MRS - Spermatic Cord

Question 1

What structures are contained within the spermatic cord?

Answer 1

Blood vessels:
1) Cremasteric artery

2) Testicular artery
3) Artery to vas deferens
4) Pampiniform plexus of testicular veins

Nerves:

1) Genital branch of the genitofemoral nerve - supplies cremasteric muscle
2) Autonomic nerves

Other structures:

1) Vas deferens - the duct that transports sperm from the epididymis to the ampulla, ready for ejaculation.`
2) Processus vaginialis - projection of peritoneum that forms the pathway of descent for the testes during embryonic development. In the adult, it is fused shut.
3) Lymph vessels - these drain into para-aortic nodes, located in the lumbar region.

Question 2

Anatomical course?

Answer 2

It is relatively short, beginning in the inferior abdomen and ending in the scrotum.

The spermatic cord is formed at the opening of the inguinal canal, known as the deep inguinal ring. This opening is located laterally to the inferior epigastric vessels.

The cord passes through inguinal canal, entering the scrotum via the superficial inguinal ring. It continues into the scrotum, ending at the posterior border of the testes. Here, its contents disperse to supply the various structures of the testes and scrotum.

Question 3

Fascial coverings?

Answer 3

The spermatic cord are mainly bound together by three fascial layers. They are all derived from the anterior abdominal wall:

1) External spermatic fascia - derived from deep subcutaneous fascia (fascia innominata).
2) Cremaster muscle and fascia - derived from the internal oblique muscle and its fascial coverings.
3) Internal spermatic fascia - derived from the transversalis fascia.

The three fascias themselves are covered by a layer of superficial fascia, which lies directly below the scrotal skin.

The cremaster muscle forms the middle layer of the spermatic cord fascia. It is a discontinuous layer of striated muscle that is oriented longitudinally.

Question 4

Clinical relevance - cremasteric reflex?

Answer 4

This can be stimulated by stroking the superior and medial parts of the thigh. This produces an immediate contraction of the cremaster muscle, elevating the testis on the side that has been stimulated.

This spinal reflex consists of two parts:
1) Afferent (sensory) limb - ilioinguinal nerve (innervates the skin of the superomedial thigh). Fibres from this nerve enter the spinal cord at L1.

2) Efferent (motor) limb - genital branch of the genitofemoral nerve (innervates the cremaster muscle).

Question 5

Vas deferens?

Structure and function?

Answer 5

This is a straight, thick muscular tube that conveys sperm from the epididymis to the ampulla and eventually, to the ejaculatory duct (formed by the convergency of the vas deferens and seminal vesicle duct). From the ejaculatory duct, sperm can pass through to the prostatic urethra.

The wall of the vas deferens consists largely of smooth muscle, arranged in three muscle layers:

1) Inner layer - longitudinal smooth muscle
2) Intermediate layer - circular smooth muscle
3) Outer layer - longitudinal smooth muscle

There is rich autonomic innervation of these muscle fibres, which permits fast movement of sperm towards the ejaculatory duct This movement is also facilitated by the inner mucosal layer of the vas deferens - which is lined by cells that possess microvilli. Their seaweed-like movement helps advance spermatozoa through the spermatic tube.

Question 6

Vas deferens?

Anatomical course?

Answer 6

1) Continuous with the tail of the epididymis.
2) Travels through the inguinal canal, as part of the spermatic cord.
3) Moves down the lateral pelvic wall close to the ischial spine.
4) Turns medially to pass between the bladder and the ureter and then travels downward on the posterior surface of the bladder.
5) The inferior narrow part of the ampulla joins the duct from the seminal vescile to form the ejaculatory duct.

Question 7

Clinical relevance - testicular torsion?

Answer 7

Testicular torsion is a surgical emergency, where the spermatic cord twists upon itself. This can lead to strangulation of the testicular artery, resulting in necrosis of the testis.

A common cause of testicular torsion is spasm of the cremasteric muscle fibres which then force the testicle to spin around its own cord. Certain anatomic conditions (e.g. a loose testicle in a large peritoneal sac - tunica vaginalis) may facilitate this movement.

Diagnosis can be confirmed via ultrasound and colour doppler scanning. The main clinical feature of testicular torsion is severe, sudden pain in the affected testis which usually lies higher (due to the torsion of the cord) in the scrotum.

Testicular torsion is an absolute surgical emergency. A few hours later can lead to testicular necrosis.