Erection

Erection and ejaculation are reflex phenomena not under the direct control of the brain and can take place even in the 'spinal' man. During the Second World War there were cases of wounded men whose spinal cords were injured by a fracture of the spinal column or cut due to gunshot injuries. The individual became completely paralyzed below the level of the cord injury (spinal man). After some time when the reflexes returned, stimulation of the glans penis or the inner part of the thighs produced a reflex erection of the penis as the erection centre in the cord can act on its own without the intervention of the brain. But the feeling of pleasure is absent, as the wiring from the spinal cord to the centre is severed.

Comparison of arousal and erection mechanism

Sexual arousal and erection (copulatory mechanism) are two different mechanisms independent of each other. They usually act together, yet there may be situations where you may be aroused but erection may be absent, as the copulatory mechanism has not got the go ahead signal because the modulatory mechanism has inhibited it. This diversity of action is only found in man; in animals the two mechanisms always act in unison. Thinking and feeling aroused are two entirely different things. Men often 'think' that they are aroused but they just mechanically want to get aroused. Under such circumstances there is no erection response. On the other hand, when a man sees a beautiful thigh, he 'feels' aroused, a natural process resulting in an erection. Thinking yourself to arousal involves the central nervous system, while feeling yourself aroused is the natural process mediated by the autonomic nervous system.