310 



THE MUSCLES OF THE HEAD AND NECK. 



The scalenus medius is attached superiorly to the posterior tubercles of the 

 transverse processes of all the cervical vertebrae (sometimes not to the atlas), 

 and inferiorly to a rough impression on the first rib, extending from the tuberosity 

 to the groove for the subclavian artery. 



Relations. In front of this muscle, between it and the anterior scalenus, are the cervical 

 nerves and the subclavian artery ; behind it are the posterior scalenus and levator anguli 

 scapulae muscles. 



The scalenus posticus, smaller than the other scaleni muscles, is attached 

 above by two or three small tendons to the transverse processes of as many of the 

 lower cervical vertebrae, and inferiorly by an aponeurotic tendon to the second rib 

 external to the attachment of the serratus posticus superior. 



Varieties. The scaleni muscles are subject to a considerable amount of variation, both in 

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



Fig. 283. THE DEEP LATERAL AND PREVER- 



TEBRAL MUSCLES OP THE NECK, FROM 



BEFORE. (Allen Thomson.) ^ 



a, cut surface of basilar process ; b, 

 transverse process of atlas ; c, transverse 

 process of seventh cervical vertebra ; d, body 

 of first, d', of fourth dorsal vertebra ; e, 

 first, and e', second rib ; 1, rectus capitis 

 anticus major muscle ; 2, rectus anticus 

 minor ; 3, middle part, 3', upper part, and 

 3", lower part of longus colli ; 4, rectus 

 lateralis ; 4', first pair, and 4", second pair 

 of intertransversales ; 5, scalenus anticus 

 of right side ; 5', its attachment to the first 

 rib on left side ; 6, scalenus medius ; 6', 

 lower portion of corresponding muscle of left 

 side ; 7, scalenus posticus, its superior at- 

 tachments shown upon the left side ; 8, upper 

 part of levator scapulae drawn out from its 

 vertebral attachments ; 9, splenius colli, 

 shown in the same manner. 



the scalenus anticus sometimes passes 

 behind the subclavian artery. The sca- 

 lenus posticus is not unfrequently absent ; 

 on the other hand it has been seen ex- 

 tending to the third rib. The scalemix 

 pleiiralis (Sibson) consists of fibres which 

 arise from the transverse process of the 

 seventh cervical vertebra, and spread out 



in the fascia supporting 1 the cervical dome of the pleura, by means of which they are inserted 



into the inner border of the first rib. 



The PREVERTEBRAL muscles of the cervical region are three in number, two of 

 which pass to the head from the upper vertebrae, viz., the rectus capitis anticus major 

 and minor, and the third is confined to vertebral attachments, the longus colli. Along 

 with these the rectus capitis lateralis muscle may also be described in this place. 



The rectus capitis anticus major muscle arises by tendinous slips from 

 the anterior tubercles of the transverse processes of the third, fourth, fifth and sixth 

 cervical vertebrae : 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. 



Belations. Its anterior surface supports the pharynx, the sympathetic and vagus nerves, 

 and the great cervical vessels. The posterior surface rests upon the vertebras, part of the 

 longus colli and the rectus anticus minor. 



