{"schema":"https://ver.cy/schemas/card/1.0.0","id":"vr.tr.free-nerve-ending","code":"thing-q3290037","url":"https://ver.cy/models/thing/q3290037/","name":"free nerve ending","alternateNames":["unencapsulated nerve ending innervating cavitated organ","unencapsulated nerve ending innervating skin","unencapsulated nerve ending innervating solid organ"],"kind":"thing","status":"published","version":"0.1.0-research.1","language":"en","classifiers":{"family":"Thing Registry","category":"Physical world and living systems","entryKind":"thing","plane":"PHY","domain":["PHY.LIV"],"industry":[],"navPath":"","tags":[],"facets":{}},"whatItIs":"A free nerve ending is a peripheral sensory axon terminal lacking an organized connective-tissue capsule or specialized receptor corpuscle, whose sensory function depends on its neuronal subtype and tissue location.","purpose":"Enable an agent to recognize a free nerve ending, assess its local structural and sensory state, and select justified observations or experimental actions.","scope":{"in":["Terminal morphology and evidence for an unencapsulated sensory ending","Anatomical location, tissue compartment and local cellular relationships","Connection to a parent sensory axon and the limits of terminal identification","Measured stimulus responses and evidence supporting functional classification","Terminal integrity, local changes and methods used to assess them"],"out":["The complete sensory neuron, its soma and central projections","Encapsulated sensory corpuscles and specialized receptor-cell complexes","Motor endplates and autonomic effector terminals","Whole-organ anatomy and organism taxonomy","Pain experience, neurological diagnoses and treatment decisions"],"boundaries":[]},"distinguishingFeatures":["Identify a peripheral sensory terminal without an enclosing sensory corpuscle; insufficient imaging must remain an unresolved classification. Anatomical basis: [Cutaneous and Subcutaneous Somatic Sensory Receptors](https://www.ncbi.nlm.nih.gov/books/NBK11162/).","Establish a terminal branch or arbor rather than classifying any small nerve profile or passing axon as an ending.","Distinguish a free terminal from a sensory ending organized around a specialized receptor cell; absence of a capsule alone does not resolve this boundary.","Record terminal myelination separately from parent-axon myelination; an unmyelinated terminal does not establish that its entire parent axon is unmyelinated.","Separate morphological identification from functional classification; the label free nerve ending alone does not establish a measured nociceptive or thermal response."],"structure":{"bundles":[{"id":"terminal-identity","name":"Terminal identity","description":"Establish what anatomical unit is being called a free nerve ending.","layers":[{"id":"sensory-terminal-boundary","name":"Sensory terminal boundary","description":"Determine whether the observed structure is a peripheral sensory termination.","findings":[{"id":"terminal-continuity","name":"Terminal continuity","description":"Record evidence for a terminal branch and sensory identity separately from simple nerve-label positivity.","questions":[{"text":"What establishes that this profile terminates here rather than continuing outside the section or image?","id":"terminal-continuity-q01","kind":"boundary"},{"text":"What tracing, anatomical or functional evidence identifies it as sensory rather than motor or autonomic?","id":"terminal-continuity-q02","kind":"provenance"}]}]},{"id":"free-ending-morphology","name":"Free-ending morphology","description":"Assess encapsulation and organization around other receptor structures.","findings":[{"id":"encapsulation-and-specialization","name":"Encapsulation and specialization","description":"Document the observed terminal organization and the resolution needed to exclude competing receptor identities.","questions":[{"text":"Does the available reconstruction demonstrate absence of an enclosing sensory corpuscle?","id":"encapsulation-and-specialization-q01","kind":"definition"},{"text":"Is the terminal organized into a specialized receptor-cell complex that requires a neighboring model?","id":"encapsulation-and-specialization-q02","kind":"boundary"}]}]}]},{"id":"tissue-placement","name":"Tissue placement","description":"Locate the terminal and describe its immediate biological surroundings.","layers":[{"id":"anatomical-address","name":"Anatomical address","description":"Anchor the ending to a host specimen and a specific tissue compartment.","findings":[{"id":"compartment-localization","name":"Compartment localization","description":"Record site and depth without treating every free ending as a cutaneous structure.","questions":[{"text":"Which host, organ, anatomical site and tissue layer contain the observed terminal?","id":"compartment-localization-q01","kind":"provenance"},{"text":"What landmarks establish its depth and position relative to tissue boundaries?","id":"compartment-localization-q02","kind":"measurement"}]}]},{"id":"local-cellular-interface","name":"Local cellular