The male urethra

Parts

About 15-20 cm long  and conveys both urine and semen
Has three parts

1. Prostatic part
   
   (+) Star shaped
   (+) Enclosed by the prostate gland.
   (+) The is the most dilatable part.
   (+) The prostatic ducts and ejaculatory ducts , opens into it.
   
   
2. Membranous part:
   
   (+) Shortest, least dilatable.
   (+) Apart from external urethral orifice, the narrowest part of the urethra.
   (+) Descends from the prostate to the bulb of the penis
   (+) traverses the sphincter urethrae muscle and inferior fascia of the urogenital diaphragm.
   (+) Bulbo-urethral glands are found on its side.

• Spongy (Penile part)
  
  (+) The longest part
  (+) runs the full length of the corpus spongiosum.
  (+) It has two dilatations.
  
  a) Bulb of urethra in the bulb of the penis
  b) Navicular fossa, in the glans penis
  
  (+)Two glands open into it.
  
  a) Bulbo urethral glands
  b) Mucus secreting urethral glands.

Blood supply

• Arteries derived from the structures it traverses
• Prostatic arteries from internal pudendal
• Artery of the bulb
• Urethral artery

Lymphatics

• With the glans penis – deep inguinal nodes, some to superficial inguinal
• From the upper part- internal iliac (a few sacral)

Innervation

• Branches of the pudendal nerve
• Autonomic from the inferior hypogastric plexus.
• Affarent fibres run in pudendal nerve and in pelvic splanchnic nerves.