Muscles used under a handstand

Shoulders

• Anterior, Middle and Lateral deltoids
• Rotator Cuffs  (For shoulder Stabilization)
  
  • infraspinatus,
  • supraspinatus,
  • teres minor
  • subscapularis

Upper Back And Arms

• Trapezius Upper Portion (Rotator cuff is primary beneath this, but supports the shoulder, therefore it’s placed in the shoulder section although it’s upper back)
• Rhomboid
• Wrist Flexors
  • Flexor Pollicis Longus
  • Flexor Digitorum Superficialis
  • Flexor Carpi Radialis
• Wrist Extensors
  • Extensor Pollicis Brevis
  • Extensor Carpi Radialis Brevis
  • Extensor Carpi Radialis Longus

The Abdominal Core

• External Oblique
• Internal Oblique
• Transversus Abdominis
• Rectus Abdominis
• Multifidus
• Erector Spinae

These are the main muscles used under the handstand. Note that this is for the static handstand, straight up and down. No movements.