Anatomy

The penis (Figure 33.1) comprises the body or shaft and the two ends, anterior and posterior (root). The anterior portion is composed of the glans, coronal sulcus and foreskin (prepuce). There is a vertical cleft, the meatus, in the apex 5 mm in length and this is attached to the foreskin by a triangular piece of mucosa, known as the frenulum. The base of the cone is represented by the corona, an elevated ridge surrounding the glans. The coronal sulcus below the corona separates the glans from the foreskin.

The glans is composed of the following layers: epithelium, lamina propria, corpus spongiosum, tunica albuginea and corpus cavernosum. The stratified epithelium is thin and non-keratinised in uncircumcised males but keratinised in circumcised males. The lamina propria is loose, 1-4 mm thick, and separates the epithelium from the corpus spongiosum. The corpus spongiosum is the main component of the glans and consists of specialised erectile tissues with numerous anastomosing venous sinuses. It is 8-10 mm in thickness. The tunica albuginea is a very dense, white, fibrous membrane which terminates in or near the glans separating the corpus spongiosum from the corpora cavernosa and constitutes an important barrier to the spread of cancer to the latter. The coronal sulcus is a narrow and circumferential "cul-de-sac" located just below the glans corona. It is a common site for recurrence of carcinoma or of a positive margin in cases of foreskin carcinoma. The foreskin is a double membrane which encases the glans and from which it is separated by a potential space.

Prepuce (foreskin)

Glans

Urethral meatus

Corpus spongiosum Sulcus

Prepuce (foreskin)

Corpus spongiosum Sulcus

Glans

Urethral meatus

Corpus cavernosum Urethra

Corpus spongiosum

Coronal sulcus

Shaft

Figure 33.1. Anatomy of the penis. Reproduced from Hermanek P, Hutter RVP, Sobin LH, Wagner G, Wittekind Ch (eds.). TNM Atlas: illustrated guide to the TNM/pTNM classification of malignant tumours, 4th edition. Springer-Verlag: Berlin and Heidelberg, 1997.

Corpus cavernosum Urethra

Corpus spongiosum

Coronal sulcus

Shaft

Figure 33.1. Anatomy of the penis. Reproduced from Hermanek P, Hutter RVP, Sobin LH, Wagner G, Wittekind Ch (eds.). TNM Atlas: illustrated guide to the TNM/pTNM classification of malignant tumours, 4th edition. Springer-Verlag: Berlin and Heidelberg, 1997.

The shaft comprises three cylindrical masses of cavernous erectile tissue bound together by the fibrous tunica albuginea and encased in Buck's fascia. These cylinders are the ventral corpus spongiosum with a centrally located urethra and two corpora cavernosa separated by a median raphe.

The posterior part (root) of the penis is deeply embedded in the perineum. It is fixed to the anterior wall of the pelvis by a ligamentous insertion of the corpora cavernosa to the ischium and pelvic bones.

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