中・下咽頭の解剖

Anatomy and Histology of the Pharynx

要旨　内視鏡および周辺環境の進歩に伴い，消化管内視鏡医が咽頭部の観察・治療を行う機会が近年増加している．このため消化器内科医にも，中・下咽頭について詳細な解剖学的知識が必要とされてきている．本稿では実際の内視鏡画像を含め中・下咽頭の解剖を概説する．咽頭は，口腔の後側，鼻腔の後下方，脊椎の前面，食道・喉頭の上面に位置する中腔の管腔臓器である．中・下咽頭の構造は，重層扁平上皮より成る粘膜とそれを取り囲む筋層（咽頭収縮筋群，咽頭挙筋群），弾性線維に富む外膜より成る．食道とは異なり中・下咽頭部では粘膜筋板を欠き，その部には弾性線維が層構造を形成している．

　Recent advances in endoscopic procedures have enabled more thorough observation of the pharynx. For observation of pharyngeal lesions, endoscopists need a good knowledge of pharyngeal anatomy. In this paper, we demonstrate the anatomy and histology of the pharynx, as well as the endoscopic view of the normal pharynx. The pharynx is that part of the digestive tube, which is located behind the nasal cavity, the mouth and the larynx. The pharynx is limited by the posterior part of the sphenoid bone body and the basilar part of the occipital bone (above). It is continuous with the esophagus (below) and is separated by loose areolar tissue from the cervical portion of the vertebral column (behind) and opens into the nasal cavity, the mouth and the larynx (in front). Histologically, the pharyngeal wall has three coats : the mucosa, the proper muscles and the adventitia.