26 ANTHROPOLOGY. 



The posterior vertebral ligameyit {pi. 124, fcf. 7 *), in part a prolongation of 

 the apparatus ligamentosus, extends down the back part of the bodies of 

 the vertebriB, along the front of the spinal canal. It adheres more closely 

 to the edges of the vertebrte and to the intervertebral ligaments than to the 

 middle of each vertebra, and runs out in the sacral canal. Its object is to 

 give strength to the spine by opposing too much flexion of the column. 



The intervertebral ligaments {fg. 10 '- ') are placed between the bodies of 

 all the vertebrae except of the first and second. They are fibro-car til ages, 

 partaking both of cartilage and ligament in their character. Their union 

 above and below to the flat surfaces of the vertebrae is so intimate, that 

 maceration or boiling alone can separate them completely ; and their own 

 strength and cohesion surpass that of even the bones themselves, the bone 

 breaking before the ligament can be ruptured or torn from its attachment. 

 In the neck and loins they are thicker in front than behind, the contrary 

 being the case in the back ; this causes much of the peculiar curvature of 

 the spine. 



The oblique or articulating processes of the vertebrae are connected by 

 synovial membranes and by ligamentous capsules extending irregularly 

 around these so as to form imperfect capsular ligaments. 



T'he ligamenta suhjlava {fg. 11 ') are situated between the back parts of 

 the plates or the arches of the vertebrae; they close the intervals between 

 them, and thus complete the back part of the spinal canal. The name is 

 derived from their yellow color. The supra-sp)inous ligament ( fig. 12 *) 

 extends in the median line from the occiput to the sacrum, connecting the 

 extremities of the spinous processes. The cervical portion is usually 

 considered as a distinct portion under the name of ligamentum nuchm, 

 attached above to the occipital bone, below to the last cervical spine, and 

 intermediately by distinct slips to all the cervical spines except that of the 

 atlas. The interspinous ligaments {fig. 12 '") are fibrous membranes placed 

 vertically, and filling the space between the spinous process. The inter- 

 transverse ligaments are ligamentous fibres extending between the transverse 

 processes. 



4. Special Anatomy of the Thorax. 

 A. Bones of the Thorax. 



The thorax is constituted posteriorly by the twelve dorsal vertebrse, 

 laterally by the twelve pairs of ribs, and anteriorly by the costal cartilages 

 and sternum. 



The sternum or breast bone {pi. 122, fg. 3, h) is situated in the anterior 

 portion of the thorax, in its median line. The anterior surface is flat or 

 slightly convex, and is marked by transverse lines which indicate an 

 original division into six pieces. Of these lines the two uppermost are 

 most prominent. The posterior surface is smooth and slightly concave. 

 The superior or cervical end is thick and broad, and very concave trans- 

 versely. In the adult, it consists of three distinct divisions, the upper of 

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