CHAPTER II. 



ON THE LIGAMENTS. 



THE bones are variously connected with each other in the con- 

 struction of the skeleton, and the connexion between any two bones 

 constitutes a joint or articulation. If the joint be immovable, the 

 surfaces of the bones are applied in direct contact ; but if motion 

 be intended, the opposing surfaces are expanded, and coated by an 

 elastic substance, named cartilage ; a fluid secreted by a membrane 

 closed on all sides lubricates their surface, and they are firmly held 

 together by means of short bands of glistening fibres, which are 

 called ligaments (ligare, to bind). The study of ligaments is named 

 syndesmology (tfuv together, detfpos, bond), which, with the anatomy 

 of the articulations, forms the subject of the present chapter. 



The forms of articulation met with in the human frame may be 

 considered under three classes : Syriarthrosis, Amphi-arthrosis and 

 Diarthrosis. 



SYNARTHROSIS (tfOv, ag&gutfis articulation) is expressive of the fixed 

 form of joint in which the bones are immovably connected with 

 each other. The kinds of synarthrosis are four in number. 1. 

 Sutura. 2. Harmonia. 3. Schindylesis. 4. Gomphosis. The cha- 

 racters of the three first have been sufficiently explained in the pre- 

 ceding chapter, p. 54. It is here only necessary to state that in the 

 construction of sutures, the substance of the bones is not in imme- 

 diate contact, but it is separated by a layer of membrane which is 

 continuous externally with the pericranium and internally with the 

 dura mater. It is the latter connexion which gives rise to the great 

 difficulty sometimes experienced in tearing the calvarium from the 

 dura mater. Cruveilhier describes this interposed membrane as the 

 sutural cartilage : I never saw any structure in the sutures, which 

 could be regarded as cartilage, and the history of the formation of 

 the cranial bones would seem to point to a different explanation. 

 The fourth, Gomphosis (70^05, a nail) is expressive of the insertion 

 of one bone into another, in the same manner that a nail is fixed 

 into a board ; this is illustrated in the articulation of the teeth with the 

 alveoli of the maxillary bones. 



AMPHI-ARTHROSIS (a/xtpi both, a^utfj?) is a joint intermediate in 

 aptitude for motion between the immovable synarthrosis and the 

 movable diarthrosis. It is constituted by the approximation of sur- 

 faces partly coated with cartilage lined by synovial membrane, and 

 partly connected by the interosseous ligaments, or by the interveri- 



