MYOLOGY 73 



Shape. — Triangular, fan-shape. 



Relations. — Superiorly with the skin. 



Action. — Controls the skin in this region. The anterior end being 

 fixed, the muscles are raised; and the posterior end acting as the 

 fixed point, the feathers are caused to lie close to the body. 



Dermo-pectoralis. Location. — On each side of the chest, lying 

 in a longitudinal manner. 



Origin and Insertion. — ^Attached to the skin on either side of the 

 thorax corresponding to the dermo-dorsalis. Anteriorly it disap- 

 pears over the region of the origin of the cleido-trachealis, and pos- 

 teriorly just behind the tips of the postpubic parts of the pelvis. 



Shape. — ^Thin, delicate. 



Relations. — Superiorly with the skin. 



Action. — The anterior part acting as the fixed point, the feathers 

 of the chest are raised; and the posterior end acting as the fixed 

 point, the feathers are made to lie flat. 



THE DERMO-OSSEOtrS MUSCLES 



Dermo-temporalis Platysma myoides 



Dermo-cleido dorsalis Cleido-trachealis 



Dermo-spinalis Dermo-iliacus 



Dermo-ulnaris 



Dermo-temporalis (Fig. i8. No. i). Location. — From the tempo- 

 ral region down the side of the neck to the anterior part of the 

 thoracic region. 



Origin. — By a broad tendinous attachment from a small depres- 

 sion above and anterior to the temporal fossa. From here the 

 fibers pass upward and backward and then downward. 



Insertion. — ^A few fibers blend with those of the cleido-trachealis. 

 The fibers are then lost upon the skin in front and opposite the 

 shoulder-joint. Some of the fibers blend with those of the dermo- 

 tensor patagii. 



Shape. — Long, flat, and ribbon-shaped. The lower portion con- 

 sists of delicate fibers. 



Relations.' — Superior to the temporal muscle and sphenotic 

 process. Superior to the cleido-trachealis and inferiorly to the 

 shoulder-joint. The superior portion touches the skin throughout 

 its entire length. 



