osseous one third that is contained within the skull base, and a distal two thirds that is the cartilaginous portion. It has a slightly S-shaped course and passes generally posterosuperially and laterally from the nasopharynx. At the nasopharyngeal orifice, its cross section is triangular in shape, measuring 2 to 3 mm vertically and 3 to 4 mm in the horizontal base. The narrowest portion of the eustachian tube, the isthmus, which is located in the cartilaginous portion, is a vertical slit measuring 2 mm in height and 0.6 to 0.9 mm in width. The segment in which the cartilaginous and osseous portions connect has been termed the junctional portion by Sudo et al. The osseous portion opens funnel-like into the middle ear, and it remains fixed and patent under normal circumstances; in contrast, the cartilaginous portion of the eustachian tube is dynamic
(particularly the most nasopharyngeal portion), closed at rest and opened when active. Within the cartilaginous superior and middle portion, the mucosal surfaces of the anterolateral and posteromedial walls meet in apposition, closing the lumen in the resting position. This roughly 8- to 15-mm-long section serves as a functional “valve” and is composed of the mucosa, submucosa, lateral cartilaginous lamina, the Ostmann’s
fat pad, and the relaxed bulk of the tensor veli palatini muscle. The bony portion is lined by a layer of cuboidal respiratory epithelium and the cartilaginous portion is lined by pseudostratified columnar respiratory epithelium that is taller, more densely ciliated, and abundant in secreting goblet cells. The eustachian tube orifice can be identified just posterior to the inferior turbinate. The fossa of Rosenmüller is located posterior
to the torus tubarius and courses laterally toward the internal carotid artery, which lies just deep to the apex of the fossa. The torus tubarius, also known as the posterior cushion, contains the medial cartilaginous lamina, which is the mobile portion of the eustachian tube orifice. The lateral cartilaginous lamina (an-
terolaterally located) is smaller and immobile. The entire cartilaginous skeleton is shaped like an inverted J in cross section.
This article is wonderful. By the way, we would like to let you know about our company: Phong Nha Pioneer Travel (PPT) is a professional, leading tour operator based in Da Nang city – central Vietnam. Our office is at Tran Hung Dao street, Dong Hoi city. We have been in the tourism industry for many years and with a comprehensive experience in this field, we are proud to be one of the best travel agents in Dong Hoi in particular and in Vietnam in general. Everyday,we provide tourists with local tours to all tourist sightseeings in central Vietnam such as many historical sites of My Son Holyland, Hoi An ancient town, Hue ancient capital, Demilitarized Zone, Phong Nha National Park, Ba Na Hills. As you know, central Vietnam is an amazing area and it is known as World Heritage Road in Vietnam due to its various UNESCO sites such as Hoi An ancient town, My Son Holyland, Hue ancient capital, Phong Nha National Park. Moreover, central Vietnam is not only picturesque region but the people are so friendly, warm hearted and welcoming. Today, there are more and more people coming to visit central Vietnam, especially Dong Hoi city. And their means of transport is by airplane. Dong Hoi is known as City of Roses in Vietnam. It is a small, lovely city by Nhat Le river. This is a coastal city with beautiful beaches and friendly people. Especially, this city is near The Kingdom of Caves in Vietnam. Therefore, it has been attracting thousands of tourists every year. So, in order to meet demand of customers coming to sightseeing Dong Hoi city by airplane, we, PPT, therefore organise Dong Hoi Airport Transfer. Coming with our services, we are happy to provide you with the best services as we can. We have a wide range of latest cars/vehicles with comfortable seats, perfect air conditioning, English speaking drives. Moreover, we supply you with pure water and wet tissues. We will pick you up from Dong Hoi Airport and drop you anywhere in central Vietnam. We daily arrange airport pick up from Dong Hoi Airport/Train Station to Phong Nha Park or vice versa ect. Let’s come and book services with us. We will totally make your pick up in Dong Hoi Airport a safe, special and comfortable one. Besides, our company also arranges package tours, private tours or day tours to all tourist attractions in central Vietnam. So, let’s come and explore various spectacular landscapes in central Vietnam with Premium Vietnam Travel. If you want to know more about this tour, kindly contact us at premiumvietnamtravel@gmail.com or whatsapp us at 0084979613777. We are very pleased to serve you and be a reliable partner to you.
ReplyDelete