VERTEBRAL AND OCCIPITAL MUSCULATURE 343 



muscle. This muscle has been shown to be morphologically 

 a part of the same sheet as the external oblique muscle of 

 the abdomen. 



The foregoing muscles, comprising the scalenus group, 

 are destroyed by the removal of the ventral thoracic wall 

 (p. 323). 



(e) The longus colli. Origin: Bodies of the first six thoracic 

 vertebrae. Insertion: The muscle passes forward on the 

 ventral surface of the bodies of the vertebrae, giving ofT 

 insertion fibres, and also receiving strands of origin. It 

 terminates on the anterior tubercle of the atlas. 



(/) The longus capitis is partly fused with the foregoing muscle, 

 but its origin is in a more lateral position from the trans- 

 verse processes of the first six cervical vertebrae. Insertion : 

 Sphenooccipital synchondrosis. 



(g) The longus atlantis. Origin: Lateral to the longus capitis, 

 from the transverse processes of the third to sixth cervical 

 vertebrae. Insertion: Transverse process of the atlas. 

 The longus capitis should be divided near its insertion. 



{h) The rectus capitis anterior. Medial portion of the ventral 

 surface of the transverse process of the atlas. Insertion: 

 Basioccipital bone. 



4. The caudal musculature in the rabbit comprises, in addition to the 

 posterior extension of the cutaneus maximus, the following axial muscles: 



(a) The extensor caudae medialis. It lies in the furrow between the 

 spinous and articular processes of the posterior sacral and anterior 

 caudal vertebrae, and is inserted on the transverse processes and 

 dorsal surfaces of the caudal vertebrae. 



(b) The abductor caudae posterior lies in the groove between the 

 articular and transverse processes and is inserted on succeeding 

 vertebrae. It appears to continue the multifidus, but corresponds 

 to the more medial portion of the longissimus. 



(c) The abductor caudae anterior. Origin: Ischial spine. In- 

 sertion: Lateral surface of the sacrum and the transverse processes 

 of the caudal vertebrae. 



(d) The flexor caudae. Origin: Ventral surface of the sacrum and 

 anterior caudal vertebrae^ Insertion: Ventral surfaces of succeed- 

 ing vertebrae. 



These muscles are also known as sacro-coccygei, dorsalis, lateralis, 

 and ventralis {a, b, d), and coccygeus (c). 



