CHAPTER II. 



THE LIGAMENTOUS STRUCTURES OF THE FOOT. 



The tissues connecting the bones of the foot are termed liga- 

 ments. The capsular ligaments surround all the bony elements 

 of the joint like a sheath or capsule, and consist of two super- 

 posed layers. 



The external layer is firm and fibrous, and in certain of the 

 joints is exceptionally developed. It may be regarded as a 

 prolongation of a portion of the periosteum from one bone to 

 another. 



The inner or synovial layer is a soft, delicate, and vascular 

 tissue, which clothes the interior of the outer sheath, and is 

 intimately connected with it. This sheath, however, is not con- 

 tinued on to the articular surface of the bone, as was formerly 

 supposed, and, therefore, does not form in itself a closed sack. 

 Its function is to secrete the fluid which lubricates the joint 

 and facilitates movement. This fluid is mucoid and sticky, 

 closely resembling egg-albumen, is of a yellowish-white or 

 yellowish-red colour, and is termed synovia or joint oil. 



The lateral and other ligaments consist of whitish, glistening, 

 fibrous material, and form strong bonds of union, varying in 

 thickness and length, between one bone and another. They 

 possess enormous strength, so that they rarely rupture, the 

 bones into which they are inserted usually breaking more 

 readily than the ligaments. Their points of attachment on the 

 bones are usually rough and uneven. 



The joints we have been considering are known as gingly- 

 moid or hinge-like, and only permit of flexion and extension. 

 Movement is certainly considerable, but only occurs in one 

 plane. Lateral displacement is either impossible or only 

 practicable in a very slight degree. Such articulations may be 

 compared to those of a pocket-knife or of a door. In a gingly- 



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