Download 04-Reflexes - U of L Class Index

Lab Book
BIOLOGY 3420
Lab #5
Reflexes and EMG 5.1
ANIMAL PHYSIOLOGY
LAB BOOK
FALL 2007
HUMAN REFLEXSES AND THE ELECTROMYOGRAM
Data Sheet
Name:
Lab section:
Date:
ELECTROMYOGRAM
Simultaneous Recording from Gastrocnemius and Anterior Tibialis
1. Determine to what extent this muscle is involved in:
•
Flexion of the foot upwards and downwards when the subject is sitting without weight being placed on
the leg. Record your observations in the space below.
•
Raising the foot onto the toes, and then rocking the foot back onto the heels when the subject is
standing.
•
Control of balance with eyes open or closed. Is the muscle “quieter” when the eyes are open?
To what extent is the excitation of the muscle under voluntary control?
2. Investigations of reflex responses to a tendon tap (patellar tendon and Achilles tendon).
•
Which, if either, of these treatments elicits a response?
•
Is the magnitude of the EMG signal related to strength of the tap on the tendon?
Lab Book
Reflexes and EMG 5.2
Patellar reflex (or Achilles Reflex)
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
Trial 4
Trial 5
Average
Trial 3
Trial 4
Trial 5
Average
Trial 3
Trial 4
Trial 5
Average
Hammer Strike Force
(volts)
Reaction Time
(msec)
Magnitude of respond
(volts)
SPINAL NERVE STRETCH REFLEXES
A. Involuntary Knee Jerk (Femoral Nerve)
Trial 1
Trial 2
Trial 3
Reaction Time
(msec)
Magnitude of respond
(volts)
B. Involuntary Knee Jerk with Jendrassik’s Maneuver
Trial 1
Trial 2
Reaction Time
(msec)
Magnitude of respond
(volts)
C. Involuntary Knee Jerk with mental distraction
Trial 1
Reaction Time
(msec)
Magnitude of respond
(volts)
Trial 2
Lab Book
Reflexes and EMG 5.3
D. Involuntary Knee Jerk with Flexor Withdrawal Reflex
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
Reaction Time
(msec)
Magnitude of respond
(volts)
E. Involuntary Knee Jerk with iced quadriceps muscle
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
Trial 1
Trial 2
Trial 3
Trial 4
Trial 5
Average
Reaction Time
(msec)
Magnitude of respond
(volts)
F. Voluntary Knee Jerk
Reaction Time
(msec)
Magnitude of respond
(volts)
Questions
1. Several factors that influence the rapidity and effectiveness of the patellar reflex arc were investigated
in this lab.
• Which of these factors increases the excitatory level of the spinal cord?
•
Which factor decreases the excitatory level of the muscles?
2. How do reactions times vary when doing normal knee jerk, distracted jerk, and voluntary knee jerk?
Lab Book
Reflexes and EMG 5.4
Why do we see these results?
3. Why would the reaction time vary when doing the Jendrassik’s maneuver?
4. How do you think a strenuous exercise might alter knee jerk reaction time? Explain
5. Compare the size of responses between normal knee jerk and knee jerk with Jendrassik’s maneuver.
What effect would a spinal-cord lesion have on the gain?
6. In the space below draw a fully-labelled diagram of the patellar reflex arc and its inhibitory reflex arc
showing the muscles involved, the sensory and motor neurons, the muscle fibres involved, and the spinal
cord with roots, matter, and synapses. Include a written description of a reflex that traces the signal from
sensation to effect.
Lab Book
Reflexes and EMG 5.5
Test yourself
1. Stimulation of the_________________ motoneurons results in muscle contraction and shortening.
2. A reflex arc always involves the CNS.
a. True
b. False
3. Is the patellar reflex ipsilateral or contralateral?
4. Those muscles that decrease the angle of their attached bones at the joint, are known
as_________________ muscles and the antagonistic muscles are known as____________________.
5. If enough muscle fibers contract to make the muscle as a whole shorten in length, the muscle is said to
exhibit
a. complete tetanus
b. graded contraction
c. isometric contraction
d. isotonic contraction
6. The stretch reflex that results extension of the lower leg in most neuromuscular examinations is
referred to as the_______________________________ (hyphenated word) reflex. Which muscle is
stretched when this test is performed?
7. During the patellar reflex, are the motor neurons supplying the hamstrings stimulated or inhibited?
8. What parts of a reflex arc constitute a motor unit?