The muscle of hand that contains a sesamoid bone is
Flexor pollicis brevis
Flexor pollicis longus
Opponens pollicis
Adductor pollicis
The tendon of inseion of adductor pollicis on the medial side of base of proximal phalanx of thumb contains a sesamoid bone.Reference: Textbook of anatomy, Upper limb, and thorax, Vishram Singh, 2nd edition, page no.144
Upper limb