The lower slips of serratus anterior are the most functionally important component — their pull on the inferior scapular angle produces the upward rotation essential for arm elevation above 90 degrees. Without them, full elevation is impossible.
| Origin | Outer surfaces of ribs 6-9 — lower digitations |
|---|---|
| Insertion | Inferior angle of the scapula — the largest and most powerful attachment zone |
| Nerve Supply | Long thoracic nerve (C5, C6, C7) |
| Blood Supply | Lateral thoracic artery |
| Actions | Upward rotation of the scapula — the primary function of the lower slips; The inferior angle pull produces the rotational force that elevates the glenoid for full arm elevation |
|---|
Lower serratus slip weakness is the most clinically significant pattern of serratus palsy, producing inability to elevate the arm above 90 degrees and the classic winging seen during wall push-ups. The long thoracic nerve to the lower slips is the most distal and therefore most vulnerable to stretch injury.
Observed as inferior angle winging during arm elevation and wall push-up testing.
Loss of lower serratus slips producing inferior angle winging and inability to elevate above 90 degrees, the most functionally limiting pattern of serratus anterior palsy.
