Study of motor units of M. pectineus of the dog (Canis familiaris).

Cross sections of M. pectineus of 6 adult dogs were used to study the number of motor units. Our results revealed that M. pectineus possesses 29,451 muscle fibres and 165 large nerve fibres. Since 60% of these latter fibres are motor fibres, the number of fibres per motor unit of M. pectineus is 294. This fact suggests that this muscle executes finely adjusted movements.