Practice questions for Muscle test

What are the functional units of skeletal muscle?

Sarcomeres

What is the cell membrane of a muscle cell called?

Sarcolemma

The areas near the Z lines that contain only thin filaments are what?

I-bands

Which area of a sarcomere only contains thick filaments?

H-zone

What is the neurotransmitter that causes skeletal muscle contraction?

Acetylcholine (AcH)

What produces the striations of a skeletal muscle cell?

Myofilaments

Which of the following surrounds an entire muscle

Epimysium

The muscle term abdominis indicates the muscle is found in which part of the body?

Abdomen

The muscle term cleido or clavius indicates which part of the body?

Clavicle

The muscle term femoris indicates which part of the body?

Femur

The muscle term deltoid refers to what shape of the muscle?

Triangle

The muscle that has brevis in its name is what?

Short

Which of the following best describes the orbicularis oris?

It closes, purses, and protrudes the lips

Which muscle acts to close the eye in an exaggerated blink?

Orbicularis oculi

Which of the following muscles is involved in producing horizontal wrinkles in the forehead?

The frontal belly of epicranius

What is the principle muscle of the neck?

Sternocleidomastoid

All of the following are infrahyoid muscles EXCEPT what?

1.) Sternothyroid 2.) Omohyoid 3.) Sternohyoid 4.) Digastrics Answer: Digastrics

What is the origin of the sternocleidomastoid?

Sternal end of the clavicle and to the manubrium

The muscle that provides the major force for producing a specific movement is called a(n)?

Agonist

Which of the following muscles change the size of the chest for breathing?

1.) External oblique muscles 2.) Transverses abdominis muscle 3.) Intercostal muscles 4.) Transverses thoracis muscle Answer: Intercostal muscles

Which muscles originate on the superior surface of the pubis around the symphysis?

Rectus abdominis

All of the following are functions of the abdominal muscles EXCEPT what?

1.) Moving the legs 2.) Supporting the lower back 3.) Moving the arms 4.) Supporting the abdomen Answer: Moving the arms

Action potential propagation in a skeletal muscle fiber ceases when acetylcholine is removed from the synaptic cleft. Which mechanism ensures a rapid and efficient removal of acetylcholine?

Acetylcholine (AcH) is degraded by acetylcholinesterase

The neuromuscular junction is a well-studied example of a chemical synapse. Which of the following statements describes a critical event that occurs at the neuromuscular junction?

1.) Acetylcholine binds to its receptor in the junctional folds of the sarcolemma. Its receptor is linked to a G protein. 2.) Acetylcholine is released and moves across the synaptic cleft bound to a transport protein. 3.) Acetylcholine is released by axon terminals of the motor neuron. 4.) When the action potential reaches the end of the axon terminal, voltage-gated sodium channels open and sodium ions diffuse into the terminal. Answer: #3

Action potentials travel the length of the axons of motor neurons to the axon terminals. These motor neurons __________.

Extend from the brain or spinal cord to the sarcolemma of a skeletal muscle fiber

Calcium entry into the axon terminal triggers which of the following events?

Synaptic vesicles fuse to the plasma membrane of the axon terminal and release acetylcholine

Acetylcholine binds to its receptor in the sarcolemma and triggers __________.

The opening of ligand-gated cation channels

Sodium and potassium ions do not diffuse in equal numbers through ligand-gated cation channels. Why?

The inside surface of the sarcolemma is negatively charged compared to the outside surface. Sodium ions diffuse inward along favorable chemical and electrical gradients

Excitation-contraction coupling is a series of events that occur after the events of the neuromuscular junction have transpired. The term excitation refers to which step in the process?

Excitation, in this case, refers to the propagation of action potentials along the sarcolemma

Excitation of the sarcolemma is coupled or linked to the contraction of a skeletal muscle fiber. What specific event initiates the contraction?

Calcium release from the sarcoplasmic reticulum initiates the contraction

A triad is composed of a T-tubule and two adjacent terminal cisternae of the sarcoplasmic reticulum. How are these components connected?

