Involuntary arm abduction that follows sustained isometric contraction of the deltoid and supraspinatus muscles (usually performed by pushing the upper extremity forcibly and against an immovable vertical surface while standing beside it).
Synonym(s): Kohnstamm phenomenon
Persistent, spontaneous contraction of a muscle after a strong contraction against resistance has ceased. This is seen when a person forcibly pushes an arm against a wall while standing with the frontal plane perpendicular to the wall. When this is stopped and the person moves away from the wall, the arm abducts involuntarily and is elevated by the deltoid muscle.Synonym: Kohnstamm phenomenon