MUSCLES OF THE LIMBS. 211 



Insertion. — By tendons to the inferior surface of all the 

 coccygeal vertebrae successively. 



Relation. — Superiorly with the sacrum, coccyx, and curvator ; 

 inferiorly with the rectum; externally with the curvator and 

 sacro-sciatic ligament ; internally with its fellow. 



Action.— To bend the tail downwards; singly, to draw it 

 downwards and to one side. 



CURVATOR COCCYGIS. 

 [Sacro-coccygeus Lateralis.) 

 (PL. III. 32.) 

 Situated on the side of the tail, and similar in structure to the 

 preceding, it is merely a continuation of the semispinalis lumborum. 

 Origin. — From the spines of the last lumbar, and lateral 

 aspect of the sacral and coccygeal vertebrae. 



Insertion. — The side of the coccyx, between the erector and 

 depressor. 



Relation. — Superiorly with the erector and sacral ligament ; 

 inferiorly with the dejDressor ; externally with the compressor. 



Action. — To curve the tail, drawing it sideways over the 

 quarter. 



COMPRESSOR COCCYGIS. 

 ( Ischio-coccygeus. ) 



Situated at the side of the pelvis, it is a large, thin, and tri- 

 angular muscle. 



Origin. — By aponeurosis, from the superior ischiatic spine and 

 the inner surface of the sacro-sciatic ligament, running upwards 

 and backwards. 



Insertion. — By jBeshy fibres, to the side of the terminal sacral 

 and first two coccygeal vertebras. 



Relation. — Externally with the sacro-sciatic ligament ; inter- 

 nally with the curvator and rectum. 



Action. — To depress the entire tail. 



Muscles of the Limbs. 



The muscles of this class are those which are specially related 

 to the limbs, for the most part acting upon them alone ; they are 

 intrinsic and extrinsic, according to their origin. These muscles 



