The Anal Triangle Flashcards
What are the base and apex of the anal triangle?
- The base is the imaginary line between the ischial tuberosities
- The apex is the coccyx
When does the rectum become the anal canal?
When it pierces the pelvic floor in the anal triangle
What is the name of the spaces either side of the rectum?
Ishiorectal fossae
What nerve innervates the external anal sphincter?
The inferior rectal nerve
What nerve innervates the wall of the rectum and anal canal?
The inferior rectal nerve
What forms the walls of the ishiorectal fossa?
Ischial tuberosity, rectum/anal canal
What forms the roof of the ishiorectal fossa?
Levator ani
What forms the floor of the ishiorectal fossa?
Skin
What forms the contents of the ishiorectal fossa?
Branches of the pudendal nerve, artery, vein and adipose tissue
How do the inferior erectile vessels and nerves reach the external anal sphincter?
By crossing the ishiorectal fossa
What is the name of the small internal folds in the anal canal?
Anal columns
The wall of the anal canal forms the?
Involuntary internal anal sphincter
Where is voluntary control of deification from?
The skeletal muscles that surround the opening of the anal canal
Where is the external anal sphincter located?
Wraps around the opening of the anal canal and passes between the perineal body and anococcygeal ligament
What is the perineal body of the anal canal?
A small dense structure found on the edge of the urogenital diaphragm providing attachment for muscles of the perineum
What muscle aids the external anal sphincter by bending the rectum to slow passage of feces?
Puborectalis
What vein forms an internal venus rectal plexus that is superficial to the internal sphincter?
Inferior rectal vein
What is the pectinate line?
An imaginary line which divides the upper two thirds and lower third of the anal canal
What is the anocutaneous line?
Is the transition line between the anal canal to true skin
What structures are supplied by the superior rectal artery?
The wall of the rectum (superior area)
What structures are supplied by the middle rectal artery?
The middle are of the rectum
What structures are supplied by the inferior rectal artery?
The inferior area of the rectum and the anal canal
