QuestionSBA
QuestionChoice
This describes the anal columns which are folds of epithelium with anal valves located at the bottom of each column.
10040769
d
It is longitudinal folds of epithelium which are joined by anal valves at the inferior ends.
QuestionChoice
This statement describes the external anal sphincter which is labelled by the blue arrow. The external anal sphincter is innervated by the pudendal nerve and acts to constrict the anal canal thereby keeping the anal canal closed and maintaining faecal continence.
10040766
a
It is a voluntary muscle that surrounds the lower 2/3rds of the anal canal.
QuestionChoice
This describes the internal anal sphincter which is made of involuntary circular smooth muscle. The internal anal sphincter is responsible for maintaining approximately 70% of resting anal tone and keeping the anal canal closed. There is some anatomical overlap between the internal and external anal sphincter.
10040767
b
It is an involuntary muscle that surrounds the upper 2/3rds of the anal canal.
QuestionChoice
This describes the pectinate (dentate) line which divides the anal canal into upper and lower parts. Clinically, the anal canal below the dentate line is innervated by the inferior rectal nerve, which means that pain can be felt. The autonomic nervous system innervates the area above the dentate line.
10040768
c
It is formed by the anal valves which divides the anal canal into upper and lower parts.
QuestionChoice
The anal valves collectively form the pectinate (dentate) line. Just superior to these valves lie small pouches termed anal sinuses, which contain mucus secreting glands.
10040770
e
It is a mucus secreting area located just superior to the anal columns
Concept
Chapter
2693
5343
Anal canal
Topic
197
Abdominal anatomy
20452
Picture
3051
6 - External anal sphincter.png
images/ye74v9bs1727763688521.jpg
images/ye74v9bs1727763688521_256.jpg
images/ye74v9bs1727763688521_512.jpg
JggGDAJ6/GTImah4tsf2eWqPpw==
Topic
197
Abdominal anatomy
Which statement correctly describes the labelled structure?
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a