[Innervation of the external ear in humans and the musk shrew]

The external ear appears only in mammals and possesses a great diversity of forms. In addition, multiple nerves are distributed in the external ear. The nerves which are distributed in the external ear were investigated in humans and in the musk shrew (Suncus murinus) in a macroscopic study. The following results were obtained. Cranial nerves (CN) V, VII, X and cervical nerves supply the auricle and the external meatus in both humans and the musk shrew. Branches of the third division of CN V supply an anterior part of the external meatus and the anterior part of the auricle in both humans and the musk shrew. A branch of CN X, together with a branch of CN VII, supply the posterior parts of the external meatus in humans. In the musk shrew, a branch of CN X, together with a branch of CN VII, supplies the posterior part of the external meatus and the central part and the anterior portion of the auricle. Branches of the cervical nerve supply the posterior part of the auricle. Branches of the cervical nerve supply the posterior part of the external meatus and the central and posterior parts of the auricle in the musk shrew.