172 TOPOGRAPHICAL ANATOMY OF THE 



muscle abutting upon the median plane and arising from the spinous 

 processes of the last two or three sacral vertebra\ It also receives 

 fibres from the multifidus, and terminates in a tendon which blends with 

 that of the following muscle. 



M. SACROCOCCYGEUS DORSALis LATERALIS. — The lateral dorsal sacro- 

 coccygeus muscle follows the lateral border of the foregoing, and appears 

 to be a continuation of the multifidus muscle. Fibres join it from the 

 transverse processes of the sacrum and the first few coccygeal vertebne, 

 and it terminates in a tendon (with which the medial muscle is 

 blended) that is inserted into the rudiments of the transverse pro- 

 cesses of the coccygeal vertebras witli the exception of the first three or 

 four. 



M "sacrncoccygeus dorsalis medialis. 

 Sixth coccygeal vertebra i ^^ sacrococcygeus dorsalis lateralis. 



Lateral coccygeal J__^^ ^ 



vessels and nerves. ^^^-^T^ ?r~~~N)---^ Mm. intertransversarii. 



M sacrococcygeus ventralis lateralis. 



I M. sacrococcygeus ventralis medialis. 

 A. coccygea. 



Fig. 75. — Transverse section of the tail on a level with the sixtli coccj^geal vertebra. 



M. SACROCOCCYGEUS VENTRALIS MEDIALIS. — This muscle lies ven- 

 tral to the coccygeal vertebrae and lateral to the recto - coccygeal 

 muscle. Its origin is from the pelvic surface of the sacrum and the 

 ventral aspect of the bodies of the first seven or eight coccygeal 

 vertebrae. Its insertion — in common with part of the lateral muscle 

 of the same name — is to the ventral surface of the bodies of the 

 coccygeal vertebrae. 



M. SACROCOCCYGEUS VENTRALIS LATERALIS. — A stronger muscle 

 than the preceding, the lateral ventral sacro-coccygeal arises from 

 the pelvic surface of the sacral vertebrae from the second or third 

 to the last and from the transverse process of the first coccygeal 

 vertebra. Bundles of muscular fibres are succeeded by a double 

 series of tendons. Some of these join the tendons of the preceding 

 muscle. Others are attached to the transverse processes of the coccy- 

 geal vertebra'. 



Mm. INTERTRANSVERSARII. — Lying between the lateral dorsal and 



