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The Golgi Tendon Reflex (Inverse
Stretch Reflex)
Lec:2
When muscle tension is increased (by active muscle
contraction), the Golgi tendon organs are stimulated and
signals are sent to spinal cord to synapse with inhibitory
inter-neurons that in turn inhibit the anterior alpha motor
neurons innervated the same muscle from which same
signals were originated, this reflex:
 Prevents tearing of the muscle or avulsion of the
tendon from its attachment to the bone.
 Equalizes the contractile forces of the separate muscle
fibers. When the tension becomes too little, impulses
from the tendon organ cease, and the loss of inhibition
leads to activation of alpha motor neurons again.
Control of Golgi Tendon Reflex
The brain sends:
1. Signals to the target muscle through alpha motor
neurons to cause muscle contraction at a required
tension.
2. Signals to inhibitory inter-neurons of the spinal cord to
inform them of the tension required as detected by
feedback from the Golgi tendon organs, the inhibitory
inter-neurons automatically inhibit the muscle
contraction to prevent additional tension. In this way
the muscle tension is adjusted to set-point dictated by
the brain.
Clinical Application
In a hypertonic muscle, if passive and sustained muscle
stretch is applied this leads to:
1. Clasp-knife reflex: in a hypertonic muscle, moderate
passive stretch will lead to muscle contraction,
however, stronger passive stretch will lead to
relaxation due to resistance followed by relaxation.
2. Clonus: regular, rhythmic contraction of a hypertonic
muscle that is subjected to sudden sustained passive
stretch. It is due to increased gamma efferent
discharge. Best example in Ankle Clonus, when
dorsiflex the foot there will be rhythmic plantar flexion
at the ankle (the stretch reflex – inverse stretch reflex
sequence may contribute ti this response).
The Withdrawal (Flexor) Reflex
It is a polysynaptic reflex, the painful (other sensory)
stimulus passes into a group of inter-neurons and then to the
anterior motor neurons to elicit muscle contraction and
usually withdrawal of the affected limb. In the inter-neurons,
the signals will stimulate the necessary muscles for
withdrawal and inhibit the antagonistic side muscles
(reciprocal inhibition circuits) and cross to the other side of
the spinal cord to cause opposite reflex in the opposite limb
(crossed extensor reflex) i.e. extend the opposite limb and
push the entire body away from the object causing the
Muscle
painful stimulus.
Clinical Application
1. Abdominal Reflex.
2. Cremastric Reflex