UAMS Department of Neurobiology and Developmental Sciences - Topographical Anatomy of the Pelvis and Perineum

Gross Anatomy


Topographical Anatomy of the Pelvis & Perineum - Listed Alphabetically

Structure/Space Description/Boundaries Significance
anal triangle posterior subdivision of the diamond-shaped perineum; its boundaries are: anteriorly - posterior margin of the perineal membrane (corresponds to an imaginary line connecting the ischial tuberosities); posterolaterally - sacrotuberous ligament anal triangle is the location of the terminal end of the gastrointestinal tract (anus)
ischioanal fossa a fat-filled space located lateral to the anal canal and inferior to the pelvic diaphragm; its boundaries are: superomedially - pelvic diaphragm (anterior recess extends superior to the urogenital diaphragm); medially - external anal sphincter muscle and anal canal; laterally - obturator internus fascia and ischial tuberosity; posterolaterally - sacrotuberous ligament and gluteus maximus m.; (posterior recess extends superior to the gluteus maximus m.) the fat and loose connective tissue in the ischioanal fossa compresses to allow passage of feces; also known as: ischiorectal fossa
natal cleft midline cleft between the buttocks natal cleft lies between the gluteus maximus muscles
perineum a diamond-shaped space forming the outlet of the pelvis; its boundaries are: anterolaterally - inferior pubic ramus, ischial ramus and ischial tuberosity; posterolaterally - sacrotuberous ligament perineum is subdivided into the anal triangle and urogenital triangle by an imaginary line connecting the ischial tuberosities
urogenital triangle anterior subdivision of the diamond-shaped perineum; its boundaries are: anterolaterally - inferior pubic ramus, ischial ramus; posteriorly - posterior margin of perineal membrane (corresponds to an imaginary line connecting the ischial tuberosities) urogenital triangle is the location of the terminal portion of the urinary tract and genital tract


Some of the material presented in these tables is contained in the book:
MedCharts Anatomy by Thomas R. Gest and Jaye Schlesinger
Published by ILOC, Inc., New York. Copyright 1995.

The content of these tables has been edited for use in this course by Patrick W. Tank, Ph.D.
Copyright 2009, Department of Neurobiology and Developmental Sciences, University of Arkansas for Medical Sciences.
Unauthorized use is prohibited.




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