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ANATOMY: SCROTUM & SPERMATIC CORD

Gross Structure

• Median raphe
  • Runs longitudinally in the midline from the urethral meatus to the anus
  • The arteries, veins, lymphatics, and nerves of the scrotum do not cross the raphe
  • Deep to the raphe, the scrotum is divided by a septum into two compartments, each containing a testis.
• Layers of the scrotum (superficial to deep):Some Damn Englishman Called It The Testis
  1. Skin
  2. Dartos
  3. External spermatic fascia
  4. Cremaster
  5. Internal spermatic fascia
  6. Tunica vaginalis
  7. Tunica albuginea
  8. Tunica vasculosa
  9. Testicle
• The spermatic fasciae are layers of the abdominal wall that extend to form parts of the scrotal wall:
  • The Scarpa fascia extends to form the dartos smooth muscle (and the dartos fascia of the penis; also continuous with Colle’s fascia)
  • The external oblique extends to form the external spermatic fascia
  • The internal oblique extends to form the cremaster muscle and fascia
  • The transversalis fascia continues to become the internal spermatic fascia
• A peritoneal derivative known as the parietal and visceral tunica vaginalis surrounds the testis with a mesothelium-lined pouch.
  • The tunica vaginalis is continuous with the testis posterolaterally at its mesentery, where it is attached to the scrotal wall.
• The gubernaculum fixes the testis at its inferior pole
• Absence of gubernaculum and testicular mesentery is known as Bell-Clapper deformity and predisposes testicle to torsion

Vasculature

• Arterial supply
  • The external pudendal arteries supply the anterior wall of the scrotum. The arteries run parallel to the rugae
  • The posterior aspect of the scrotum has arterial supply from perineal branches.
  • The testicles and internal/external spermatic fascia can be preserved during debridement of a Fournier’s gangrene because of different blood supply than scrotum. Only the skin and dartos need to be taken
• Venous drainage
  • The external pudendal veins drain the anterior scrotal wall. The veins run parallel to the rugae

Lymphatic Drainage

• Scrotal lymphatics do not cross the median raphe
• Drain into the superficial inguinal nodes on the ipsilateral side.

Innervation

• Anterior scrotal wall: branches of the ilioinguinal (L1) and genital branch of the genitofemoral (L1-L2) nerves. The nerves run parallel to the rugae
• Posterior scrotal wall: branches of the perineal (derived from pudendal nerve) and posterior femoral cutaneous nerve (S3)

Spermatic cord

• Contents:
  1. Vas deferens (found posteriorly)
  2. Testicular artery [and deferential and cremestaric arteries?]
  3. Pampiniform plexus and testicular vein
  4. Spermatic fascia and cremasterics
  5. Lymphatics
  6. Genital branch of genitofemoral nerve
• The ilio-inguinal nerve is not located inside the spermatic cord, but runs along the outside of it, in the inguinal canal. The ilioinguinal nerve runs in the cremaster layer and can be effectively spared by opening the cremaster and separating it from the remainder of the cord. The nerve does not have to be individually dissected.

Questions

1. What are the layers of the scrotum?
2. Which layers of the abdomen contribute layers to the spermatic fascia?
3. Which defects comprise the “Bell-Clapper” deformity?
4. What provides innervation to the anterior scrotum?

Answers

1. What are the layers of the scrotum?
1. Skin
2. Dartos
3. External spermatic fascia
4. Cremaster
5. Internal spermatic cascia
6. Tunica vaginalis
7. Tunica albuginea
8. Tunica vasculosa
9. Testis
2. Which layers of the abdomen contribute layers to the spermatic fascia?
   • External spermatic fascia – External oblique
   • Cremaster – internal oblique
   • Internal spermatic fascia – transversalis fascia
3. Which defects comprise the “Bell-Clapper” deformity?
   • Absence of gubernaculum and posterior fixation of testicle
4. What provides innervation to the anterior scrotum?
1. Ilioinguinal (L1)
2. Genital branch of genitofemoral (L1, L2)

 

References

• Wein AJ, Kavoussi LR, Partin AW, Peters CA (eds): CAMPBELL-WALSH UROLOGY, ed 11. Philadelphia, Elsevier, 2015, chap 21