interface","description":"Describe neighboring cells and extracellular relationships without implying functional coupling.","findings":[{"id":"terminal-neighbor-relations","name":"Terminal-neighbor relations","description":"Distinguish verified membrane relationships from apparent proximity in a projection.","questions":[{"text":"Which epithelial, glial, stromal or other cells are adjacent to the terminal?","id":"terminal-neighbor-relations-q01","kind":"measurement"},{"text":"Does the evidence show contact, intervening material or only unresolved proximity?","id":"terminal-neighbor-relations-q02","kind":"boundary"}]}]}]},{"id":"arbor-and-axon","name":"Arbor and axon","description":"Represent terminal branching and its connection to the supplying sensory fiber.","layers":[{"id":"terminal-reconstruction","name":"Terminal reconstruction","description":"Define the extent and completeness of the reconstructed terminal unit.","findings":[{"id":"arbor-extent","name":"Arbor extent","description":"Record branches, tips and truncation before comparing terminal architecture.","questions":[{"text":"Is the observation one tip, a complete arbor, a fragment or several overlapping endings?","id":"arbor-extent-q01","kind":"definition"},{"text":"What branch lengths, branch-point counts and spatial extent are measurable, and where is the reconstruction truncated?","id":"arbor-extent-q02","kind":"measurement"}]}]},{"id":"supplying-fiber","name":"Supplying fiber","description":"Link the terminal to its parent axon while distinguishing observed and inferred fiber properties.","findings":[{"id":"axon-link-and-classification","name":"Axon link and classification","description":"Keep continuity, myelination and physiological fiber classification as separate evidence-bearing statements.","questions":[{"text":"How was continuity between this ending and the identified parent axon established?","id":"axon-link-and-classification-q01","kind":"provenance"},{"text":"Where were myelination or conduction properties assessed, and do those measurements justify a parent-fiber classification?","id":"axon-link-and-classification-q02","kind":"measurement"}]}]}]},{"id":"sensory-transduction","name":"Sensory transduction","description":"Determine which stimuli produce a response and how specifically that response is attributed.","layers":[{"id":"stimulus-selectivity","name":"Stimulus selectivity","description":"Record tested modalities, delivered stimuli and the limits of functional classification.","findings":[{"id":"tested-response-profile","name":"Tested response profile","description":"Distinguish measured responsiveness from modality labels inferred from location or markers.","questions":[{"text":"Which mechanical, thermal or chemical stimuli were delivered at the terminal, at what magnitude and duration?","id":"tested-response-profile-q01","kind":"measurement"},{"text":"What evidence supports a functional label such as nociceptive, and which relevant stimuli remain untested?","id":"tested-response-profile-q02","kind":"boundary"}]}]},{"id":"response-attribution","name":"Response attribution","description":"Connect a recorded signal to the terminal and characterize its temporal behavior.","findings":[{"id":"threshold-and-dynamics","name":"Threshold and dynamics","description":"Record response criteria, latency and behavior during sustained or repeated stimulation.","questions":[{"text":"What response criterion defines threshold, and what latency or adaptation is observed under the stated protocol?","id":"threshold-and-dynamics-q01","kind":"measurement"},{"text":"How does the recording isolate this terminal or its supplying unit from neighboring afferents?","id":"threshold-and-dynamics-q02","kind":"provenance"}]}]}]},{"id":"terminal-condition","name":"Terminal condition","description":"Assess structural integrity and changes in responsiveness over time or between conditions.","layers":[{"id":"structural-integrity","name":"Structural integrity","description":"Evaluate disruption, loss or regrowth with attention to preparation and detection artifacts.","findings":[{"id":"damage-and-remodeling-evidence","name":"Damage and remodeling evidence","description":"Separate supported biological change from sectioning, incomplete labeling or different sampled regions.","questions":[{"text":"What observations support intactness, degeneration or regeneration of this terminal?","id":"damage-and-remodeling-evidence-q01","kind":"measurement"},{"text":"What controls distinguish true terminal loss or branching change from preparation and detection effects?","id":"damage-and-remodeling-evidence-q02","kind":"provenance"}]}]},{"id":"functional-state-change","name":"Functional state change","description":"Compare responsiveness under matched conditions without assigning a whole-person diagnosis.","findings":[{"id":"responsiveness-shift","name":"Responsiveness shift","description":"Track threshold or response changes relative to an explicit baseline.","questions":[{"text":"Relative to which baseline did threshold, spontaneous activity or evoked response