Atlas · Chest

Subclavius

Subclavius is a small muscle between the first rib and the underside of the clavicle. Discomfort below the collarbone needs a regional shoulder and chest assessment, especially when arm tingling, swelling or color change accompanies it.

Body region: Chest · Shoulder
Trigger points: 0; documented in this muscle
Common symptoms: 4; patterns cataloged
Common causes: 3; contributory factors

Muscle overview

Symptoms and first steps

Practical first steps

Temporarily reduce the specific carrying or overhead exposure that reproduces symptoms and support the forearm when comfortable.
Keep easy shoulder motion rather than forcefully pulling the shoulders down and back.
Avoid balls, hooks or deep fingertip pressure under the clavicle, particularly if arm symptoms occur.

When to seek assessment

Chest pressure, breathlessness, sweating, faintness or unexplained acute chest/arm pain requires emergency assessment.
New arm swelling, bluish discoloration, a cold/pale hand or rapidly progressive weakness needs urgent assessment.
Significant trauma, visible clavicular deformity or severe pain around the sternoclavicular joint needs prompt medical review.

Costoclavicular tenderness is an observation, while thoracic outlet syndrome is a clinical diagnosis. Do not use firm pressure under the clavicle or a change in pulse as proof of a subclavius problem.

Examination, palpation and treatment evidence

Anatomy reference; no mapped trigger points yet.

Symptoms patients report

Ache just below the clavicle

Note whether carrying, reaching or local contact changes it; sternoclavicular, clavicular, shoulder and chest-wall structures share this region.

Discomfort during sustained arm elevation

Record the time and task that provoke symptoms rather than attributing the response to one small muscle.

Arm tingling, heaviness or weakness

These findings require a neck/peripheral nerve and possible thoracic-outlet assessment; they are not simply a muscle referral pattern.

Arm swelling, discoloration or coldness

New vascular-type changes require urgent medical assessment rather than self-massage.

Common causes

Increased carrying or overhead demand

A change in work, training or bag load may alter tolerance in the shoulder girdle; gradual exposure can be assessed.

Clavicular or shoulder injury history

Prior fracture, joint injury or surgery changes the anatomical and clinical assessment.

Costoclavicular neurovascular relationships

The bundle passes near the clavicle and first rib; anatomical variation alone does not establish symptomatic compression.

Treatment & self-care

Everyday adjustments

Adjust provoking carrying and overhead tasks

Assessed load-related shoulder-girdle symptoms without vascular changes or progressive deficit. Reduce a heavy bag load, support the forearm during sustained tasks and break overhead work into shorter bouts. Let the scapula move naturally rather than forcefully holding it down and back. Reintroduce one task demand at a time as the arm remains comfortable during and after activity. Conservative thoracic-outlet and shoulder care uses activity modification. This does not establish that subclavius was compressing the bundle or that a posture correction releases it.

Duration: Choose a task duration below the sustained symptom threshold; no validated subclavius-specific schedule.

Exercise and movement

Restore comfortable shoulder-girdle movement

A tolerable movement limitation after injury and neurological/vascular causes have been considered. With the forearm resting on a table, slide the hand forward through a comfortable arc and return, allowing natural scapular motion. A clinician can add light shoulder-girdle resistance or endurance work appropriate to the diagnosis. Build comfortable range before repetitions, resistance or overhead time. Active rehabilitation is supported for assessed shoulder presentations. It does not selectively strengthen subclavius or demonstrate correction of a costoclavicular compression.

Duration: Pragmatic example: 5–8 supported reaches once daily; adjust to response. This is regional movement practice, not an isolated subclavius trial protocol.

Professional care

Condition-specific rehabilitation for diagnosed NTOS

A clinician-supported neurogenic thoracic-outlet diagnosis without a reason for urgent vascular or surgical assessment. An experienced clinician tailors shoulder-girdle endurance, task modification and, when tolerated, nerve mobility to the examination. Recheck distal symptoms and function; avoid deep infraclavicular compression and aggressive shoulder depression. Review a meaningful overhead, carrying or work task at agreed intervals and progress only with stable neurological function. The 2024 INTOS workgroup describes conservative care as first-line for most NTOS. It is expert consensus and does not establish efficacy of subclavius DN, ESWT, toxin or injection.

Duration: INTOS consensus generally supports 3–6 months of conservative care before considering surgery, but weakness/atrophy may warrant earlier escalation. This is a consensus pathway, not a fixed subclavius exercise dose.

Differential diagnosis

Neurogenic thoracic outlet syndrome
Venous or arterial thoracic-outlet/upper-limb vascular disease
Clavicle or sternoclavicular/acromioclavicular joint disorder
Cervical radiculopathy or distal nerve entrapment
Rotator-cuff or other shoulder pain

For clinicians and supervised training

Clinical reference

Record local pain separately from neurological or vascular arm symptoms. A trigger-point map is not yet documented.

