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Joint Structure Function Comprehensive Analysis 5th Edition Levangie Norkin – Test Bank
Sample  Question           

 

Chapter 1: Biomechanical Applications to Joint Structure and Function

 

Multiple Choice

Identify the choice that best completes the statement or answers the question.

 

____       1.   When you raise a cup to your mouth, a ____________________ of motion occurs at the elbow joint.

a. rotation only
b. translation only
c. translation and rotation
d. None of the above answers are correct.

 

 

____       2.   Hip abduction from an anatomic position would occur in which plane?

a. Sagittal
b. Frontal
c. Transverse
d. Horizontal

 

 

____       3.   Which of the following describes the phenomenon that when two forces come in contact, the second force will respond to the contact by the first force with equal magnitude and in the opposite direction?

a. Law of Inertia
b. Law of Reaction
c. Law of Acceleration
d. None of the above answers are correct.

 

 

____       4.   A ____________________ class lever is described by the fulcrum occurring at one end, followed by the resistance (load or weight) and then the force (effort).

a. First
b. Second
c. Third
d. Fourth

 

 

____       5.   In what type of lever is the M Ad always less than one?

a. First
b. Second
c. Third
d. Fourth

 

 

____       6.   Which of the following best describes torque?

a. The force a muscle generates
b. A force times the perpendicular distance from the line of force to the axis of rotation
c. A force times the distance measured along the lever from the line of force to the axis of rotation
d. The distance a muscle can move

 

 

Figure 1-7

 

____       7.   In Figure 1-7, the biceps is acting on the forearm. What is the force of the biceps, FB, given the following: moment arm of the biceps, d = 0.02 m and torque due to the biceps, TM = –5 Nm?

a. –0.1 N
b. 1,250 N
c. 5 N
d. –250 N

 

 

____       8.   As your patient abducts her shoulder from 90° to 120°, the moment arm decreases. If the torque from the deltoid remains constant, the force of the deltoid would ____________________ as the shoulder abducted.

a. remain the same
b. increase
c. decrease
d. become 0 N

 

 

Figure 1-9

 

____       9.   In Figure 1-9, at which position does the weight have the greatest torque capabilities on the knee joint?

a. A
b. B
c. C
d. D

 

 

____     10.   In Figure 1-9, at which position does the weight produce the greatest distractive on the knee joint?

a. A
b. B
c. C
d. D

 

 

Figure 1-11

 

____     11.   Which of the following represents the magnitude of each of the two component forces of the resultant, FR, in Figure 1-11?

a. F1 = 86.6 N, F2 = 50 N
b. F1 = 50 N, F2 = 60 N
c. F1 = 10 N, F2 = 90 N
d. F1 = 20.6 N, F2 = 79.4 N

 

 

____     12.   Considering the figure below, which of the following answers best represents the direction of the resultant force?

 

a.
b.
c.
d.

 

 

____     13.   Which of the following describes the phenomenon that causes a body moving at a constant speed to remain at that speed, unless it is acted upon by another body or force?

a. Impulse
b. Energy level
c. Law of Reaction
d. Law of Inertia

 

 

____     14.   Which of the following statements describes the relationship between joint reaction forces and the translational/rotatory component forces?

a. The contact force and translation component force run parallel to each other.
b. The contact force and rotatory component force run parallel to each other.
c. The shear force and translation component force run parallel to each other.

 

 

True/False

Indicate whether the statement is true or false.

 

____       1.   When the centers of mass (CoM) of two adjacent segments are combined, the combined CoM will be located somewhere along a line connecting the two individual CoMs.

 

____       2.   The relative line of gravity changes with changes in body position.

 

____       3.   An eccentric muscle contraction is an example of a second-class lever system.

 

Short Answer

 

  1. Is naming the plane of motion considered part of kinetics or kinematics? Why?

 

  1. What happens to the center of gravity (CoG) of the body when the body segments are rearranged? What happens to the CoG if the right upper extremity is amputated?

 

  1. A student is carrying all his books for his Fall semester courses (first year) in his right arm. What does the additional weight do to the combined center of gravity (CoG) of body and books? How will his body most likely respond to this change?

