372 GENERAL ANATOMY. 



while the sternum, pelvis, and limbs are so in but a very small 

 degree. 



It has also been established as a general proposition, that the 

 bones which are first formed are those which are near the san- 

 guineous and nervous centres, the ribs and vertebrae being in 

 fact developed at a very early period. 



It has also been said, that the long bones appear first, then 

 the broad bones, afterwards the short bones; the clavicle, fe- 

 mur, and tibia appearing from the commencement, and the 

 bones of the tarsus and carpus at a much later period. 



Lastly, It has been thought that the large bones ossify first 

 and the others successively. 



There are many exceptions to these rules. 



590. Ossification commences at the end of the first month 

 in the clavicle, and successively in the inferior maxillar bone, 

 the femur, the tibia, the humerus, the upper maxillary bone, 

 and the bones of the fore-arm, in which it commences about 

 the thirty-fifth day. It commences about the fortieth day in 

 the fibula, the scapula, and the palatal bones, and the follow- 

 ing days in the proral portion of the occipital bone, in the 

 frontal bone, the arches of the first vertebrae, the ribs, the great 

 wing of the sphenoid bone, the zygomatic process, the pha- 

 langes of the fingers, the bodies of the middle vertebrae, the 

 nasal and zygomatic bones, the ilium, the metacarpal bones, 

 the extreme phalanges of the fingers and toes, the condyles of 

 the occipital bone, and then in its basilar portion, in the 

 squamous portion of the temporal bone, in the parietal bone, 

 and in the vomer, in all which bones it commences about the 

 middle of the seventh week. In the course of the same week 

 it also commences in the orbitar wing of the sphenoid bone, 

 and lastly in the matatarsal bones, the phalanges of the toes 

 and the second phalanges of the fingers. In the ten following 

 days it commences in the body of the sphenoid bone, in those 

 of the first sacral vertebras, and in the ring of the tympanum. 

 About the middle of the third month it shows itself in the 

 costiform appendage of the seventh vertebra, before the end 

 of the third month, in the labyrinth, and towards the end ol 

 the same month, in -the ischium and inner pterygoid process ; 



