A&P 10-11
Which of the following statements is/are false regarding human muscles?
. B) Slow fibers are abundant in the muscles of the hand.
The most important factor in decreasing the intracellular concentration of calcium ion after contraction is
. B) active transport of calcium into the sarcoplasmic reticulum.
Receptors for acetylcholine are located on the
. B) motor end plate.
Stem cells located between the endomysium and sarcolemma that function in the repair of damaged muscle tissue are called
. B) satellite cells.
The orbicularis oculi origin has its origin on the
. B) skin around the eyelids
During activities requiring aerobic endurance,
. C) most of the muscle's energy is produced in mitochondria
The contraction of a muscle exerts a pull on a bone because muscles attach to bones by
. C) tendons
At peak levels of muscle exertion the mitochondria can supply
. D) only about one-third of the energy required by the muscle
The ability of smooth muscle to function over a wide range of lengths is called
. D) plasticity
The temporalis muscle passes through the
. D) zygomatic arch.
Communication between axons and muscle fibers occurs at specialized synapses called
. E) neuromuscular junctions.
The increase in muscle tension that is produced by increasing the number of active motor units is called
. E) recruitment.
) The names of the muscles can indicate all of the following except
. E) the collagen content of the muscle.
Describe a motor unit. How many fibers does a motor unit contain?
A motor unit consists of all of the skeletal muscle fibers controlled by a single motor neuron. They may have as few as 10 fibers (eye muscles) or as many as 10,000 (back muscles).
Which structure has pumps to remove calcium ions from the sarcoplasm to produce relaxation?
A) 6
) Cross bridge detachment is caused by ________ binding to the myosin head.
A) ATP
During anaerobic glycolysis,
A) ATP is produced. B) pyruvic acid is produced. C) oxygen is not consumed. D) carbohydrate is metabolized. E) All of the answers are correct.
Which of the following statements about excitation-contraction coupling is incorrect?
A) Calcium ions travel through the transverse tubule.
________ muscle fibers pull in different directions, permitting different actions depending on stimulation.
A) Convergent
Identify the incorrect statement about a single motor unit.
A) The more neurons involved, the more powerful the contraction.
Which of the following is not characteristic of smooth muscle?
A) The striations are due to the orderly arrangement of actin and myosin.
The whole deltoid muscle ________ the humerus.
A) abducts
Triggering of the muscle action potential occurs after
A) acetylcholine binds to chemically-gated channels in the motor end plate
Thin filaments are mostly made of the protein
A) actin
Which of the following are found in the structure labeled "3"?
A) actin B) myosin C) titin D) tropomyosin E) All of the answers are correct.
The protein that is found in the Z line of a sarcomere is called
A) actinin
The muscle that adducts the thumb is the
A) adductor pollicis
After heavy exercise, if energy reserves in a muscle are depleted, ________ occurs.
A) an oxygen debt
The quadriceps group includes all of the following except the
A) biceps femoris
Which of the following muscles functions to expel urine or semen in males?
A) bulbospongiosus
What is the contraction in graph (d) called?
A) complete tetanus
The delicate connective tissue that surrounds the skeletal muscle fibers and ties adjacent muscle fibers together is the
A) endomysium
Nerves and blood vessels that service a muscle fiber are located in the connective tissues of its
A) endomysium.
Muscles that move the eyeball have ________ fibers.
A) fast
When the fulcrum is located between the load and the force, it is called a ________ lever
A) first-class
Which of the following originates on the medial epicondyle of the humerus?
A) flexor carpi radialis B) flexor carpi ulnaris C) palmaris longus D) pronator teres E) All of the answers are correct.
Which muscle is active when opposing the thumb?
A) flexor pollicis longus
When doing squat exercises, rising up from the squat to an erect position uses the
A) gluteal muscles. B) biceps femoris. C) rectus femoris. D) semitendinosus. E) all of the above
Which of these muscles produces lateral rotation at the hip?
A) gluteus maximus B) piriformis C) obturator externus D) obturator internus E) All of the answers are correct.
The infraspinatus has its insertion on the
A) greater tubercle of the humerus
A fascicle is a
A) group of muscle fibers that are encased in the perimysium.
The muscle group on the posterior thigh is called the ________ group
A) hamstring
Muscles including the term capitis would be found within or attached to the
A) head.
