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Labia minora

The labia minora are paired folds of thin, delicate, hairless skin that form part of the external female genitalia (vulva). They lie medial to the labia majora and extend anteriorly to form the prepuce and frenulum of the clitoris, while posteriorly they merge at the posterior commissure. Unlike the labia majora, they contain no fat and are primarily composed of connective tissue, elastic fibers, and abundant sebaceous glands. Their size and shape are highly variable between individuals.

The labia minora are important for protecting the vaginal vestibule, urethral opening, and clitoris, as well as maintaining lubrication and sensitivity of the vulvar region.

Synonyms

  • Inner labia

  • Nymphae

  • Vulvar folds (inner)

Location and Relations

  • Anteriorly: Join to form the prepuce and frenulum of the clitoris

  • Posteriorly: Fuse together at the posterior commissure, forming the fourchette

  • Laterally: Bordered by the labia majora

  • Medially: Enclose the vestibule of the vagina, including the external urethral orifice and vaginal opening

Function

  • Protects the vaginal and urethral openings

  • Maintains a moist environment by housing sebaceous and mucous glands

  • Enhances sexual sensitivity due to abundant nerve endings

  • Helps direct urinary stream in females

  • Provides coverage and protection to the clitoris

Clinical Significance

  • Infections/inflammation: Can be involved in vulvovaginitis, lichen sclerosus, or dermatitis

  • Congenital variations: Labial hypertrophy or asymmetry

  • Trauma: May be injured during childbirth or sexual trauma

  • Neoplasia: Can be a site for vulvar intraepithelial neoplasia (VIN) and squamous cell carcinoma

  • Surgical relevance: Labia minora reduction (labiaplasty) is performed for functional or cosmetic reasons

MRI Appearance

T1-weighted images:

  • Labia minora appear as thin, intermediate-to-bright signal signal soft tissue folds

  • No fat content (unlike labia majora), so no bright signal from fat

T2-weighted images:

  • Appear as thin folds with intermediate-to-bright signal

  • Edema, inflammation, or cysts show bright signal intensity

STIR (Short Tau Inversion Recovery):

  • Normal labia minora appear as low-to-intermediate signal structures

  • Inflammation, edema, or infection appear bright

T1 Fat-Sat Post-Contrast:

  • Normal tissue shows mild, uniform enhancement

  • Inflammatory or neoplastic lesions demonstrate heterogeneous or irregular enhancement

  • Abscesses show rim enhancement with central low signal

CT Appearance

Non-Contrast CT:

  • Labia minora appear as thin, soft tissue density folds without fat

  • Best visualized with adjacent contrast in urethra or vagina

  • Swelling or mass may appear as asymmetric soft tissue thickening

Post-Contrast CT:

  • Normal labia minora show mild, uniform enhancement

  • Infections or abscesses demonstrate rim-enhancing fluid collections

  • Neoplasms appear as enhancing solid masses or nodules

MRI image

Labia minora MRI axial anatomy image-img-00000-00000

MRI image

Labia Minora MRI axial anatomy image-img-00000-00000_00001

CT image

Labia minora ct axial image 1

CT image

Labia minora ct axial image