Mediterr. J. Otol 2006; 3:112-116

Scanning electron microscopy of auditory ossicles

Ivan Zenev, E. Zenev, Nikolaj Sapundzhiev, Mario Milkov, Dimitar Marev

Department of Otolaryngology, Head and Neck Surgery, Queen Yoanna University Hospital of Sofia, Sofia, Bulgaria. mariomilkof@yahoo.com

OBJECTIVE: Middle ear auditory ossicles and the tympanic membrane are the morphologic substrate responsible for the transmission and conversion of environmental sounds to the internal ear.

MATERIALS AND METHODS: The ultrastructure of human complete ossicular chain specimens was morphologically studied with a scanning electron microscope.

RESULTS: Various essential morphologic details of the components of the ossicular chain in the middle ear were revealed. The auditory ossicles were covered with a fine complex mucoperiosteal layer, rich in capillary blood vessels, that formed complementary protrusions on the ossicular surface. Both the malleus and the incus consisted of separate osseous parts. The bone substance of the incus long process had a fibrous structure, and the incus short process was composed primarily of lamellar bone. The length of the malleus manubrium was 1.3 times that of the long process. The stapes footplate demonstrated separate embryologic development, and its surface facing the oval window was covered by a thin cartilaginous layer.

CONCLUSION: All surgical interventions performed on the ossicles should accommodate anatomic peculiarities as well as the articulations between and the connections of the ossicles with the tympanic membrane. Extensive knowledge of those characteristics is essential to ensure a successful outcome of functional middle ear surgery.