Geographic Range. The original range of Canis lupus consisted of the majority of the Northern hemisphere -- from the Arctic continuing south to a latitude of 20Â° S, which runs through southern Central Mexico, northern Africa, and southern Asia.
Disc desiccation is an extremely common degenerative change of intervertebral discs. The incidence climbs with age, and to a large degree a gradual desiccation is a 'normal' part of disc aging. It results from replacement of the hydrophilic glycosaminoglycans within the nucleus polposus with fibrocartilage.
tracheal bifurcation. 1. the division of the trachea into the right and left main bronchi; it occurs at the level of the fifth or sixth thoracic vertebral body and is marked internally by the presence of a carina or keellike ridge between the diverging bronchi.