 

  1. Upon what variables is the magnitude of friction dependent?

 

  1. What kind of force system do the fibers within a muscle form? Explain.

 

  1. How do you determine the net effect of two muscle pulls applied to the same spot? What is this process called?

 

  1. Explain how anatomical pulleys affect the magnitude and direction of a muscle force (Fms).

 

  1. If a force is applied at an angle to a lever (not 90°, not 0°), what is the process by which you determine the torque applied to the lever by that force?

 

  1. If a force is applied at an angle to a lever (not 90°, not 0°), what is the process by which you determine the torque applied to the lever by that force?

 

  1. If not all of a muscle’s force is contributing to rotation, what happens to the “wasted” force? Describe by resolution of forces.

 

  1. Using the values given in the following problem, determine whether the lever is in rotational or linear (translatory) equilibrium.
Fms = 50 lb. (rt. of axis) Wt = 10 lb. (rt. of axis)
Fr = 15 lb. (counterclockwise) Wr = 6 lb. (clockwise)
Ft = 40 lb. (toward jt) Wt = 6 lb. (away from joint)
la = 1² (rt. of jt)  la = 12² (rt. of jt)

 

 

  1. If you have a patient with a recent ligamentous injury to his knee, which of the following positions would you want to avoid and why: sitting, prone, supine, sitting with legs over the edge of the bed, or prone with knees flexed to 90°.

 

 

Chapter 1: Biomechanical Applications to Joint Structure and Function

Answer Section

 

MULTIPLE CHOICE

 

  1. ANS:   C

Rotatory and translatory motions in the human body most commonly occur together.

 

PTS:    1

 

  1. ANS:   B

The frontal (coronal) plane divides the body into front and back halves. Movements in this plane occur side to side, such as the case in abduction of the hip.

 

PTS:    1

 

  1. ANS:   B                     PTS:    1

 

  1. ANS:   B                     PTS:    1

 

  1. ANS:   C

A mechanical advantage occurs when the effort arm is greater than the resistance arm. This is always the case in a third-class level if all forces are equal.

 

PTS:    1

 

  1. ANS:   B

Torque equals force times distance. The distance must be represented by the moment arm of the force, not just the direct distance as measured up the lever. The moment arm is the perpendicular distance of the line of the force from the axis of rotation.

 

PTS:    1

 

  1. ANS:   D

Because T = (F) (MA) therefore, F = T/MA: (–)5 Nm/0.02 m = (–)250 N. The negative sign is used to show direction of the force. Due to the small moment arm, the force necessary to produce (–)5 Nm of torque is quite large.

 

PTS:    1

 

  1. ANS:   B

If the torque were to remain the same, the force would have to increase as the moment arm decreases. Force and moment arm have an inverse relationship if torque is to remain constant.

 

PTS:    1

 

  1. ANS:   D

The force of the weight did not change from position to position; therefore, position D would have the greatest torque capabilities due to this position offering the largest moment arm of the weight on the lever.

 

PTS:    1

 

  1. ANS:   A

When the line of force is parallel with the moving segment, it will create either a distractive or compressive force between the two boney segments. Distraction occurs when there is a pull or movement of one bony segment away from another. Because the weight would be moving the tibia away from the femur, it will create a distractive force.

 

PTS:    1

 

  1. ANS:   A

Sin 60 = 0.866 multiplied by the force of 100 N = 86.6 N, and Cos 60 = 0.05 multiplied by the force of 100 N = 50 N.

 

PTS:    1

 

  1. ANS:   C

You find the resultant pull of the two forces by drawing the two forces, creating a parallelogram by adding sides parallel to each of the forces, and drawing a diagonal within the parallelogram. The resultant is the diagonal with its point of application at the original source and whose arrow head (limit of magnitude) is at the opposite corner of the parallelogram. This is called composition of forces.

 

PTS:    1

 

  1. ANS:   D

Newton’s Law of Inertia addresses the conditions under which an object will be in equilibrium.

 

PTS:    1

 

  1. ANS:   A

The contact force runs perpendicular to the joint surface which is in the same plane as the lever. The translational force runs parallel with the lever; therefore, these two forces run parallel to each other.

 

PTS:    1

 

TRUE/FALSE

 

  1. ANS:   T                      PTS:    1

 

  1. ANS:   T

 

The human body can be considered as a single rigid object. Even though the center of gravity does not change base on position, the relative line of gravity will shift so that it remains vertically downward.

