Systems Atlas Project

Level 2

Peripheral nervous system

human-biological/nervous-system/peripheral-nervous-system

Justification

What has been written down.

Six fields are required of every node. Empty ones are shown as declared gaps — a gap means nothing has been written, not that there is nothing to write.

Definition

Comment

Declared gap No definition has been written.

Inclusion

Comment

Declared gap No inclusion criteria have been written.

Exclusion

Comment

Declared gap No exclusions have been recorded.

Sources

Comment

Declared gap No sources have been cited.

Boundary cases

Comment
  • Cranial nerves are placed here on anatomical grounds. For CN I and CN II this is not histologically clean — both are central nervous tissue — but anatomical placement is applied consistently across the division rather than making an exception for two nerves.

Uncertainty

Comment
  • Whether anatomical or histological criteria should govern this division is unresolved. See diagnostics.

Divides into

3 components at level 3.

Comment
Cranial nerves Level 3

Declared gap No definition has been written.

 Spinal nerves Level 3

Declared gap No definition has been written.

 Peripheral ganglia Level 3

Declared gap No definition has been written.

Rules

Whether this division survives the six rules.

Rules 1, 5 and 6 are checked by the validator and reported here. Rules 2, 3 and 4 are judgements about meaning and cannot be automated — no state is claimed for them. The rules themselves are set out in the method.

Rule 01

At most seven

Divides into 3 components.

Passes
Rule 02

Mutually exclusive

A judgement about whether the parts overlap. Not automated.

Not checked
Rule 03

Collectively exhaustive

A judgement about what the parts leave out. Not automated.

Not checked
Rule 04

Equal abstraction

A judgement about whether the parts answer the same question type. Not automated.

Not checked
Rule 05

Decomposable or terminal

Divides into 3 parts.

Passes
Rule 06

Justified in writing

2 of the six fields carry content. The rest are declared gaps.

Warning

Diagnostics

1 entry against this node.

Where this division has been put under pressure and what happened. An entry is not a task list — some record that the question is open and that leaving it open was the decision.

Cranial nerve placement 2026-07-31

Cranial nerves are placed in the peripheral nervous system on anatomical grounds. CN I and CN II are histologically central nervous tissue, and CN II is a tract of the diencephalon rather than a peripheral nerve. Placing them peripherally makes the division fail on histological criteria while passing on anatomical ones, which means the division is only mutually exclusive once it is fixed which criterion governs.

Unresolved, left standing

Proposals

What has been argued about this node.

Nothing has been decided against this node. That is not the same as nothing being wrong with it.

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Discussion

What has been said about this node.

Nothing published on this node yet.

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