Decreased number of alpha-motoneurons in the cervical intumescence of calves with arthrogryposis multiplex congenita of both thoracic limbs.

The number of alpha-motoneurons in the spinal cord segments C6 to Th2 of five calves with Arthrogryposis Multiplex Congenita (AMC) and of five normal calves was compared. A statistically highly significant reduction in the number of alpha-motoneurons in segment C6 was observed in the affected calves. Two hypotheses to explain the effect of these findings were proposed. Firstly, it was thought that AMC may result from paresis of some muscles of the girdle, shoulder and elbow. Secondly, it was postulated that the decrease in the number of alpha-motoneurons in C6 may have induced a radial nerve dysfunction resulting in AMC.