Syrinx - meikan (English spelling)

The vocal organs of birds. Birds do not vocalize using the larynx as mammals do, but use the syringe located at the back of the trachea. In most birds, the syringe is located at the bifurcation of the trachea into two bronchi (tracheobronchial syringe), but in some birds, it is located in the lower part of the trachea (tracheobronchial syringe in some subsongbirds) or in the upper part of the bronchi (bronchial syringe in cuckoos and nightjars). The syringe is structured with a tympanum, formed by the fusion of several cartilage rings in the lower or upper part of the trachea, and several vibrating membranes. Vocalization is achieved by the vibration of these vibrating membranes as the air is exhaled. Several pairs of muscles called syringeal muscles are attached to the syringe, and their contraction adjusts the tension of the vibrating membranes, so birds with more syringeal muscles can generally produce more complex songs.

[Hiroyuki Morioka]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

鳥類の発声器官。鳥類は、哺乳(ほにゅう)類のように喉頭(こうとう)で発声せず、気管の奥にある鳴管で声を出す。鳴管は、多くの鳥類では気管が2本の気管支に分かれる分岐点に位置するが（気管気管支型鳴管）、ある種の鳥類では、気管の下部（一部の亜鳴禽(めいきん)類の気管型鳴管）、あるいは気管支の上部（カッコウ・ヨタカ類などの気管支型鳴管）にある。鳴管の構造は、気管下部ないし気管支上部の数個の軟骨環が癒合して形成される鼓室tympanumといくつかの振動膜とよりなり、発声は呼気とともにこれらの振動膜が振動することによって行われる。鳴管には数対の鳴管筋syringeal muscleとよばれる筋肉が付着し、その収縮が振動膜の緊張度を調節するので一般に鳴管筋の多いものほど複雑なさえずりができる。

［森岡弘之］

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