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138 THE ANATOMY OF THE HORSE. 



INTER-VERTEBRAL JOINTS AND LIGAMENTS. 



In the dorsal and lumbar regions adjacent vertebrse are connected 

 (1) by an amphiarthrodial joint between their bodies, and (2) by 

 synovial joints between their articular processes. These same joints are 

 formed between the last lumbar vertebra and the sacrum ; and, in 

 addition, there is a synovial joint between the last lumbar transverse 

 process and the base of the sacrum. Inter-transverse joints are also 

 developed between the 4th and 5th, and 5th and 6th lumbar transverse 

 processes. The ligaments may be classified into: 1. Those connecting 

 the processes and neural arches of adjacent bones. 2. Those connecting 

 adjacent vertebral bodies. 



Ligaments of the Processes and Neural Arches :— 



The Supraspinous Ligament is a strong longitudinal band, or cord, 

 extending along the tips of the spinous processes. It is continued 

 backwards on the sacral spines ; and in the anterior part of the dorsal 

 region its texture changes from white fibrous to yellow elastic tissue, 

 and is continued forwards as the funicular portion of the ligamentum 

 nuclue. It not only tends to maintain the union of the vertebrae, but 

 also affords a point of origin to muscles of the back and loins. 



The Interspinous Ligaments occupy the interspaces of the spinous 

 processes. In each space the ligament consists of a right and a left 

 layer, whose fibres have a downward and backward direction. This 

 oblique direction of the fibres favours the separation of the spines 

 during flexion. 



Capsular Ligaments of the Articular Processes.— These complete the 

 diarthrodial joint formed between the articular processes of adjacent 

 vertebrse, and support the synovial sac of the joint. One of the 

 ligaments should be slit open to display the synovial membrane lining 

 its inner surface. 



The TAg amenta subjtava, or Ligaments of the Arches. — These pass 

 between the edges of adjacent neural arches. They are best seen 

 by sawing horizontally through the pedicles of two vertebrae, close to 

 the body, and then pulling the arches apart w r hile they are viewed 

 from below. 



Capsular Ligaments of the Transverse Processes. — These surround the 

 joints developed between the transverse processes of the 4th and 5th, 

 and 5th and 6th lumbar transverse processes, and between the last 

 Of these processes and the base of the sacrum. On removing them the 

 joints will be found to possess a synovial membrane. In old subjects, 

 however, these joints are generally obliterated by anchylosis. 



Ligaments of the Bodies : — 



The Inferior Common Ligament is a thin stratum of fibres covering 

 the lower face of the vertebral bodies and the intervertebral disc. It 



