Reflexes and Segmental Reflexes Flashcards
What do reflexes involve?
A receptor structure, associated afferent neuron, efferent neuron, and effector organ
Do most reflexes also involve interneurons?
Yes
What is the functional use of reflexes?
Test functionality of various segments of the spinal cord through dermatomes and myotomes
What is a reflex?
An involuntary response to sensory input
What is a stretch reflex?
A deep tendon reflex, such as a knee jerk reflex
What does the stretch reflex involve?
Muscle spindle sends activation to spinal cord and the afferent fibers synapse onto alpha motor neurons to cause the quadriceps (or other muscle) to contract
Where else can stretch reflexes be done?
Ankle, wrist, elbow, and jaw
What is the functional purpose of the stretch reflex?
Trying to determine where normal function ends when injured
What is the H-reflex?
Electrical stimulation of the posterior tibial nerve
Indicate level of reflex activity
Test efficacy of treatments
What is the tonic vibratory reflex?
High frequency vibration applied to muscle causes minute stretching of spindles
What is the tendon organ reflex?
Muscle tension/tone increases quickly and then muscle gives up
Abnormal reflex
Helps determine if pathology is present
What is flexor withdrawal?
Withdrawal of a limb from a painful stimulus
Involves several spinal segments (more than one level) to withdraw entire limb
What is reciprocal innervation?
Activate mover muscle
Inhibit antagonist muscle
What is the crossed extension reflex?
Extensor muscles activate on contralateral side to hold all the weight
What three reflexes/actions happen at the same time?
Flexor withdrawal, reciprocal innervation, and crossed extension reflex
What is the babinski reflex?
Scratching the sole of the foot along lateral edge toward toes
Normal adult extends ankle and points foot
Abnormal result of extension and flaring of toes (normal in babies)
What does an abnormal babinski indicate?
UMN lesion of the cortico-spinal tract
Reverted back to baby response
What is the bing reflex?
Sticking the top of the foot with a pin
Normal response is to extend ankle to move foot away
Abnormal response is to flex the toe and foot towards stimulus
What does an abnormal bing indicate?
UMN lesion
