119. The trapezius
There has been much uncertainty as to the occurrence of a trapezius muscle in the ganoids. Two distinct muscles have caused confusion - a levator of the fifth branchial arch and a true trapezius; both present in Amia (and probably in Polypterus Allis), but the trapezius vestigial. In Lepidosteus a functional trapezius occurs in the same relative position as the vestigial one in Amia. In Polyodon, Scaphirhynchus and Acipenser the trapezius is functional and is innervated by a branch of the ramus lateralis vagi that enters the latter from the vagus proper near the vagus ganglion; in Acipenser, however, the nerve for the trapezius merely accompanies the ramus lateralis. Conclusion: the trapezius muscle is present in all ganoids, but vestigial in Amia and Polypterus.
Proceedings of the Iowa Academy of Science
©1925 Iowa Academy of Science, Inc.
Norris, H. W.
"The Trapezius Muscle of the Ganoid Fishes,"
Proceedings of the Iowa Academy of Science, 32(1), 444-444.
Available at: https://scholarworks.uni.edu/pias/vol32/iss1/120