In recent years, some taxonomic controversy has occurred over the genus of North American rat snakes. Based on mitochondrial DNA, Utiger et al. (2002) showed that North American rat snakes of the genus Elaphe, along with closely related genera such as Pituophis and Lampropeltis, form a monophyletic group separate from Old World members of the genus.
A pinched nerve is a type of injury or damage to a nerve or a group of nerves. The injury can result from compression, constriction, or stretching. A pinched nerve can lead to other conditions and cause temporary or permanent damage depending on the extent of the injury. pinched nerve is a type of injury or damage to a nerve or a group of nerves. The injury can result from compression, constriction, or stretching. A pinched nerve can lead to other conditions and cause temporary or permanent damage depending on the extent of the injury.
Causes of Esophageal Strictures. 1  Esophagitis is the inflammation of the lining of the esophagus which often leads to swelling. 2  Gastroesophageal reflux disease (GERD) is worth considering on its own.  Esophageal webs and rings are common structural abnormalities of the esophagus more often found in the distal esophagus.