The perineal body (central tendon of the perineum) is the fibromuscular node at the centre of the perineum between the anal and urogenital triangles. Which muscles do NOT insert into the perineal body?

• A External anal sphincter (anterior fibres)
• B Bulbospongiosus
• C Obturator internus ✓
• D Superficial transverse perineal muscle

Explanation

The perineal body is the central fibromuscular structure of the perineum where multiple muscles converge: the external anal sphincter (anterior fibres), the superficial and deep transverse perineal muscles, bulbospongiosus, pubovaginalis (part of levator ani), and the anterior fibres of the puborectalis. The obturator internus muscle lies on the lateral wall of the ischiorectal fossa/ischioanal fossa and inserts into the greater trochanter of the femur — it has no attachment to the perineal body. Damage to the perineal body during childbirth (third-degree tear) disrupts the external anal sphincter attachment and can cause faecal incontinence.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.