 

PTS:    1

 

  1. ANS:   T

 

In this case, the force of gravity would be considered the effort force, and the muscle resisting this force would be considered the resistance force. Because gravity typically acts at a distance farther from the axis than does the pull of the muscle, this would mean that the force involved is acting on the system as a second-class lever.

 

PTS:    1

 

SHORT ANSWER

 

  1. ANS:

Kinematics. It is purely a description of motion without regard to the forces causing it.

 

PTS:    1

 

  1. ANS:

(1) The CoG shifts in the direction(s) of the location of the segments with the greatest mass. (2) The CoG shifts down and to the left once the mass of the right arm is removed, because the lower and left halves of the body are now relatively heavier.)

 

PTS:    1

 

  1. ANS:

The center of gravity (for body and books) will be higher and to the right of S2. Because this new location of the CoG would bring the line of gravity (LoG) to the right side of his base of support, he will lean to the left to bring the LoG back to the middle of the base of support (most stable place). The shift in the CoG is unavoidable. The shift of the LoG is an automatic adaptation but under some volitional control.

 

PTS:    1

 

  1. ANS:

The magnitude of friction is dependent upon (1) the magnitude of contact between the two surfaces on which the friction is occurring—increased contact increases the maximum value of static friction or the absolute value of kinetic friction; (2) the nature of the contacting surfaces—the rougher one or both of the surfaces (increased coefficient of static or kinetic friction), the greater is the maximum value of static friction or the absolute value of kinetic friction; and (3) the shear force(s) on the objects—friction has magnitude only when there is attempted motion (static friction) or actual motion (kinetic friction) between the two surfaces—the magnitude of friction on a static object will always equal the net shear force on that object; the magnitude of friction on a moving object is always the product of the contact force and the coefficient of kinetic friction.

 

PTS:    1

 

  1. ANS:

Concurrent. Each fiber represents a separate force vector with the same general point of application but which pulls at an angle to each other.

 

PTS:    1

 

  1. ANS:

You find the resultant pull of the two forces by drawing the two forces, creating a parallelogram by adding sides parallel to each of the forces, and drawing a diagonal within the parallelogram. The resultant is the diagonal with its point of application at the original source and whose arrow head (limit of magnitude) is at the opposite corner of the parallelogram. This is called composition of forces.

 

PTS:    1

 

  1. ANS:

Anatomical pulleys (always single pulleys) do not affect the magnitude of Fms but do change the direction of pull. The change in action line generally brings the action line away from the joint axis, thus increasing the moment arm or rotatory component of the applied force.

 

PTS:    1

 

  1. ANS:

Resolve the force into its components, which are perpendicular (rotatory) and parallel (translatory) to the lever. Torque for the force is then determined by multiplying the magnitude of the rotatory component by its distance (lever arm) from the joint axis.

 

PTS:    1

 

  1. ANS:

Resolve the force into its components that are perpendicular (rotatory) and parallel (translatory) to the lever. Torque for the force is then determined by multiplying the magnitude of the rotatory component by its distance (lever arm) from the joint axis.

 

PTS:    1

 

  1. ANS:

The “wasted” force goes toward translation. The translatory component (ft) is a force applied parallel to the shaft of the bone, either toward the joint (compression or joint reaction force) or away from the joint (distraction).

 

PTS:    1

 

  1. ANS:

In this instance, the lever is rotating clockwise with a magnitude of 57 in-lb. The lever is not in linear equilibrium according to the information given. There is a net joint compression of 34 lb.

 

PTS:    1

 

  1. ANS:

Sitting with legs over the edge of the bed. In this position, gravity is parallel to the limb, creating a full distractive force. Because this is usually a position of relaxation for the muscles, the only force to counteract the distraction of the limb weight is tension in the injured ligaments.

 

PTS:    1

Chapter 3: Muscle Structure and Function

 

Multiple Choice

Identify the choice that best completes the statement or answers the question.

 

____       1.   Which of the following statements is true regarding cross-bridges?

a. A cross-bridge is the basic unit of active muscle tension.
b. A cross-bridge is formed when head groups on the actin myofilament bind with tropomyosin on the myosin filament.
c. Cross-bridges do not occur in lengthening contractions.
d. A release of sodium is necessary to reveal the binding site on the actin.

