Abstract: The nasal muscles consists of five muscle layers: pars posteroexternus, pars anter- oexernus, pars posterointernus, pars anterointernus and pars protundus. Pars interme-dius is absent. The major and miner intrinsic muscles are very weak. No diagonal membrane muscles are found.Study on the architecture of the nasal tract muscles was made by three specimens. Physiological cross-sectional area, estimated maximum tetanic tension and ratio of wet weight to estimated maximum tetanic tension for each muscle were calculated by determining muscle weight,muscle fiber length,average sarcomere length and fiber angle of pinnation. Fiber lengths varied from 19.7 to 42.7mm. The muscle length and fiber length of deeper layers are shorter than those of superficial ones. All muscles have similar relative fiber length. The fiber angles of pinnation for all muscles are zero and this arrangement of fibers permit the maximum force potential during contraction. Velocity and displacement of anterior portion of nasal muscles are about 50% greater than those of posterior ones. This superiority is conspicuous for the anterior portion of pars anteroexternus, which control the vestibular sac. The posterior portion of nasal muscles has greater ability of force production. The rostral muscle inserting the melon has great potential in force production.

Key words: Neophocaena phocaenoides, Nasal tract muscles, Anatomy, Architecture

摘要： 江豚的鼻部肌共分为后外肌、前外肌、后内肌、前内肌和深肌5层,无间肌和大小内肌较退化,无对角膜肌。通过测定各肌的肌重、平均肌纤维长、平均肌小节长以及肌纤维角度,计算了各肌的生理横截面积,估计最大强直张力和肌鲜重对估计最大强直张力之比值等指标。鼻部肌各肌的相对肌纤维长度相似。各鼻部肌的肌纤维角度均为零。前部肌比后部肌具有较大的收缩速度和收缩位移优势,后部肌则具有较强的张力产生能力。着于额隆和唇部吻肌的张力产生能力很强。

关键词: 江豚, 鼻道肌, 解剖, 构筑