APPENDICES TO THE SECTION ON OSTEOLOGY. 



A. Architecture of the Bones of the Skeleton. 



B. Variations in the Skeleton. 



C. Serial Homologies of the Vertebrae. 



D. Measurements and Indices employed in Physical Anthropology. 



E. Development of the Chondro- Cranium and Morphology of the Skull. 



F. Morphology of the Limbs. 



APPENDIX A. 



ARCHITECTURE OF THE BONES OF THE SKELETON. 



The Vertebrae. The vertebrae are formed of spongy bone confined within a thin and dense 

 envelope. In the bodies the arrangement of the spongy tissue, which is traversed by venous 

 channels, is such as to display a vertical striation with lamellae arranged horizontally. The 

 lateral, superior, and inferior walls are very thin that directed to the vertebral canal being 

 usually thicker and denser than the others. In the roots of the vertebral arches and roots 

 of the transverse processes the spongy tissue is much more open. The outer envelope is much 

 thicker where it bounds the vertebral canal, and where it forms the bottom of the superior and 

 inferior intervertebral notches. In the laminae the spongy tissue is confined between two compact 

 layers, of which that directed to the vertebral canal is the thicker. In the spinous processes 

 the upper edge is always the more compact. 



The Sternum consists of large-celled spongy bone, which is highly vascular, and is contained 

 between two layers of thin compact tissue. 



The Ribs. Each rib consists of a curved and compressed bar of bone, the interior of which 

 consists of highly vascular spongy tissue with an external envelope of compact bone. The 

 inner table is much the stronger, attaining its maximum thickness opposite the angle in front 

 and behind which it becomes gradually reduced. The outer table, much thinner, is stoutest 

 opposite the angle ; on the posterior surface of the tubercle and neck it forms but a thin layer. 

 The compact layers forming the upper and lower borders are not so thick as those forming 

 the inner and outer surfaces. The spongy tissue, loose and open in the body, is most compact 

 in the region of the head and towards the anterior extremity. 



The Frontal Bone. The frontal bone is composed, like the other bones of the cranial vault, 

 of two layers of compact tissue, enclosing between them a layer of spongy cancellous texture the 

 diploe. In certain definite situations, owing to the absorption of this intermediate layer, the 

 bone is hollow, forming the frontal air-sinuses. The position and extent of these is to some 

 extent indicated by the degree of projection of the superciliary ridges, though this must not be 

 taken as an absolutely reliable guide, for cases are recorded where the ridges were low and the 

 sinuses large, and vice versa. Of much surgical importance, these air-spaces only attain their full 

 development after the age of puberty, being of larger size in the male than in the female, a 

 circumstance which accounts for the more vertical appearance of the forehead in woman as con- 

 trasted with man. Usually two in number, they are placed one on either side of the median 

 flane, and communicate by means of the infundibulum with the nasal cavity of the same side, 

 t is exceptional to find the sinuses of opposite sides in communication with each other, as they 

 are generally separated by a complete partition which, however, is occasionally much deflected 

 to one or other side. Logan Turner (" On the Illumination of the Air Sinuses of the Skull, with 

 some Observations upon the Surgical Anatomy of the Frontal Sinus," Edin. Med. Journ., May 1898) 

 gives the average dimensions of these sinuses as follows : Height, 31 mm., i.e. from the fronto- 

 nasal aperture upwards ; breadth, 30 mm., i.e. from the septum horizontally in a lateral direction; 

 depth, 17 mm., from the anterior wall at the level of fronto-nasal suture backwards along the 

 orbital roof. Exceptionally large sinuses are sometimes met with extending backwards over the 

 orbit so as to form a double roof to that space. There is a specimen in the Oxford collection 

 in which the sinus is so large, and extends so far back, that the optic nerve is transmitted through 

 it in a bony tube. Another point of some practical importance is that the sinuses are hardly 

 ever symmetrical. It is rare to meet with cases of their complete absence, although sometimes 

 the sinus on one or other sid6 may be wanting. 



The zygomatic process, from the arrangement of its surfaces and the density of its structure, 

 is particularly well adapted to resist the pressure to which it is subjected when the jaws are 

 firmly closed. 



The Parietal Bone. Thin towards its lower part, where it enters into the formation of the 

 temporal fossa, it is thickest along the superior border and in the neighbourhood of the posterior 

 superior angle. 



The Occipital Bone. The squamous part displays thickenings in the position of the various 

 ridge and crests, the stoutest part corresponding to the internal and external occipital protuberances, 



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