Human Anatomy and Physiology : Help with General Muscle Structures

Study concepts, example questions & explanations for Human Anatomy and Physiology

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Example Questions

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Example Question #1 : Help With General Muscle Structures

Which of the following accurately describes a characteristic of fast twitch fibers located within a muscle?

Possible Answers:

Endurance power

Large amounts of myoglobin

Fewer glycolytic enzymes

Fewer mitochondria

Aerobic glycolysis

Correct answer:

Fewer mitochondria

Explanation:

Slow twitch fibers are located within muscles used for endurance and posture. They have a red coloring due to an abundance of myoglobin and participate in aerobic glycolysis. Slow twitch fibers contain large amounts of mitochondria and fewer glycolytic enzymes in order to enhance ATP production and maintain contractions for longe periods of time. Slow twitch fibers are associated with endurance fitness, such as running a marathon, and prolonged postural contractions, such as the muscles that keep the spine and neck erect.

Fast twitch fibers are located within muscles used for spurt and explosive excercises. They have a white coloring due to a lack in myoglobin and participate in anaerobic glycolysis. Fast twitch fibers contain fewer mitochondria and more glycolytic enzymes, aiding in rapid (but unsastainable) energy production. Fast twitch fibers are associated with speed and agility fitness, such as a sprinting a short distance.

Example Question #2 : Help With General Muscle Structures

Which of the following correctly relates a muscle's origin and insertion?

Possible Answers:

The origin is typically distal to the insertion, and the origin pulls on the insertion

The origin is typically distal to the insertion, and the origin can either push or pull on the insertion

The origin is typically proximal to the insertion, and the origin pushes on the insertion

The origin is typically proximal to the insertion, and the origin pulls on the insertion

The origin is typically proximal to the insertion, and the insertion pulls on the origin

Correct answer:

The origin is typically proximal to the insertion, and the origin pulls on the insertion

Explanation:

Most skeletal muscles have origins closer to the midline than their insertions. The bone from which the muscle originates is typically held steady, while the bone onto which the muscle inserts is pulled toward the origin point of the muscle during flexion. For example, the biceps brachii originate on the scapula and insert on the radius. When activated, the biceps brachii pull the radius toward the scapula.

Example Question #3 : Help With General Muscle Structures

Which of the following is not a characteristic of skeletal muscle?

Possible Answers:

Multinucleated

Voluntary contraction

Transverse tubules

Troponin-tropomyosin protein complexes

Gap junctions

Correct answer:

Gap junctions

Explanation:

Gap junctions only occur in skeletal and smooth muscle. Through gap junctions, the signal from the neuron to contract may diffuse throughout the muscle, causing wave-like contraction of smooth and/or cardiac muscle.

Example Question #4 : Help With General Muscle Structures

Cardiac and skeletal muscle have some similarities, but some important differences too. Which of these features are found in cardiac muscle, but not skeletal muscle?

Possible Answers:

Transverse tubules

Intercalated discs

Myosin and actin filaments

Sarcoplasmic reticulum

Striated muscle fibers

Correct answer:

Intercalated discs

Explanation:

Intercalated discs are found only in cardiac muscle; they add structural stability to cardiac muscle, and help the propagation of action potentials due to gap junctions. The other features listed are features common to both skeletal and cardiac muscle.

Example Question #5 : Help With General Muscle Structures

Type I muscle fibers __________.

Possible Answers:

are fast-twitch with red fibers

are slow-twitch with red fibers

are slow-twitch with white fibers

are fast-twitch with white fibers

None of these

Correct answer:

are slow-twitch with red fibers

Explanation:

Type I muscle (slow oxidative) consists of slow-twitch muscle fibers. Its fibers are red due to high concentrations of myoglobin, and it has a high density of mitochondria (and thus increased oxidative phosphorylation). This leads to a sustained contraction, and resistance to fatigue. Think "one slow red ox."

Example Question #6 : Help With General Muscle Structures

Which of the following is correct in regards to individual skeletal muscle fibers?

Possible Answers:

They contain thick filaments only

They do not repeat

They are mononucleate

The are multinucleate

Correct answer:

The are multinucleate

Explanation:

Individual skeletal muscle fibers are multinucleate and behave as single units. They contain bundles of myofibrils which are surrounded by a sarcoplasmic reticulum and is invaginated by transverse tubules. Each myofibril contains interdigitating thick and thin filaments arranged longitudinally in sarcomeres. Repeating units of sarcomeres account for the unique banding pattern in striated muscle.

Example Question #7 : Help With General Muscle Structures

The vastus medialis is supplied by __________.

Possible Answers:

the anterior tibial artery

the posterior tibial artery

the femoral artery

the dorsalis pedis artery

the popliteal artery

Correct answer:

the femoral artery

Explanation:

The vastus medialis, one of the quadricep muscles is located in the anterior compartment of the thigh and is supplied by the femoral artery. 

Example Question #8 : Help With General Muscle Structures

____________________, and __________ are examples of pennate muscles, because __________

Possible Answers:

Sternocleidomastoid . . . sartorius . . . biceps brachii . . . their proximal attachment is wider than their point of insertion

Vastus medialis . . . rectus femoris . . . deltoid . . . they are made of fibers that insert obliquely into their tendons

Sternocleidomastoid . . . sartorius . . . biceps brachii . . . they are made of fibers that insert obliquely into their tendons

Sternocleidomastoid . . . sartorius . . . biceps brachii . . . they are spindle-shaped, with a muscle belly that is wider than the origin and insertion 

Vastus medialis . . . rectus femoris . . . deltoid . . . their proximal attachment is wider than their point of insertion

Correct answer:

Vastus medialis . . . rectus femoris . . . deltoid . . . they are made of fibers that insert obliquely into their tendons

Explanation:

The term pennate describes muscles whose fibers insert obliquely into the tendon. The vastus medialis, rectus femoris, and deltoid are all examples of this type of muscle. 

Example Question #9 : Help With General Muscle Structures

Which of the following statements is false?

Possible Answers:

The fibularis longus has a tendon that makes an abrupt turn of approximately 90 degrees. 

The fibularis longus is anterior to the soleus. 

The fibularis longus and fibularis brevis should be strengthened in people who have had inversion sprains of the ankle joint. 

The fibularis longus becomes tendon halfway down the leg. 

The fibularis longus is supplied by the popliteal artery. 

Correct answer:

The fibularis longus is supplied by the popliteal artery. 

Explanation:

The fibularis longus is supplied by the fibular artery, a branch of the posterior tibial artery. All other statements are true.

Example Question #10 : Help With General Muscle Structures

Which of the following muscles attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5?

Possible Answers:

Extensor digitorum brevis

Extensor digitorum longus

Flexor hallucis longus

Flexor digitorum longus

Extensor hallucis longus

Correct answer:

Extensor digitorum longus

Explanation:

The extensor digitorum longus attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5. 

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