Next, let’s learn the layers of the scrotum, which is the sac that houses the testicles, and the spermatic cord, which comprises neurovascular structures and sheaths of tissue that suspend the testes within the scrotum.
The scrotum comprises skin and a layer of smooth dartos muscle and fascia; notice that the dartos muscle and fascia creates a septum that divides the right and left testes.
Next we’ll show the layers that comprise the spermatic cord, which forms during the fetal period during the testes’ descent from the abdomen to the scrotum.
On their way to the scrotum, the testes pass through the inguinal canal, which is an oblique tunnel in the anterior abdominal wall.
As they descend, the testes push layers of the abdominal wall through the inguinal canal and into the scrotum, forming the walls of the spermatic cord.
Fascia and Muscle
The eternal spermatic fascia is derived from the fascia of the external oblique muscle.
The cremasteric muscle and fascia are derived from the internal oblique muscle and its fascia. In response to cold temperatures, the loops of cremasteric muscle fibers contract, pulling the testicles closer to the warmth of the body.
The internal spermatic fascia is derived from the transversalsis fascia.
Contents
Neurovascular structures and the ductus deferens travel within the spermatic cord.
- The ductus deferens artery, testicular artery, and cremasteric artery.
- The genital branch of the genitofemoral nerve and testicular sympathetic nerves.
- Lymphatic vessels, the pampiniform venous plexus, and the ductus deferens.
The ilioinguinal nerve travels alongside the spermatic cord within the inguinal canal; after exiting the canal through the abdominal wall, the ilioinguinal nerve provides sensory innervation to the skin of the scrotum, root of the penis, and upper medial thigh.
Torsion of the spermatic cord can disrupt the blood supply to the testes, leading to pain, swelling, and necrosis. Testicular torsion is most common in people under 25 years old, and is often due to congenital abnormalities in the tunica vaginalis that allow for twisting of the spermatic cord (this is referred to as a bell clapper deformity).
A pampiniform plexus varicocele occurs when the veins that drain the testicles become abnormally dilated creating a “bag of worms” appearance. Varicoceles can cause pain and infertility and can be repaired surgically.
Varicoceles are more common on the left side due to asymmetries in testicular vein drainage: on the left side, the testicular vein drains at a nearly perpendicular angle into the left renal vein, which then drains into the inferior vena cava; on the right side, the testicular vein drains directly into the inferior vena cava.
Any impairment of blood flow through the left renal vein can also contribute to varicocele formation. Thus, in an older adult with a new-onset varicocele, we need to consider the possibility of left renal cell carcinoma.
