MYOLOGY. 55 



third cervical vertebrae. Use : to bend the neck on one side, and rotate the 

 atlas on the vertebra, dentata; when both muscles act, they bend the neck 

 directly forwards. 



Rectus ccqntis anticus major, long and flat, thick above and below, arises 

 by small tendons from the anterior tubercles of the transverse processes of 

 the last four cervical vertebra; they soon unite in a fleshy substance, which 

 is inserted into the cuneiform process of the occipital bone. It serves to 

 bend forwards the head and neck. 



Rectus capitis anticus minor, short and narrow, arises from the transverse 

 process of the atlas, and is inserted into the cuneiform process. It serves 

 to bend the head forwards and to one side on the atlas. 



Rectus capitis lateralis, very short, arises from the transverse process of 

 the atlas, and is inserted into the semilunar ridge or jugular process of the 

 occipital bone which extends from the condyle to the mastoid process. 

 With the last muscle it serves to bend the head forwards or to incline it to 

 one side. 



Scalenus anticus, in part continuous with the rectus anticus major, arises 

 from the anterior tubercles of the transverse processes of the third, fourth, 

 fifth, and sixth cervical vertebrse; the fibres «lescending form a flat muscle, 

 which is inserted tendinous into the upper surface of the first rib, near its 

 cartilage. Its use is to bend the neck forwards and laterally, also to elevate 

 and fix the rib, as in inspiration. 



Scalenus medius, larger and longer than the last, arises from the posterior 

 tubercles of the transverse processes of four or five inferior cervical verte- 

 brae, and is inserted into the upper surface of the first rib, behind the sub- 

 clavian artery. Its use is similar to that of the last. 



Scalenus posticus arises from the posterior tubercles of two or three lower 

 cervical vertebrae, and is inserted into the upper edge of the second rib, 

 between the tubercle and angle. Use : to elevate the second rib ; to bend 

 the neck to one side and a little backwards. 



PI. 127, fig. 3 \ platysma myoides ; ^ branch of the latter known as 

 musculus risorius santorini ; ', sterno-cleido-mastoid ; ', trapezius. 



Fig. 4'' ', the digastric muscle. 



PI. 124:, fi^. 15'°, platysma myoides. 



PI. 12b, fig. 19', sterno-cleido-mastoid. 



C. Muscles of the Anterior and Lateral Parts of the Thorax. 



The thorax is the middle division of the body, continuous with the neck 

 above and the abdomen below ; it presents an anterior or sternal, a posterior 

 or dorsal, and two lateral asjDCCts. 



Pectoralis major, flat and triangular, arises from the sternal half of the 

 clavicle, from the anterior surface of the sternum, from the cartilages of 

 the third, fourth, fifth, and sixth true ribs, and from an aponeurosis common 

 to it and to the external oblique muscle ; its fibres are inserted by a flat 

 tendon into the anterior edge of the bicipital groove, and by an aponeurosis 

 into the fascia of the arm. A line of cellular membrane separates the 

 clavicular from the sternal portion, these in some cases appearing as di?- 



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