An extension of the internal oblique abdominal muscle over the spermatic cord and testis.

The cremaster muscle covers the testis. Its function is to raise and lower the scrotum in order to regulate the temperature of the testis and promote spermatogenesis. In a cool environment the cremaster draws the testis closer to the body preventing heat loss, while when it is warmer the cremaster relaxes allowing the testis to cool.

The cremaster develops to its full extent only in males; in females it is represented by only a few muscle loops.