The deep transverse perineal muscle (DTPM) is a small, flat, paired muscle that is part of the pelvic floor musculature. Located deep within the pelvis, it acts as a supportive sling at the base of the torso. The muscle’s structure grants it a specific role in maintaining the integrity of the pelvic outlet and contributing to core stability. The pelvic floor’s ability to withstand downward pressures and manage sphincteric control relies on the cooperative strength of muscles like the DTPM.
Precise Anatomical Location
The deep transverse perineal muscle is situated within the deep perineal pouch, lying immediately beneath the main pelvic floor muscles, the levator ani. This places the DTPM in a deeper layer compared to the superficial transverse perineal muscle. It is a short, thin sheet of muscle that spans horizontally across the anterior section of the pelvic outlet.
The muscle originates laterally from the internal surface of the inferior ramus of the ischium. From this bony anchor, the muscle fibers travel medially toward the center of the pelvis. The DTPM inserts into the perineal body, a dense, central fibromuscular structure also known as the central tendon of the perineum.
The fibers from the left and right sides meet at this midline point, often intermingling to create a strong, interwoven anchor. This deep location, superior to the perineal membrane, positions the DTPM strategically to support structures passing through the pelvis. Its attachment to the stable ischium provides the necessary tension to brace the central tendon against downward forces.
Isolated Physiological Function
When the deep transverse perineal muscle contracts, its primary mechanical action is to pull and stabilize the perineal body in a posterior direction. This fixation of the central tendon is important because the perineal body serves as the attachment site for several other surrounding muscles. By bracing this central anchor, the DTPM ensures that other muscles can generate effective tension and contraction.
The muscle’s contraction maintains tension across the deep perineal space itself. This sustained tension helps to reinforce the entire pelvic floor structure from below, providing a firm, horizontal shelf of support. This specific kinetic action is focused on structural reinforcement rather than a large range of motion.
The DTPM acts as a stabilizer that ensures the mechanical advantage of the other sphincteric and supportive muscles. It works to resist the downward pressure exerted by the abdominal contents during activities like coughing or lifting. Its function is a continuous, low-level bracing action that maintains the structural geometry of the pelvis under stress.
Integration into the Urogenital Diaphragm
The deep transverse perineal muscle is a component of the deep perineal pouch, a triangular, multilayered sheet spanning the anterior pelvic outlet. This complex was historically referred to as the urogenital diaphragm. The DTPM, along with the external urethral sphincter and associated fascia, forms the muscular content of this deep space.
This arrangement creates a robust, horizontal layer situated inferior to the main pelvic diaphragm, which is formed by the levator ani muscles. This collective unit provides a firm base for the passage of the urethra in both sexes and the vagina in females, offering support directly beneath the pelvic organs.
The DTPM fibers lie in the same plane as the external urethral sphincter, which controls urine flow. This close physical relationship means that DTPM contraction contributes to the overall firmness of the region, indirectly assisting the sphincteric mechanism. The DTPM solidifies the deep perineal pouch, allowing it to function as a unified supportive and compressive unit.
Role in Pelvic Stability and Continence
The functional integration of the deep transverse perineal muscle provides practical outcomes for overall pelvic health, particularly in two major areas: pelvic stability and urinary continence. Its stabilizing action on the central tendon is transmitted to the entire pelvic girdle, helping to anchor the base of the trunk during dynamic movements. This stability is important during physical exertion, such as running or weightlifting, where intra-abdominal pressure increases significantly.
The DTPM’s location within the urogenital diaphragm makes it a direct contributor to urinary continence, especially stress continence. By reinforcing the structure around the urethra, the muscle helps to support the position of the bladder neck and the external urethral sphincter. When the DTPM contracts, it provides a firm, supportive backstop that allows the urethral sphincter to compress the urethra effectively.
A weakened DTPM or damage to the perineal body can compromise this supportive mechanism, potentially contributing to pelvic floor dysfunction. Maintaining the integrity of this muscle is fundamental to the long-term health and stability of the entire lower core. It works with the other deep muscles to ensure that the passageways remain closed and that the pelvic organs retain their correct anatomical position under stress.