In this BSL Spinal Cord Reflexes lesson, students examine properties of some simple neuromuscular reflexes commonly tested in physical diagnosis.
They will record and compare
Subject’s contractile force vs. stimulus strength
influence of the Jendrassik maneuver
voluntary vs. involuntary (reflex) effector responses
Achilles’ tendon reflex and patellar tendon reflex latent periods
Physicians and other clinicians test for the functional integrity of reflex pathways to obtain objective evidence regarding the function of muscles, peripheral nerves (motor and sensory), and the central nervous system. Conclusions drawn from testing reflexes are not the sole consideration in diagnosis but rather are considered in conjunction with other symptoms and signs of pathophysiology.
To become familiar with anatomical and physiological elements of simple spinal reflexes.
To examine properties of some simple neuromuscular reflexes commonly tested in physical diagnosis.
To measure and compare latent periods and reaction times of extensor and flexor reflexes.
To elicit an extensor reflex and compare contractile force vs. stimulus strength.
To apply the Jendrassik maneuver and observe exaggeration of an extensor reflex.
To measure and compare reaction times of voluntary activation of skeletal muscle vs. involuntary (reflex) activation of skeletal muscle.
Tasks Performed by the Student
Students will note the spinal cord reflexes in the following six scenarios:
Knee Jerk Reflex—Subject sits with legs hanging at 90 degrees
Knee Jerk Reflex—Subject sits and perform the Jendrassik maneuver
Knee Jerk Reflex—Subject performs mental math with three-digit numbers
Flexor Withdrawal Reflex—Subject is pricked by a pin or other cutaneous stimulus
Voluntary Knee Jerk Reflex—Subject sits with eyes closed and voluntarily jerks the knee at the sound of the reflex hammer hitting a flat surface
Ankle Jerk Reflex—Subject rests the knee and shin on the seat of a chair while Achilles tendon is struck
BSL Lessons are designed to allow at least four students to record and save data in a normal lab period (60-90 minutes). Typically, labs work most efficiently with three or more students working together at each BSL station.
Add event markers throughout the recording.
The software automates the calibration procedure for the student. There are no knobs and dials to confuse the student.
Graph template files ensure consistent setup for subsequent Subjects or repeated trials—plus, you can easily add your own lesson plan to the onscreen journal.
The lesson will also work as part of a group study.
BSL Instructor’s Guide provides lab tips and lesson options.
BSL Answer Guide is included on the installation disc.
BSL L20 Calibration
BSL 4 L20 Spinal Cord Reflexes
Biopac Student Lab Student Download
This lesson requires a Biopac Student Lab (BSL) System and the following hardware: Reflex Hammer Transducer (SS36L); the response can be recorded with electrodes (such as EL503) and/or a goniometer (such as SS21L with TAPE1 adhesive). If your BSL System does not include all hardware items, expand your system by selecting the required items below. For more details, launch BSL or BSL Student to review the BSL Lab Manual for Lesson 20 Setup.
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