Male Anatomy

Testes

These are the main male reproductive organs which are suspended in the scrotum on the pedicles of the spermatic cords.

– These hang outside the body as the lower temperature is needed for effective spermatogenesis

– They develop from the posterior abdominal wall and carry peritoneum as they migrate through the inguinal canal.

– This peritoneum forms a double layer (tunica vaginalis) around the testes.

– The residual connection to the peritoneal cavity is obliterated as the processus vaginalis.

– Testes are also covered by outer fibrous tunica albuginea

– At the head of the testis is the epididymis, which absorbs water

Blood supply:

Gonadal artery (direct branch of abdominal aorta)

Venous drainage:

Pampiniform plexus –> gonadal veins –> IVC on right/ renal vein on left side

Nerve input:

Sympathetic effects from T10 –> pain referred to periumbilical region 

Vas deferens

This enters abdominal cavity at deep inguinal ring.

– It is responsible for carrying sperm from testis to the urethra

– It unites with duct of seminal vesicle to form ejaculatory ducts. These two ducts pierce the prostate to open onto seminal colliculus into the urethra.

Blood supply:

Artery of the vas (from superior vesical artery)

Seminal vesicles

These release up to 60% of the fluid found in semen

– The excretory duct of each seminal gland unites with the vas deferens to form two ejaculatory ducts.

Prostate gland

After exiting the bladder, the urethra passes through the prostate gland.

– This produces fluid that is needed to provide nutrients for the sperm cells.

– From middle age, the prostate naturally enlarges and can start to compress the urethra.

– The prostate makes a protein called PSA, which increases as the prostate enlarges.

– Therefore, it is monitored in men as raised values can be a marker of underlying prostate cancer

Urethra

This tube connects the urinary bladder to the external urethral meatus in the penis.

– Internal urethral sphincter at bladder neck is made of smooth muscle, which relaxes when the bladder is full. Also contracts in ejaculation to prevent retrograde ejaculation.

– External urethral sphincter is made of striated muscle giving voluntary control over urination (innervated by pudendal nerve)

– 3 parts of urethra – prostatic, membranous (narrowest part) and spongy urethra

Cremaster muscle

This is part of the spermatic cord and holds the testicles.

– It gives rise to the cremasteric reflex, important in clinical diagnoses.

– This reflex is elicited by lightly stroking the superior and medial part of the thigh

– The normal response is an immediate contraction of the cremaster muscle pulling up the ipsilateral testis

Penis

This is divided into the root, body and glans

– The body is made of two groups of erectile tissue, corpora cavernosa and a ventral corpus spongiosum which engorge in blood.

– Glans is formed by expansion of corpus spongiosum + has external urethral meatus.

– Prepuce (foreskin) is attached to the glans below by a frenulum (membrane)

– Entire body of penis is surrounded by deep fascia sleeve called Buck’s fascia.