Trachea them as wider rings shortening the length of the trachea. Slide tracheoplasty is said to be the best option in treating tracheal stenosis. Mounier-Kuhn syndrome is a very rare congenital disorder of an abnormally enlarged trachea. Allowing for variations in the length of the neck, the trachea in other mammals is, in general, similar to that in humans. Generally, it is also similar to the reptilian trachea. In birds, the trachea runs from the pharynx to the syrinx, from which the primary bronchi diverge. Swans have an unusually elongated trachea, part of which is coiled beneath the sternum; this may
Composition of the human body Not all elements which are found in the human body in trace quantities play a role in life. Some of these elements are thought to be simple bystander contaminants without function (examples: caesium, titanium), while many others are thought to be active toxics, depending on amount (cadmium, mercury, radioactives). The possible utility and toxicity of a few elements at levels normally found in the body (aluminium) is debated. Functions have been proposed for trace amounts of cadmium and lead, although these are almost certainly toxic in amounts very much larger than normally found in the body. There is evidence that