Cervical anatomy of phrenic nerve roots in the rabbit

The cervical anatomy of the different nerve contributions that constitute t he phrenic nerve (phrenic nerve roots and accessory phrenic nerve) were stu died in rabbits. In 55 dissections, 6 main root arrangement types were obse rved. The roots that issued from the fourth and fifth cervical nerves (C4 a nd C5 roots) were constant. The C4 root was either short or long. The C6 ro ot was at times absent, or sometimes double. An accessory phrenic nerve was present in 43% of the right and 28% of the left dissections. The distribut ion of the phrenic nerve roots often displayed left-right asymmetry. We con clude that a better knowledge of the cervical anatomy of the phonic nerve i s useful both in physiological studies involving diaphragm denervation and in experimental laryngeal reinnervation.