ANATOMY IX A NUTSHELL. 585 



(a) a longitudinal portion, (b) a superior oblique portion, (c) inferior oblique 

 portion. 



Origin of the longitudinal portion is from the bodies of the first, second, 

 and third dorsal, and of the sixth and seventh cervical vertebra?. 



Insertion of this portion into the body of the second, third, and fourth 

 cervical vertebra?. 



Origin of superior oblique portion is from the anterior tubercle of the trans- 

 verse processes of the third, fourth, and fifth cervical vertebra?. 



Insertion of this portion into the anterior tubercle of atlas. 



Origin of inferior oblique portion is from the bodies of the first, second, and 

 third thoracic vertebra?. 



Insertion of this portion is into the anterior tubercle of the transverse 

 processes of the fifth and sixth cervical vertebra?. 



Action. — To flex the cervical portion of the spinal column, and rotates it. 



Nerve Supply. — Anterior branches of the lower cervical before the}' go 

 into the brachial plexus 



Blood Supply. — 



Muscles of the Lateral Vertebral Region. 



Scalenus anttcus. — 



Origin. — From the anterior tubercles of the transverse processes of the 

 third, fourth, fifth, and sixth cervical vertebrae. 



Insertion. — Into the tubercle on the inner and upper surface of the first 

 rib in front of the subclavian artery. 



Action. — It flexes the neck and elevates the first rib. 



Xerve Supply. — Anterior primary branches of the fourth, fifth, and 

 sixth cervical nerves. 



Blood Supply. — 



Scalenus medius. — Description. — Is the largest of the Scaleni muscles 

 and passing through its substance is the posterior thoracic or long thoracic 

 nerve. 



Origin. — From the posterior tubercles of the transverse processes of the 

 lower six cervical vertebrae. 



Insertion. — Into the upper surface of the first rib behind the groove for 

 the subclavian artery. 



Action. — It flexes the cervical portion of the spinal column and elevates 

 the first rib. 



Xerve Supply. — From the posterior primary branches of the cervical 

 nerves. 



Blood Supply. — 



Scalenus posticus. — Description. — Tlii< is the smallest and deepest 

 of the Scaleni muscles and sometimes blends with the Scalenus medius. 



Origin. — From the posterior tubercle of the transverse processes of the 

 lower two or three cervical vertebra'. 



Insertion. — Into the outer surface of the second rib behind the origin 

 of the Serratus magnus. 



Action. — It flexes the cervical vertebrae laterally and raises the Brs1 rib. 



