Labia minora and vestibule of vagina

The labia minora are sagittal-oriented skin folds located inwards to the labia majoraThe labia minora begin at the clitoris and go downward. 

Anterior endings of both labia minora split and form two layers or two portions.

The lower layer (also called the medial portion) joins with the same layer of the opposite side and forms the frenulum of the clitoris as it goes below the clitoris and is attached to the glans of the clitoris.

The upper layer (also known as the lateral portion) also joins with the layer from the opposite labium and forms the prepuce or the hood of the clitoris, which overhangs the glans of the clitoris.

Posterior endings of both labia join together and form a skin fold called the frenulum of the labia minora (also called the fourchette of the labia minora).

The labia minora consist of smooth muscle cells, connective tissue (many elastic fibers), and venous plexuses.

They are thinner than the labia majora and are not covered by hair. Also, opposite the labia majora, they do not contain any fat cells. But they have a rich amount of blood vessels that become engorged during sexual intercourse, and it causes labia minora to become swelled and more sensitive.

The inner surface of the labia minora is covered by a mucous membrane.

Between the labia minora is located the vestibule of vagina.

Vestibule of vagina

The vestibule of vagina (sometimes called the vulva vestibule or vulval vestibule) is the enclosed area of the labia minora. It starts right under the frenulum of the clitoris and ends with the frenulum of the labia minora.

The junction zone between the labia minora and vestibule is known as Hart's line.

The vestibule contains two larger openings or orifices:

  • External urethral orifice - located approximately 2 to 3 centimeters below the clitoris;
  • Vaginal orifice - situated immediately below the previous opening.

Also, openings of the greater and lesser vestibular glands are found in the vestibule. The first ones are located on the sides of the vaginal orifice, while the second ones are closer to the external urethral orifice.

The vaginal orifice and, therefore, the posterior part of the vestibule of vagina is covered by hymen until the first sexual intercourse.

Most females do have it, but not all.

The hymen is a thin fold made by a mucous membrane that partially reduces the size of the vaginal orifice.

The shape and size vary, although usually, it has a semilunar or circular shape with smooth edges or circular shape with fringes going into the center. The center of the vaginal orifice usually stays open, although rarely can the hymen cover the vaginal orifice entirely (it is called the imperforate hymen).

Adult females have remnants of the hymen called the hymenal caruncles that are small elevations in the mucous membrane around the orifice.