196 MUSCLES OF THE HEAD AND NECK. 



The scaleni muscles are subject to some amount of variation, both in the number of 

 their points of attachment, and in the arrangement of their fibres. A slip from the 

 scalenus anticus sometimes passes behind the subclavian artery. 



The rectus colitis anticus major arises from the tubercles of the trans- 

 verse processes of the third, fourth, fifth, and sixth cervical vertebrse by 

 tendinous slips, its origin corresponding in extent to the superior attachment 

 of the anterior scalenus muscle : it is inserted into the basilar process of 

 the occipital bone, a little in front of the foramen magnum. The muscles of 

 opposite sides converge as they ascend, and their mesial fibres are longest. 



The anterior surface of the rectus eapitis anticus major supports the pharynx, 

 the sympathetic and vagus nerves, and the great cervical vessels. The posterior 

 surface rests upon part of the longus colli and the rectus anticus minor. 



The rectus eapitis anticus minor, under cover of the preceding, arises 

 from the anterior arch of the atlas, and slightly from the root of its 

 transverse process ; it is inserted into the basilar process, between the 

 margin of the foramen magnum and the preceding muscle, half an inch from 

 its fellow. 



The rectus eapitis lateralis is a short thick muscle arising from the upper 

 surface of the anterior division of the transverse process of the atlas, and 

 inserted into the rough surface beneath the jugular eminence of the occi- 

 pital bone. It completes the series of intertransversales muscles. 



The anterior surface of this muscle is in contact with the internal jugular vein, the 

 posterior with the vertebral artery. 



The longus colli muscle rests on the front of the vertebral column from 

 the atlas to the third dorsal vertebra : it consists of three sets of fibres, of 

 which two are oblique, and one vertical, a. The superior oblique portion 

 arises, by a narrow tendinous process, from the anterior tubercle of th& 

 body of the atlas, and is inserted into the fore part of the transverse 

 processes of the third, fourth, and fifth cervical vertebrae, b. The inferior 

 oblique, the smallest part of the muscle, extends obliquely inwards from 

 the transverse processes of the fifth and sixth cervical to the bodies of the 

 first two or three dorsal vertebrse. c. The vertical part, connected by its 

 extremities with the other divisions, is attached superiorly to the bodies of 

 the second, third, and fourth cervical vertebrse, and inferiorly to the bodies 

 of the three lower cervical and two or three upper dorsal vertebrse. 



ACTIONS. The sterno-cleido-mastoid muscles, and in a less degree the scaleni 

 muscles, bend forwards the head and neck towards the sternum. The sterno-mastoid 

 muscles, when acting in concert with the extensor muscles of the head, assist in the 

 extension, and project the chin. When the sterno-mastoid muscle of one side only 

 is in action, the head, while it is slightly flexed, is inclined laterally to the side on 

 which the muscle contracts, and rotation is produced, by which the face, and especially 

 the chin, is directed towards the opposite side. This is the position which occurs in 

 wry-neck, depending upon an unequal action of the opposite sterno-mastoid muscles. 



The scalene muscles, when the vertebral column is iixed, act as elevators of the ribs, 

 and by many are considered as constant aids in the movement of inspiration. It 

 seems certain that when the head is fixed the sterno-mastoid muscles also assist in 

 forcible inspiration by the elevation of the sternum and clavicles. 



FASCIJE OF THE HEAD AND NECK. 



The SUPERFICIAL FASCIA is little developed on the head and neck, and is 

 in gretit measure blended with structures described under other names. A 



