Perineum Flashcards
What is the anterior boundary of the perineum?
the symphysis pubis.
What is the posterior boundary of the perineum?
the coccyx
What is the lateral boundary of the perineum?
the ischial tuberosities
What is the posterolateral boundary of the perineum?
the sacrotuberous ligament and gluteus maximus muscle
What is the floor of the perineum?
the skin and subcutaneous fascia.
What is the roof of the perineum?
the pelvic diaphragm
What is the anterolateral boundary of the perineum?
the ischiopubic rami.
The perineum is divided into two triangles by an imaginary line drawn between what structures?
the ischial tuberosities.
The line made connecting the ischial tuberosities and dividing the perineum makes what regions?
the urogenital (UG) triangle (anterior) and the anal triangle
What muscles make up the pelvic diaphragm?
the levator ani and coccygeus muscles
What structures pass through this diaphragm to enter the perineum?
The urethra, vagina (via the urogenital hiatus) and the anal canal (via the anal hiatus)
What is the innervation to the levator ani?
Inferior Rectal Nerve (S2-S4) and Direct Branches from S4
What is the innervation to the coccygeus?
Direct Branches from S3 and S4
What three fused bones compose the os coxae?
the ilium, pubic, and ischium
The two os coxae are fused to one another anteriorly at the _____ and are fused with the sacrum posteriorly at the _____ , forming the pelvic girdle.
pubic symphysis; the right and left sacroiliac joints
What does the linea terminalis define and what is it composed of?
it defines the superior pelvic aperture, a line circumscribing the sacral promontory (S1 Vertebra), the arcuate line of the ilium, the pectineal line of the pubis and the pubic symphysis.
What are the boundaries of the pelvic outlet?
the inferior margin of the pubic symphysis, inferior pubic rami, sacrotuberous ligaments and tip of the coccyx.
What are the main contents of the anal canal?
the anal canal and its external orifice (anus) in the midline and the right and left ischioanal fossa on either side of the canal
What are the The ischioanal fossae filled with?
What does this space allow for?
mostly fat. These spaces allow for movement of the pelvic diaphragm and expansion of the anal canal during defecation.
also contains the External Anal Sphincter muscle
What is the lateral boundary of the sischioanal fossa?
Obturator Internus muscle (perineal portion)
What is the superomedial boundary of the sischioanal fossa?
pelvic diaphragm
What is the inferior boundary of the sischioanal fossa?
skin/fascia
What is the posterior boundary of the sischioanal fossa?
sacrotuberous ligament with overlying fibers of gluteus maximus, fascia, and skin.
What are the three parts of the external anal sphincter (EAS)?
the deep, superficial, and subcutaneous portions