Muscle activation patterns in snapping triceps syndrome.
OBJECTIVE
To compare the muscle activation pattern in subjects with and without "snapping triceps syndrome" (dislocation of the medial head of the triceps and ulnar nerve over the medial epicondyle).


METHODS
Controlled study.


METHODS
Biomechanics laboratory.


METHODS
Eight male subjects (9 elbows), with symptomatic snapping triceps and 9 male controls.


METHODS
Not applicable.


METHODS
Activation pattern of the 3 triceps heads during active elbow extension at 0 degrees , 45 degrees , 70 degrees , 90 degrees , and 115 degrees of flexion, recorded by fine-wire electromyography.


RESULTS
There were no significant differences between subjects and controls in the firing pattern of the triceps heads. The medial head fired first in 6 of 9 symptomatic elbows and in 7 of 9 controls at 90 degrees of flexion, and in 6 of 9 elbows of both subjects and controls at 115 degrees of flexion, positions where snapping typically occurs. There was no significant difference between the groups as to how often the medial head fired maximally.


CONCLUSIONS
This study suggests the firing pattern of the triceps heads may not contribute to the pathogenesis of this syndrome. Rather, the authors believe the anatomic position of the medial head causes it to dislocate over the medial epicondyle, often resulting in ulnar neuritis.
Boon
Andrea J
AJ
Department of Physical Medicine and Rehabilitation, Mayo Clinic, Rochester, MN 55905, USA.
Spinner
Robert J
RJ
Bernhardt
Kathie A
KA
Ross
Scott R
SR
Kaufman
Kenton R
KR
D000328:Adult; D016022:Case-Control Studies; D004551:Elbow Joint / Q000503:physiopathology*; D004576:Electromyography; D006801:Humans; D007537:Isometric Contraction / Q000502:physiology; D008297:Male; D018482:Muscle, Skeletal / Q000503:physiopathology*; D016059:Range of Motion, Articular / Q000502:physiology; D013577:Syndrome; D014459:Ulnar Nerve / Q000503:physiopathology*