Early Development of the Cervical Vertebras 



18^ 



median center of chondrification appears in all the hypochordal braces, 

 but, except in the first two vertebrae, the brace disappears before car- 

 tilage is actually formed. In the hypochordal brace of the second 



nalis hypoglossi 

 'Atlas arcus ventralis 



Costa I 



Fig. 1. — Lateral view of a model of the occipital cartilage, the cervical 

 vertebras the first thoracic vertebra and the proximal end of the first rib in 

 an embryo 20 mm. long. The costal elements of the cervical vertebrae are 

 cartilaginous and are connected by ligamentous tissue with the transverse 

 processes of the neural arches and with the vertebral bodies. The interverte- 

 bral discs are shown except between the fourth and fifth, and the fifth and 

 sixth vertebrae. Dense interarticular tissue is shown between the articular 

 processes from the second cervical to the first thoracic vertebra and, posterior 

 to this, interlaminar connective tissue membranes and a ligamentous band 

 running from the neural process of the atlas to the thoracic region. 



