Skin of Scrotum: Anatomy, Layers, Relations, Function, Clinical Significance, MRI & CT Imaging

Topic

Skin of scrotum

The skin of the scrotum forms the outer covering of the scrotal sac, which contains the testes, epididymides, and spermatic cords. It is thin, rugose (wrinkled), pigmented, and closely associated with the underlying dartos fascia, a layer of smooth muscle responsible for scrotal wrinkling. Unlike other body skin, scrotal skin lacks fat, which aids in thermoregulation of the testes.

It is highly vascular and richly innervated, making it sensitive to pain, temperature, and touch. These properties, combined with its mobility and elasticity, help maintain an optimal testicular environment for spermatogenesis.

Synonyms

Scrotal skin
Cutaneous covering of scrotum
External scrotal layer

Layers and Relations

Skin: Thin, rugose, pigmented, and elastic
Dartos fascia: Thin layer of smooth muscle directly beneath skin, responsible for scrotal wrinkling and temperature regulation
Deep relations: External spermatic fascia, cremasteric fascia and muscle, internal spermatic fascia, and testis within tunica vaginalis

Innervation

Anterior scrotum: Ilioinguinal nerve and genital branch of the genitofemoral nerve
Posterior scrotum: Perineal branches of the pudendal nerve and posterior femoral cutaneous nerve
Provides sensory innervation for pain, touch, and temperature

Arterial Supply

Anterior scrotal arteries: Branches of the external pudendal arteries (from femoral artery)
Posterior scrotal arteries: Branches of the internal pudendal arteries
Additional supply from cremasteric branches of the inferior epigastric artery

Venous Drainage

Anterior scrotum drains into external pudendal veins → great saphenous vein
Posterior scrotum drains into internal pudendal veins → internal iliac vein

Function

Protects and supports the testes and spermatic cords
Provides thermoregulation (wrinkling by dartos fascia reduces heat loss, relaxation increases cooling)
Facilitates sensory input important for reflexes (e.g., cremasteric reflex)
Acts as a protective barrier against trauma and infection

Clinical Significance

Common site for infections (cellulitis, abscess, Fournier’s gangrene)
Involved in trauma and lacerations due to superficial location
May harbor benign or malignant tumors (e.g., squamous cell carcinoma, melanoma)
Scrotal edema seen in systemic disease (cardiac, renal, hepatic failure)
Critical in urologic and oncologic imaging

MRI Appearance

T1-weighted images:

Skin appears as a thin low-signal line
Surrounding fat is bright, helping to delineate skin
Hemorrhage within skin/subcutaneous tissue may appear bright

T2-weighted images:

Skin appears as a thin dark line
Edema, infection, or inflammation of skin/subcutaneous tissue appears bright
Fat beneath skin appears intermediate to bright

STIR (Short Tau Inversion Recovery):

Normal skin remains low signal
Edema, cellulitis, or inflammatory changes appear bright hyperintense
Fat suppressed, aiding visualization of pathology

T1 Fat-Sat Post-Contrast:

Normal skin enhances mildly and uniformly
Infection or inflammation shows diffuse or patchy enhancement
Tumors may show heterogeneous enhancement

3D T2 SPACE / CISS:

Skin itself remains low signal
Provides excellent visualization of scrotal layers and adjacent fluid collections
Useful for identifying fine anatomical detail and detecting small lesions or adhesions

CT Appearance

Non-Contrast CT:

Skin visible as a thin soft tissue density surrounding the scrotum
Edema appears as skin thickening with increased density of subcutaneous tissues
Fat planes are well seen in normal scrotum

Post-Contrast CT:

Normal skin enhances faintly and uniformly
Inflammatory conditions show thickened enhancing skin with surrounding fat stranding
Tumors may appear as irregular enhancing masses
Abscesses show rim enhancement with central low attenuation

MRI images

Topics