Perineum Flashcards
Diamond shaped region between the thighs containing the external genitalia, anal canal, and the neurovascular structures that supply them
Perineum
The perineum is bordered anteriorly by the
Pubic symphysis
The perineum is bordered anterolaterally by the
Ischiopubic rami
The perineum is bordered posterolaterally by the
Sacrotuberous ligaments
The perineum is bordered posteriorly by the
Coccyx
By extending a line from ischial tuberosity to ischial tuberosity, the perineum is divided into which two triangles?
- ) Urogenital (anterior)
2. ) Anal (posterior)
Contains the anal canal in the midline with the ischioanal fossae on either side
Anal triangle
Approximately 4cm in length extending between the anorectal junction (perineal flexure) and its opening
Anal canal
The mucosa of the proximal 2/3 of the canal is thrown into folds by underlying branches of the suerior rectal blood vessels. These folds are called called
Anal columns
The base of the anal column marks the transition between the
Hindgut (endoderm) portion and the proctodeum (ectoderm) derived distal 1/3
Marks the transition between the hindgut (endoderm) portion and the proctodeum (ectoderm) derived distal 1/3
Base of the anal canal
This area of transition is called the
Pectinate line
Fecal continence is controlled by which two muscular sphincters?
- ) Internal anal sphincter
2. ) External anal sphincter
Involuntary smooth muscle under autonomic controll
Internal anal sphincter
Voluntary skeletal muscle under somatic motor control
External anal sphincter
What is the embyonic derivation above the pectinate line
Hindgut (endoderm)
What is the motor innervation above the pectinate mind?
Autonomic
What is the sensory innervation of the anal canal above the pectinate line?
Visceral afferent and pressure
What is the arterial supply to the anal column above the pectinate line?
Superior rectal artery
What is the venous return from the anal canal above the pectinate line?
Superior rectal vein to hepatic portal venous system
What is the lymphatic drainage from the anal canal above the pectinate line?
Internal iliac nodes
Hemorrhoids of the anal canal ABOVE the pectinate line are
Internal and covered with mucosa
-Painless
Hemorrhoids BELOW the pectinate line are
External and covered by skin
-painful
Fat-filled triangular shaped spaces that allow for the distension and contraction of the anal canal during defecation
Ischioanal fossae