الفهرس 
The Anatomical consideration of The ThumbOnly 14 pages are availabe for public view
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Abstract
The Thumb owing to its particular position and action forms a separate entity without which a very large part of hand function would be lost.
In fact, its presence is essential to achieve a pinch grip with each of the other fingers and in particular with the index. Its presence is also essential for the formation of a power grip with the other fingers.
This unique function of the thumb is partly due to the special arrangement of its bony column and associated muscles. These factors all result in the ability of the thumb to perform its specific movement of opposition, thus enabling it to come into contact with other fingers, either individually or together (Sarwat.Aziz.Gobrial 1986).
Functions of the Thumb
* Thumb is responsible for 40% of hand function.
* Abduction, adduction, opposition, flexion, extension, pronation, supination.(James.Chang 2010)
The thumb reigns over the hand because of its ability to oppose, but it could do nothing without the CMC. Joint(Sarwat.Aziz.Gobrial 1986).
The motor muscles of the thumb may be divided into two groups:
1. Extrinsic muscles: whose muscle bellies are situated in the forearm, they are the one used to release the grip except the flexor pollicis longus.
(Abductor pollicis longus - Extensor pollicis brevis - Extensor pollicis longus - Flexor pollicis longus)
2. Intrinsic muscles: which are situated in thenar eminence and are responsible for performing the different types of grip.
(The opponens - abductor pollicis brevis - flexor pollicis brevis +adductor pollicis muscle)
However, taken as a whole in relationship to the thumb, the intrinsic are the motor muscles of opposition and the extrinsic are the motor muscles of contra-opposition.
Similarly, the radial nerve brings about contra-opposition; the median nerve controls the attitude of opposition; & the ulnar nerve completes and adds strength to the movement of opposition(Sarwat.Aziz.Gobrial 1986).
Congenital absent thumb is type V thumb hypoplasia according to Blauth Classification (Tonkin 2011).
Total absence of the thumb may be an isolated anomaly, but it is often associated with some other congenital malformation;
Absent thumb may be inherited as autosomal dominant or may be sporadic (Buck-Gramcko.D 1971, DI.Clark 1998, Clifford.R 2011)
Related syndromes or associations warrant consideration and systemic evaluation. The primary concerns are:
Holt-Oram syndrome,
Thrombocytopenia–absent-radius (TAR) syndrome,
VACTERL association (vertebral abnormalities, anal atresia, cardiac abnormalities, tracheoesophageal fistula, esophageal atresia, renal defects, radial dysplasia, lower limb abnormalities),
And Fanconi’s anemia(Auerbach.AD 1989, Kozin.SH 2003)
Absent radius is almost always associated with an absent thumb, except in thrombocytopenia radial aplasia (Fanconi’s syndrome), where thumb is present even when the radius is absent(Buck-Gramcko.D 1971, DI.Clark 1998, Clifford.R 2011)
Pollicization is the procedure of choice in congenital absent thumb. Good outcomes have been reported for range of movement, power, appearance and sensation.