Anomaly of the hypoglossal nerve: embryologic, anatomic, and surgical considerations.

An anomaly of the hypoglossal nerve was discovered during a procedure to anastomose the 12th and 7th cranial nerves. This anomaly is described, and an embryologic mechanism is proposed to explain the occurrence of this particular anomaly. The surgical anatomy of the hypoglossal nerve is reviewed, and reasonable approaches to the surgical identification of the hypoglossal nerve are discussed.