Microanatomical And Clinical Application Anatomical Study Of The Upper Esophageal Sphincter

Objective To investigate the architecture of the upper esophageal sphincter (UES) using gross anatomical, sectional anatomical, microanatomical, and endoscopy techniques, to evaluate the clinical appearance of the UES, and to correlate both clinical and anatomical data in order to better understand the mechanism underlying dysphagia. Methods Gross anatomical structures of pharyngoesophagus region were examined in 63 adult cadavers which ages were estimated by forensic medicine technique. According to the estimated age, 63 cadavers were divided into three age groups, young adult (<25 years old), adult (25-59 years old) and elderly (> 59 years old). Two specimens, one with a thickened posterior wall of cricopharyngeal muscle and another with a normal posterior wall of cricopharyngeal muscle, were sectioned and stained with H.E. staining for histology examination. Nine pharyngoesophagus regions were prepared as sets of serial sections. 2 sections were systematically sampled from each set. One section was unstained, the other was stained with van-Gieson staining. The UES in both unstained and stained sections were examined under a microscope. One hundred forty-six patients with dysphagia were undertaken a barium swallow radiological examination to reveal if they had cricopharyngeal bar. Three cricopharyngeal bar positive patients were further examined with esophagoscopy.Results: (1) On the basis of their thickness and density, three layers of fasciae were identified on the posterior wall of the pharyngoesophageal region. (2) There were three muscles in the pharyngoesophageal region: the thyropharyngeal (TP), cricopharyngeal (CP) and circular esophageal muscles. The width of the TP at posteromargin of lamina cartilaginis thyroidea was 30.60 +4.36mm, and the thickness of the TP at median rapheof pharynx posterior wall was 2.66 +0.67mm. At posterior wall, the CP appeared as a rhombus with a triangle superior angle and an arc inferior angle. The thickness of the CP 1.51 ±0.35mm. The hight of the rahombus was 19.23 ±2.01mm. The thickness of the circular muscle of esophagus at median raphe of pharynx posterior wall was 1.18 ± 0.27mm. (3) The width of lumen of pharyngoesophagus was measured at superior and inferior edges of cricoid cartilage and at inferior edge of the first tracheal cartilage. They were 14.97 ±3.62 mm, 11.74 ±2.21 mm, and 13.70 ±3.19mm, respectively. The narrowest point was at the inferior edge of cricoid cartilage (p < 0.01). (4) Changes of their configuration of the TP, CP and superior esophagus were better demonstrated in the serial sections. At a lower magnification, the shape and orientation of muscular fibers were clearly exhibited. According to their origin, the muscle fibers of the TP could be divided into three types, the first type arose from connective tissue which conjointed with cricothyreoideus, the second type the lateral margin of thyroid cartilage, and the third type from the mucous layer of posterior wall. The CP could be divided into oblique part and transverse part. Circular muscular fibers of esophagus attached to connective tissue of middle anterior wall of esophagus, the longitudinal muscle fibers stopped at the inferior margin and median suture of post surface of lamina cartilaginis cricoideae. (5) On the transverse section, the UES had a reticulate network of connective tissue but such reticulation varied between three components of the UES -the TP, CP and upper esophagus. The reticulation of TP was larger and rarefaction, the reticulation of CP was tightly close, and the reticulation of circular muscle of esophagus was larger. There were some connective tissue bundles in longitudinal muscle of esophagus and they communicated with each other. On the sagittal section, connctive tissue was declination in the TP, reticulation in the CP, horizontal in the circular muscle of esophagus and microtubule in longitudinal muscle of esophagus. Some connective tissue bundles run through the whole UES. On the coronal section, the muscular layer in esophagus arranged similar to that on the sagittal section. (6)...