> For the complete documentation index, see [llms.txt](https://docs.snomed.org/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.snomed.org/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/body-structure/index/naming-convention-for-digits-of-hand-and-foot.md).
# Naming Convention for Digits of Hand and Foot
**This Editorial Guide is used for Education Purposes Only. It is used in the Authoring Courses and Certifications. It is based on the January 2026 Editorial Guide.**
Fully specified names and preferred names should use proper names of digits of hand and foot. The names by order of digits can be added as optional synonyms. The order of fingers is different from the order of digits of hand because the thumb is not a finger in SNOMED CT. Therefore, the order of the finger should not be used to avoid potential confusion.
### Naming convention for the structure of digits of hand
| FSN | PT | SYN | SYN |
| ---------------------------------------- | ----------------------- | -------------------- | ------------- |
| Index finger structure (body structure) | Index finger structure | Second digit of hand | Index finger |
| Little finger structure (body structure) | Little finger structure | Fifth digit of hand | Little finger |
| Middle finger structure (body structure) | Middle finger structure | Third digit of hand | Middle finger |
| Ring finger structure (body structure) | Ring finger structure | Fourth digit of hand | Ring finger |
| Thumb structure (body structure) | Thumb structure | First digit of hand | Thumb |
### Naming convention for the structure of digits of foot
| FSN | PT | SYN | SYN |
| ------------------------------------- | -------------------- | -------------------- | ---------- |
| Great toe structure (body structure) | Great toe structure | First digit of foot | First toe |
| Second toe structure (body structure) | Second toe structure | Second digit of foot | Second toe |
| Third toe structure (body structure) | Third toe structure | Third digit of foot | Third toe |
| Fourth toe structure (body structure) | Fourth toe structure | Fourth digit of foot | Fourth toe |
| Little toe structure (body structure) | Little toe structure | Fifth digit of foot | Fifth toe |
Provide Feedback
---
# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.
## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.
Perform an HTTP GET request on the current page URL with the `ask` query parameter, and the optional `goal` query parameter:
```
GET https://docs.snomed.org/education/snomed-ct-education-editorial-guide/readme/authoring/domain-specific-modeling/body-structure/index/naming-convention-for-digits-of-hand-and-foot.md?ask=&goal=
```
`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is optional and describes the broader end goal you are ultimately trying to accomplish on behalf of the user. GitBook uses it to tailor the answer towards what is most useful for that goal.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.
Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.