How are deep versus superficial reflexes assessed in electrodiagnostic medicine?

Updated: Aug 06, 2019
  • Author: Brian M Kelly, DO; Chief Editor: Stephen Kishner, MD, MHA  more...
  • Print
Answer

Answer

Although the term "deep tendon reflex" has been used historically to describe the deep reflexes, this name actually is a misnomer, because the deep reflexes are muscle stretch reflexes (not to be confused with true tendon reflexes, ie, Golgi tendon reflex). The superficial reflexes are elicited by sensory afferents from skin, rather than muscle.

  • Deep reflexes are muscle stretch reflexes mediated by lower motor neuron (LMN) pathways, typically monosynaptic. These reflexes decrease with an LMN lesion and increase with an upper motor neuron (UMN) lesion.

  • Superficial reflexes are mediated by UMN pathways, typically polysynaptic. Either an LMN lesion or a UMN lesion causes loss of these reflexes in general; however, because of the polysynaptic connections in some superficial reflexes, a UMN lesion changes the response instead of extinguishing it (ie, the plantar responses).

  • The Golgi tendon reflex represents neither of the above reflexes. The Golgi tendon organ is a stretch receptor at the musculotendinous junction. These receptors are one tenth to one thirtieth as sensitive as the muscle spindle; when stretched sufficiently, they induce inhibition of that muscle's alpha motor neuron and its associated gamma motor neuron to the spindle (opposite response of spindle).


Did this answer your question?
Additional feedback? (Optional)
Thank you for your feedback!