Perineal body

The perineal body, also known as the central tendon of the perineum, (TA: corpus perineale) is a key midline fibromuscular structure, with important muscular attachments, which acts to stabilize the structures of the pelvis and perineum. It is located between the anal canal and the bulb of the penis, or, in females, the vagina.

Gross anatomy

The perineal body has a trilaminar structure :

• superficial layer
  • muscle fibers of the external anal sphincter which pass anteriorly into the bulbospongiosus muscle
• intermediate layer
  • superficial transverse perineal muscle
• deep layer
  • deep transverse perineal muscle

In young women the perineal body is approximately twice the size of the perineal body in men .

Relations

• females
  • anteriorly: posterior wall of the vagina and frenulum of the labia
  • anterolaterally: bulbospongiosus muscle
  • posteriorly: anal canal, merging with fibers of the external anal sphincter
  • superiorly: contacts the puborectalis muscle, although if true anatomic contiguity is present is now contentious
• males
  • anatomic relations same as in females, except that anteriorly lies the urethra instead of the vagina

Arterial supply

The internal pudendal artery, a branch of the internal iliac artery forms the primary blood supply for the perineal body.

Innervation

The perineal branch of the pudendal nerve (S2 to S4), supplies the perineal body.

Radiographic features

In general the perineal body is much easier to visualize in women than men due to its much larger size.

Ultrasound

The perineal body is clearly visible on transperineal ultrasound in healthy women .

MRI

The perineal body can be easily identified on thin slice MRI in healthy women and its internal structure is appreciable on optimized sequences .

Related pathology

• pelvic floor prolapse

Injury to it during childbirth may weaken the pelvic floor and contribute to prolapse of the vagina and uterus.