A series of proteins that control calcium release

What is name given to the regularly spaced in-foldings of the sarcolemma?

Transverse or T tubules

Which of the following is most directly responsible for the coupling of excitation to contraction of skeletal muscle fibers?

1.) Calcium ions. 2.) Acetylcholine. 3.) Action potentials. 4.) Sodium ions. Answer: Calcium ions

What is the relationship between the number of motor neurons recruited and the number of skeletal muscle fibers innervated?

Typically, hundreds of skeletal muscle fibers are innervated by a single motor neuron – The ratio of neurons to fibers varies from approximately one to ten to approximately one to thousands.

What prevents the ACh from continuing to stimulate the muscle?

Acetylcholinesterase (AcHase) destroys the ACh

The cross bridge cycle is a series of molecular events that occur after excitation of the sarcolemma. What is a cross bridge?

A myosin head bound to actin

What structure is the functional unit of contraction in a skeletal muscle fiber?

The sarcomere

Calcium ions couple excitation of a skeletal muscle fiber to contraction of the fiber. Where are calcium ions stored within the fiber?

Calcium ions are stored in the sarcoplasmic reticulum

After a power stroke, the myosin head must detach from actin before another power stroke can occur. What causes cross bridge detachment?

ATP binds to the myosin head

How does the myosin head obtain the energy required for activation?

The energy comes from the hydrolysis of ATP

What specific event triggers the uncovering of the myosin binding site on actin?

Calcium ions bind to troponin and change its shape

When does cross bridge cycling end?

When sufficient calcium has been actively transported back into the sarcoplasmic reticulum to allow calcium to unbind from troponin

What controls the force of muscle contraction?

Multimotor unit recruitment

Most muscle work is accomplished by what?

Complete tetanus

What is the main factor that determines the power of a muscle?

The total number of muscles cells available for contraction

A(n) _______ muscle contraction occurs when the muscle length is relatively constant, but the muscle tension changes.

Isometric

In an isotonic contraction, the muscle does what?

Changes in length and moves the "load"

A tracing of the muscle’s electrical activity is an?

EMG (electromyography)

What are sensors that are placed on the skin to detect the electrical activity by a muscle?

Electrodes

The measurement of power is?

Dynamometry

Muscle and nerve tissues produce electrical impulses called?

Action potentials

Which ion flows into the cell during depolarization?

Sodium

Which muscle appears as fan-shaped wedges of the side of the chest?

Serratus anterior

What is the large diamond-shaped muscle of the upper back?

Trapezius

Which joint in the body is the most movable?

The shoulder

Which muscle elevates the scapula?

Levator scapulae

The deltoid muscle fibers are separated into __________.

Anterior, middle, and posterior

The middle fibers of the deltoid muscle __________.

Abduct the arm

The latissimus dorsi inserts __________.

On the intertubercular groove of the humerus

One of the actions of the latissimus dorsi muscle is to __________.

Adduct the arm

The subscapularis muscle inserts on the __________.

Lesser tubercle of the humerus

The insertion of the supraspinatus muscle is on the __________.

Greater tubercle of the humerus

All of the following muscles are involved with adduction of the shoulder EXCEPT what?

1.) Teres major 2.) Supraspinatus 3.) Pectoralis major 4.) Coracobrachialis Answer: Supraspinatus

All of the following insert onto the humerus EXCEPT __________.

1.) None of the above 2.) Deltoid 3.) Supraspinatus 4.) Teres major Answer: None of the above

The two heads of the biceps brachii combine to insert on the __________.

1.) Radial tuberosity 2.) Ulnar notch 3.) Radial notch 4.) Olecranon process Answer: Radial tuberosity

The brachialis muscle is located __________ to the biceps brachii muscle.

1.) Superficially 2.) Deep 3.) Laterally 4.) Superiorly Answer: Deep

The brachioradialis is a strong forearm __________.

