Thumbs are innervated by the superficial fibular nerve, (L2-L4) and the flexor digitorum brevis originates on the ventral side of the fibula and the extensor digitorum brevis originates on the dorsal side of the fibula.
It is innervated by the anterior interosseus branch of the median nerve (C7-C8) It is a persistence of one of the former contrahentes muscles that pulled the fingers or toes together. It is innervated by the deep branch of the radial nerve (C7-C8). It is innervated by the deep branch of the radial nerve (C7-C8). It is innervated by the deep branch of the radial nerve (C7-T1). It is innervated by the median nerve (C8-T1). The superficial head is innervated by the median nerve, while the deep head is innervated by the ulnar nerve (C8-T1). It is innervated by the median nerve. It is innervated by the deep branch of the ulnar nerve (C8-T1). The extensor digitorum brevis manus usually originates from the dorsal aspect (backside) of the wrist, either from the joint capsule, the distal end (the most distant end) of the radius, the metacarpal, or from the radiocarpal ligament in the area of the fourth extensor compartment. In the first layer, the flexor digitorum brevis is the large central muscle located immediately above the plantar aponeurosis. 
