The atlantomastoid: a muscle variant relevant to point-of-care ultrasound?
Bibliographic record
Abstract
The atlantomastoid is a variant muscle of the suboccipital region, originating from the transverse process of the atlas (C1) and inserting on the posterior aspect of the mastoid process of the temporal bone (Fig. 1 A). The atlantomastoid is supplied by the occipital artery and innervated by the suboccipital nerve(1); the former is a branch of the external carotid artery and the latter is formed by the dorsal ramus of C1. A recent study determined the muscle’s prevalence to be 15%(2). Because of the atlantomastoid's proximity to the four typical suboccipital muscles and certain neurovascular structures of the posterior cervical region, detection of the atlantomastoid muscle using ultrasound may be beneficial for clinicians performing interventional procedures in the suboccipital region, and for manual therapists that manipulate the cervical spine. Summarized in this letter is a point-of-care ultrasound (POCUS) simulation that was conducted on a cadaveric specimen, whereby the mastoid process, the transverse process of C1, and the obliquus capitis inferior served as anatomical landmarks to aid in the imaging of the muscle. This letter aims to bring attention to the atlantomastoid variant and highlight its potential clinical importance for POCUS practitioner
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.007 |
| Meta-epidemiology (narrow) | 0.002 | 0.001 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.002 | 0.002 |
| Science and technology studies | 0.001 | 0.002 |
| Scholarly communication | 0.001 | 0.002 |
| Open science | 0.002 | 0.001 |
| Research integrity | 0.008 | 0.003 |
| Insufficient payload (model declined to judge) | 0.005 | 0.001 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".