WINGS OF BIRDS, 
15 
polffi, which, arising from the transverse process of the last cervical vertebra, 
and a.few of the anterior ribs, is inserted into the dorsal edge of the scapula, 
which it pulls upwards and forwards. 
2. The serratus magnus anticus arises by digitatioiis from the last four ribs, 
excepting two, and is inserted into the extremity of the scapula. A slender 
slip, 2 a, separates from it to be inserted into the skin of the posterior edge of 
the brachium. . ' 
There is also a serratus parvus anticus or costo scapulari, which arises in like 
manner from the first two ribs, and is inserted into the anterior part of the 
low'er edge of the scapula. 
2. Muscles inserted into the humeral or brachial bone ^ 
3. The two superficial slips seen on the back are analogous to the latissi- 
mm dorsi in man. They arise from the spinous processes of the last cervical, 
and some of the anterior dorsal vertebrae. The first, 3 is inserted into the 
coracoid bone, the other, 3 into the middle of the linea aspera or dorsal 
ridge of the humerus, which it draws toward the back. The other muscles 
which arise from the trunk to be inserted into the humerus are situated in 
front. 
4. Pectoralis major^ Fig. 2.—Arises from the whole length of the crest of 
the sternum, from its posterior and lateral margins, from the ribs, and from 
the outer edge of the furcula, forming a triangular mass of vast size, some¬ 
times exceeding in bulk all the other muscles of the body together. Its fibres 
run obliquely forwards and outwards, pass over the shoulder-joint, and are 
inserted fleshy into the anterior or upper crest of the head of the humerus, 
and by a flat tendon where they cross the insertion of the next muscle. Its 
action has not been correctly described. Its anterior part raises the hu¬ 
merus, and brings it forward; its middle part brings the wring dowrnwards ; and 
its posterior portion brings the humerus backward, close to the body. Its 
combined action is powerfully to depress the wing, and bring its anterior 
edge downw'ard, by which the quills are obliquely raised. 
5. Under the great pectoral muscle, is seen in Fig. 3, the pectoralis medius. 
It arises, properly speaking, over the other, from tlje whole length of the 
under surface of the sternum, and the upper half of its crest, and from the 
fore edge of the coracoid bone, and the membrane betw^een it and the furcula. 
The fibres converge into a central tendon, extending’ its whole length, which 
passes forwards between the coracoid bone and the furcula, curves round the 
joint, and is inserted upon the upper tubercle or crest of the humerus, close 
to the insertion of the pectoralis major, and anterior to it. Although this 
muscle is similar in its origin to the pectoralis major; its action, owing to the 
direction of its tendon, is the reverse of that muscle, as it elevates the humerus 
and brings it fonvard. 
