Abductor digiti minimi muscle of hand in three slips that are inserted into the ulnopalmar margin of the proximal phalanx, the palmar plate of the metacarpophalangeal joint, and the sesamoid bone when present. Some fibers insert into the finger's dorsal aponeurosis, which is why the muscle acts similar to a dorsal interosseus muscle. Additionally, the ulnar-most portion of the tendon inserts into the little finger's digital cord, and the muscle thus forms part of a structure that flexes the metacarpophalangeal joint and extends the interphalangeal joints. It is innervated by the deep branch of the ulnar nerve (C8–T1). The abductor digit minimi develops at an early
Bertram A. Bone solving the many problems which confronted him." During the Japanese Attack on Pearl Harbor on December 7, 1941, Bone was stationed on Hawaii and coordinated the trucks with ammunition. In May 1942, Bone was transferred to the staff of South Pacific Island Base Inspection Board under Rear Admiral Richard E. Byrd and travelled to the South Pacific Area as a member of the inspecting party. He was promoted to the rank of colonel on July 24, 1942. During September of that year, Bone was transferred to Washington, D.C. and appointed Chief of the Gunnery Section, Division of Plans and Policies