change?","id":"responsiveness-shift-q01","kind":"measurement"},{"text":"What evidence separates a local terminal change from altered conduction, recording stability or stimulus delivery?","id":"responsiveness-shift-q02","kind":"boundary"}]}]}]},{"id":"assessment-and-action","name":"Assessment and action","description":"Select observations and experiments that resolve specific uncertainties about the ending.","layers":[{"id":"observation-validity","name":"Observation validity","description":"Establish what an imaging or sampling method can reliably count and identify.","findings":[{"id":"detection-and-counting","name":"Detection and counting","description":"Specify detection limits and distinguish counts of fibers, crossings, tips and reconstructed endings.","questions":[{"text":"What labeling specificity and spatial resolution support identification of this free ending?","id":"detection-and-counting-q01","kind":"provenance"},{"text":"If abundance is reported, what exactly is counted and what length, area or volume supplies the denominator?","id":"detection-and-counting-q02","kind":"measurement"}]}]},{"id":"targeted-investigation","name":"Targeted investigation","description":"Choose a proportionate next assessment with interpretable controls.","findings":[{"id":"next-resolving-action","name":"Next resolving action","description":"Connect each proposed observation or perturbation to a terminal-specific uncertainty and an interpretation rule.","questions":[{"text":"Would serial imaging, axon tracing or controlled stimulation best resolve the current uncertainty?","id":"next-resolving-action-q01","kind":"action"},{"text":"Which controls and stopping criteria would make an authorized perturbation interpretable while preserving the preparation's required viability?","id":"next-resolving-action-q02","kind":"action"}]}]}]},{"id":"evidence-and-external-alignment","name":"Evidence and external alignment","description":"What the world already says about this thing, gathered so the model can be checked against it.","layers":[{"id":"reported-evidence","name":"Reported evidence","description":"Findings from the breadth pass, kept separate from the structural claims.","findings":[{"id":"evidence-confidence-notes","name":"Check these first","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these check these first hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-confidence-notes-q01","kind":"provenance"}]},{"id":"evidence-kinds","name":"Kinds and varieties","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these kinds and varieties hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-kinds-q01","kind":"provenance"}]},{"id":"evidence-real-world-use","name":"Real-world use","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these real-world use hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-real-world-use-q01","kind":"provenance"}]},{"id":"evidence-measurements","name":"Typical measurements","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these typical measurements hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-measurements-q01","kind":"provenance"}]},{"id":"evidence-failure-modes-and-hazards","name":"Failure modes and hazards","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these failure modes and hazards hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-failure-modes-and-hazards-q01","kind":"provenance"}]},{"id":"evidence-regional-variation","name":"Regional variation","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these regional variation hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-regional-variation-q01","kind":"provenance"}]},{"id":"evidence-neighbours","name":"Neighbouring kinds and how to tell them apart","description":"Recalled without web access and unsourced; every item is a lead to verify.","questions":[{"text":"Which of these neighbouring kinds and how to tell them apart hold for the sense of free nerve ending this model covers, and on what evidence?","id":"evidence-neighbours-q01","kind":"provenance"}]}]}]}]},"agentConduct":{"may":["Explain what free nerve endings are and the sensations they carry, such as pain and temperature, from scientific sources.","Summarise research on pain and touch receptors with citations."],"mustNot":["Use knowledge of pain receptors to help cause pain to people or animals.","Present a person's pain as imagined or exaggerated because it has no visible cause.","Interpret a person's nerve test results as a diagnosis.","Promote unproven devices or remedies that claim to switch off pain nerves."],"requiresHuman":["Advising on pain treatment for a specific patient."]