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Muscurs oF THE TRUNK. 
A. On the Dorsal Aspect. 
The muscles on the dorsal aspect of the vertebral column in Birds 
have only of late years received any attention from Comparative 
Anatomists: they have been mentioned rather than described by 
Tiedemann and Meckel: Carus has given a side-view of the super- 
ficial layer of muscles in the Sparrow-hawk ; their best description 
is contained in the second edition of the ‘ Lecons d’Anatomie Com- 
parée’ of Cuvier. 
The muscles of the back are in general so feebly developed in 
birds of flight, that they were affirmed by Cuvier to be wanting 
altogether in the first edition of the ‘ Lecons.’ And this is almost 
true as respects their carneous portion, for they are chiefly tendinous 
in Birds of Flight. In the Struthious birds, and in the Penguin, 
in which the dorsal vertebre are unfettered in their movements by 
anchylosis, these muscles are more fleshy and conspicuous; but they 
attain their greatest relative size and distinctness in the Apéeryz. 
From the very small size of the muscles which pass from the 
spine to the scapula and humerus in the Ap/eryz, the true muscles of 
the back, which correspond to the second layer of the dorsal muscles 
in Man, become immediately visible on removing the dorsal integu- 
ments and fascie; they consist of the sacro-lumbalis, longissimus 
dorsi, and spinalis dorsi. The first two muscles are blended toge- 
ther at their posterior origins, but soon assume the disposition cha- 
racteristic of each, as they advance forwards. 
The sacro-lumbalis is a strong and fleshy muscle, six lines in 
breadth, and three or four lines in thickness: it is, as usual, the most 
external or lateral of the muscles of the back, and extends from the 
anterior border of the ilium to the penultimate cervical vertebra. 
Origin. By short tendinous and carneous fibres from the outer half 
of the anterior margin of the ilium, and by a succession of long, 
strong, and flattened tendons from the angles of the fifth and fourth 
ribs, and from the extremities of the transverse processes of the 
third, second, and first dorsal vertebre ; also by a shorter tendon 
from the transverse process of the last cervical vertebra; these 
latter origins represent the musculi accessorii ad sacro-lumbalem ; 
they have not hitherto been described in the class of Birds: to bring 
them into view, the external margin of the sacro-lumbalis must be 
raised. These accessory tendons run obliquely forward, expanding 
as they proceed, and are lost in the under surface of the muscle. 
Insertion. By a fleshy fasciculus with very short tendinous fibres 
into the angle of the sixth rib, and by a series of corresponding fas- 
ciculi, which become progressively longer and more tendinous, into 
the angles of the fifth, fourth, third and second ribs, and into the 
lower transverse processes of the first dorsal and last two cervical 
vertebrz ; the last insertion is fleshy and strong; the four anterior 
of these insertions are concealed by the upper and outer fleshy por- 
tion of the sacro-lumbalis, which divides into five elongated fleshy 
bundles, inserted successively into the upper transverse processes of 
