STERNO- CLA VICULAR ARTICULA TION. 



245 



and back part. 



Fm. 167. Vertical section of the symphysis pn 

 Made near its posterior surface. 



The Anterior Pubic Ligament consists of several superimposed layers which 

 pass across the front of the articulation. The superficial fibres pass obliquely 

 from one bone to the other, decussating 



and forming an interlacement with the Hi > al ' me cartila <> e coverin bone - 



fibres of the aponeurosis of the Ex- 

 ternal Oblique and the tendon of the Intermediate fibro-cartilage. 

 1 , mi , Camty at upper 



Kectus muscles. Ihe deep fibres pass 

 transversely across the symphysis, and 

 are blended with the fibro-cartilage. 



The Posterior Pubic Ligament con- 

 sists of a few thin, scattered fibres 

 which unite the two pubic bones pos- 

 teriorly. 



The Superior Pubic Ligament is a 

 band of fibres which connects together 

 the two pubic bones superiorly. 



The Subpubic Ligament is a thick, 

 triangular arch of ligamentous fibres, 

 connecting together the two pubic 

 bones below and forming the upper 

 boundary of the pubic arch. Above, 

 it is blended with the interarticular 



fibro-cartilage ; laterally it is united with the descending rami of the os pubis. 

 Its fibres are closely connected and have an arched direction. 



The Interpubic Disk consists of a disk of cartilage and fibro-cartilage con- 

 necting the surfaces of the pubic bones in front. Each of the two surfaces is 

 covered by a thin layer of hyaline cartilage which is firmly connected to the bone 

 by a series of nipple-like processes which accurately fit within corresponding depres- 

 sions on the osseous surfaces. These opposed cartilaginous surfaces are connected 

 together by an intermediate stratum of fibrous tissue and fibro-cartilage which 

 varies in thickness in different subjects. It often contains a cavity in its centre, 

 probably formed by the softening and absorption of the fibro-cartilage, since it 

 rarely appears before the tenth year of life, and is not lined by synovial membrane. 

 It is larger in the female than in the male, but it is very questionable whether it 

 enlarges, as was formerly supposed, during pregnancy. It is most frequently 

 limited to the upper and back part of the joint, but it occasionally reaches to the 

 front, and may extend the entire length of the cartilage. This cavity may be 

 easily demonstrated by making a vertical section of the symphysis pubis near its 

 posterior surface (Fig. 167). 



The Obturator Ligament is more properly regarded as analogous to the 

 muscular fasciae, with which it will be described. 



ARTICULATIONS OF THE UPPER EXTREMITY. 



The articulations of the upper extremity may be arranged in the following 

 groups : I. Sterno-clavicular articulation. II. Acromio-clavicular articulation. 

 III. Ligaments of the Scapula. IV. Shoulder-joint. V. Elbow-joint. VI. 

 Radio-ulnar articulations. VII. Wrist-joint. VIII. Articulations of the Carpal 

 Bones. IX. Carpo-metacarpal articulations. X. Metacarpo-phalangeal articula- 

 tions. XI. Articulations of the Phalanges. 



I. Sterno-clavicular Articulation (Fig. 168). 



The Sterno-clavicular is regarded by most anatomists as an arthrodial joint, 

 but Cruveilhier considers it to be an articulation by reciprocal reception. Probably 

 the former opinion is the correct one, the varied movement which the joint 

 enjoys being due to the interposition of an interarticular fibro-cartilage between 

 the joint surfaces. The parts entering into its formation are the sternal end of the 



