Flexor Pollicis Longus

FLEXOR POLLICIS LONGUS

Origin: Anterior surface of the body of the radius below the tuberosity, interosseous membrane, medial border of the coronoid process of the ulna, and/or the medial epi-condyle of the humerus.

Insertion: Base of the distal phalanx of the thumb, palmar surface.

Action: Flexes the interphalangeal joint of the thumb. Assists in flexion of the metacarpophalangeal and car-pometacarpal joints, and may assist in flexion of the wrist.

Patient: Sitting or supine.

Fixation: The hand may rest on the table for support (as illustrated), with the examiner stabilizing the metacarpal bone and proximal phalanx of the thumb in extension. Alternatively, the hand may rest on its ulnar side, with the wrist in slight extension and the examiner stabilizing the proximal phalanx of the thumb in extension.

Test: Flexion of the interphalangeal joint of the thumb.

Pressure: Against the palmar surface of the distal phalanx, in the direction of extension.

Weakness: Decreases the ability to flex the distal phalanx, making it difficult to hold a pencil for writing or to pick up minute objects between the thumb and fingers. Marked weakness may result in a hyperextension deformity of the interphalangeal joint.

Contracture: Flexion deformity of the interphalangeal joint.

FLEXOR POLLICIS BREVIS

Origin of Superficial Head: Flexor retinaculum and trapezium bone.

Origin of Deep Head: Trapezoid and capitate bones.

Insertion: Base of the proximal phalanx of the thumb, radial side and extensor expansion.

Action: Flexes the metacarpophalangeal and carpometacarpal joints of the thumb, and assists in opposition of the thumb toward the little finger. By virtue of its attachment into the dorsal extensor expansion, may extend the interphalangeal joint.

Nerve to Superficial Head: Median, C6. 7, 8, Tl. Nerve to Deep Head: Ulnar, C8, Tl.

Patient: Sitting or supine.

Fixation: The examiner stabilizes the hand.

Test: Flexion of the metacarpophalangeal joint of the thumb without flexion of the interphalangeal joint.

Pressure: Against the palmar surface of the proximal phalanx, in the direction of extension.

Weakness: Decreases the ability to flex the metacarpophalangeal joint, making it difficult to grip objects firmly between the thumb and fingers. Marked weakness may result in a hyperextension deformity of the metacar-pophalangeal joint.

Contracture: langeal joint.

Flexion deformity of the metacarpopha-

EXTENSOR POLLICIS LONGUS

Origin: Middle '/3 of the posterior surface of the ulna distal to origin of the abductor pollicis longus, and to the interosseous membrane.

Insertion: Base of the distal phalanx of the thumb, dorsal surface.

Action: Extends the interphalangeal joint, and assists in extension of the metacarpophalangeal and car-pometacarpal joints of the thumb. Assists in abduction and extension of the wrist.

Patient: Sitting or supine.

Fixation: The examiner stabilizes the hand and gives counterpressure against the palmar surface of the first metacarpal and proximal phalanx.

Test: Extension of the interphalangeal joint of the thumb.

Pressure: Against the dorsal surface of the interpha-langeal joint of the thumb, in the direction of flexion.

Weakness: Decreases the ability to extend the interpha-langeal joint, and may result in a flexion deformity of that joint.

Note: In a radial nerve lesion, the interphalangeal joint of the thumb may be extended by action of the abductor pollicis brevis, the flexor pollicis brevis, the oblique fibers of the adductor pollicis, or the first palmar interosseous by virtue of their insertions into the extensor expansion of the thumb. Interphalangealjoint extension in an otherwise complete radial nerve lesion should not be interpreted as regeneration or partial involvement if only this one action is observed.

EXTENSOR POLLICIS BREVIS

Origin: Posterior surface of the body of radius distal to origin of abductor pollicis longus, and to the interosseous membrane.

Insertion: Base of the proximal phalanx of the thumb, dorsal surface.

Action: Extends the metacarpophalangeal joint of the thumb, and extends and abducts the carpometacarpal joint. Also assists in abduction (radial deviation) of the wrist.

Patient: Sitting or supine.

Fixation: The examiner stabilizes the wrist.

Test: Extension of the metacarpophalangeal joint of the thumb.

Pressure: Against the dorsal surface of the proximal phalanx, in the direction of flexion.

Weakness: Decreases the ability to extend the metacar-pophalangeal joint, and may result in a position of flexion of that joint.

Lett posterior

ABDUCTOR POLUCIS LONGUS

Origin: Posterior surface of the body of the ulna distal to origin of the supinator, interosseous membrane, and posterior surface of middle xh of the body of the radius.

Insertion: Base of the first metacarpal bone, radial side.

Action: Abducts and extends the carpometacarpal joint of the thumb, and abducts (radial deviation) and assists in flexing the wrist.

Patient: Sitting or supine.

Fixation: The examiner stabilizes the wrist.

Test: Abduction and slight extension of the first metacarpal bone.

Pressure: Against the lateral surface of the distal end of the first metacarpal, in the direction of adduction and flexion.

Weakness: Decreases the ability to abduct the first metacarpal and the wrist.

Contracture: Abducted and slightly extended position of the first metacarpal, with slight radial deviation of the hand.

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