128 ATLAS AND TEXT-BOOK OF HUMAN ANATOMY. 



Fig. 206. — The female pelvis with its ligaments, seen from behind (f) 

 Fig. 207. — The female pelvis with its ligaments, seen from below (f) 

 Fig. 208. — The male pelvis with its ligaments, seen from in front (f) 

 Fig. 209. — The female pelvis with its ligaments, seen from in front (-f) 

 Fig. 210. — The male pelvis with its ligaments, seen from above (-§) 

 Fig. 211. — The female pelvis with its ligaments, seen from above (f) 



while extensive rotation is impossible, the phalanges and consequently the fingers can be abducted and adducted. The 

 metacarpo-phalangeal articulation of the thumb is a pure hinge joint. 



The digital or inter phalangeal articulations (Fig. 205) are the joints between the individual 

 phalanges of the fingers, the bases forming the articular sockets and the trochlear surfaces con- 

 stituting the articular heads. The articulations are pure hinge joints. Lateral ligaments (Fig. 

 205) at the sides of the capsules prevent any lateral motion, and the articular capsules are roomy. 

 Volar flexion is the only movement of which these joints are capable. 



THE JOINTS AND LIGAMENTS OF THE PELVIC GIRDLE. 



THE PELVIC LIGAMENTS, SYNARTHROSES AND DIARTHROSES. 



The pelvic girdle and its ligaments form the pelvis (Figs. 206 to 211 and 215), which, unlike 

 the shoulder girdle, is complete both anteriorly and posteriorly, the pubic bones being connected 

 anteriorly by a symphysis and the pelvic girdle completed posteriorly by the sacrum, which 

 articulates with the two iliac bones either by joints or half joints. 



The symphysis pubis (Figs. 208 and 209) is a mixed synarthrosis connecting the symphysial 

 surfaces of the two pubic . bones. These surfaces are covered with cartilage and the space 

 between them is filled by a mass, consisting largely of dense connective tissue and partly of fibro- 

 cartilage, which is termed the inter pubic fibrocarlilage. This interpubic tissue is broader in front 

 than behind and its posterior portion frequently contains a space resembling an articular cavity, 

 so that the symphysis is converted into a half joint (amphiarthrosis). 



The symphysis is reinforced by fibers which pass across its upper margin from the pubic 

 spine of one side to that of the other; these fibers are intimately connected with the interpubic 

 fibrocartilage and form the superior pubic ligament (Fig. 210). The lower margin of the sym- 

 physis is reinforced by a more independent structure, the arcuate (inferior pubic) ligament (Figs. 

 206 and 208), which is approximately triangular and rounds off the pubic angle. 



The posterior connection of the pelvic girdle is a paired articulation which is termed the 

 sacroiliac articulation. It occurs between the auricular surface of the sacrum and the •similarly 

 named surface of the ilium, and is an almost immovable joint, a true amphiarthrosis. The 

 rough irregular surfaces of the two bones are scarcely adapted for reciprocal movements, and 

 the strong ligaments surrounding the articulation further insure its immobility. 



In addition to being connected by the auricular surfaces, the innominate bone and the 

 sacrum are also held together by a strong ligament passing between the tuberosities of the two 



