Rare diseases · Sign or symptom
Neck flexor weakness
Neck flexion weakness
HP:0003722
What it means
Weakness of the muscles involved in neck flexion (sternocleidomastoid, longus capitus, longus colli, and scalenus anterior).
Rare diseases that can present with this16
Common30–79%
9- Adult-onset nemaline myopathy
- Autosomal dominant mitochondrial myopathy with exercise intolerance
- Autosomal recessive distal nebulin myopathy
- Glycogen storage disease with severe cardiomyopathy due to glycogenin deficiency
- Hereditary myopathy with early respiratory failure
- Maternal uniparental disomy of chromosome 4 syndrome
- Postsynaptic congenital myasthenic syndrome
- Pure mitochondrial myopathy
- Typical nemaline myopathy
Sometimes5–29%
6The range is how often this sign appears among people diagnosed with each disease — it is not a probability of having any of them. Many of these signs also occur in common, non-rare conditions. A sign on this page is a conversation to have with a clinician, not a conclusion.
Part of the broader category
Also called: Neck flexor muscle weakness
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Start free with EleplanThis page uses the Human Phenotype Ontology (2026-06-23) — Human Phenotype Ontology Consortium, hpo.jax.org. Disease associations from Orphanet (INSERM), CC BY 4.0. Content is educational and is not medical advice.