 

 

____       2.   Maintaining a posture for a prolonged period of time requires muscles that are slow to fatigue and able to make small adjustments in muscle tension. Therefore, muscles with a high percentage of ____________________ muscle fibers would be very active during a maintained posture.

a. Type I
b. Type IIB
c. Type IIA

 

 

____       3.   The function of a Sharpey fiber is to:

a. Attach the periosteum to the bone
b. Attach ligaments to capsules
c. Attach muscle to tendon
d. Attach tendon to bone

 

 

____       4.   Which of the following statements is true regarding connective tissue and muscle?

a. Parallel elastic components only move after the muscle has completed a contraction.
b. Epimysium is an example of a series elastic component.
c. Parallel elastic components help to “uncrimp” the tendon.
d. A tendon is an example of a series elastic component.

 

 

____       5.   Which of the following statements best describes the length-tension relationship of a muscle?

a. The total amount of tension a muscle can develop is related only to the muscle’s active tension.
b. During active concentric contraction, maximal tension is developed in the muscle’s midrange.
c. During active shortening, no tension is present after all cross-bridges have formed and the myofilaments are overlapping.
d. All of the above answers are correct.

 

 

____       6.   Your patient attempts to strengthen his triceps by positioning his shoulder at the end of range of shoulder and elbow extension. He reports weakness and inability to extend his shoulder more in this position. His report may best be explained by which of the following?

a. Active insufficiency of the biceps
b. Active insufficiency of the triceps
c. Passive insufficiency of the biceps
d. Passive insufficiency of the triceps

 

 

____       7.   Your patient holds a weight in his right hand. Consider only the muscle activity of the elbow flexors. What type of muscle contraction would occur if TM = 400 N, and TL = 500 N, and motion is in the direction of elbow extension? (TM = torque of muscle; TL = torque of load)

a. Isometric
b. Concentric
c. Eccentric
d. Synergistic

 

 

____       8.   The elbow flexors will exert the greatest amount of torque/tension for which type of muscle contraction?

a. Isometric
b. Eccentric
c. Concentric
d. Synergistic

 

 

____       9.   Which of the following would result in increased active muscle tension if the task required the muscle to produce greater torque/tension?

a. Increased firing rate of the activated motor units
b. Decreased number of motor units activated
c. Increased amount of perimysium and endomysium
d. Decreased number of cross-bridges formed

 

 

____     10.   You are passively stretching the hip flexors of a patient in the position of prone hip extension and knee flexion. You later note that the patient demonstrates greater hip extension passive range of motion (PROM) when you allow the knee to be straight during the stretching procedure. The reason for the improved hip extension PROM may best be explained by ____________________.

a. elimination of active insufficiency that occurred during the original position
b. elimination of passive insufficiency that occurred during the original position
c. elimination of both active and passive insufficiency that occurred during the original position
d. activation of passive insufficiency that occurred in the second position

 

 

____     11.   The complete sarcomere unit lies within the boundaries of the ____________________.

a. Z disks
b. A bands
c. H zone
d. M band

 

 

____     12.   The soleus muscle exhibits which type of fiber arrangement?

a. Fusiform
b. Unipennate
c. Bipennate
d. Multipennate

 

 

____     13.   A decrease in the torque of a muscle when full range of motion (ROM) is attempted over all joints in a multijoint muscle is referred to as ____________________.

a. passive insufficiency
b. active insufficiency
c. passive tension
d. active tension

 

 

____     14.   Aging will cause the following normal connective tissue change:

a. Decreased connective tissue stiffness
b. Increase in the amount of connective tissue in the extracellular matrix
c. Increase in the number of motor units
d. Decrease of sarcopenia

 

 

Short Answer

 

  1. Name four components of a motor unit. In what ways can these components vary among motor units?

 

  1. What must happen before a motor unit will fire (discharge)? What occurs immediately after discharge of the motor unit?

 

  1. The human body selectively recruits one size motor unit before another. Which size is recruited first, and why is this efficient?

 

  1. How do pennate muscles compare to fusiform or strap muscles with respect to ability to generate tension? What causes whatever differences to exist?

 

  1. When the body segments act in a closed kinematic chain, are muscles most commonly acting in normal or reverse action?

 

  1. Describe what happens to the angular velocity of a limb during a constant concentric muscle contraction when the load (resistance) is increased. Describe this in terms of net torque.

