Quiz 11 (Ch 9 and 10)

A ligamentous connection, such as that between the bones of the lower leg, is called a ________

• gomphosis

• symphysis

• synchondrosis

• syndesmosis

Answer explanation

In the syndesmosis at the distal tibiofibular joint, the fibrous tissue connecting the bone is longer than that in the sutures, and slight to considerable movement is possible.

Movement of a limb towards the midline of the body is called __________.

• adduction

• abduction

• flexion

• extension

Answer explanation

Adduction, which is the opposite of abduction, is the movement of a limb toward the body midline.

An entire skeletal muscle is surrounded by __________.

• endomysium

• tendon sheath

• perimysium

• epimysium

Answer explanation

Perimysium surrounds bundles of fibers (fasciculi), and endomysium surrounds each fiber. The entire muscle is surrounded by epimysium.

motor neuron along with all the muscle fibers it supplies is called a(n) __________.

• synaptic cleft

• motor end plate

• neuromuscular junction

• motor unit

Answer explanation

A motor unit is a nerve-muscle functional unit, with a motor neuron supplying all the muscle fibers within the motor unit.

Which of the following does NOT occur during skeletal muscle contraction?

• Myosin heads bind to actin.

• Calcium concentration in the sarcoplasm increases.

• Calcium binds to myosin heads.

• The I bands shorten, and H zones disappear.

Answer explanation

ncrease of hemoglobin concentration in muscle fibers is not a process that occurs during muscle contraction.

What is the ion released from the terminal cisternae that combines with troponin and removes the blocking action of tropomyosin, resulting in the formation of cross bridges?

• Cl^-

• H⁺

• Na⁺

• Ca²⁺

Answer explanation

Ca²⁺ combines with troponin, causing troponin to change shape which removes the blocking action of tropomyosin, allowing cross bridges to form.

a skeletal muscle fiber is controlled by a neuron at a single __________.

• transverse tubule

• varicosity

• neuromuscular junction

• sarcomere

Answer explanation

The axon of each motor neuron divides as it enters the muscle, and each of these axonal endings forms a branching neuromuscular junction with a single muscle fiber. As a rule, each muscle fiber has only one neuromuscular junction.

The most common lever systems in the body are those that have the applied force between the fulcrum and the resistance. These are called __________ levers.

• first-class

• second-class

• third-class

• fourth-class

Answer explanation

Most skeletal muscles of the body act as third-class lever systems.

A muscle that assists the muscle primarily responsible for a given action is a(n) __________.

• originator

• antagonist

• synergist

• levator

Answer explanation

Synergists are muscles that help the prime mover by contracting at the same time to add more force or stabilize a part so the movement is more effective.

A muscle that is inserted on the mandible is probably involved in __________.

• wrinkling the forehead

• blowing

• chewing

• frowning

Answer explanation

The muscles of mastication insert on the mandible, causing movement of the jaw during chewing.