Deep Transverse Perineal Muscle

The deep transverse perineal muscle is a paired skeletal muscle located in the deep perineal pouch of the urogenital triangle. It provides structural support to the pelvic floor and plays a stabilizing role for the perineal body and external urethral sphincter. It is more developed in males, where it contributes to urinary continence and perineal stability. In females, it is often smaller, variably present, and replaced in function by surrounding smooth muscle and connective tissue.

Structure

The muscle is narrow and horizontal, composed of skeletal muscle fibers. It stretches from one side of the ischial ramus to the central perineal body, lying just superior to the superficial transverse perineal muscle, deep to the perineal membrane.

Origin and Insertion

• Origin: Medial surface of the ischial ramus
• Insertion: Perineal body (central tendon of perineum) and fibers interlace with those from the opposite side

Layer

• Located in the **deep perineal pouch**
• Positioned superior (deep) to the perineal membrane

Location

The deep transverse perineal muscle lies in the urogenital triangle and is one of the components of the deep perineal layer. It is situated lateral to the midline and contributes to the structure between the urogenital organs and the pelvic diaphragm.

Function

• Pelvic floor support: Helps stabilize the perineal body and provides foundational support for pelvic organs
• Assists urethral control: Coordinates with external urethral sphincter to aid urinary continence (especially in males)
• Maintains integrity of deep perineal pouch: Acts as a horizontal sling in the urogenital triangle

Innervation

• Deep branch of the perineal nerve (from pudendal nerve, S2–S4)

Blood Supply

• Perineal branches of the internal pudendal artery

Clinical Significance

• Pelvic floor dysfunction: Weakness may contribute to urinary incontinence or prolapse in males and females
• Surgical relevance: Important muscle in reconstructive perineal surgeries and pelvic floor repairs
• Obstetric injury: Often disrupted in deep perineal lacerations during childbirth