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: An electrodiagnostic study , including a nerve conduction study of the LACN , was helpful to diagnose right LACNP and to find the passage of the LACN on the lateral epicondyle .
### Output Text:
An electrodiagnostic study , including a nerve conduction study of the LACN , was helpful to diagnose right LACNP and to find the passage of the LACN on the lateral epicondyle . 