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Deep transverse perineal muscle

The deep transverse perineal muscle is a paired, flat, muscular structure located in the deep perineal pouch. It plays an important role in supporting the pelvic floor, stabilizing the perineal body, and aiding in urinary continence. Although it is relatively small, it is a key component of the urogenital diaphragm and is clinically important in pelvic surgery, obstetrics, and imaging of pelvic floor dysfunction.

Synonyms

  • Transversus perinei profundus

  • Deep perineal transverse muscle

  • Muscle of the urogenital diaphragm

Origin, Course, and Insertion

  • Origin: Arises from the inferior ramus of the ischium on both sides of the pelvis

  • Course: Fibers run medially and horizontally across the deep perineal pouch, passing toward the midline

  • Insertion: Inserts into the perineal body (central tendinous point of the perineum), where it interdigitates with fibers of the external anal sphincter and superficial perineal muscles

Relations

  • Superiorly: Perineal membrane and prostate (in males) or vagina (in females)

  • Inferiorly: Superficial transverse perineal muscle

  • Anteriorly: External urethral sphincter

  • Posteriorly: Perineal body and anal sphincter complex

  • Medially: Meets its counterpart at the perineal body

Function

  • Provides structural support to the perineal body

  • Stabilizes the central tendon of the perineum

  • Contributes to pelvic floor integrity

  • Assists in urinary continence by supporting the external urethral sphincter

  • Plays a role in sexual and reproductive function by stabilizing perineal structures

Clinical Significance

  • Can be damaged during childbirth, leading to pelvic floor weakness or perineal tears

  • Involved in pelvic floor dysfunction and urinary incontinence

  • Important landmark in perineal surgery and urogenital reconstruction

  • Weakening or atrophy may be identified on pelvic MRI in prolapse patients

MRI Appearance

T1-weighted images:

  • Muscle shows low-to-intermediate signal intensity

  • Surrounded by bright perineal fat, providing contrast

T2-weighted images:

  • Muscle demonstrates low-to-intermediate signal intensity

  • Pathology (edema, trauma, inflammation) appears as areas of bright signal

STIR (Short Tau Inversion Recovery):

  • Normal muscle appears dark to intermediate

  • Pathological changes such as inflammation or injury appear bright hyperintense

T1 Fat-Sat Post-Contrast:

  • Normal muscle shows mild, homogeneous enhancement

  • Inflammation or tumor involvement shows focal or heterogeneous enhancement

CT Appearance

Non-Contrast CT:

  • Muscle appears as a small soft tissue density band lateral to the perineal body

  • Difficult to delineate unless enlarged or surrounded by fat planes

Post-Contrast CT:

  • Normal muscle enhances mildly and uniformly

  • Pathological processes (infection, tumor, abscess) may show heterogeneous or rim enhancement

MRI image

Deep transverse perineal muscle MRI axial anatomy image-img-00000-00000

MRI image

Deep transverse perineal muscle MRI axial anatomy image-img-00000-00000_00001

CT image

Deep transverse perineal muscle CT axial anatomy image-img-00000-00000