ANATOMY PRACTICE LECTURE NOTES #2

What do transverse tubules do in muscle cells?

Transverse tubules transmit muscle impulses into the cell interior.

What is the extent of a sarcomere?

A sarcomere extends from one Z disk to an adjacent Z disk.

Where does the muscle that originates along the linea aspera of the femur attach?

The muscle is the vastus medialis.

What occurs if a second stimulus arrives before the relaxation phase has ended?

A second, more powerful contraction occurs, known as wave summation.

What type of levers are most common in the body with the applied force between the fulcrum and load?

These are called third-class levers.

What is the correct order of a skeletal muscle's components from smallest to largest?

Myofibrils, muscle fiber, fascicle, skeletal muscle.

What is the first event in muscle fiber contraction?

Acetylcholine is released from the end of the motor neuron.

What structure in skeletal muscle cells functions in calcium storage?

The sarcoplasmic reticulum.

Which spinal nerves contribute to the brachial plexus?

C5–T1.

What is troponin's role in muscle contraction?

Troponin has a calcium-binding site.

Which muscle extends the thigh?

Both biceps femoris and semitendinosus have this action.

Which muscles dorsiflex the foot?

Tibialis anterior.

What nerve innervates the flexor muscles in the anterior arm?

Musculocutaneous nerve.

Which proteins are specifically involved in contraction of a muscle?

Actin and myosin.

Which nerve innervates the thenar eminence of the hand?

Median nerve.

Which proteins make up a thick filament in muscle?

Myosin and titin.

Which plexus supplies the upper limbs?

Brachial plexus.

What is the region of the sarcomere containing thick and thin filaments called?

A band.

What does 'triceps' in a muscle name indicate?

The muscle has three heads or tendons of origin.

Which muscle is innervated by the intercostal nerve?

Serratus posterior inferior.

What type of muscle has a single nucleus, striated and heavily branched?

Cardiac muscle.

Which muscle has an action of wrist adduction?

Flexor carpi ulnaris.

What covers the binding site on the thin filament?

Tropomyosin.

Which muscle inserts into the intertubercular sulcus of the humerus?

Pectoralis major.

Which nerve is likely damaged if a patient cannot extend their forearm, wrist, and digits?

Radial nerve.

What protein makes up the thick filaments?

Myosin.

What is the structural explanation of how a muscle fiber contracts called?

Sliding filament theory.

What is endomysium?

A delicate network of loose connective tissue that surrounds each muscle fiber.

Which muscle has its origin on the scapula?

Pectoralis major is the exception.

What is the correct sequence of events for muscle contractions?

Motor neuron action potential, neurotransmitter release, muscle cell action potential, release of calcium ions from the SR, ATP-driven power stroke, sliding of myofilaments.

Which of the following does not occur when a skeletal muscle fiber contracts?

Myosin and actin filaments do not decrease in length.

What is the sarcolemma?

The plasma membrane of a muscle fiber.

What happens to Z disks during skeletal muscle contraction?

Z disks are pulled closer together as the I bands between them shorten.

What nerve does the quadriceps femoris muscle get innervated by?

Femoral nerve.

What is the difference between a tendon and an aponeurosis?

A tendon is cordlike and connects muscles to bones, while an aponeurosis is a broad sheet of dense connective tissue that connects muscles to muscles.

Which muscles are involved in elevating the ribs during inhalation?

External intercostals.

What type of innervation is found in iliocostalis, longissimus, and spinalis?

Dorsal rami.

What is the repeating contractile unit of a skeletal muscle fiber?

Sarcomere.

What is the complex of a transverse tubule and two adjacent terminal cisternae called?

Triad.