Physiotherapy Online on Instagram: "Clinical breakdown: • Primary muscle: Deltoid • Nerve: Axillary nerve • Root level: C5 • Patient position: Sitting or standing • Test: Ask the patient to lift their arm out to the side against resistance What weakness may indicate: • C5 nerve root compression • Cervical radiculopathy • Upper trunk brachial plexus involvement Quick clinical tip: Compare both sides and always correlate with C5 dermatome (lateral upper arm) and biceps reflex (C5–C6) for a complet