Which of the following muscles has its origin on the hyoid and inserts on the tongue?
A) hyoglossus
The ________ muscle allows you to look down.
A) inferior rectus
Heat energy gained from muscle contraction is released by the ________ system.
A) integumentary
Which of the following muscles is found within the pelvic floor?
A) ischiocavernosus B) perineal group C) bulbospongiosus D) coccygeus E) All of the answers are correct.
A weight-lifter strains to lift a heavy weight and there is no movement of the person's arms holding on to the weight. This type of contraction is called a(n) ________ contraction.
A) isometric
The fulcrum of a lever system is the
A) joint
A ________ is a rigid structure that moves on a fixed point.
A) lever
The eye muscles include which of the following muscles?
A) medial rectus B) inferior rectus C) superior oblique D) inferior oblique E) All of the answers are correct.
Identify the structure labeled "1."
A) mitochondria
When acetylcholine binds to receptors at the motor end plate, the sarcolemma becomes
A) more permeable to sodium ions.
The temporoparietalis muscle acts to
A) move the external ear
In an isotonic contraction,
A) muscle tension exceeds the load and the muscle lifts the load.
Which of the following is the insertion of the triceps brachii?
A) olecranon process of the ulna
The end of a muscle that remains stationary when the muscle contracts is called the
A) origin.
All of the following originate on the scapula except the
A) pectoralis major
Which muscle is named for either shape or size?
A) pectoralis major B) latissimus dorsi C) deltoid D) vastus lateralis E) All of the above are named for shape or size.
5) Which of the following is not one of the forms of fascicle organization?
A) perpendicular
A(n) ________ is a muscle whose contraction is chiefly responsible for producing a particular movement.
A) prime mover
Which of the following is a recognized function of skeletal muscle?
A) produce movement B) maintain posture C) maintain body temperature D) guard body entrances and exits E) All of the answers are correct.
Which of the following best describes the term titin?
A) protein that accounts for elasticity of resting muscle
The iliac crest is the origin of the
A) quadratus lumborum
Which of the following is a spinal flexor?
A) quadratus lumborum B) longus capitis C) longus colli D) All of the answers are correct. E) both the longus capitis and the longus colli
The four prominent muscles on the anterior thigh comprise the ________ muscle group.
A) quadriceps femoris
Fast muscle fibers can adapt to aerobic metabolism by generating more mitochondria in response to
A) repeated, exhaustive stimulation.
The plasma membrane of a skeletal muscle fiber is called the
A) sarcolemma.
The series of membranous channels that surround each myofibril is the
A) sarcoplasmic reticulum.
The structural theory that explains how a muscle fiber contracts is called the ________ theory.
A) sliding filament
Identify the muscle labeled "15."
A) sternocleidomastoid
When comparing slow muscle fibers to fast muscle fibers, slow fibers
A) take about three times as long to reach peak tension. B) have much smaller fiber diameters. C) generate much less tension. D) are rich in the red protein myoglobin. E) All of the answers are correct.
At each end of the muscle, the collagen fibers of the epimysium, perimysium, and endomysium, come together to form a
A) tendon
In rigor mortis
A) the myosin heads are attached to actin. B) ATP is depleted. C) calcium ions keep binding to troponin. D) sustained contractions occur. E) All of the answers are correct.
Which of the following become connected by myosin cross-bridges during muscle contraction?
A) thin filaments and thick filaments
The scalenes have their origin on the
A) transverse and costal processes of cervical vertebrae
Identify the muscle labeled "1."
A) trapezius
When calcium ion binds to troponin
A) tropomyosin rolls away from the active site
Each thin filament consists of
A) two actin protein strands coiled helically around each other.
Muscular force can be adjusted to match different loads by
A) varying the frequency of action potentials in motor neurons. B) recruiting larger motor units. C) recruiting more motor units. D) involving more muscle fibers in the contraction. E) All of the answers are correct.
Which of these muscles is a member of the quadriceps group?
A) vastus lateralis B) vastus medialis C) vastus intermedius D) rectus femoris E) All of the answers are correct.
In a sarcomere, cross-bridge attachment occurs specifically in the
A) zone of overlap.
Which three functional roles in a movement are used to characterize muscle groups? Give a brief description of each action.
