1st Rib Angle Assessment

Objective

To evaluate the positional alignment, slope, and functional mobility of the first rib relative to the horizontal plane at the cervicothoracic junction (C7–T1) using a clinical inclinometer alongside visual, palpatory, and functional movement assessment. This hybrid approach enhances objectivity in detecting 1st rib elevation, rotational asymmetry, and thoracic outlet risk factors.

Expanded Rationale

While visual and palpatory assessments provide qualitative insights, incorporating quantitative inclinometer measurement improves diagnostic precision and allows for progress tracking over time. This is particularly useful when evaluating:

  • Postural deviations involving scapular elevation

  • Hypertonicity of scalene and upper trapezius

  • Altered respiratory mechanics and apical breathing

  • Cervical spine instability

  • Subclinical or early-stage thoracic outlet compression

1. Setup and Client Positioning

  • Client Position: Seated upright in a neutral, unsupported posture with arms resting at sides. Feet flat on the floor, spine vertical, eyes level.

  • Examiner Position: Standing behind or to the side of the client, depending on the step being performed.

2. Step-by-Step Assessment Procedure

A. Visual and Structural Observation

  • From anterior view, inspect clavicle height, supraclavicular fossa depth, and symmetry.

  • From lateral view, estimate the 1st rib’s angle by observing its descent under the clavicle.

    • A normal rib angle should slope downwards from posterior to anterior at approximately 20–30 degrees in a healthy adult with neutral posture.

    • A more horizontal angle suggests rib elevation or fixation.

B. Palpation and Manual Rib Spring Test

  • Locate the posterior-superior aspect of the 1st rib:

    • Palpate just anterior to the upper trapezius, lateral to the transverse process of T1.

  • Apply gentle inferior pressure to assess spring (mobility) and compare bilaterally.

  • Palpate during inhalation and exhalation:

    • Normal: rib moves inferiorly during inhalation, superiorly on exhalation.

    • Dysfunction: rib remains elevated, stiff, or painful.

C. Inclinometer Measurement Protocol

Instrument Required:

  • Gravity-based or digital inclinometer calibrated to 0° before testing. (Chek inclinometer, PALM – Palpation Meter)

Landmarking and Placement:

  1. Palpate and visually mark the superior surface of the 1st rib just posterior to the clavicle.

  2. Place the inclinometer in the frontal plane, aligned vertically along the rib’s anterior surface as it descends beneath the clavicle.

  3. Hold gently in place ensuring the device sits flush to the rib’s surface, not the clavicle or soft tissue.

Reading the Angle:

  • Record the slope angle of the 1st rib on both left and right sides.

  • Normal range: 20°–30° downward slope from posterior to anterior.

  • Elevated rib: angle reduces toward horizontal (e.g., <15°), or angle differs >5° side-to-side.

  • Flattened rib or posterior rotation: angle may appear >35°, often with rib fixation.

Side Measured Rib Angle (°) Interpretation
Right ____° Normal / Elevated / Flattened
Left ____° Normal / Elevated / Flattened

D. Functional Correlation Tests

  1. Cervical Rotation + Lateral Flexion Test

    • Rotate head to one side, then side-bend to the opposite side.

    • Limited range or pain may suggest elevated rib on the same side as rotation or opposite side of side-bend.

  2. Breathing Observation

    • Hands on lower ribs; assess for upper chest dominance (clavicular/scalene recruitment).

    • If rib elevation occurs during quiet breathing, suggests overuse of accessory breathing patterns.

  3. Neurodynamic Testing (optional for advanced users)

    • Use ULTT (Upper Limb Tension Test) to check for brachial plexus tension.

    • Positive test may indicate neurovascular compression linked to 1st rib elevation.

Assessment Interpretation Table

Finding Potential Cause Clinical Implication
Rib angle < 15° Rib elevation due to scalene hypertonicity, forward head posture, apical breathing Impaired diaphragmatic function, thoracic outlet risk
Rib angle > 35° Rib depression, thoracic rigidity, fascial restriction Restricted thoracic rotation and posterior rib glide
> 5° asymmetry L vs. R Unilateral postural distortion or protective guarding Scapular imbalance, cervical rotation dysfunction

Closing Notes for Advanced Practitioners

  • Use the inclinometer to track changes over time as part of a corrective strategy involving:

    • Rib mobility drills

    • Diaphragmatic re-training

    • Fascial decompression

    • Upper quadrant muscle balancing

  • For more precision, use photo/video capture + inclinometer overlay apps to document client progress visually and numerically.

  • Integrate with neurosensory re-patterning when dysfunction is accompanied by vestibular, visual, or cerebellar involvement.