12 ANATOMY. 



What is the Marrow of Bone ? In young bones a tenacious, transparent 

 fluid, free from fat. In adult bones of a yellow color, consisting of fat in vary- 

 ing proportion and extractive matters. It is found in the medullary canal, the 

 cancellous texture, and the large Haversian spaces. 



What Vessels are found in Bones ? Arteries, veins, and some say lym- 

 phatics. The Arteries are, the nutrient, entering at the nutrient foramen ; 

 the articular, nourishing the cancellous structure ; and the periosteal, which 

 supply the periosteum and the compact structure. The Veins emerge from 

 the ends, the shaft, and from the nutrient foramen. 



Describe the process of Ossification. The site of bone is first occupied 

 by a mucoid substance, which becomes temporary cartilage (blastema) in the 

 second month of foetal life. The young bone-cells [osteo-blasts] are then de- 

 posited in the cartilage at certain points, and their deposition and subsequent 

 pressure cause the absorption of the cartilage. In most of the bones of the 

 head and face, ossification is intra-membranous instead of intra-cartilaginous. 

 Thefirtt bones in which ossification appears are the clavicle and inferior max- 

 illary (5th to yth foetal week); the last is the pisiform bone (i2th year). 

 Epiphyses ossify after birth and begin uniting to the bone from the age of pu- 

 berty, and in the inverse order to that in which their ossification began, except 

 the lower end of the fibula, which ossifies and is joined to the shaft earlier 

 than its upper end. 



THE BONES OF THE HEAD. 



THE FRONTAL BONE. 



Describe the points on its vertical portion. They are as follows: 

 Externally, 



Frontal Eminences, one on each side of the median line. 



Depression, marking the site of the frontal suture before obliteration. 



Superciliary Ridges, behind which are the : frontal sinuses. 



Supraorbital Notches or Foramina, in the supraorbital arches, at about their 

 inner third, for the supraprbital vessels and nerves. 



Nasal Eminence, at lower end of the frontal depression. 



External Angular Processes, articulate with the malar bones and form th? 

 anterior part of the temporal ridges. 



Internal Angular Processes, articulate with the lachrymal bones. 



Nasal Spine and Notch, between the internal angular processes. 

 Internally, 



Groove, for superior longitudinal sinus and the falx cerebri. 



Frontal Crest, for attachment of the falx cerebri. 



Foramen Ccecum, for a small vein to the longitudinal sinus. 



Depressions and Elevations, for convolutions of the brain. 