Agonist, antagonist, or synergist. Agonists are chiefly responsible for a movement. Antagonists oppose the agonists, keeping the movements smooth. Synergists provide additional force or stabilize the origin.
Which structure contains the motor end plate?
B) 2
In a sarcomere, the central portion of thick filaments are linked laterally by proteins of the
B) M line.
What is thought to happen in a muscle during the response shown in graph (a)?
B) There is a gradual increase in calcium ion concentration in the sarcoplasm.
The skeletal muscle complex known as the triad consists of
B) a transverse tubule and two terminal cisternae.
The insertion end of the biceps brachii muscle of the anterior upper arm is
B) at the distal end of the muscle.
Identify the muscle labeled "20."
B) brachioradialis
The levator ani inserts on the
B) coccyx.
When a muscle is stimulated repeatedly at a high rate, the amount of tension gradually increases to a steady maximum tension. This state of maximum tension is called
B) complete tetanus
What physiological process occurs in the structure labeled "7"?
B) conduction of the action potential into the cell interior
Muscle tissue, one of the four basic tissue groups, consists chiefly of cells that are highly specialized for
B) contraction.
Physical evidence that supports the sliding filament theory of muscle contraction includes
B) decreased width of the H band during contraction.
Which of the following does not move the shoulder girdle?
B) deltoid
The action of the masseter muscle is to ________ the mandible.
B) elevate
Which of the following describes the action of the digastric muscle?
B) elevates the larynx and depresses the mandible
The dense layer of connective tissue that surrounds an entire skeletal muscle is the
B) epimysium
Muscles that insert on the olecranon process of the ulna can act to
B) extend the forearm.
Superficial muscles that position or stabilize an organ are called
B) extrinsic
Identify the muscle labeled "27."
B) gastrocnemius
In assessing a stroke patient, you ask her to stick out (protract) her tongue. You note that it deviates to one side. You suspect that damage to the neural control of the ________ muscle has occurred
B) genioglossus
Which of the following muscles pulls on the iliotibial tract?
B) gluteus maximus
The inferior ramus of the pubis is the origin and the medial tibia is the insertion of the ________ muscle
B) gracilis
Muscle fibers differ from "typical cells" in that muscle fibers
B) have many nuclei
The extensor digitorum muscle is named for
B) insertion and action
The muscle weakness of myasthenia gravis results from
B) loss of acetylcholine receptors in the end-plate membrane.
To produce a contraction similar to the one in graph (b), the muscle
B) must be stimulated again before it has relaxed from the previous stimulation.
Cross-bridges are portions of
B) myosin molecules
The "kissing muscle" that purses the lips is the
B) orbicularis oris.
Most of the skeletal muscles in the body are ________ muscles.
B) parallel
The freedom of movement is greatest in the
B) pectoral girdle.
The adductor brevis has its origin on the
B) pubis.
In a convergent muscle, fascicles converge on a common attachment site that may be a slender band of collagen fibers known as a(n)
B) raphe
Which of the following is not an extrinsic eye muscle?
B) rectus abdominis
16) Which of the following best describes the term sarcomere?
B) repeating unit of striated myofibrils
The repeating unit of a skeletal muscle fiber is the
B) sarcomere.
Contracting the gastrocnemius muscles to elevate the body on the toes involves a ________ lever.
B) second-class
Since each myofibril is attached at either end of the muscle fiber, when sarcomeres shorten, the muscle fiber
B) shortens
The mentalis muscle inserts on the
B) skin of the chin.
The type of muscle fiber that is most resistant to fatigue is the ________ fiber.
B) slow
) Which eye muscle sends its tendon of origin through a pulley or trochlea before inserting on the globe
B) superior oblique
Tom, a trumpet player, asks you which muscles he should develop in order to be a better trumpeter. What would you tell him?
B) the buccinator and orbicularis oris
A sesamoid bone occasionally found within the lateral head of the gastrocnemius is
B) the fabella.
Which of the following is the insertion of the pectoralis major?
B) the greater tubercle of the humerus
Which pair of muscles is antagonistic to each other in action?
B) the trapezius and the sternocleidomastoid
Walking requires the contraction of the
B) tibialis anterior and the gastrocnemius.
