Bulbocavernosus Reflex (BCR)

Synonyms: Bulbospongiosus reflex (BSR), Osinski reflex

Reflex arc:

a. Stimulus: Briskly squeezing glans penis or clitoris or Tugging Foley’s catheter (pulling the balloon of foley’s catheter against the bladder neck)

b. Afferent: Sensory fibers of pudendal nerve

c. Reflex center: S2-S4 spinal segments (Polysynaptic)

d. Efferent: Motor fibers of pudendal nerve

e. Response: Contraction of Perineal muscles (External Anal Sphincer)

bulbocavernosus reflex


  1. Perform per-rectal examination and evaluate anal tone
  2. Apply stimulus for BCR to evaluate for increased anal tone


1. Normally present in almost all men and 70% women.

2. In spinal cord injury, return of BCR marks the end of spinal shock.

3. It may be preserved in high conus medullaris lesions but it is lost in cauda equina syndrome.

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