Study of the cremasteric muscle during erection.

BACKGROUND

Mechanism of testicular elevation during erection is not known. We investigated the hypothesis that erection evokes reflex cremasteric muscle (CM) contraction which effects testicular elevation.

METHODS

Electromyographic (EMG) response of CM to erection was recorded in 26 healthy volunteers (age 36.7 +/- 6.8 SD years). Erection was induced by intracavernosal injection of alprostadil. CM response was tested before and after individual glans penis (GP) and CM anesthetization.

RESULTS

The CM exhibited resting electric activity of mean amplitude of 74.8 +/- 6.3 microV which, on erection, increased to 486.6 +/- 36.8 microV (P < 0.001). Response was momentary. Anesthetization of erect GP did not effect increase of CM EMG activity, while bland gel did. Anesthetized CM did not respond to GC erection while saline infiltrated did.

CONCLUSIONS

The CM appears to contract during erection through a reflex which we call 'peno-cremasteric reflex'. CM contraction assumingly elevates testicle and support cord veins; it may effect testicular compression, thus expressing its secretions into vas deferens.