The term “cavernosa” most often refers to the corpora cavernosa, which are the primary erectile tissues found in the human penis. These structures are responsible for enabling an erection. Similar erectile tissue structures also exist in the clitoris, playing an analogous role in female sexual arousal. It is important to distinguish “cavernosa” from cavernoma, which is a distinct medical condition involving an abnormal cluster of blood vessels, often found in the brain or spinal cord, that can bleed. This article focuses specifically on the erectile tissues and their function.
Anatomy of the Corpora Cavernosa
The corpora cavernosa are two parallel, sponge-like columns of tissue that extend along the length of the penis shaft. These cylindrical bodies originate from the pubic bone and reach towards the glans, or head, of the penis. Each column is encased by a fibrous sheath known as the tunica albuginea, which plays a significant role in trapping blood during an erection.
Positioned beneath these two columns is the corpus spongiosum, a smaller, single column of erectile tissue that contains the urethra, the tube through which urine and semen exit the body. The corpus spongiosum extends to form the glans penis.
The Mechanism of Erection
An erection begins with sensory or mental stimulation, prompting the brain to send nerve signals to the penis. These signals trigger the release of chemical messengers, such as nitric oxide, within the erectile tissues. Nitric oxide causes the smooth muscles within the corpora cavernosa to relax.
This relaxation allows a rapid influx of arterial blood into the lacunar spaces, which are the interconnected, blood-filled chambers within the corpora cavernosa. As these spaces fill, the corpora cavernosa expand, increasing both in length and diameter. The expanding tissue then compresses the small veins against the tunica albuginea. This veno-occlusive mechanism traps the blood within the corpora cavernosa, creating and maintaining rigidity for an erection.
Conditions Affecting the Corpora Cavernosa
Several medical conditions can directly impact the structure or function of the corpora cavernosa, affecting erectile capabilities. Erectile Dysfunction (ED) is a common concern linked to impaired blood flow into these tissues. Conditions like atherosclerosis, diabetes, and hypertension can damage the blood vessels and smooth muscle cells, hindering their ability to fill with blood.
Peyronie’s disease involves the formation of fibrous scar tissue, or plaques, within the tunica albuginea. This scar tissue can cause abnormal curvature, indentation, or shortening of the penis during an erection, often accompanied by pain. The inelasticity caused by these plaques impedes the normal expansion of the erectile tissue.
Priapism refers to a prolonged, often painful, erection that persists without sexual stimulation. Ischemic priapism occurs when blood becomes trapped and stagnant within the corpora cavernosa. This lack of fresh, oxygenated blood can lead to tissue damage if not treated promptly.
Medical Interventions and Support
Medical interventions for conditions affecting the corpora cavernosa often target specific physiological mechanisms. Oral medications, such as phosphodiesterase type 5 (PDE5) inhibitors, are prescribed for erectile dysfunction. These medications work by enhancing the effects of naturally occurring nitric oxide, promoting smooth muscle relaxation and increasing blood flow into the corpora cavernosa.
Injectable medications, administered directly into the corpora cavernosa, contain vasodilators. This direct action leads to increased blood flow and subsequent engorgement of the erectile tissues, inducing an erection. These injections can be effective even when oral medications are not.
For mechanical solutions, vacuum erection devices can be used to draw blood into the corpora cavernosa, creating an erection. Penile implants, a surgical option, involve placing inflatable or malleable rods directly within the corpora cavernosa. These implants can achieve an erection when other treatments are not suitable or effective.