OSTEOLOGY AND SYNDESMOLOGY. 13 
‘the pivot. The best illustration of this articulation in the human subject is 
that between the atlas and odontoid process of the axis or vertebra dentata. 
Another example is seen in the superior radio-ulnar articulation. 
The ligaments which tie the bones together are of two kinds, capsular 
and funicular. ‘The former resemble a bag open at both ends, in which the 
extremities of the bone forming the joint are included. The latter are 
simple cords extending from one bone to another; they may be either 
cylindrical or flattened. ‘They are variously placed; in some instances 
they are within the capsular ligament, in others on the outer surface, and 
sometimes so blended with it as not to be separable without an artificial 
dissection. The attachment of the head of the thigh bone to its socket in 
the pelvis illustrates the capsular ligament, while that of the tibia to the 
thigh furnishes an example of the funicular. Cartilages are also found 
placed between joints for the purpose of diminishing friction. All the 
movable articulations also have their surfaces covered with a layer of 
cartilage of the most exquisite smoothness. In addition to this, there is 
a closed sac called the synovial membrane, lining the articulation and 
reflected over the inner faces of the capsular hgament and the articular 
cartilages. This membrane, unlike the capsular ligament, has no opening 
whatever. Its whole inner surface appears to secrete the oily fluid called 
synovia, whose object is to give suppleness and lubricity to the joint. 
The human skeleton, considered as a whole, may be conveniently divided 
into head, trunk, and limbs, all together including from 218 to 217 distinct 
bones. 
Projections on the bones either form articulations with other bones, and 
-are known as head, condyle, &c., or they serve for the attachment of muscles 
and tendons, in which case they become projections, processes, trochanters, 
crests, lines, spines, ridges, &e. Depressions, cavities, or fissures are for the 
attachment of muscles, the formation of articulations, or for the passage of 
vessels and nerves. ‘They are called furrows, impressions, holes, fissures, 
canals, grooves, notches, &c. 
2. BONES OF THE HEAD. 
Beginning with the head we find a primary division into the bones of the 
- cranium or skull, and bones of the face. 
we. 
A. Bones of the. Cranium. 
The cranium is composed of eight bones: the os frontis, the os occipitis, 
the two ossa temporum, two ossa parietalia, the os sphenoides, and the os 
ethmoides. The first of these, the os frontis, or frontal bone, is represented 
in pl. 121, figs. 1’, 4’, 5’, and 7, from the anterior surface, fig.8 from the 
interior, and pl. 128, fig. 1, from below. It forms the whole anterior and a 
portion of the superior lateral and inferior walls of the cranium, and may be 
divided into the frontal, the two orbitar, and the nasal portions. Between 
the two tables of the bone are to be found certain cavities or cells called 
frontal sinuses (p/. 123, fig. 3°), lined by a mucous membrane. A median 
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