs the shoulder?
Trapezius
Which muscle moves the clavicle and scapula and allows for a shrugging and rotating movement of the pectoral girdles when contracted?
Trapezius
Which muscle causes medial rotation by pulling the shoulder blades (scapulae) together posteriorly?
Trapezius
The muscle gets its name because the right and left trapezius form the shape of a trapezoid.
Which muscle lies along the posterior surface of the humerus; it has its origins on the scapula and humerus and its insertion on the ulna?
Triceps Brachii
Which muscle causes extension of the forearm at the elbow joint when contracted; it also extends the arm at the shoulder joint?
Triceps Brachii
Which muscle supports the weight of the body when a person does push-ups or walks with crutches?
Triceps Brachii
It is also the muscle that packs the greatest punch for a boxer, hence the nickname “the boxer’s muscle”.
Which muscle group is located on the anterior thigh, the most powerful muscle in the body, and has four heads as its origin?
Quadriceps Femoris
Quads
Where do all four parts of the quadriceps femoris insert by the quadriceps ligament?
Tibia
The quadriceps ___ extends distally to the tibial tuberosity as the quadriceps ___.
tendon
ligament
Which muscle group straightens, or extends, the leg at the knee, as in kicking a football?
Quadriceps Femoris
Which four muscle parts do the quadriceps femoris’ four heads give rise?
Vastus Lateralis
Vastus Intermedius
Vastus Medialis
Rectus Femoris
Which quadricep femoris muscle is frequently used as an injection site for children because it is more developed than the gluteal muscles?
Vastus Lateralis
Major Muscles of the Body (Anterior)
Major Muscles of the Body (Posterior)
Origin and Insertion: Prime Mover
Breathing Muscles
