The retractor penis muscle, also known as the bulbus glandis muscle, is a specialized skeletal muscle found in certain male mammals, primarily in canines, that controls the retraction and extension of the penis during sexual activity or periods of rest. This muscle is particularly prominent in species such as dogs, wolves, and foxes and plays a central role in their reproductive physiology.
Functionally, the retractor penis muscle facilitates the retraction of the penis into the prepuce, the protective sheath of skin surrounding the organ. This muscle is responsible for pulling the penis inward and relaxing the tissues that allow it to extend during mating or urination. By contracting, it tightens around the base of the penis, drawing it back into its relaxed position within the prepuce.
During sexual arousal, the relaxation of the retractor penis muscle enables the penis to protrude from the prepuce, facilitating copulation by allowing the organ to engage with the female reproductive tract. Once sexual activity is complete, or when the animal is at rest, the retractor penis muscle contracts again, drawing the penis back into its sheath.
The retractor penis muscle is an involuntary muscle, meaning that its contractions are not under conscious control. Instead, its activity is regulated by the autonomic nervous system, responding to hormonal and neurological signals associated with sexual stimulation and activity.
