a dorsal is an organ that protects the nervous system.
The roots are two split bases of spinal nerves that connect to the spinal cord. The rami are branches of the spinal nerve that form a complex system throughout the body with the two primary ones...
There's no such thing.
Dorsal rhizotomy-- A surgical procedure that cuts nerve roots to reduce spasticity in affected muscles.
Lying on back, knees bent. Usually called 'dorsal recumbent position'.