Each crus is attached at the angle between the perineal membrane and ischiopubic ramus.

Distally, each crus transitions into either corpus cavernosum of the body of the penis.

[citation needed] Each crus begins proximally as a blunt-pointed process in anterior to the tuberosity of the ischium, along the perineal surface of the conjoined (ischiopubic) ramus.

[citation needed] Just proximal to the convergence of the two crura, they come into contact with the bulb of (corpus cavernosum of) penis.

This article incorporates text in the public domain from page 1248 of the 20th edition of Gray's Anatomy (1918)