Hey man, have you ever tweaked your nuts?

Attentive gentlemen might have noticed that sometimes their testicles hang low, while at other times they seem to be pulled upward, closer to the body. This movement is particularly noticeable when the inner thigh is tapped or subjected to a sharp stimulus, causing the testicle on that side to rise or contract towards the body. This phenomenon is known as the cremasteric reflex.

### The Muscle That "Lifts the Eggs"

Human movement relies on muscle contraction, and the cremasteric reflex is no exception. It is facilitated by the cremaster muscle. When this muscle contracts, it pulls the scrotum and testicles upward.

The cremaster muscle is a thin layer of muscle tissue that envelops the testicles and spermatic cord. It is fully developed only in males, while in females, this muscle tissue is smaller and weaker, located on the round ligament of the uterus and is almost negligible. So, what is the primary function of the cremaster muscle in men?

As the name suggests, the primary role of the cremaster muscle is to lift the testicles. In fact, its main function is to regulate the temperature of the scrotum. When in a cold environment, the cremaster muscle contracts, bringing the scrotum and testicles closer to the body for warmth. Conversely, in a hot environment, the muscle relaxes to allow better heat dissipation. Sometimes, even in moments of fear, the cremaster muscle will contract.

As an integral part of a man's "little friend," the cremaster muscle also plays a role during intimate moments. During particularly passionate encounters, the cremaster muscle often contracts to protect the testicles from impact. Of course, whether the cremaster muscle contracts can also depend on the specific position and room temperature.

### The Doctor's Little Helper

The cremaster muscle not only protects the testicles but also assists doctors. The cremasteric reflex, controlled by the nervous system, can be used in clinical settings to assess the status of the nervous system's superficial reflexes. For example, the presence of the cremasteric reflex can help diagnose damage to the lumbar spine, and conditions like varicocele can cause the reflex to disappear.

Some researchers have even attempted to use the cremasteric reflex to gauge the depth of anesthesia. Nazim Dogan, Fikret Silbir, and Ali Fuat Erdem from the Department of Anesthesiology at Ataturk University Medical School in Turkey conducted a study to verify the effectiveness of neural anesthesia using the cremasteric reflex.

They injected two groups of subjects with the anesthetic drugs bupivacaine and meperidine and checked the cremasteric reflex in both scrotums a few minutes later. The results showed that within four minutes of the injection, the cremasteric reflex disappeared in almost all subjects.

### The Reflex and Age

Individual differences mean that the cremasteric reflex can vary from person to person. Some may be more sensitive, while others are less so. Age is also a significant factor. In 1994, R. E. Caesar and G. W. Kaplan from the Department of Urology at the University of California, San Diego, reported on the cremasteric reflex in 225 boys aged 0 to 12 years in the Journal of Urology.

They found that when stimulating the upper inner thigh, 48 out of 100 newborns under one month old showed the reflex; 32 out of 71 boys aged 1 to 30 months exhibited the reflex; whereas all 54 boys over 30 months old had a positive response. Based on these findings, Caesar and Kaplan concluded that testing the cremasteric reflex in infants under 30 months is not reliable.

### The Reflex and Testicular Torsion

In adults, the absence of the cremasteric reflex may indicate testicular torsion (a twisting of the testicle and spermatic cord that can lead to swelling and even necrosis), spinal injury, or neuronal disorders. Testicular torsion is the most common cause of this reflex's disappearance.

A study of 245 boys aged 0 to 18 years found that none of the 125 boys with a normal cremasteric reflex had testicular torsion on the affected side, while all 56 boys who had experienced testicular torsion lacked the reflex.

T. Beni-Israel and colleagues also linked abnormal cremasteric reflex to testicular torsion. However, a normal reflex does not rule out the possibility of torsion. In Beni-Israel's study, five out of 17 patients with testicular torsion had a normal reflex. So, while the cremasteric reflex can be helpful in diagnosing testicular torsion, it is not foolproof.

### When "Lifting" Goes Wrong

While the cremasteric reflex is essential for protecting the testicles, an overactive reflex can cause significant discomfort. Cremaster muscle spasms, for example, occur when the muscle contracts excessively, pulling the testicles up too far and causing severe abdominal pain. Sometimes, this embarrassing pain can be triggered by extreme nervousness.

One case involved a pastor who suffered from cremaster muscle spasms. He experienced abdominal cramps and pain, especially during his sermons, due to his nervousness. Fortunately, surgery restored his health.

Men know their own business best. Verifying the cremasteric reflex might require some assistance, as self-testing is quite challenging—similar to how it's difficult to blink when you wave your hand in front of your own eyes.