Because we expose our feet to potential injury in our daily lives by walking, we have all experienced pains in the feet at one time or another. There are many common causes of foot pains, such as blisters and corns. There are also less common causes of foot pain, such as sciatica and osteomyelitis.
The trachea, or windpipe (figs. 21-1 and 21-2), which has cervical and thoracic parts, extends from the inferior end of the larynx (C6 vertebra) to its point of bifurcation (between T5 and 7 vertebral level). It is about 9 to 15 cm in length. The trachea descends anterior to the esophagus, enters the superior mediastinum, and divides into right and left main bronchi. The trachea is a median structure but, near its lower end, deviates slightly to the right, resulting in the left main bronchus crossing anterior to the esophagus. Owing to the translucency of the air within it, the trachea is usually visible above the arch of the aorta in radiographs.
1 Longitudinal smooth muscle fibers are present in the posterior trachea between the ends of the cartilage rings. 2  This smooth muscle tissue allows the trachea to adjust its diameter as needed. 3  Surrounding the submucosa is a layer of hyaline cartilage that forms the supportive rings of the trachea.t is located along the bodyâs midline, anterior to the esophagus and just deep to the skin, so that it is possible to feel the larynx through the skin of the neck. From its origin at the larynx, the trachea extends inferiorly into the thorax posterior to the sternum....