What is the primary function of the cremaster muscle?

The primary function of the cremaster muscle is to raise and lower the testes. This muscle is a part of the spermatic cord and is involved in regulating the position of the testes in relation to the body. Temperature regulation is crucial for proper sperm development, and the cremaster muscle helps achieve this by contracting to elevate the testes when it's cold, bringing them closer to the body for warmth, and relaxing to lower them when it’s warm, allowing for cooling. This dynamic adjustment is essential for maintaining optimal conditions for spermatogenesis.

The other options do not align with the specific role of the cremaster muscle in testicular function and temperature regulation. Supporting the bladder, assisting with abdominal compression, and protecting the kidneys are functions associated with other muscles and structures in the body, not the cremaster muscle itself.