1.) Extensor 2.) Pronator 3.) Supinator 4.) Flexor Answer: Flexor

The muscle that generates the most power during elbow flexion is the __________.

1.) Brachioradialis 2.) Triceps brachii 3.) Brachialis 4.) Biceps brachii Answer: Brachialis

The prime mover of elbow extension is the __________.

1.) Biceps brachii 2.) Brachialis 3.) Triceps brachii 4.) Anconeus Answer: Triceps brachii

At the completion of supinator action, the palm is turned __________.

1.) Anteriorly 2.) Medially 3.) Posteriorly 4.) Laterally Answer: Anteriorly

Movement of the elbow joint movement is limited to __________.

1.) Supination and flexion 2.) Pronation and supination 3.) Extension and pronation 4.) Flexion and extension Answer: Flexion and extension

Movement of the forearm includes __________.

1.) Flexion and extension 2.) Extension and pronation 3.) Supination and flexion 4.) Pronation and supination Answer: Pronation and supination

Which muscle inserts on the tuberosity of the radius?

Biceps brachii

A reduction in the lateral angle of the glenohumeral joint in relation to the anatomical position would be called __________.

1.) Extension 2.) Abduction 3.) Flexion 4.) Adduction Answer: Adduction

Movement of the shoulder laterally away from the body is called __________.

1.) Flexion 2.) Adduction 3.) Extension 4.) Abduction Answer: Abduction

To keep the humeral head centered within the glenoidal cavity the rotator cuff muscles must be __________.

1.) Located anteriorly 2.) Located distally 3.) Located in the same plane 4.) Located posteriorly Answer: Located in the same plane

The location of the rotator cuff muscles in relation to the glenohumoral joint minimizes the upward pressure against the __________.

1.) Acromion of the scapula 2.) Coracoid process of the scapula 3.) Clavicle 4.) Humerus Answer: Acromion of the scapula

Which type of joint is the hip joint?

Ball and socket

All of the muscles are gluteal muscles EXCEPT what?

1.) Tensor fasciae latae 2.) Gluteus medius 3.) Gluteus maximus 4.) Obturator internus Answer: Obturator internus

Both heads of the biceps femoris muscle __________.

Flex the leg at the knee

The long head of the biceps femoris muscle originates on the __________.

Ischial tuberosity

Where is the biceps femoris located?

Posterior thigh

The origin of the rectus femoris is the ____________.

Anterior inferior iliac spine

The rectus femoris muscle extends the leg at the __________.

Knee

The origin of the Sartorius muscle is from the __________ spine.

Anterior superior iliac

Downward dislocation of the humerus from the glenohumeral joint when carrying weight is prevented by the __________.

Supraspinatus muscle

The angle of which muscle prevents the humeral head from sliding upward out of the joint as the arm is raised?

Subscapularis

All fibers of the semimembranosus muscle converge to insert on the __________.

Posterior tibia

The semimembranosus __________ the thigh at the hip and __________ the leg at the knee.

Extends; flexes

Paralysis of which of the following muscles would make an individual unable to flex the knee?

1.) Hamstring muscles 2.) Brachioradialis 3.) Soleus 4.) Gluteal muscles Answer: Hamstring muscles

Which of the following is NOT a member of the hamstrings?

1.) Gracilis 2.) Semitendinosus 3.) Biceps femoris 4.) Semimembranosus Answer: Gracilis

Which of the following muscles is involved in crossing one leg over the other while in a sitting position?

1.) Quadriceps femoris 2.) Gastrocnemius 3.) All of the hamstrings 4.) Sartorius Answer: Sartorius

The main action of the fibularis longus is to __________.

Evert the foot

The soleus muscle shares an insertion with the __________.

Gastrocnemius muscle

The soleus muscle __________ the foot at the ankle and is innervated by the __________.

Flexes; tibial nerve

he tibialis anterior muscle dorsiflexes the foot at the ankle and also assists in __________ of the foot.

Inversion