98 ANATOMY OF THE DOMESTIC FOWL 



Origin. By three digitations from the outer surface of the first 

 three ribs above the origin of the serratus magnus anticus and the 

 thoraco-scapularis. 



Insertion. The thin sheet of fibers passes upward and backward, 

 and is inserted to the inferior margin of the scapula. 



Shape Thin, flat. 



Relations. Internally, with the ribs. 



Action. If the scapula is fixed, it is a muscle of respiration. 



Teres et Infraspinatus (Fig. 13, No. n). Location. Scapular 

 region. 



Origin. From the superior surface and outer margin of the pos- 

 terior two-thirds of the scapula. 



Insertion. The fibers pass forward and outward, and insert to the 

 humerus at the middle of the ulnar margin of the pneumatic fossa, 

 between the forks of the triceps. 



Shape. Flat, triangular-shaped. 



Relations. Anteriorly, with the supraspinatus. Internally, with 

 the ribs. 



Action. Aids in keeping the humerus in its socket. Assists in 

 closing the wing by drawing the humerus to the side of the body. 



Intercostales (Fig. 24, No. 5). Location. Between the ribs of the 

 upper thoracic region. 



Origin and Insertion.' From the anterior border of one rib, the 

 fibers, passing obliquely upward and forward, and the lower portion 

 downward and forward, are inserted to the posterior border of the 

 rib just in front. 



Shape. They are best developed in the anterior portion of the 

 thoracic region and extend down as far as the sternal ribs. 



Relations. Internally the pleura, and anteriorly and posteriorly 

 the ribs. 



Action. The first rib being rendered fixed by the scalenus me- 

 dius, the muscles draw the ribs forward, thus aiding inspiration. 



Levatores Costarum (Fig. 24, No. 2). Location Supero-lateral 

 portion of the thorax. 



Origin and Insertion. A series of muscles, the first of which 

 extends from the extremity of the transverse process of the twelfth 

 vertebra, the fibers passing downward and backward to the anterior 

 free margin of the upper third of the long posterior rib, and to 

 the external surface close to its margin. The others arise and 

 insert in a similar manner from the ends of the diapophyses of all 



