thumb|A diagram illustrating crossed extensor reflex.
The crossed extensor reflex or crossed extensor response or crossed extension reflex or Sherrington reflex is a reflex in which the contralateral limb compensates for loss of support when the ipsilateral limb withdraws from painful stimulus in a withdrawal reflex.
Besides shifting the body weight to the other side, the reflex pathway is also associated with leg coordination when walking by flexing muscle on one side, while extending muscle on the other side.
This crossed extensor response is properly part of the withdrawal reflex.
An example of this is when a person steps on a nail: The leg that is stepping on the nail pulls away, while the other leg takes the weight of the whole body.
The crossed extensor reflex is contralateral, meaning the reflex occurs on the opposite side of the body from the stimulus.
To produce this reflex, branches of the afferent nerve fibers cross from the stimulated side of the body to the contralateral side of the spinal cord. There, they synapse with interneurons, which, in turn, excite or inhibit alpha motor neurons to the muscles of the contralateral limb.