In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: The likely mechanism of paralysis is diffusion of Botox around the muscular process of the arytenoid to the posterior cricoarytenoid muscles .
### Output Text:
The likely mechanism of paralysis is diffusion of <span class="chemical">Botox</span> around the muscular process of the arytenoid to the posterior cricoarytenoid muscles . 