The cremaster muscle is found in the male human body, covering the testis. The muscle moves the testes, promoting healthy and mobile sperm. It also changes the testes' temperature, both lowering and raising the testes to control the temperature.
When a man enters an environment with a colder temperature, the muscle causes the testis to move against the body. The more the testis presses against the body, the less is exposed to the colder air. The muscle protects the testis by slowly warming it against the temperature of the body. The Cremaster muscle also works during fight or flight scenarios, when the man must either fight or run. The muscle pulls the testis towards the body, to protect it.
The cremasteris reflex refers to the stroking of the inner thigh, moving the hand softly along the area from the hip to the knee. The muscle immediately reacts by raising the tescitle. The reflex may occur when a man breathes in deeply, or contracts his abdomen.