 

  1. In order to produce maximum torque for an isokinetic concentric contraction, should the speed of the motion be fast or slow? For an isokinetic eccentric contraction?

 

  1. Contrast active and passive insufficiency. Give examples of each using the same muscle.

 

  1. What is tenodesis? Give an example.

 

  1. What protects the muscle from overcontraction or overstretch? What “monitors” length of a muscle?

 

 

Chapter 3: Muscle Structure and Function

Answer Section

 

MULTIPLE CHOICE

 

  1. ANS:   A

A cross-bridge is the basic unit of muscle tension formed by movement of the thin actin filaments by the head groups of the thicker myosin filaments. The movement of actin via the myosin head groups occurs in both concentric and eccentric contractions. A release of calcium is necessary to initiate this process. The calcium causes a shift by the tropomyosin on the actin filament that uncovers the binding sites on the actin for the head groups to attach. The cycling of cross-bridges will continue to occur as long as there is a sufficient supply of calcium, adenosine triphosphate (ATP), and action potential to initiate the process.

 

PTS:    1

 

  1. ANS:   A

Type I, oxidative, slow-twitch muscle fibers have a slow rate of fatigue compared to the more glycolytic types IIa and IIb. All muscles have a combination of all fiber types, but in varying proportion. Muscles used in more endurance-type activities, such as postural muscles, would most likely have a higher number of type I fibers in order to be most effective.

 

PTS:    1

 

  1. ANS:   D

Sharpey’s fibers are found at the junction of tendon and bone, bone and joint capsule, and ligaments and bone. In many cases, Sharpey’s fibers are stiffer than the materials they connect and may fail more rapidly than the corresponding tissues.

 

PTS:    1

 

  1. ANS:   D

The connective tissue structures of muscle fall into two basic categories: parallel elastic components and series components. A tendon is an example of a series component, as it moves in series with the contractile portion of the muscle. The connective tissues that surround the muscle fibers and fiber bundles are considered the parallel elastic components. As a muscle lengthens or shortens, these structures function in parallel with the contractile unit.

 

PTS:    1

 

  1. ANS:   B

Total muscle tension is made up of active tension (number of cross-bridges formed at the sarcomere level) and passive elastic tension (state of the parallel elastic elements). Active tension is greatest at optimal length and equally poor in both the lengthened and shortened ends of the contractile range. The passive elements are slack in the shortened range and under maximum tension in the lengthened range.

 

PTS:    1

 

  1. ANS:   B

In a position of full shoulder and elbow extension, the triceps would be trying to contract when the sarcomeres are already maximally shortened and there is maximal overlap between the myofilaments. This position could also produce passive insufficiency of the biceps, but the patient’s complaint of “weakness” would indicate that the issue is more focused on an inability to produce more tension rather than lengthen the antagonist muscle.

 

PTS:    1

 

  1. ANS:   C

In a condition where the torque of the load is greater than the torque of the muscle, an eccentric contraction would occur. This is a lengthening type of contraction that acts as a brake to control the movement of the lever with gravity.

 

PTS:    1

 

  1. ANS:   B

The amount of tension that can be developed in a muscle varies according to the type of contraction. A greater amount of tension can be developed in an isometric contraction than in a concentric contraction. In general, the tension developed in an eccentric contraction is greater than what can be developed in an isometric contraction.

 

PTS:    1

 

  1. ANS:   A

Active tension occurs as a result of several factors, including the number of motor units recruited, the fiber type of the motor units recruited, the type of contraction being performed, and the frequency of motor unit firing.

 

PTS:    1

 

  1. ANS:   B

Because the activity being performed was purely passive, active insufficiency cannot be possible. Active insufficiency would require a production of cross-bridges. In the initial position, the rectus femoris would have been elongated over both joints over which it acts, and this could have led to the muscle being in a passively insufficient position. When the therapists allowed the knee to be straight, the muscle was no longer elongated over one of its joints (the knee) and therefore could be elongated more over the other joint (hip).

 

PTS:    1

 

  1. ANS:   A                     PTS:    1

 

  1. ANS:   D

The soleus muscle is a good example of multiple oblique fascicles converging onto a single tendon.

 

PTS:    1

 

  1. ANS:   B

This is an example of active insufficiency due to the muscle’s inability to make any further cross-bridges when fully shortened over multiple joints.