Anatomy and palpation

Anatomical relationships

Subclavius runs from the first rib near its costochondral junction to the subclavian groove on the inferior middle clavicle. The nerve to subclavius supplies it. It helps control clavicular movement; cadaveric work also describes variable fibrous extensions toward the coracoid, which should not be mistaken for the standard muscle insertion.[1][2][3]

Right subclavius beneath the clavicle, anterior view with first-rib context. Source model: Essential Anatomy 5.

The clavicle is palpable from the sternoclavicular joint medially to the acromioclavicular joint laterally.
The subclavian groove lies on its inferior surface; the muscle is deep to the local fascial/pectoral tissues.
The first rib is a deep relationship, not a structure to seek by forceful infraclavicular probing.

Nearby structures. The subclavian/axillary vessels and brachial plexus occupy the nearby costoclavicular passage, with pleura deeper in the thoracic inlet. Surface tenderness cannot define their relationship to an instrument or establish the source of arm symptoms.

Palpation

Patient position. Seated or supine with the forearm supported and shoulder relaxed; compare comfortable arm positions without forced depression.

Find the landmarks

Identify the clavicle and both clavicular joints before gentle superficial contact below it.
Distinguish joint-localized pain from a broader infraclavicular ache.

Examination sequence

Use light regional contact only to document familiar pain, swelling or focal bony tenderness.
Compare a comfortable reach or carry with the arm supported; record local pain separately from tingling or heaviness.
A specialist may use ultrasound or other imaging when a specific vascular, structural or post-injury question would change care.

Document the findings

Record the patient-recognized symptom and the task/position that reproduces it.
Do not label a deep band as isolated subclavius or infer nerve compression from tenderness alone.

Limits and precautions

Do not hook fingers or instruments beneath the clavicle, compress a pulsating area or attempt to reproduce distal symptoms.
Defer local treatment with new swelling, discoloration, coldness or progressive weakness.

[3][4][1]

Examination and tests

Shoulder elevation and supported-task comparison[5][4]

Identify the movement or load associated with the infraclavicular complaint.

Position: Seated or standing; arm initially relaxed, then supported as needed.
Technique: Observe slow comfortable arm elevation and a light version of the relevant reach/carry. Record local pain, range, scapular movement and arm symptoms, then compare with forearm support.
Positive finding: A repeatable task-related complaint or clear movement/force limitation is a regional finding.
Interpretation: Helps select load adjustments and whether a shoulder, clavicular-joint or neurological examination is needed.
Limitations: Many muscles and joints contribute. Symptom change with support does not isolate subclavius or diagnose thoracic outlet syndrome.

Clinician thoracic-outlet assessment[4]

Evaluate an arm-symptom pattern that may involve the thoracic outlet and exclude common alternatives.

Position: Seated or standing with symptoms and limb appearance documented at rest.
Technique: Take a task-related history and compare strength, sensation and limb appearance. If appropriate, a trained clinician adds the elevated-arm stress test using the published method and stops for intolerable symptoms. Interpret with the full examination; pulse changes are not a stand-alone diagnostic test.
Positive finding: Familiar arm symptoms in a coherent clinical pattern may support further NTOS assessment; vascular change requires a separate pathway.
Interpretation: Helps decide on targeted conservative care, specialist assessment or investigation.
Limitations: Provocative tests have limited specificity and cannot identify the exact compressing tissue. They do not establish a subclavius trigger point and are not endurance challenges to perform at home.

Cervical and peripheral nerve examination[6][4]

Differentiate cervical-root and distal nerve involvement from a costoclavicular hypothesis.

Position: Seated with both upper limbs available for comparison.
Technique: Assess cervical symptom response, myotomal strength, sensation and reflexes. Examine common distal entrapment sites when the distribution fits, adding graded neurodynamic testing only when clinically indicated.
Positive finding: Concordant objective deficits or reproducible nerve-distribution symptoms guide the differential.
Interpretation: A root or distal nerve pattern may explain arm symptoms even when the infraclavicular region is tender.
Limitations: One negative maneuver cannot exclude all neural disease; local tenderness does not settle the diagnosis.

Distinguishing other causes

Neurogenic thoracic outlet syndrome[4]

Findings that matter. Arm pain/paresthesia related to overhead activity or other positions, with a coherent history/examination and consideration of alternatives.

Next step. Specialist or experienced rehabilitation assessment using current clinical criteria; progressive weakness/atrophy changes escalation.

Venous or arterial thoracic-outlet/upper-limb vascular disease[3][4]

Findings that matter. New swelling, cyanosis, coldness, pallor or exertional vascular symptoms; acute changes may indicate thrombosis or compromised flow.

Next step. Urgent medical/vascular assessment; do not massage or stretch through the symptoms.

Clavicle or sternoclavicular/acromioclavicular joint disorder[1]

Findings that matter. Trauma, deformity, swelling or focal joint/bone pain that differs from diffuse soft-tissue tenderness.

Next step. Assess injury and joint findings; medical imaging is selected when it affects management.

Cervical radiculopathy or distal nerve entrapment[6][4]

Findings that matter. Symptoms follow a root or peripheral-nerve distribution, with weakness, reflex or sensory findings and relevant provocation.

