12 PHYSIOLOGY FOR THE LABORATORY. 



e. The marrow is within the cavity. What is its color ? 

 What is its use to the bone ? 



f. Make a sketch of the longitudinal section. 



C. The Gross Structure of an Irregular Bone, a Vertebra. 



Materials. A dorsal vertebra of the human skeleton or of a dog, 

 sheep, or other vertebrate. The axis, or second cervical vertebra, of 

 the human skeleton. The atlas, or first cervical vertebra, of the human 

 skeleton. The spinal column just taken from a fresh fish or a rabbit. 



1. Examine carefully a human vertebra of the dorsal 

 region. If that is not possible, study the vertebra 

 of a cat, a dog, a bird, a sheep, or of any other of 

 the vertebrates. Identify the following parts when 

 present: 



a. The centrum, or body, is the large solid part. 



5. The neural arch is the bony arch on one side ; its use ? 

 Study the spinal column of the human skeleton and see 

 whether the arch is on the dorsal (back) or ventral (front) 

 side of the vertebral column. 



c. The neural ring is formed by the neural arch and the 

 centrum. 



d. The neural canal is the cavity within the ring. See a 

 fresh specimen of the spinal column of a fish and find what 

 is in the neural canal. 



e. The spinous process is the outward projection on the 

 dorsal side of the neural arch. 



/. The transverse processes are projections at the side. 



g. The anterior articular process is the projection by which 

 the vertebra joins the next vertebra above towards the 

 head. 



