268 MUSCLES AND FASCIJE. 



bodies of the first two or three dorsal vertebrae ; and, passing obliquely outwards, 

 is inserted into the transverse processes of the fifth and sixth cervical vertebra. 



The vertical portion lies directly on the front of the spine, and is extended 

 between the bodies of the lower three cervical and the upper three dorsal vertebrae 

 below, and the bodies of the second, third, and fourth cervical vertebrae above. 



Relations. By its anterior surface, with the pharynx, the oesophagus, sympathetic 

 nerve, the sheath of the carotid artery, internal jugular vein, and pneumogastric 

 nerve, inferior thyroid artery, and recurrent laryngeal nerve. By its posterior 

 surface, with the cervical and dorsal portions of the spine. Its inner border is 

 separated from the opposite muscle by a considerable interval below ; but they 

 approach each other above. 



8. LATERAL VERTEBRAL REGION". 



Scalenus Anticus. Scalenus Medius. 



Scalenus Posticus. 



The /Scalenus Anticus is a conical-shaped muscle, situated deeply at the side of 

 the neck, behind the Sterno-mastoid. It arises by a narrow, flat tendon from the 

 tubercle on the inner border and upper surface of the first rib ; and, ascending 

 vertically upwards, is inserted into the anterior tubercles of the transverse pro- 

 cesses of the third, fourth, fifth, and sixth cervical vertebrae. The lower part of 

 this muscle separates the subclavian artery and vein ; the latter being in front, 

 and the former, with the brachial plexus, behind. 



Relations. It is covered by the clavicle, the Subclavius, Sterno-mastoid, and 

 Omo-hyoid muscles, the transversalis colli, and ascending cervical arteries, the 

 subclavian vein, and the phrenic nerve. By its posterior surface, with the pleura, 

 the subclavian artery, and brachial plexus of nerves. It is separated from the 

 Longus colli, on the inner side, by the subclavian artery. 



The Scalenus Medius, the largest and longest of the three Scaleni, arises, by 

 a broad origin, from the upper surface of the first rib, behind the groove for the 

 subclavian artery, as far back as the tubercle ; and, ascending along the side of 

 the vertebral column, is inserted, by separate tendinous slips, into the posterior 

 tubercles of the transverse processes of the lower six cervical vertebrae. It is 

 separated from the Scalenus anticus by the subclavian artery below, and the 

 cervical nerves above. 



Relations. By its external surface, with the Sterno-mastoid ; it is crossed by 

 the clavicle, and Omo-hyoid muscle. To its outer side, are the Levator anguli 

 scapulae, and the Scalenus posticus muscles. 



The Scalenus posticus, the smallest of the three Scaleni, arises by a thin tendon 

 from the outer surface of the second rib, behind the attachment of the Serratus 

 magnus, and, enlarging as it ascends, is inserted, by two or three separate tendons, 

 into the posterior tubercles of the transverse processes of the lower two or three 

 cervical vertebrae. This is the most deeply placed of the three Scaleni, and is 

 occasionally blended with the Scalenus medius. 



Nerves. The Rectus capitis anticus major and Rectus capitis anticus minor are 

 supplied by the suboccipital and deep branches of the cervical plexus ; the Rectus 

 lateralis, by the suboccipital ; and the Longus colli and Scaleni, by branches from 

 the lower cervical nerves. 



Actions. The Rectus anticus major and Rectus anticus minor are the direct 

 antagonists of those placed at the back of the neck, serving to restore the head to 

 its natural position when drawn backwards by the posterior muscles. These 

 muscles also serve to flex the head, and, from their obliquity, rotate it, so as to 

 turn the face to one or the other side. The Longus colli will flex and slightly 

 rotate the cervical portion of the spine. The Scaleni muscles, taking their fixed 

 point from below, draw down the transverse processes of the cervical vertebrae, 

 flexing the spinal column to one or the other side. If the muscles of both sides 

 act, the spine will be kept erect. When taking their fixed point from above, 

 they elevate the first and second ribs, and are, therefore, inspiratory muscles. 



