Anatomy of the Eustachian Tube
It runs from within a soft-tissue viscus into a cavity of the skull; and it links the two major areas middle ear and nasopharynx .On its brief but entertaining course, it has many important companions and neighbors … and it seems unlikely that the last has been written about it”. During the approximate 2400 years since Alcmaeon of Sparta first described the tube, much has been written on its anatomy, function, and dysfunction. Alcmaeon thought that the tube that connected the nasal airway and the ear enabled goats to breathe through their ears as well as through their noses. The eustachian tube is part of a system of contiguous organs, including the nose, nasopharynx, middle ear, and It is usually divided into an osseous intratemporal portion and a cartilaginous portion. Respiratory mucosa lines the entire system. Thus effects of infection or obstruction, such as inflammation, in one area are likely to be reflected in the other areas. A knowledge of the anatomy and physiology of the eustachian tube is a necessary prerequisite of the proper diagnosis of the symptoms of this region. Descriptions of eustachian tube anatomy and knowledge of its function have evolved over many years. This chapter reviews our present understanding of the structure and function of the eustachian tube and middle ear system. As in the past, however, this knowledge will expand with continued study (Ostfeld and Silberberg, et al 1991).
Anatomy Development Adult eustachian tube morphology is the culmination of 18 years of development and growth; thus its structure and function can best be appreciated in the context of these processes. Further, identification of abnormalities and their consequences depend on a knowledge of normal anatomy. The eustachian tube lumen is the persistence of the first pharyngeal pouch. The structures associated with this lumen develop from the surrounding mesenchyme in a predictable sequence. Swarts et al (2005) studied tubal development in 20 human fetuses between 7 and 38 weeks post conception. (Swarts and Rood, et al , 2005)
Figure 6: Eustachian tube
age-related changes in eustachian tube function (Bylander et al, 2011; Bylander and Tjernstrom, 2011) suggest more efficient muscular activity and a system that is less likely to act as a passive conduit for nasal secretions. The period between birth and adulthood is one of the great lacunae in our understanding of the ontogeny of this region. The importance of developmental changes to our understanding of middle ear disease during this interval should not be underestimated because there is a concurrent decrease in the prevalence of disease with increasing age. (Bylander and Tjernstrom, 2011)