90 ANATOMY OF THE RABBIT 



course of the fibers is craniodorsad and caudoventrad. Method: 

 Insert the grooved director under the ventral margin between 

 and two ribs, near the sternal cartilages (preferably fourth to 

 eighth ribs) and transect the muscle in order to expose the 

 internal intercostal mm. (57). 



57. Internal intercostal mm. Mediocaudal surface of each 

 of the first eleven ribs and costal cartilages; to mediocranial 

 border of each succeeding rib. The function is not clearly 

 understood, for, as in the externals, it depends upon '^ fixation." 

 Most probably they raise the ribs. The fibers extend ventro- 

 craniad and dorsocaudad, thus crossing obliquely under those 

 of the externals (56). Do not transect. 



58. Splenius capitis et colli m.: Ligamentum nachae and 

 possibly spines of first three thoracic vertebrae; to mastoid 

 process and base of skull. Turns head sidewise and inclines 

 face, both muscles acting raise the face. The caudal portion 

 forms the splenius colli in man. Do not transect. 



59. Sacrolumbalis (sacrospinaHs, erector spinae) mm.:Lum- 

 bodorsal tendon, sacrum, ihum, mammillary processes of last 

 six lumbar vertebrae ; by seven to nine subdivisions to proximal 

 portion of ribs and to all the vertebrae caudad to the second 

 cervical. Thus, including all its parts, this is the largest, 

 longest, and strongest muscle in the body. It is antagonistic 

 to the psoas muscles (65) and is divided into three major 

 divisions each of which is subdivided into three major parts. 

 Method: Insert the grooved director under the lumbar fascia, 

 transect and reflex it laterad and mediad so as to expose the 

 sacrolumbalis group. It is not necessary to transect any 

 muscles of this group. 



59a. Iliocostal (lateral division of erector spinae) mm. : Inserts 

 into all the ribs. 



596. Longissimus dorsi (middle division of erector spinae) m. : 

 Inserts mainly on transverse and accessory processes of vertebrae 

 and proximodorsal regions of all but the first two to four ribs. 



59c. Spinalis dorsi (medial division of erector spinae) 

 m.: Spines of first two lumbar to last two or three thoracic 



