Rectum and Anus Flashcards
What separates the pelvic cavity from the abdominal cavity?
Peritoneum
What muscle is associated with the pelvic floor?
Levator ani
What is the purpose of the rectum?
A holding area
When doing a PR exam what can be palpated anteriorly in males/females?
Males - prostate
Females - cervix
Which nerve supplies the levator ani and which parts of the spinal cord supply this?
Pudendal nerve
‘S2,3,4 keeps the guts off the floor’
Which muscle in the levator ani acts as a voluntary sphincter and what is its mechanism of action?
Puborectalis
Travels from pubis-pubis around the anal canal, when contracted increases the rectal-anal angle and when relaxed decreases the angle for defecation to occur
What forms the internal anal sphincter?
Thickening of the circular smooth muscles of the GI tract
Which nerve supplies the external anal sphincter?
Pudendal - part of levator ani muscle
Where is the transition between smooth and skeletal muscle in the distal GI tract?
Levator ani muscle onwards is skeletal (somatic)
Which nerves supply the rectum and anal canal and what type of outflow are they?
T12-L2: Sympathetic
S2-4: Somatic motor, visceral afferent, Parasympathetics
What is the pectinate line?
The junction between the parts of the GI tract derived from ectoderm and endoderm
Above: endoderm
Below: ectoderm
What changes occur at the pectinate line?
Arterial supply: From IMA to internal iliacs
Nerve supply: from autonomic to somatic/pudendal
Venous drainage: Hepatic portal (via IMA) to systemic (via internal iliacs)
What is the difference between rectal varices and haemorrhoids?
Rectal varices are due to portal hypertension
Haemorrhoids the dilated vessels move away from anatomical position
What is the difference between external and internal haemorrhoids?
Internal: above pectinate line - doesn’t leave body (not as painful - visceral)
External: Below pectinate line - can leave the body (very painful - somatic)
