Tunica albuginea (penis)

The tunica albuginea is a fibrous envelope of the corpora cavernosa of the penis. It is an essential structure that plays a significant role in the erectile function of the penis.

The tunica albuginea surrounding the corpora cavernosa.

Cross-section of the penis showing the tunica albuginea.

Ultrasound image of a normal penis showing the tunica albuginea.

Structure

The tunica albuginea is composed of dense connective tissue and is primarily made up of collagen fibers. It surrounds the corpora cavernosa, which are two cylindrical structures that run along the length of the penis. The tunica albuginea is thicker on the dorsal side of the penis and thinner on the ventral side. This asymmetry is important for the function of the penis during erection.

The tunica albuginea also contains elastic fibers, which allow it to stretch during an erection. The inner layer of the tunica albuginea is more elastic and allows for the expansion of the corpora cavernosa as they fill with blood.

Function

The primary function of the tunica albuginea is to help maintain an erection by trapping blood within the corpora cavernosa. During sexual arousal, the arteries supplying the penis dilate, increasing blood flow into the corpora cavernosa. The tunica albuginea helps to compress the veins that drain blood from the penis, thus maintaining the erection by preventing blood from leaving the corpora cavernosa.

Clinical significance

Damage to the tunica albuginea can lead to conditions such as Peyronie's disease, where scar tissue forms within the tunica albuginea, causing the penis to bend or become misshapen during an erection. This can lead to pain and difficulty with sexual intercourse.

Injuries to the tunica albuginea can also occur during trauma to the penis, such as a penile fracture, which is a rupture of the tunica albuginea due to blunt force trauma.

Related pages

• Penis
• Erection
• Peyronie's disease
• Penile fracture