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L20 Spinal Cord Reflexes

Anatomical and Physiological Elements of Simple Spinal Reflexes

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

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.


Experimental Objectives

  1. To become familiar with anatomical and physiological elements of simple spinal reflexes.
  2. To examine properties of some simple neuromuscular reflexes commonly tested in physical diagnosis.
  3. To measure and compare latent periods and reaction times of extensor and flexor reflexes.
  4. To elicit an extensor reflex and compare contractile force vs. stimulus strength.
  5. To apply the Jendrassik maneuver and observe exaggeration of an extensor reflex.
  6. 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:

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.


BSL L20 Calibration

BSL 4 L20 Spinal Cord Reflexes

Biopac Student Lab Student Download

Lesson Hardware

This lesson requires a Biopac Student Lab (BSL) System and the following hardware. If your BSL System does not include all hardware items, expand your system by selecting required items below. For more details, review the Lesson: L# BSL Lessons - see the Lab Manual or launch BSL; A# and H# BSL PRO Lessons, click the PDF link above to review full setup, recording, and analysis procedures.

Item Name Cart
SS11LB SS11LB Factory-calibrated Airflow Transducer Add to Cart
SS21L Twin-axis Goniometer 150mm, BSL Add to Cart
TAPE2 Adhesive Tape, double-sided, 25.6m Add to Cart
SS36L Reflex Hammer Transducer - MP3X/45 Add to Cart
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