Musculus bulbospongiosus
In the male horse (stallion/gelding): encircles the urethra at the base of the penis, providing pulsatile ejaculation and urethral emptying. In the mare: constrictor vestibuli encircles the vestibule of the vagina.
Origin: Perineal body and median raphe
Insertion: Surrounds the bulb of the penis (male) or vestibule (female)
Action: Male: expels semen during ejaculation and residual urine after urination. Female: constricts the vestibule
Innervation: Pudendal nerve (S3-S5)
Damage to the bulbospongiosus from pudendal nerve injury impairs ejaculation in stallions, causing urine contamination of semen.
Damage to the bulbospongiosus from pudendal nerve injury impairs ejaculation in stallions, causing urine contamination of semen. Signs include: Urine-contaminated semen (yellowish, ammonia odor); poor fertility; incomplete ejaculation; dribbling of urine after urination.
See the Bulbospongiosus on our interactive 3D horse model. Open 3D Model