DISSECTION OP THE HEAD AND NECK. 155 



The Superior Cervical Artery, like the preceding, arises within the 

 chest, and from the same source. It leaves the thorax by the upper 

 part of the first intercostal space ; and placing itself on the inner 

 surface of the oomplexus, it ascends between that muscle and the liga- 

 mentum nuchae, as far as the 2nd or 3rd cervical vertebra, where its 

 terminal branches anastomose with those of the occipito-muscular and 

 dorsal arteries. 



Veins. The dorsal and superior cervical arteries are accompanied 

 by veins of the same names, which, after entering the chest, discharge 

 themselves into the anterior vena cava. 



Directions. — The complexus, splenius, and trachelo-mastoideus muscles 

 may now be removed as far as the hinder end of the axis. This will 

 expose the semispinalis colli muscle and the ligamentum nuchse. 



The Semispinalis Colli Muscle (Fig. 18) rests on the laminse.of 

 the cervical vertebrae, and consists of five bundles. The most posterior 

 of these bundles may be described as taking origin from the anterior 

 articular process of the 7th cervical vertebra, and passing forwards 

 and inwards to be inserted into the superior spine of the 6th vertebra. 

 The most anterior bundle passes in the same way between the 3rd 

 vertebra and the axis, while the intermediate bundles have corresponding- 

 attachments. 



Action. — The right and left muscles, acting in concert, will extend 

 (elevate) the cervical part of the spinal column. The muscle of one side, 

 acting singly, will rotate and incline the spinal column to the opposite side. 



The Intertransvbrsalbs Colli Muscles (Fig. 18). These form a 

 set of six muscular bundles with strong tendinous intersections, and 

 cover the sides of the cervical vertebrae. There is one bundle for each 

 intervertebral articulation except the first. Each muscular bundle 

 consists of an upper and a lower slip ; and it may be described as arising 

 from the articular process of one vertebra, and passing forwards to be 

 inserted into the transverse process of the vertebra in front. The 

 muscles conceal the intervertebral foramina and the vertebral vessels ; 

 and they are perforated by branches of these vessels, and by the superior 

 and inferior primary branches of the spinal nerves of the neck. 



Action. — To bend the neck laterally. 



The Kectus Capitis Anticus Major (Plate 28 and Fig. 18). This 

 muscle begins by a tapering point on the side of the vertebral column 

 at the 5th cervical vertebra ; and passing forwards and inwards, it gains 

 the inferior face of the atlas, in passing to the base of the skull. It 

 arises from the transverse processes of the 5th, 4th, and 3rd vertebrae, 

 the slip of origin from the first of these crossing the point of the 

 scalenus. Its insertion, which is not to be exposed at present, is into 

 the tubercular processes at the junction of the basilar process with the 

 body of the sphenoid. 



