Question

What is the difference between venous drainage from the rectum above the pectinate line and below the pectinate line?

Answer 1

The difference lies in the sensitivity and innervation of the two regions. Above the pectinate line, the mucosa is fairly insensitive and innervated by visceral sensory fibers. Below the pectinate line, the area is very sensitive and innervated by somatic sensory fibers.

Step-by-step explanation:

The difference between venous drainage from the rectum above the pectinate line and below the pectinate line lies in the sensitivity and innervation of these regions.

1. 
   
2. Above the pectinate line: The mucosa in this region is fairly insensitive, and it is innervated by visceral sensory fibers.
3. 
   
4. Below the pectinate line: The area in this region is very sensitive, and it is innervated by somatic sensory fibers.

This difference in pain threshold is due to the type of sensory fibers present in each region.