On Motion in the lumbar division of the spine of birds, by George Oakley Fleming

                                observed in that part of the spine which corresponds to the 
dorsal and lumbar divisions, which in birds do not admit 
of motion; for here we find no variation, either in the 
spinal canal or the marrow, except where the numerous 
branches are given off to form the great sciatic plexus to 
supply the lower extremities, where it swells out into a 
bulbous shape corresponding to the cavity of the bone.” 
I conjectured that these muscles could have no other office 
than that of moving the lumbar vertebrae, and upon further investigation of the subject, I found other beautiful 
contrivances to facilitate its <u>lateral<\u> motion, whilst at 
the same time, motion in an antero-posterior direction is preven-
ted, so necessary to flight; and the spinal marrow most 
completely protected from pressure.
Cuvier, Blumenbach, Tiedman, Macartney, Vic d’Azyr, 
Carus, Earle, Dr Grant, and Dr Roget, particular passa-
ges of whose works I have thought it right to transcribe*, 
have either denied the motion of the dorsal and lumber 
portion of the spine of birds altogether, or have spoken of 
it as existing in a very limited degree; or state that the 
apparatus 
* Mons Cuvier observes, “Les Oiseaux n’ont point de muscles pour partie 
dorsale de l’epine. Leur cou seul est mobile, il porte beaucoup de muscles” 
Lecons d’Anatomie comparative, Vol: 1. p. 199. And a few pages before this pas-
sage, he has stated, “Autant le cou des oiseaux est mobile, autant leur 
dos est fixe. Les vertebres qui le compose ont des apophyses epineceres 
qui