What reflex is responsible for testicle elevation when the thigh is stroked?

The reflex responsible for testicle elevation when the thigh is stroked is the cremasteric reflex. This reflex involves the contraction of the cremaster muscle, which is located around the testicles and responsible for raising them closer to the body in response to certain stimuli, such as the stroking of the inner thigh. This reaction serves a protective function by regulating the temperature of the testes, which is vital for sperm production.

The cremasteric reflex is a neurogenic reflex, meaning it is mediated by the nervous system. When the inner thigh is stimulated, sensory fibers send signals to the spinal cord, which then activate motor neurons that contract the cremaster muscle.

In contrast, the other reflexes mentioned in the choices do not pertain to this specific function. The psoas reflex involves the psoas muscle, the bulbocavernosus reflex is related to the contractions of the bulbocavernosus muscle, and the patellar reflex is connected to the knee-jerk reaction. Each of these reflexes serves different physiological roles unrelated to the elevation of the testicles.