},"ethics":{"considerations":["Pain is real to the person who feels it even when it cannot be seen.","Research on pain often involves animals, whose welfare must be weighed."],"affectedParties":["People with chronic pain","Laboratory animals","Patients with nerve damage"]},"owners":{"steward":"Nobody owns them; they are part of each body.","roles":[],"masterSystems":[]},"relations":[{"target":"Q66591886","type":"parent","note":"registry parent class"}],"interaction":{"identity":{"applicability":"required","items":["Vercy registry: vr.tr.free-nerve-ending","Wikidata: Q3290037 (https://www.wikidata.org/wiki/Q3290037)"]},"properties":{"applicability":"required","items":["Observation unit: terminal tip | reconstructed arbor | terminal fragment | sampled population","Host and tissue compartment: organism or specimen reference; organ, anatomical site and tissue layer","Encapsulation assessment: absent with adequate evidence | present | unresolved","Terminal arbor geometry: length in µm; branch-point count; reconstructed extent in µm² or µm³","Parent sensory axon: traced axon reference with tracing method and confidence; unknown permitted","Myelination by segment: terminal and proximal segment each recorded as myelinated | unmyelinated | unresolved","Supported sensory response: mechanical | thermal | chemical | multiple tested modalities | no response under stated protocol | untested","Stimulus-response threshold: protocol-specific units such as °C, mN or mol/L, with response criterion","Evoked response: spikes/s, latency in ms, or explicitly identified optical signal units","Terminal condition: apparently intact | disrupted | degenerating | regenerating | indeterminate, with evidence","Sampling and detection method: preparation, labeling method, imaging resolution, sampling geometry and recording technique"]},"recognition":{"applicability":"required","items":["Under a microscope, fine branching nerve fibres ending bare among tissue cells, with no capsule.","Common in the skin, the cornea and the lining of organs."]},"capabilities":{"applicability":"required","items":["Annotate candidate endings and record the evidence supporting or limiting identification.","Trace terminal branches to a parent axon and map their tissue relationships.","Select imaging or labeling methods that can resolve the remaining anatomical boundary.","Design a controlled stimulus-response assessment for an appropriately authorized preparation.","Compare terminal structure or activity across matched sites, conditions or time points.","Flag claims about sensory modality, injury or recovery that exceed the available evidence."]},"hazards":{"applicability":"required","items":["Damage or disease of small nerve fibres can cause numbness or lasting burning pain.","Loss of pain sensation lets injuries go unnoticed, for example in the feet of people with diabetes."]},"interfaces":{"applicability":"required","items":["Terminologia Histologica, issued by the Federative International Committee on Anatomical Terminology, provides standardized terminology for describing histological structures including nerve endings."]},"context":{"applicability":"required","items":["Free nerve endings occur in skin and other tissues where sensory neurons detect local conditions.","They are studied in anatomy, histology and sensory physiology to relate terminal structure and location to functions such as pain, temperature and itch."]}},"sources":[{"title":"Wikidata item Q3290037: free nerve ending","url":"https://www.wikidata.org/wiki/Q3290037","note":"identity and sense of the item"},{"title":"Wikipedia: Free nerve ending","url":"https://en.wikipedia.org/wiki/Free_nerve_ending","note":"general description of the item"}],"openQuestions":["Which anatomical reference and operational criteria should govern the boundary between free endings and other unencapsulated sensory specializations across tissues?","Should the default individual unit be one terminal tip or the complete peripheral arbor of one afferent, and how should incomplete reconstructions be represented?","Which identification methods reliably distinguish sensory free endings from autonomic terminals in each target tissue and species?","What direct evidence is sufficient to assign nociceptive, thermal, mechanical or itch-related function to an individually identified ending?","Which site-, species- and method-specific reference data support interpretations of terminal abundance, degeneration, regeneration and altered responsiveness?"],"resources":{"spec":"/models/things/publications/thing-q3290037/spec.json"},"provenance":{"origin":"thing registry research (pass 2)","builtFrom":["models/things/publications/thing-q3290037/spec.json"],"providers":["Codex"],"researchStatus":"unreviewed","generatedAt":"2026-09-12T09:52:33Z","builder":"tools/build_cards.py@1.0.0"},"completeness":{"sections":{"classifiers":"filled","whatItIs":"filled","purpose":"filled","distinguishingFeatures":"filled","structure":"filled","agentConduct":"filled","ethics":"filled","owners":"filled","relations":"filled","interaction.identity":"filled","interaction.properties":"filled","interaction.recognition":"filled","interaction.capabilities":"filled","interaction.hazards":"filled","interaction.interfaces":"filled","interaction.context":"filled","sources":"filled"},"notes":{"_gate":"Published through the thing publication gate 1.0 on 2026-10-07T10:10:30+00:00: completeness 1.00; sense: Wikidata description; 2 live sources; review by codex: pass"},"score":1.0}}