GAO Guofu, ZHOU Kaiya
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.
Nasal tract muscles,
高国富, 周开亚. 江豚鼻道肌的解剖和构筑研究[J]. .
GAO Guofu, ZHOU Kaiya . STUDIES ON THE ANATOMY AND ARCHITECTURE OF THE NASAL TRACT MUSCLES OF THE FINLESS PORPOISE, NEOPHOCAENA PHOCAENOIDES[J]. .