CERVICALIS ASCENDENS—LOXGISSLMUS DORSI 417 



Origin. — The ui)per borders of the angles of the seventh to the eleventh ribs 

 and tlie l)ack of the last rib. 



Insertion. — The back of the transverse process of the seventh cervical vertel^ra, 

 the lirst rib just external to its tubercle, and the angles of the second to the fifth 

 ribs. 



4. CERVICALIS ASCENDENS 



The cervicalis ascendens — named from its position in the neck and its 

 direction — is a still thinner musculo-tendinous band with serrated margins. 



Origin. — The back of the four or five ujiper ril:)s just internal to the insertion 

 of the preceding muscle. 



Insertion. — The back of the transverse processes of the fourth, fifth, and sixth 

 cervical vertel)rie. 



Structure. — These three sections form a compound muscle, composed for the 

 most jjart of fusiform bellies with tendinous origins and insertions, placed in series 

 so that the origins of the higher slips are on a level with the insertions of those that 

 arise six or seven vertebras or ribs lower down. The lowest of the series arise 

 directly from the muscular mass of the erector spinse; and the insertions of these 

 lower slips, especially those into the lumbar fascia and last rib, are fleshy. A part 

 of the tendinous origin of the slips of muscle is so closely blended that a complete 

 separation of the muscle into its component parts is impossible. There is a 

 gradual diminution of the size of each component muscle and its tendons as we 

 trace the compound mass upwards. 



Nerve-supply. — The external branches of the posterior divisions of the spinal 

 nerves from the lower cervical nerves to the last thoracic. 



Action. — (1) To extend the vertebral column, in the lower cervical, thoracic, 

 and upper lumbar regions; (2) to flex it laterally in these regions; (3) to depress 

 the ril)s, and so help in expiration. 



Relations. — Superficially, the trapezius, rhomboidei, latissimus dorsi, the ser- 

 ratus posticus superior and inferior, and the two splenii; deeph^, the intercostal 

 muscles and the levatores costarum; internally, the muscles of the middle division, 

 and the external divisions of the posterior spinal nerves. 



Middle Division 



The middle division extends along the liack of the transverse processes of 

 the lumbar and thoracic vertebrae, the articular processes, and adjacent i)art of 

 the transverse processes of the cervical vertebrae, and ends at the mastoid pro- 

 cess of the temporal bone. It consists of the longissimus dorsi, transver- 

 salis colli, and trachclo-mastoid. 



5. LONGISSIMUS DORSI 



The longissimus dorsi — named from its great length and its position in the 

 dorsal regi(jn — is a compound muscle forming a long band, with its surfaces directed 

 outwards and inwards, and an anterior margin provided with an outer and inner 

 row of teeth by which it is inserted. 



Origin. — (1) The middle part of the erector spina*; and (2) tlie transverse 

 processes of some of the lower thoracic verteljrje. 



Insertion. — Externally: (1) the lower l)order of the back of the transverse 

 processes of the upper lumbar vertebrte; (2) the lower border of the ribs just exter- 

 nal to their tubercles. Internally: (1) The accessory tubercles of the ui)i)er 

 lumbar and lower thoracic vertel)rie; and (2) the back of the transverse processes 

 of the rest of the thoracic vertebrae. 

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