Final answer:
The anatomical basis of the pelvic pain line is junction between the hindgut and external skin, where the mucosa above is less sensitive and the area below is highly sensitive. The dermatomes and region of the body wall to which visceral pain from viscera (or portions thereof) located inferior to the pelvic pain line can be referred such as the umbilicus, perineum, lower sacrum, inguinal region, and upper thigh.
Step-by-step explanation:
The pelvic pain line is a horizontal band called the pectinate line, which represents the junction between the hindgut and external skin. The area above this line is fairly insensitive, while the area below is very sensitive. Visceral pain information from abdominopelvic viscera located superior to this line is projected to the central nervous system (CNS) through visceral sensory fibers. On the other hand, visceral pain from viscera located inferior to the pelvic pain line can be referred to different regions of the body wall due to the misinterpretation of sensory fibers at the spinal cord level.
To identify the dermatomes and region of the body wall to which visceral pain from viscera located inferior to the pelvic pain line can be referred, we need to refer to a referred pain chart. According to the chart provided, visceral pain from the kidney can be referred to the T10-T12 dermatomes, which correspond to the region of the body wall around the umbilicus.
Visceral pain from the urinary bladder can be referred to the S2-S4 dermatomes, which correspond to the region of the body wall around the perineum and lower sacrum. Visceral pain from the ureter can be referred to the T11-L2 dermatomes, which correspond to the region of the body wall around the inguinal region and upper thigh.
So therefore the pelvic pain line, also known as the pectinate line, refers to the junction between the hindgut and external skin, where the mucosa above is less sensitive and the area below is highly sensitive. Visceral pain from the viscera located inferior to the pelvic pain line can be referred to different regions of the body wall, such as the umbilicus, perineum, lower sacrum, inguinal region, and upper thigh.