> For the complete documentation index, see [llms.txt](https://docs.procedural-anatomy.com/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.procedural-anatomy.com/nodes/model-nodes/anatomy-muscle.md).

# Anatomy Muscle

The Muscle node creates the geometry muscle shapes as well as collision meshes for them.

Correct initial settings

Using the name and visibility controls

## Visualize

* Out Model - View the model or the collision model for the simulation.
* Group - Used to set selection.

## Shaping

* Subdivisions - Add extra detail to the muscle geometries
* Tangential Smooth - Smooth the underlying shape
* Envelope - Enable smoothing
* Step Size - Amount of smoothing

## SDF

* **Thickness** - Thickness of the skin, recommended to be a low value.
* **Resample Enable** - resample the SDF to be finer detail by smoothing it.
* **Scale** - Lowering this value creates more detail.
* **Size** - Raising this value creates more detail.

{% hint style="info" %}
Be careful about how much RAM you use!  You can sometimes double your usage with this.
{% endhint %}

### Expansion

**Samples** - how many increments we test to solve the muscle.  High samples will be more accurate.  Alternatively shorten projection distance.

**Iterations** - How many times we iterate the muscle solve, higher values will have an inflation effect to the muscles, lower will be faster to work with.

**Bias** - how close the muscles inflate to each other, 

**Projection Distance** - How far we test the muscles, usually should be between 0.1 - 1.0 for Human sized characters.  Might need to be bigger/smaller if your character is bigger/smaller.

**Threshold** - Limits expansion based on angle of the muscle versus the SDF gradient.

**Step Size** - Amount of smoothing.

### Self Intersections

**Samples** - Number of iterations to check self intersections on muscle geometry

**Threshold** - Limits expansion based on angle of the muscle versus the SDF gradient incorporated into the self intersection check.


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