Medical Definition of ARTHRODESIS. : the surgical immobilization of a joint so that the bones grow solidly together: artificial ankylosis. the surgical immobilization of a joint so that the bones grow solidly together. ADVERTISEMENT.
Trapdoor spiders are not particularly harmful to man however, like Tarantulas, the tiny hairs on the legs of some species leave tiny red marks where the toothed hairs on the spiders' feet have clung to the skin. Mouse spiders are also a type of Trapdoor spider with huge chelicerae and may measure up to 35mm in body length.
Almost all spiders are venomous. That's how they hunt. Most spiders are too small, or their venom too weak, to be dangerous to humans. Some spiders are pretty well-known, and seem to get blamed for most of the spider bites out there. In the United States, black widow spiders are often considered the most venomous.