DISSECTION OF THE BACK AND THORAX. 135 



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 back- 

 wards 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 con- 

 tinued forwards as the funicixlar portion of the ligamentum nuchfe. 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 

 vertebrae, 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 Ligamenta suhflava, 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 while they are viewed from below. 



Capsular Ligaments of the Transverse Pi-ocesses. — 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 discs. It is con- 

 tinued backwards beneath the sacrum, but it is not traceable as a distinct 

 ligament farther forwards than the 6th dorsal vertebra. 



The Superior Common Ligament lies on the floor of the spinal canal, 

 and must be exposed by the removal of the nexiral arches. It is a 

 riband-like structure adherent to the vertebral bodies, and to the inter- 

 articular ligament of the ribs or to the upper edge of the intervertebral 

 disc. The edges of the ligament are scalloped, the ligament being 

 widest where it passes over the intervertebral discs, and narrowest at 



