Ergonomics & Posture
Travel Sleep and Ergonomics Glossary
Plain-English definitions of the terms you'll meet in our guides and on product listings.
Last reviewed
Anatomy & posture
- Cervical spine (C1–C7)
- The seven vertebrae of the neck, numbered from the top (C1, just below the skull) to the bottom (C7, at the base of the neck).
- Cervical lordosis
- The natural gentle inward curve of the neck. Good neck support helps keep this curve rather than flattening or exaggerating it.
- Neutral alignment
- Head balanced over the shoulders, ears roughly above the shoulders, chin level.
- Flexion
- Bending the head forward, chin toward chest — the most common drop when sleeping upright.
- Extension
- Tipping the head backward.
- Lateral flexion
- Tilting the head sideways, ear toward shoulder.
- Lateral head excursion
- How far the head moves sideways from center. Side bolsters aim to limit it.
- Occipital support
- Support at the back of the skull (the occiput), where a headrest or the rear of a collar meets the head.
- Sternocleidomastoid
- A pair of large muscles running from behind the ears to the collarbone and breastbone; they turn and tilt the head and can feel sore after awkward sleep.
- Trapezius
- A broad upper-back and neck muscle that often feels tight after long periods sitting.
- Lumbar support
- Support for the lower back's natural curve. It helps prevent slumping that pulls the head forward.
Materials & products
- Viscoelastic foam
- Memory foam: foam that responds slowly to pressure and heat, conforming to shape.
- Viscoelastic recovery
- The time memory foam takes to return to its original shape after pressure is removed.
- High-resilience (HR) foam
- Polyurethane foam with quick rebound and a supportive feel.
- Density
- Mass of foam per volume; generally relates to durability more than firmness.
- Open-cell foam
- Foam whose cell walls are partly open, allowing more airflow.
- Structured collar
- A travel neck support with a firm panel, frame or dense foam that holds the head rather than just cushioning it.
- Chin rest
- The raised front section of a pillow or collar that supports the jaw.
- ANC
- Active noise cancellation: headphones that generate opposing sound waves to reduce steady background noise.
See these ideas in context in the ergonomics guide and the travel neck pillows guide.