Ape hand is a physical deformity in humans causing an inability to abduct or oppose the thumb thereby causing the thumb little or no abduction and opposition.  Abduction of the thumb is the ability to move the perpendicular (90°) away from the plane of the palm. The opposition is the ability of the first metacarpal to swing over the palmar surface of the hand so that the thumb and the tip of the little finger are in contact. The thumb may also experience limited flexion and extension.
The term "ape hand" is however misleading as apes have opposable hands but due to the limitations in the function of the thumb, some people believe it makes the hand looks like that of an ape.
Mechanism of Injury / Pathological Process
The condition is a part of median nerve palsy and it typically presents with problems moving the thumb in various planes. There is a limited range of motion of the thumb.
Management / Interventions
Surgery may be prescribed depending on the severity of the deformity, anti-inflammatory drugs and corticosteroid injections may also be used.  Occupational therapy, Physiotherapy and dynamic splinting which pulls the thumb in opposition may prevent excess in deformity. It is however possible to recover without treatment. Physical therapy helps to regain muscle strength while splints (C-splints) and braces help to recover.  However, not much research work has been done on Physiotherapy and Ape Hand.
- Anatomy Tables - Hand. Available from; https://web.archive.org/web/20080118014710/http://anatomy.med.umich.edu/musculoskeletal_system/hand_tables.html (Last accessed 11/Oct/2020)
- Gross Anatomy - The Brachial Plexus. Available from; https://web.archive.org/web/20090904141914/http://www.upstate.edu/cdb/grossanat/limbs2.shtml (Last accessed 11/Oct/2020)
- Washington State Department of Labor and Industry. Work-Related Proximal Median Nerve Entrapment (PMNE) Diagnosis and Treatment (PDF). 2009.
- US National Library of Medicine. MedlinePlus. Distal median nerve dysfunction. Available from; https://medlineplus.gov/ency/article/000691.htm (Last accessed 11/10/2020)