bulb of penis

n.
  1. The expanded posterior part of the corpus spongiosum of the penis lying in the interval between the crura of the penis.bulb of corpus spongiosum bulb of urethra
The American Heritage® Stedman's Medical Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Company. Published by Houghton Mifflin Company.