276 ANATOMY IN A NUTSHELL. 



spinous processes in the cervical region. This muscle is absent in about twenty 

 per cent of the cases. 



Origin. — (1) Spinous processes of the fifth, sixth, and seventh cervical 

 vertebrae, (2) and occasionally from the first and second dorsal vertebras. 



Insertion. — Spine of axis and third and fourth cervical vertebrae. 



Action. — To approximate the spines of the vertebrae. 



LESSON LXXVII. 



Fifth Layer of Muscles of Back. 



Semispinalis dorsi. — Description. — This muscle takes its name on account 

 of its inner half being attached to the spine, and its situation in the dorsal 

 region. 



Origin. — From transverse processes of fifth, sixth, seventh, eighth, ninth, 

 and tenth dorsal vertebra?. 



Ixskrtion. — Into the spinous processes of seventh and eighth cervical, 

 first, second, third, and fourth dorsal vertebrse. 



Action. — To erect the spinal column. 



Semispinalis colli. — Description. — This muscle takes its name from the 

 attachment of its one-half to the spines in the cervical region. 



Origin. — Transverse processes of the upper five or six dorsal vertebra?. 



Insertion. — Into the spinous processes of the second, third, fourth, and 

 fifth cervical vertebrse. 



Action. — To erect the spinal column. 



Multindus spinas — Description. — This muscle takes its name from its 

 many clefts. 



Origin. — (1) Back of sacrum as far as the fourth sacral foramen, (2) 

 aponeurosis of the Erector spina? muscle, (3) Posterior superior spine of the 

 ilium, (4) posterior sacrc-iliac ligament, (5) articular processes of lumbar ver- 

 tebras (6) transverse processes of dorsal vertebras, (7) articular prosesses of 

 three or four lower cervical vertebra?. 



Insertion. — Into the lamina?, and spinous processes of all the vertebra? 

 except the atlas. 



Action. — To preserve the erect position of the spine and to rotate it. 



Rotatores spinae. — Description. — This muscle takes its name from its 

 functions. There are generally eleven pairs, but they may be found in the 

 cervical and lumbar regions. 



Origin.- Upper and hack parts of the transverse processes in the dorsal 

 region i I t he S] inc. 



Insertion.- Lower border and outer surface of the first lamina above the 

 oi igin. 



Action. — Assists the Mrlli.idus spina? to rotate the spine, turning the trunk 

 to i he opposite si le. 



Suprasplnales.— Description.- These muscles lie on the spinous pro- 

 c( sses in t he cervical r< eion. 



