[The avian middle ear (Struthio camelus) Data for the physiology of sound transmission in systems with a single ossicle in the chain]
INTRODUCTION AND GOALS The columella of birds, often cited in the literature, has yet to be adequately described. We aim to give an account of this transmission element, describing its anchoring systems and detailing the muscle associated to it. MATERIAL AND METHOD We performed microscopic dissection and obtained images of ostrich specimens (Struthio camelus) chosen because it is the bird with the largest head. RESULTS We describe the columella: the osseous tripod formed on its external section (extracolumella) the conic shape of its inner section (stapedial) and links to the tympanic membrane and the oval window. We describe its anchoring system: posterior ligament and annular ligament. We conclude by describing the characteristics of the columella muscle, its insertions and the fibrous vein surrounding it. CONCLUSIONS The avian middle ear is a valid model for understanding the mechanical characteristics of the human ear repaired with total ossicular replacement prosthesis, ie replacement of the ossicular chain by a single element. We highlight an apparent contradiction: the existing muscle is inserted into the columella in an area close to the tympanic membrane rather than adjacent to the oval window.
Acta otorrinolaringologica espanola