title: Accessory nerve latency to the middle and lower trapezius.
abstract: Trapezius muscle dysfunction occurs following injury to the spinal accessory nerve from a variety of causes. The trapezius consists of three distinct segments: upper, middle, and lower. Since previous studies of accessory nerve latency measure conduction to the upper trapezius segment only, this present study describes a standardized technique for determining accessory nerve latency to the middle and lower trapezius, a particularly important measurement for accurate examination for those who are in pain or unable to cooperate. Mean normal latency in 21 nerves to the middle trapezius is 3.0 +/- 0.2 msec and to the lower trapezius is 4.6 +/- 0.3 msec. Accessory nerve latency measurement of the middle and lower trapezius segments is valuable in a case of surgical injury in the posterior cervical triangle, especially during recovery from accessory nerve injury when reinnervation of the upper segment precedes the middle and lower segments.
mesh_terms: D000055:Accessory Nerve / Q000502:physiology* / Q000503:physiopathology; D000293:Adolescent; D000328:Adult; D000368:Aged; D001415:Back; D005260:Female; D006801:Humans; D008875:Middle Aged; D009123:Muscle Hypotonia / Q000503:physiopathology; D009132:Muscles / Q000294:innervation*; D011930:Reaction Time