Anatomy › Help with General Muscle Structures
The vastus medialis is supplied by __________.
the femoral artery
the popliteal artery
the anterior tibial artery
the posterior tibial artery
the dorsalis pedis artery
The vastus medialis, one of the quadricep muscles is located in the anterior compartment of the thigh and is supplied by the femoral artery.
__________, __________, and __________ are examples of pennate muscles, because __________.
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
Sternocleidomastoid . . . sartorius . . . biceps brachii . . . their proximal attachment is wider than their point of insertion
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.
Which of the following statements is false?
The fibularis longus is supplied by the popliteal artery.
The fibularis longus is anterior to the soleus.
The fibularis longus becomes tendon halfway down the leg.
The fibularis longus has a tendon that makes an abrupt turn of approximately 90 degrees.
The fibularis longus and fibularis brevis should be strengthened in people who have had inversion sprains of the ankle joint.
The fibularis longus is supplied by the fibular artery, a branch of the posterior tibial artery. All other statements are true.
Which of the following is correct in regards to individual skeletal muscle fibers?
The are multinucleate
They are mononucleate
They contain thick filaments only
They do not repeat
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.
Which of the following accurately describes a characteristic of fast twitch fibers located within a muscle?
Fewer mitochondria
Aerobic glycolysis
Large amounts of myoglobin
Fewer glycolytic enzymes
Endurance power
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.
Which of the following muscles attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5?
Extensor digitorum longus
Extensor hallucis longus
Flexor digitorum longus
Flexor hallucis longus
Extensor digitorum brevis
The extensor digitorum longus attaches from the proximal anterior fibula to the dorsal surface of toes 2 through 5.
The perimysium surrounds which of the following parts of a skeletal muscle fiber?
fascicle
myofibril
myofiber
myofilament
muscle
The perimysium surrounds the fascicles in a skeletal muscle fiber. From largest to smallest, the sequence goes as follows: the Epimysium surrounds the entire muscle; the Perimysium surrounds the fascicles inside the muscle; the Endomysium surrounds the myofiber (muscle cell).
Type I muscle fibers __________.
are slow-twitch with red fibers
are slow-twitch with white fibers
are fast-twitch with red fibers
are fast-twitch with white fibers
None of these
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."
To which of the following molecules does calcium released from the sarcoplasmic reticulum bind?
Troponin
Myosin
Actin
Tropomyosin
Calcium is released from the sarcoplasmic reticulum into the the sarcoplasm. It binds the troponin molecules on the thin filaments, causing the strands of tropomyosin to shift, exposing the myosin-binding sites on the thin filaments.
Which of the following correctly relates a muscle's origin and insertion?
The origin is typically proximal to the insertion, and the origin pulls on the insertion
The origin is typically distal 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
The origin is typically proximal to the insertion, and the origin pushes on the insertion
The origin is typically distal to the insertion, and the origin can either push or pull on the insertion
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.