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Muscle
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 Click on image for larger view |
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Name
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Abductor pollicis brevis
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Subdivision
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Muscle Anatomy
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Origin
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Flexor retinaculum, tubercle of trapezium bone and tubercle of scaphoid bone. | |
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Insertion
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Base of proximal phalanx of thumb, radial side,
and extensor expansion.
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Function
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Abduct the carpometacarpal and metacarpophalangeal
joints of the thumb in a ventral direction perpendicular to the
plane of the palm. By virtue of its attachment into the dorsal extensor
expansion, may extend the interphalangeal joint of the thumb. Assists
in opposition, and may assist in flexion of the metacarpophalangeal
joint.
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Recommended sensor placement procedure
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Starting posture
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Sitting or supine with the back of the hand stabilised
on a table.
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Electrode size
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For isometric contractions: maximum size in the
direction of the muscle fibres: 5 mm.
For dynamic contractions: maximum size in the direction of the muscle fibres: 2 mm. |
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Electrode distance
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For isometrics contractions: 7.5 mm.
For dynamic contractions: 5 mm. |
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Electrode placement
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- location
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Slightly medial of the distal 1/4 of the 1st ossa
metacarpalia.
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- orientation
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Parallel to the 1st ossa metacarpalia.
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- fixation on the skin
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(Double sided) tape / rings or elastic band.
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- reference electrode
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On / around the wrist.
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| Clinical test | Abduct the thumb ventralward from the palm while applying pressure against the proximal phalanx in the direction of adduction toward the palm. | |
| Remarks |
The SENIAM guidelines include a separate sensor
placement procedure recommendation for the long head of triceps
brachii..
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