Muscles with fibers that run perpendicular to the long axis of the body are called
B) transversus
The muscle that inserts on the acromion and scapular spine is the
B) trapezius
A single contraction-relaxation cycle in a muscle fiber produces a(n)
B) twitch.
The muscle that raises the corners of the mouth as when smiling is the ________ muscle.
B) zygomaticus major
The muscle that retracts and elevates the upper lip is the ________ muscle
B) zygomaticus minor
Where are the myosin molecules located?
B)5
43) Identify the structure where ATP is produced.
C) 1
Identify the structure(s) where ATP is consumed?
C) 3 and 6
Put the following structures in order from superficial to deep. 1. muscle fiber 2.perimysium 3. Myofibril 4. Fascicle 5. Endomysium 6. epimysium
C) 6, 2, 4, 5, 1, 3
Damage to the pectoralis major would interfere with a person's ability to
C) Flexion of the humerus
The area in the center of the A band that contains no thin filaments is the
C) H band.
How would the loss of acetylcholinesterase from the motor end plate affect skeletal muscle?
C) It would cause muscles to stay contracted.
) How would an elevated level of thyroid hormone in the body affect skeletal muscles?
C) It would stimulate energy use and heat production.
Which of the following statements is false?
C) Skeletal muscle and cardiac muscle stimulation is neural.
The cytoplasm of the neuromuscular terminal contains vesicles filled with molecules of the neurotransmitter
C) acetylcholine
Creatine phosphate
C) acts as an energy reserve in muscle tissue.
During the recovery period the body's need for oxygen is increased because
C) additional oxygen is required to restore energy reserves
A resting muscle generates most of its ATP by
C) aerobic metabolism of fatty acids
Decreased blood flow to a muscle could result in all of the following except
C) an increase in intracellular glycogen
1) A(n) ________ can be described as a broad tendinous sheet.
C) aponeurosis
Which of the following are members of the hamstring group?
C) biceps femoris, semitendinosus, and semimembranosus
Active sites on the actin become available for binding after
C) calcium binds to troponin.
A muscle that inserts on the body of the mandible is probably involved in
C) chewing.
The powerful abductor muscle of the upper arm is the
C) deltoid.
At what point during excitation contraction coupling does exocytosis play a role?
C) during acetylcholine release from the synaptic terminal
The sequence of processes that links the action potential to contraction is called
C) excitation-contraction coupling.
Synaptic vesicles contain neurotransmitters that are released by ________ when the action potential arrives.
C) exocytosis
Large-diameter, densely packed myofibrils, large glycogen reserves, and few mitochondria are characteristics of
C) fast fibers
Which of the following is not a function of smooth muscle tissue?
C) forcing blood from the heart into the major arteries
In the liver, during the Cori cycle
C) glucose is produced from lactic acid
Which of the following would not lead to increased oxygen consumption?
C) increased anaerobic respiration by muscle cells
The end of a muscle that is attached to the point that moves when the muscle contracts is called the
C) insertion.
Damage to which of the following muscles would interfere most with the ability to breathe?
C) intercostals
All of the following are innervated by the facial nerve (N VII) except for the ________ muscle.
C) levator palpebrae superioris
The sternocleidomastoid inserts on the
C) mastoid process
Medial rotation of the eyeball is performed by the ________ muscle
C) medial rectus
Pam's daughter is born cross-eyed. As she grows, the problem does not become any better. Her physician suggests cutting an eye muscle to bring the eyes into a more normal position. Which muscle will he cut?
C) medial rectus
A single motor neuron together with all the muscle fibers it innervates is called a(n)
C) motor unit
Interactions between actin and myosin filaments of the sarcomere are responsible for
C) muscle contraction
During the recovery period following exercise, all of the following are true except
C) muscle fibers are unable to contract.
In which of the following would the motor units have the fewest muscle fibers?
C) muscles that control the
13) Skeletal muscle fibers are formed from embryonic cells called
C) myoblasts
Thick filaments are made of the protein
C) myosin.
Each skeletal muscle fiber is controlled by a motor neuron at a single
C) neuromuscular junction
Individuals who are engaged in repetitive hand movements such as typing or playing the piano may suffer wrist pain, especially during palmar flexion. All of the following are true concerning this condition except that it
C) never causes muscle weakness
Muscular walls of the thorax and abdomen are composed of
C) oblique and rectus muscles
The muscle that elevates the tongue is the
C) palatoglossus
The type of muscle whose functional characteristics most closely resemble those of its muscle fibers is the ________ muscle.
