The architecture of the pectoral appendage of the dogfish

✍ Scribed by A. Brazier Howell

• Book ID: 102903334
• Publisher: John Wiley and Sons
• Year: 1933
• Tongue: English
• Weight: 738 KB
• Volume: 54
• Category: Article
• ISSN: 0362-2525
• DOI: 10.1002/jmor.1050540209

✦ Synopsis

Abstract

The m. trapezius, with both brachial and branchial functions, is in seeming series with the mm. interarcuales laterales. The intrinsic muscles of the fin occur as a dorsal extensor sheet and three (or four) ventral flexor components. The spinal nerves, uncomplicated by extensive anastomoses, which supply the fin, clearly show that in the dogfish the fin muscles are derived not from dorsal and ventral elements, but from anterior and posterior, or protractor and retractor elements. The nerves prove that from the original protractor musculature only the anterior portion of the present flexor group is derived, while the original retractor musculature has become all of the extensor and the posterior part of the flexor series. Faradic stimulation of the live animal is satisfactory, although there is much variation in the sensitivity, particularly of different muscles.