## Gross Motor Milestone Sequence (0–18 months) **Key Point:** The correct developmental sequence is: **Sitting without support → Standing with support → Walking without support → Running**. ### Detailed Timeline | Age | Milestone | Key Features | | --- | --- | --- | | 4–6 months | Sitting with support | Requires hand support; trunk control developing | | 6–8 months | **Sitting without support** | Independent balance; no hand support needed | | 8–10 months | Standing with support | Pulls to stand using furniture or caregiver; weight-bearing begins | | 10–12 months | Cruising | Walks sideways while holding onto furniture | | 12–15 months | **Walking without support** | Independent ambulation; first independent steps | | 15–18 months | Running | Begins to run with stiff-legged gait; frequent falls | **High-Yield:** The **sitting-then-standing-then-walking** sequence reflects the development of **proximal-to-distal** and **cephalocaudal** control. Sitting (trunk stability) must precede standing (lower limb strength and balance), which must precede walking (coordinated limb movement). **Clinical Pearl:** Deviation from this sequence is a red flag. For example, a child who walks but cannot sit independently suggests selective motor weakness or neurological disorder (e.g., spinal muscular atrophy, cerebral palsy with lower limb predominance). **Mnemonic:** **SSW-R** — **S**itting (6–8 mo) → **S**tanding with support (8–10 mo) → **W**alking without support (12–15 mo) → **R**unning (15–18 mo). 
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