Human Anatomy
Male External Genitalia
Male external genitalia for MBBS: scrotum and coverings, testis blood supply, lymphatics and varicocele, and structure of the penis, mapped to NMC codes AN46.1 to AN46.5.
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Male External Genitalia
Male external genitalia for MBBS: scrotum and coverings, testis blood supply, lymphatics and varicocele, and structure of the penis, mapped to NMC codes AN46.1 to AN46.5.
The male external genitalia chapter covers the scrotum and its coverings, the testis and its blood, lymph and nerve supply, and the structure of the penis. It underpins the anatomy of varicocele, testicular cancer spread and the cremasteric reflex.
High-yield: Male External Genitalia
- The scrotum is a cutaneous sac containing the testes, with the dartos muscle in its wall that wrinkles the skin.
- The testis is covered by the tunica vaginalis, a remnant of the processus vaginalis of peritoneum.
- The coverings of the spermatic cord, from outside in, are the external spermatic fascia, the cremasteric fascia and the internal spermatic fascia.
- These coverings derive from the layers of the anterior abdominal wall the testis passes through during descent.
- The testis is supplied by the testicular artery, a direct branch of the abdominal aorta at the level of the renal arteries.
- The right testicular vein drains into the inferior vena cava, but the left drains into the left renal vein.
- A left-sided varicocele is more common partly because of this venous drainage into the left renal vein.
- The lymphatics of the testis drain to the para-aortic lymph nodes, following the artery back to the aorta.
- The lymphatics of the scrotal skin drain to the superficial inguinal lymph nodes, a different route.
- The cremaster muscle raises the testis and is supplied by the genital branch of the genitofemoral nerve.
- The cremasteric reflex is tested by stroking the inner thigh, which raises the testis on that side.
- The penis is made of two corpora cavernosa and one corpus spongiosum, which carries the urethra.
- The corpus spongiosum expands to form the glans penis at its distal end.
- The deep dorsal vein of the penis drains into the prostatic venous plexus, while the superficial vein drains into the femoral vein.
Testicular vessels and lymph drainage
- **Arterial supply:** Testicular artery from the abdominal aorta at the level of the renal arteries.
- **Venous drainage:** Right testicular vein to the inferior vena cava; left to the left renal vein, favouring left varicocele.
- **Lymph of testis:** Drains to para-aortic nodes, not the inguinal nodes.
- **Lymph of scrotal skin:** Drains to the superficial inguinal nodes, a separate route.
NMC competencies in this chapter
- **AN46.1:** Scrotum and its coverings and dartos muscle
- **AN46.2:** Testis and epididymis: structure, coverings and descent
- **AN46.3:** Blood supply, venous drainage and lymphatics of the testis
- **AN46.4:** Structure of the penis and its blood supply
- **AN46.5:** Applied anatomy of the male external genitalia
Frequently Asked Questions
Why is a varicocele more common on the left side?
The left testicular vein drains at a right angle into the left renal vein and is longer, so venous return is less efficient than on the right, favouring a left-sided varicocele.
Where does testicular cancer spread first?
The lymphatics of the testis follow the testicular artery back to the para-aortic lymph nodes, so these are the first nodes involved, not the inguinal nodes.
Why do the testicular vessels arise so high in the abdomen?
The testis develops in the abdomen near the kidney and descends later, dragging its artery from the aorta and its vein to the renal or caval veins with it.
How does this chapter help in NEET-PG?
Testicular lymph drainage, varicocele and the coverings of the cord are examined in surgery and urology, so this region carries directly into PG questions.
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