COCCYX. 



the body, and one for each lateral portion. In the progress of growth, 

 and after puberty, fourteen epiphysal centres are added, namely, uvo for 

 the surfaces of each body, one for each auricular surface, and one for the 

 thin edge of each lateral border. Ossification begins in the bodies of the 

 sacral pieces somewhat "later than in those of the true vertebra? ; the first 

 three appearing during the eighth and ninth week, and the last two al about 

 the middle of the intra-uterine existence. Ossification of the lamelhe 

 takes place during the interval between the sixth and the ninth month. 

 The epiphyses for the upper and under surface of the bodies are developed 

 during the interval between the fifteenth and eighteenth year; and ior the 

 auricular and marginal piece, after twenty. The two lower vertebral 

 pieces, although the last to appear, are the first to be completed (between 

 the fourth and fifth year), and to unite by their bodies. The union of the 

 bodies takes place from below upwards, and finishes between the twenty- 

 fifth and the thirtieth year, with the first two pieces. 



Articulations. With four bones ; the last lumbar vertebra, ossa inno- 

 minata, and coccyx. 



Attachment of Muscles. To seven pairs; in front the pyriforinis, on 

 the side the coccygeus, and behind the gluteus maximus, latissimus dorsi, 

 longissimus dorsi, sacro-lumbalis, and multifidus spinaB. 



The COCCYX (xoxxug cuckoo, from resembling a cuckoo's beak) is com- 

 posed of four small pieces, which form the caudal termination of the ver- 

 tebral column. The superior piece is broad, and expands laterally into 

 two transverse processes ; it is surmounted by an oval articular surface 

 and two cornua, the former to articulate with the apex of the sacrum, and 

 the latter with the sacral cornua. The lateral wings sometimes become 

 connected with the sacrum, and convert the notches for the fifth pair of 

 sacral nerves into foramina. The remaining three pieces diminish in size 

 from above downwards. 



Development. By four centres; one for each piece. Ossification com- 

 mences in the first piece soon after birth ; in the second, between five and 

 ten years ; in the third, between ten and fifteen ; and in the fourth, be- 

 tween fifteen and twenty. The pieces unite at an earlier period than the 

 bodies of the sacrum, the first two pieces first, then the third and fourth, 

 and lastly, the second and third. Between forty and sixty years, the 

 coccyx becomes consolidated with the sacrum ; this event taking place 

 later in the female than in the male. 



Articulations. With the sacrum. 



JJtfac/iment of Muscles. To t/iree pairs, and one single muscle; gluteus 

 maximus, coccygeus, posterior fibres of the levator ani, and sphincter ani. 



OF THE SKULL. 



The skull, or superior expansion of the vertebral column, is divisible 

 into two parts, the cranium and the face ; the former being adapted, by 

 its form, structure, and strength, to contain and protect the brain, and the 

 Jatter the chief organs of sense. 



The CRANIUM is composed of eight separate bones ; viz., the 

 Occipital, Two temporal, 



Two parietal, Sphenoid, 



Frontal, Ethmoid. 



