An overactive muscle causes a testicle to become a retractile testicle. The cremaster muscle is a thin pouch-like muscle in which a testicle rests. When the cremaster muscle contracts, it pulls the testicle up toward the body.

The main purpose of the cremaster muscle is to control the temperature of the testicle. In order for a testicle to develop and function properly, it needs to be slightly cooler than normal body temperature. When the environment is warm, the cremaster muscle is relaxed; when the environment is cold, the muscle contracts and draws the testicle toward the warmth of the body. The cremaster reflex can also be stimulated by rubbing the genitofemoral nerve on the inner thigh and by extreme emotion, such as anxiety.

If the cremaster reflex is strong enough, it can result in a retractile testicle, pulling the testicle out of the scrotum and up into the groin.

Causes of an ascending testicle

A small percentage of retractile testicles can become ascending testicles. This means the once-movable testicle becomes stuck in the "up position." Contributing factors may be:

  • Short spermatic cord. Each testicle is attached to the end of the spermatic cord, which extends down from the groin and into the scrotum. The cord houses blood vessels, nerves and the tube that carries semen from the testicle to the penis. If growth of the spermatic cord doesn't keep pace with other body growth, the "tight" cord may pull the testicle up.
  • A problem with the normal path of a descending testicle. The testicles develop in the abdomen during pregnancy, then drop down into the scrotum. Sometimes part of the fetal structure fails to detach from the abdomen, resulting in an upward pull on the testicle.
  • Scar tissue from hernia surgery. An inguinal hernia is caused by a small gap in the abdominal lining through which a portion of the intestines can protrude into the groin. Scar tissue following surgery to repair the hernia may limit the growth or elasticity of the spermatic cord.
Oct. 03, 2012

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