 

PTS:    1

 

  1. ANS:   B

Many normal changes occur with aging. It is normal for there to be an increase in the amount of extracellular matrix found in the makeup of the connective tissue.

 

PTS:    1

 

SHORT ANSWER

 

  1. ANS:

Anterior horn cell (AHC), axon, motor end plate, and muscle fibers. The AHCs and axons may vary in size and thickness. Larger AHCs have larger axons, which conduct more rapidly (assuming myelination). The number of fibers may vary from motor unit to motor unit (each fiber has a motor end plate). Larger AHCs and thicker axons are associated with a greater number of fibers in the motor unit.

 

PTS:    1

 

  1. ANS:

In order for a motor unit to discharge, there must be sufficient facilitation (buildup of charges) at the anterior horn cell (AHC). Once threshold is reached, an impulse is conducted down the axon and all innervated fibers contract. Immediately after firing and fiber contraction, the motor unit goes through latency, or a refractory period, during which depolarization cannot occur.

 

PTS:    1

 

  1. ANS:

Small motor units are recruited before large so that the “first” response is a small, relatively slow one. This allows the body to gauge the need for a large response in order to prevent both overresponse and waste of energy.

 

PTS:    1

 

  1. ANS:

Fusiform and strap muscles have a large contractile range because of the length of their fibers, which run the length of the muscle. Because of the large contractile range, however, they are not able to generate large amounts of tension (increased shortening leads to decreased tension production). Pennate fibers are short and connect to a single tendon that runs the length of the muscle. In this arrangement, the fibers do not have much of a contractile range because of the shortness, but they are collectively able to generate a large amount of tension on the tendon (decreased shortening capability leads to an increased tension production capability).

 

PTS:    1

 

  1. ANS:

Reverse action. This is when the proximal, rather than the distal, segment tends to be moved. This will generally only happen when the lighter distal segment has been fixed on or by something. When one grips a chinning bar, the distal forearms are fixed. A strong contraction of the elbow flexors will pull the proximal humerus (and the connected body) upwards. Even though reverse action can occur other than in a closed chain (e.g., chin-up example), fixing the distal segment frequently results in a closed chain because weight-bearing is a common source of fixation. The phenomena of closed kinematic chain and reverse action, although frequently associated, may also be independent of each other.

 

PTS:    1

 

  1. ANS:

The limb will slow down. In a concentric muscle contraction, the muscle is the effort force. If the magnitude of the resistance is increased, the result will be a reduced net torque; consequently, the angular acceleration of the limb will decrease in magnitude.

 

PTS:    1

 

  1. ANS:

Isokinetic contractions are most commonly concentric but may also be produced eccentrically. A slower concentric contraction will always produce greater tension than a faster one using the same number of motor units. The slowest isokinetic contraction (therefore, the one producing the greatest tension) is one that does not produce movement (that is, an isometric contraction—0°/sec). In an eccentric isokinetic contraction, a faster speed produces more tension than a slower contraction using the same number of motor units. Consequently, peak isokinetic eccentric torque will be greater for a given muscle with faster machine settings, as long as the person can maintain the preset speed.

 

PTS:    1

 

  1. ANS:

Active insufficiency occurs when a muscle is trying to shorten but generates inadequate tension to perform its desired function. That is, when a muscle is actively insufficient, it is either fully shortened or fully lengthened, and actively attempting to shorten further. Passive insufficiency occurs when a passive muscle is being stretched over the joint(s) it crosses and reaches the limits of its extensibility. When this occurs, the muscle prevents further movement. The biceps brachii is passively insufficient when both the elbow and the shoulder are fully extended and further extension is being attempted by some other force. The restriction in further movement is due to the tension in the passive muscle.

 

PTS:    1

 

  1. ANS:

Tenodesis, or tendon action, occurs when a passive muscle is pulled upon and passively creates a joint motion. The classical example is when the wrist is flexed, with the relaxed fingers open because of the passive tension created in the stretched finger extensors.

 

PTS:    1

 

  1. ANS:

Overcontraction and overstretch are prevented by the “abort” receptors, the Golgi tendon organs (GTOs). It is generally believed that these will not fire unless there is a reasonable threat to the muscle. The active and passive lengths of a muscle are monitored by the muscle spindle. It is the spindle that is responsible for a muscle’s tone, or resistance to passive stretch.

 

PTS:    1