Reactants and Products in Chemical Reactions. In a chemical reaction, substances (elements and/or compounds) called reactants are changed into other substances (compounds and/or elements) called products. You canât change one element into another in a chemical reaction â that happens in nuclear reactions.
The pudendal nerve is the main nerve of the perineum. It carries sensation from the external genitalia of both sexes and the skin around the anus and perineum, as well the motor supply to various pelvic muscles, including the male or female external urethral sphincter and the external anal sphincter.he pudendal nerve passes between the piriformis muscle and coccygeus (ischiococcygeus) muscles and leaves the pelvis through the lower part of the greater sciatic foramen. It crosses over the lateral part of the sacrospinous ligament and reenters the pelvis through the lesser sciatic foramen.
See the list below: 1  Pudendal nerve block does not abolish sensation to the anterior part of the perineum, as the perineum is supplied by branches of the ilioinguinal and genitofemoral nerves. 2  Failure to wait a sufficient time after injection is a common reason for block failure.