Next step. Use the regional neurological examination and appropriate referral rather than repeated infraclavicular release.

Rotator-cuff or other shoulder pain[5]

Findings that matter. Pain relates to shoulder elevation, rotation or tendon loading, with shoulder-specific weakness or motion restriction.

Next step. Follow the shoulder examination and condition-specific rehabilitation pathway.

Treatment selection and progression

Self-care and activity

Adjust provoking carrying and overhead tasks[4][5]

Consider when. Assessed load-related shoulder-girdle symptoms without vascular changes or progressive deficit.

Reduce a heavy bag load, support the forearm during sustained tasks and break overhead work into shorter bouts. Let the scapula move naturally rather than forcefully holding it down and back.

Dose and review: Choose a task duration below the sustained symptom threshold; no validated subclavius-specific schedule.
Progression: Reintroduce one task demand at a time as the arm remains comfortable during and after activity.
Stop or reassess: New swelling, color change, persistent tingling or weakness requires reassessment.
Evidence and limits: Conservative thoracic-outlet and shoulder care uses activity modification. This does not establish that subclavius was compressing the bundle or that a posture correction releases it.

Exercise and rehabilitation

Restore comfortable shoulder-girdle movement[5][4]

Consider when. A tolerable movement limitation after injury and neurological/vascular causes have been considered.

With the forearm resting on a table, slide the hand forward through a comfortable arc and return, allowing natural scapular motion. A clinician can add light shoulder-girdle resistance or endurance work appropriate to the diagnosis.

Dose and review: Pragmatic example: 5–8 supported reaches once daily; adjust to response. This is regional movement practice, not an isolated subclavius trial protocol.
Progression: Build comfortable range before repetitions, resistance or overhead time.
Stop or reassess: Stop for distal tingling, heaviness, swelling or a sustained flare; do not continue to a fixed repetition target.
Evidence and limits: Active rehabilitation is supported for assessed shoulder presentations. It does not selectively strengthen subclavius or demonstrate correction of a costoclavicular compression.

Clinician-delivered care

Condition-specific rehabilitation for diagnosed NTOS[4]

Consider when. A clinician-supported neurogenic thoracic-outlet diagnosis without a reason for urgent vascular or surgical assessment.

An experienced clinician tailors shoulder-girdle endurance, task modification and, when tolerated, nerve mobility to the examination. Recheck distal symptoms and function; avoid deep infraclavicular compression and aggressive shoulder depression.

Dose and review: INTOS consensus generally supports 3–6 months of conservative care before considering surgery, but weakness/atrophy may warrant earlier escalation. This is a consensus pathway, not a fixed subclavius exercise dose.
Progression: Review a meaningful overhead, carrying or work task at agreed intervals and progress only with stable neurological function.
Stop or reassess: Escalate progressive weakness/atrophy, vascular symptoms or failure of an appropriate program; do not extend passive treatment indefinitely.
Evidence and limits: The 2024 INTOS workgroup describes conservative care as first-line for most NTOS. It is expert consensus and does not establish efficacy of subclavius DN, ESWT, toxin or injection.

Reassessment and follow-up

Repeat a defined carry or overhead task with the same load/support and record both local and distal symptoms.
Track hand strength, sensation and any vascular appearance changes when relevant to the presenting complaint.
Revisit clavicular/joint, cervical, distal nerve and vascular diagnoses if the expected functional progress does not occur.

Evidence and sources

Anatomy, Shoulder and Upper Limb, Shoulder
2023 · Clinical anatomy reference
Subclavius from first rib to inferior middle clavicle, nerve to subclavius and clavicular action; normal attachments distinguished from accessory variants.
The anatomy and variation of the coracoid attachment of the subclavius muscle in humans
2021 · Primary cadaveric study
52 upper extremities from 26 cadavers; variable fibrous extensions toward the coracoid. Anatomical variation is not evidence that a painful point compresses a nerve or requires release.
Anatomy, Thorax, Subclavian Veins
2026 · Clinical anatomy reference
2026 update accessed September 2026. Costoclavicular neurovascular relationships used for examination context, not a needle trajectory or proof of symptomatic compression.
Chim et al. Consensus Recommendations for Neurogenic Thoracic Outlet Syndrome from the INTOS Workgroup
2024 · Expert clinical consensus
21 surgeons; diagnosis uses history, examination and differential assessment. Conservative care generally first-line, with weakness/atrophy altering escalation. No subclavius-specific procedure efficacy is established.
Rotator Cuff Tendinopathy Diagnosis, Nonsurgical Medical Care, and Rehabilitation: A Clinical Practice Guideline
2025 · Clinical practice guideline
Active shoulder rehabilitation and tendon/joint differential context; no isolated subclavius strengthening or release recommendation.
Blanpied et al. Neck Pain: Revision 2017
2017 · Clinical practice guideline
Regional classification, neurological assessment and multimodal active care. Exercise examples below are starting options, not validated doses for isolated deep-flexor pain.