Lab 2.5 (Reflexes and the EMG)

A muscle that generates tension but does not shorten or lengthen is undergoing a(n) ________ contraction.

Isometric

indicate the area(s) you could you find the cell bodies of neurons responsible for sending (efferent) motor signals from the CNS to skeletal muscles.

The area labeled

D ventral horn

A muscle that lengthens even though it is generating tension (e.g. your triceps brachii during the downward phase of a push-up) is undergoing a(n) ___________ contraction (be as specific as possible).

eccentric

Below is some data from an EMG dynamometry experiment (in which students forcefully squeeze a device called a dynamometer).

What waveform represents a weak muscle contraction ?

Waveform C

Below is some data from an EMG dynamometry experiment (in which students forcefully squeeze a device called a dynamometer).

What Waveform represents the force generated by a strong muscle contraction?

Waveform B

A motor unit with four skeletal muscle cells would be __________ all the motor units shown in this illustration.

Smaller than

Consider the diagram below.

What is the specific function of the yellow neuron?

• carries information from the muscle spindle to the central nervous system

• monitors stretch in the quadriceps femoris

To quickly assess whether your patient may have suffered damage to the femoral nerve or damage to spinal nerves in the lumbar region you should most likely test the ____________.

  Knee-jerk reflex

Consider the diagram below.

What is the specific function of the red neuron?

• acts as an inhibitory interneuron

 

• causes reciprocal inhibition of hamstrings so that the quadriceps can extend the leg at the knee

Check the boxes below that indicate the area(s) you could find the cell bodies of neurons responsible for sending (afferent) sensory signals from the periphery to the CNS.

The area labeled

A : dorsal root (ganglion)

The illustration shows:

How many motor neurons _______

Motor units _________

Skeletal muscle fibers_______

• 3 Motor Neurons

• 3 Motor Units

• 20 Skeletal Muscle Fibers

Define EMG

Electro-myo-graphy

electrical activity associated with depolarization and muscle contraction