C) parallel
In a ________ muscle, the muscle fibers and fascicles lie in a slanted or oblique position to the tendon.
C) pennate
The muscle that pronates the forearm is the
C) pronator quadratus
Which of the following describes the action of the serratus anterior?
C) protracts the shoulder, abducts and medially rotates the scapula
Muscles with fibers that run parallel to the long axis of the body are called
C) rectus
Identify the muscle labeled "19."
C) rectus abdominis
The muscle that originates from the superior surface of the pubis around the symphysis is the
C) rectus abdominis
Which of the following muscles has its insertion on the sternum?
C) rectus abdominis
During abdominal surgery, the surgeon makes a cut lateral to the linea alba. The muscle that would be cut is the
C) rectus abdominis.
The only knee flexor that originates superior to the acetabulum is the
C) sartorius
Which of the following best describes the term sarcoplasmic reticulum?
C) storage and release site for calcium ions
A muscle that assists the muscle that is primarily responsible for a given action is a(n)
C) synergist.
) Which of the following hormones directly stimulates growth of muscle tissue, leading to increased muscle mass?
C) testosterone
The insertion of the flexor hallucis longus is
C) the inferior surface of the distal phalanx of the great toe.
The most common lever systems in the body are those that have the applied force between the fulcrum and the load. These are called ________ levers.
C) third-class
The action potential is conducted into a skeletal muscle fiber by
C) transverse tubules
The ________ extends the neck.
C) trapezius
At rest, active sites on the actin are blocked by
C) tropmyosin molecules
At rest, the tropomyosin molecule is held in place by
C) troponin molecules
The rapid rise and fall in force produced by a muscle fiber after a single action potential is a(n)
C) twitch
Each of the following muscles acts to flex the leg except the
C) vastus lateralis.
The following is a list of the events that occur during a muscle contraction. What is the correct sequence of these events? 1. Myosin cross-bridges bind to the actin. 2. The free myosin head splits ATP. 3. Calcium ion is released from the sarcoplasmic reticulum. 4. The myosin head pivots toward the center of the sarcomere. 5. Calcium ion binds to troponin.6. The myosin head binds an ATP molecule and detaches from the actin.
D) 3, 5, 1, 4, 6, 2
Aerobic metabolism normally provides ________ percent of the ATP demands of a resting muscle cell.
D) 95
The region of the sarcomere containing the thick filaments is the
D) A band.
Which of the following statements about the microscopic anatomy of skeletal muscle fibers is false?
D) The net-like sarcoplasmic reticulum surrounds each myofilament.
Which of the following does not originate on the humerus?
D) biceps brachii
In response to action potentials arriving along the transverse tubules, the sarcoplasmic reticulum releases
D) calcium ions
What is released from the structure labeled "9"?
D) calcium ions
In a(n) ________ a portion of the stomach is forced upward through the diaphragm and into the thoracic cavity.
D) diaphragmatic hernia
The origin of the frontalis muscle is the
D) epicranial aponeurosis.
Muscle fibers in skeletal muscle form bundles called
D) fascicles
Jill suffers a severe cut that severs the tendon that attaches the insertion of the flexor carpi ulnaris. As a result of this injury, what action is difficult for her to perform?
D) flex and adduct her hand
The band of collagen fibers that laterally braces the knee is the
D) iliotibial tract
Muscles located entirely within an organ are called
D) intrinsic
The ________ muscle elevates the upper eyelid.
D) levator palpebrae superioris
Which of the following is not primarily a muscle of facial expression?
D) masseter
Muscles located close to the midline of the body may be called
D) medialis.
Muscles with fibers that run at an angle to the long axis of the body are called
D) oblique
Each of the following muscles is involved in the process of chewing or manipulating food in the mouth except the
D) omohyoid.
Which of the following is not a pennate muscle?
D) pectoralis
The advantage of having many nuclei in a skeletal muscle fiber is the ability to
D) produce large amounts of muscle proteins.
Identify the muscle labeled "7."
D) pronator teres
You try to pick up an object and discover that it is much heavier than you expected. Which process must occur in the muscle to increase tension so you can pick up the object?
