lobitamil.blogg.se - Thumb abduction

#Thumb abduction full#

Flexion and extension of the first CMC, MP, and IP joints occur in a plane that is perpendicular to the thumbnail. Abduction and adduction of the first CMC and MP joints occur in this plane. You can always orient yourself to the thumb's joint axes by considering the plane in which the thumbnail rests to be the thumb's frontal plane. These joints abduct and adduct in a plane that is perpendicular to the palm. The familiar AP axes, around which the MP joints abduct and adduct, are also turned 90 degrees at the thumb's CMC and MP joints. These joints flex and extend in a plane that is parallel to the palm. The familiar lateral axes, around which the fingers flex and extend, are turned 90 degrees at the thumb's CMC and MP joints. The thumbnail is oriented at a right angle to the nails of the other fingers. To appreciate this, examine the orientation of the fingernails on your relaxed hand as you point your fingertips toward yourself. This attachment is at nearly a right angle to those of the second, third, fourth, and fifth digits. The thumb or first ray, which comprises the metacarpal, proximal phalanx, and distal phalanx, attaches to the trapezium and the rest of the hand at the first carpo-metacarpal (CMC) joint. However, because the thumb attaches to the hand at a different angle than do the other digits, the thumb's AP and lateral axes are oriented differently than in the other digits.

Flexion and extension occur around a lateral axis.

Abduction and adduction occur around an antero-posterior axis.

We name thumb movements just as we do movements in the other finger joints. Naming of movements at the first CMC joint

convex in the plane of CMC flexion/extensionĭuring CMC flexion or extension (in a direction parallel to the palm), the metacarpal rolls and glides in the same direction.

concave in the plane of CMC abduction/adductionĭuring CMC abduction or adduction (in a direction perpendicular to the palm), the metacarpal rolls and glides in opposite directions.

Compare it with the figure in your text (Hertling & Kessler, 1996, Fig. 287) depicts the plane for CMC abduction/adduction. The diagram (Norkin & Levangier, 1992, p. The first metacarpal articulates with the trapezium. In these positions, the capsular fibers are maximally elongated and taut, and so prevent CMC rotation.

#Thumb abduction full#

You cannot passively rotate the CMC when you place it in full opposition or full reposition these are the CMC joint's close packed positions.

combined CMC extension and adduction produces CMC reposition.combined CMC flexion and abduction produces CMC opposition.However, its loose capsule permits rotation, and the metacarpal rotates automatically when it moves in the other two planes. Why do we name CMC movements in this manner? Some therapists refer to extension as "radial abduction," because the thumb moves toward the hand's radial side. The thumb's MP and CMC joints flex and extend in a plane parallel to the palm. Some therapists also refer to abduction as "palmar abduction."Ģ. The thumb's MP and CMC joints abduct and adduct in a plane perpendicular to the palm. Naming of movements at the first CMC joint.CMC Joint of the Thumb CMC Joint of the Thumb