THE BONES. 45 



the cartilage. Ossification commences in the cylindrical and in 

 the flat bones which appear in pairs, from the centre spreading 

 outwards towards the extremities and surfaces; in the azygos 

 and short bones, vertebra, e. g., in two or several symmetrical 

 points, puncta ossificafionis. It is earliest in the clavicle, se- 

 cond month of the embryo, and jaws, latest in the os pisiforme, 

 sixth to twelfth year. Sutures arise by the meeting together of 

 ossified parts which, as cartilage, were separated, e. g., in the 

 skull. Many foramina and canals are in the commencement 

 bounded by several separate pieces, e. g., foram. magnum 

 canal, spinalis. The extremities of the cylindrical bones are in 

 the cartilaginous state separate from the central portion for some 

 time after birth, and unite at last into one bone. 



Abnormal osseous development frequently appears in tendons and cartilages, 

 in the ovary, on the sternum, on the bones much used, &c. 



44. Particular parts of the Bones. 



The skeleton is but a system of vertebrae ; the bones must there- 

 fore be regarded as more or less perfect or metamorphosed ver- 

 tebrae. As in these, so in other bones, we find a body and con- 

 necting parts ; the former, serving generally for the attachment of 

 muscles and ligaments, encloses cavities and passages ; the latter, 

 particularly assisting in the formation of joints. 



1. Articular portions, a. Elevations, smooth, covered with 



cartilage : 



1. Head, caput, capitulum, a segment of a sphere upon a small neck (collum). 



2. Condyle, condylus, semi-oval. Hereto also belongs the processus, process 

 (pr. obliquus). 



b. Depressions ; smooth, covered with cartilage : 



1. Glenoid cavity, a smooth fossa (e. g., of the Scapula). 



2. Colyloid cavity, cup-like, deep, circular (e. g., of the hip bone). 



2. Elevations for the attachment of muscles and ligaments: 



1. Projections, tuber, tuberositas, protuberantia, tuberculum, zygoma, trochanter. 



2. Spine (sharp-pointed), spina (spina tibia, ilei, processus spinosus). 



3. Crest, crista, broad, long. 



4. Lines, linea (long, narrow), e. g., linea semicircularis, I. aspera. 



5. Process, processus, e. g., pr. Mastoideits, styloid, pterygoid, transversus. 



6. Branch, ramus (thick, long). 



3. Depressions, not assisting in the formation of joints: 



1. Fossa, fovea (flat); the entrance wider than the floor; e. g., /. parietali* 

 lacrymalis. 