D) recruitment
The pulling away of the trapezius muscle exposes the
D) rhomboid and levator scapulae muscles.
After death, muscle fibers run out of ATP and calcium begins to leak from the sarcoplasmic reticulum into the sarcoplasm. This results in a condition known as
D) rigor mortis
) Each of the following terms is a descriptive term for a muscle's action except
D) sartorius
Which of the following types of muscle fibers are best adapted for prolonged contraction such as standing all day?
D) slow fibers
) The ________ allows you to look up.
D) superior rectus
The narrow space between the synaptic terminal and the muscle fiber is the
D) synaptic cleft.
Which of these phrases most aptly describes "muscle insertion"?
D) tendon attachment that moves
An infection by the bacterium Clostridium tetani can cause the disease called
D) tetanus
Which of the following acts as an ATPase during the contraction cycle of muscle?
D) the head portion of the myosin molecule
Which of the following best describes the term Z line?
D) thin filaments are anchored here
If the anterior compartment of the lower leg was suffering from "compartment syndrome," which of these muscles would be at risk of injury?
D) tibialis anterior, extensor hallucis longus, and extensor digitorum longus
All of the following proteins are part of the thin filaments except
D) titin.
A muscle whose name ends in the suffix -glossus would be found within or attached to the
D) tongue.
The muscle that extends the forearm when doing push-ups is the
D) triceps.
The protein that regulates muscle contraction by controlling the availability of active sites on actin is called
D) tropomyosin
Active sites become exposed when calcium ions bind to
D) troponin
The preferred site for intramuscular (IM) injections in infants that is part of the four muscles in the anterior thigh is the
D) vastus lateralis.
If a second stimulus arrives before the relaxation phase has ended, a second, more powerful contraction occurs. This addition of one twitch to another is called
D) wave summation
The region of the sarcomere that always contains thin filaments is the
E) I band
Why is there partial relaxation in graph (c)?
E) Nerve stimulation frequency is below maximum.
A lever consists of
E) a rigid structure and a fulcrum.
Excessive abdominopelvic pressure can cause
E) an inguinal and a diaphragmatic hernia.
In the musculoskeletal system, levers are formed by
E) bone.
Which of the following muscles does not have an action that is antagonistic to the action of the brachialis muscle?
E) brachioradialis
In a ________ muscle, the fascicles are concentrically arranged around an opening.
E) circular
Muscles that guard entrances and exits of internal passageways are ________ muscles.
E) circular
) Which of the following is the origin of the bulbospongiosus in the female?
E) collagen sheath at the base of the clitoris
The muscle(s) that adduct(s) the humerus is/are the
E) coracobrachialis and latissimus dorsi.
The thick, flat sheet of tendon deep to the scalp is called the
E) epicranial aponeurosis.
Muscles on the posterior of the forearm________ the wrist and fingers.
E) extend
If you bruised your gluteus maximus, you would expect to experience discomfort when
E) extending and laterally rotating the hip.
Which of the following muscles compresses the abdomen?
E) external oblique, rectus abdominis, and transverse abdominis
Tom is having difficulty with plantar flexion and eversion of his foot. Which muscle is most likely involved in this problem?
E) fibularis longus
The pectoralis major muscle inserts on the greater tubercle of the humerus. When it contracts, it produces
E) flexion, medial rotation, and adduction.
A muscle that dorsiflexes the foot is the
E) gastrocnemius
The muscle that inserts on the iliotibial tract and gluteal tuberosity of the femur is the
E) gluteus maximus.
Fast fibers
E) have low resistance to fatigue and quick twitches.
24) Each skeletal muscle fiber contains ________ myofibrils.
E) hundreds to thousands
The type of contraction in which the muscle fibers do not shorten is called
E) isometric.
Ryan hears a loud noise and quickly turns his eyes sideways in the direction of the sound. To accomplish this action he must use his ________ muscles
E) lateral and medial rectus
The antagonist of the pectoralis major is the
E) latissimus dorsi.
97) Because skeletal muscle contractions demand large quantities of ATP, skeletal muscles have
E) many mitochondria and a rich blood supply.
The ________ muscle is the strongest jaw muscle.
E) masseter
Which of these is true about the muscle named levator palpebrae superioris?
E) originates at the back of the orbit and raises the upper eyelid
51) The ________ covers the anterior surface of the neck.
