324 HEALTH AND DISEASE 



Insertion. — It has numerous connections in its course towards the neck. 



1. To the spinous, transverse, and articuhir processes of the lumbar vertebrae. 



2. To the spinous and transverse processes of the dorsal vertebrae. 3. To 

 the external surfaces of the 14th and 15th posterior ribs. 4. To the spinous 

 processes of the last four cervical vertebrae. 



Action. — Acting with its fellow on the opposite side, it extends the 

 spine. By its attachments to the cervical vertebrae it raises and sujjports 

 the neck, and by its connection with the ribs it assists in expiration. It is 

 the principal muscle concerned in rearing, kicking, and jumping. 



Transversalis Costarum. — This is a long, narrow muscle, stretching 

 across the ribs a little distance from the spine. 



Origin. — It is composed of two sets of tendons. By one set it arises 

 from the transverse process of the first lumbar vertebra and the anterior 

 borders of the ribs. By the other it is inserted into the posterior edges of 

 the fourteen anterior ribs and into the transverse process of the last cervical 

 vertebra. 



Action. — To assist in expiration. 



The Semispinalis of the back and loins. — This is situated on the 



sides of the spines of the dorsal and lumbar ^■ertebrge, and extends along 

 their entire length from the sacrum to the neck. It is made up of a 

 number of short slips passing obliquely upward and forward. 



Origin. — 1. From the sacrum behind. 2. From the articular pro- 

 cesses of the lumbar vertebrae. 3. From the transverse processes of the 

 dor.sal vertebrae. 



Insertion. — Each slip becomes inserted into the spinous process of the 

 third or fourth vertebra in front of the one from which it arises. 



Action. — To fix the bones during the action of the large spinal muscle, 

 and to assist in extending the spine. 



Retractor Costse. — A small, thin, triangular muscle arising from the 

 transverse processes of the lumbar vertebrae. 



Insertion. — Into the posterior border of the last rib. 



Action. — To assist in expiration. 



By some this muscle is considered to be part of the internal oblique 

 muscle of the abdomen. 



MUSCLES OF THE INFERIOR LUMBAR REGION 



Psoas Magnus. — This is a broad, flat muscle placed beneath the loins, 

 and extending from beneath the spine backward to the upper part of the 

 thigh. 



Origin. — From the bodies of the last two dorsal vertebrae, from the 



