Muscles of the thumb
The muscles of the thumb are nine skeletal muscles located in the hand and forearm. The muscles allow for flexion, extension, adduction, abduction and opposition of the thumb. The muscles acting on the thumb can be divided into two groups: The extrinsic hand muscles, with their muscle bellies located in the forearm, and the intrinsic hand muscles, with their muscles bellies located in the hand proper.
| Muscles of the thumb | |
|---|---|
The muscles of the left hand (palmar surface) | |
| Details | |
| Origin | Hand and forearm |
| Insertion | Thumb |
| Artery | Ulnar and radial arteries |
| Nerve | Median and ulnar nerve (C7-T1) |
| Actions | Flexion, extension, adduction, abduction and oppossion of the thumb |
| Anatomical terms of muscle | |
The muscles can be compared to guy-wires supporting a flagpole; tension from these muscular guy-wires must be provided in all directions to maintain stability in the articulated column formed by the bones of the thumb. Because this stability is actively maintained by muscles rather than by articular constraints, most muscles attached to the thumb tend to be active during most thumb motions.