E) platysma
The anterior muscle of facial expression that inserts widely on the periosteum of the mandible is the
E) platysma.
A muscle that flexes the spinal column is the
E) rectus abdominis.
A patient takes a medication that blocks ACh receptors of skeletal muscle fibers. What is this drug's effect on skeletal muscle contraction?
E) reduces the muscle's ability for contraction
The spinous processes of the upper thoracic vertebrae are the origin of the
E) rhomboid major and the trapezius.
Muscles of the rotator cuff include all of the following except the
E) rhomboid.
Identify the muscle labeled "25."
E) sartorius
The long strap-like muscle on the anterior thigh is the ________ muscle.
E) sartorius
The muscle that elevates the larynx is the ________ muscle.
E) stylohyoid
Which of the following is not a muscle of the rotator cuff?
E) subclavius
Muscles visible at the body surface are often called
E) superficialis.
Muscles that laterally rotate the thigh include all of the following except the
E) tensor fasciae latae.
Identify the muscle labeled "11."
E) tibialis anterior
An antagonist to the gastrocnemius is the
E) tibialis anterior.
What is the contraction in graph (a) called?
E) treppe
Where would calcium ions be predominately found?
E)9
Many visceral smooth muscle cells lack motor neuron innervation. How are their contractions coordinated and controlled?
Gap junctions interconnect visceral smooth muscle fibers. An action potential that begins in one will spread to its surrounding neighbors. The action potential can be triggered by stretching, hormones, chemical changes, or stimulation at a myoneural junction on a distant smooth muscle cell.
Thirty minutes after Mary has completed a 25-km race, she begins to notice severe muscle soreness and stiffness in her legs. Her urine is dark colored. She wonders whether she may have damaged her muscles during the race. She visits the ER, and the doctor orders several blood tests. What kind of blood tests can help determine whether muscle damage has occurred?
If muscle damage occurred, the doctor would find enzymes such as creatine kinase and proteins such as myoglobin or troponin in the bloodstream released by injured skeletal muscle cells. The level of these substances correlates with the severity of the injury.
Jeff is interested in toning his abdomen. What muscles would you tell Jeff to exercise to accomplish his goal? What movements would best exercise these muscles?
Jeff should do exercises that flex and twist the trunk. The muscles he should target are the rectus abdominis muscles, and the external and internal oblique muscles. Sit-ups and twisting movements will stimulate these muscles. If he places a weight on his chest as he does sit-ups, it will produce faster results because the rectus abdominis muscle would be working against a greater load.
While playing softball, Sid pulls his hamstring muscle. As a result of the injury, he has difficulty extending and medially rotating his thigh. Which muscle(s) of the hamstring group did he probably injure?
Sid probably injured the semimembranosus and/or the semitendinosus, since both of these muscles have these actions.
Describe the basic sequence of events that occurs as an action potential arrives at the neuromuscular junction and is transmitted to the muscle cell.
The action potential spreads in both directions away from the motor end plate across the entire surface of the muscle fiber and into the interior via transverse tubules, triggering a pulse of calcium ion release from the sarcoplasmic reticulum, which generates a brief small twitch. With additional stimuli, calcium ion builds up and higher tensions are produced.
A hypothetical genetic disease causes the body to produce antibodies that compete with acetylcholine for receptors on the motor end plate. Patients with this disease exhibit varying degrees of muscle weakness in the affected muscles. If you could administer a drug that inhibits acetylcholinesterase or a drug that blocks acetylcholine, which one would you use to alleviate these symptoms?
This is a case of competition between acetylcholine and the antibody. To make the patient's acetylcholine more effective, a drug that inhibits acetylcholinesterase would slow the breakdown of acetylcholine, relieving some of the weakness. An acetylcholine blocker would be worse than doing nothing.
) Megan wants to enter a weight-lifting competition and consults you as to what type of muscle fibers she needs to develop and how she should go about it. What would you suggest to her?
Weight lifting requires anaerobic endurance. Megan would want to develop her fast fibers for short-term maximum strength. She would achieve this by engaging in activities that involve frequent, brief, but intensive workouts, such as with heavy weights to the point of muscle fatigue. The fatigue triggers the production of new myofilament proteins, leading to muscle bulk and strength.