Erb's palsy (C5–C6)
[object Object]
What it means
Upper brachial-plexus injury (C5–C6) — excessive increase in the head–shoulder angle (shoulder dystocia at birth; a fall onto the shoulder). Paralyses abductors/external rotators + elbow flexors → arm adducted, internally rotated, elbow extended, forearm pronated = the 'waiter's tip' posture.
Worked example
Macrosomic baby after shoulder dystocia holds the arm in the waiter's-tip position with an absent biceps/Moro on that side.
In the exam
After a difficult delivery complicated by shoulder dystocia, a newborn holds one arm adducted, internally rotated and pronated with the elbow extended.
What settles it
Erb's (C5–6) = waiter's tip, proximal arm. Klumpke's (C8–T1) = distal CLAW hand ± Horner's from T1 sympathetic loss.
Classically confused with
Klumpke's palsy (C8–T1)
Source: TeachMeAnatomy — Brachial plexus injuries