104 SPECIAL ANATOMY. 



ischii, and with a sickle-shaped extension, falx ligamentosa, from ramus ascendens 

 oss. ischii, by which arises a groove for art., ven., et nerv. pudend. commun., and 

 thus prevents pressure in the sitting posture ; passes obliquely upwards and 

 backwards, and is attached broad to the margin of the sacral, even to the most 

 superior of the coccygeal, pieces; serves for the attachment of the gluto?us 

 maximus. 



b. Minus s. ant. s. spinoso-sacrum, lies before a, springs from spina Ischii, 

 passes inwards and backwards and blends with a; serves for the attachment 

 of the muscles levator ani, coccygeus. From the manner in which the Ligg. 

 ischiad. limit the incisura ischiadicce. below, two foramina arise, of which 



1. The superior, incirura major, large, almost triangular, is in great part 

 closed by the mm. pyriformis et coccygeus, together with areola or uniting tissue, 

 -and allows the passage through it of the Nervi et vasa ischiadica, glutnea et 

 pudenda ; 



2. The inferior, incisura minor, small, between spina et tuber Ischii, for m. 

 obturator internus. Nerv. et vasa pudenda also pass through it. 



118. Connections of the Superior Extremities. 



I. The Shoulder-bones. 

 A. Of the Clavicle with the Sternum, rfrticul. Sterno-clavicularis. 



Arthroclia. The articular surface of the clavicle extends, be- 

 fore and behind, beyond that of the sternum, and the last, inci- 

 sura clavicularis manubrii, likewise inwards and outwards over 

 the clavicle. This bone is also firmly united with the first rib. 



1. Lig. capsulare, round about the circumference of the two articular sur- 

 faces; before loose, therefore on this side displacement is more easy than 

 behind ; contains : an interarticular cartilage with an external loose and an 

 internal synovial capsule, below, connected with the cartilage of the first rib, 

 above and behind, with the clavicula. 



2. Lig. interclaviculare, unites the internal extremity of one clavicle with 

 that of the other, as it passes transversely over the incisura semilunaris manubrii, 

 and indeed, lies rather behind it. 



3. Lig. costo-claviculare s. Rhomboideum, a dense fibrous bundle ; proceeds, 

 obliquely backwards and upwards, from the superior margin of the first rib 

 cartilage to the inferior and sternal end of the davicula. An articular surface 

 for the reception of the clavicula is, generally, present on the first costal 

 cartilage. 



The movements of the shoulder depend upon these articular 

 connections. 



a. Movement of the shoulder upwards. In this the sternal 

 surface of the clavicula glides downwards, upon the articular sur- 

 face of the sternum, the Lig. interclav. is relaxed ; the cartilage 

 of the first rib prevents the escape of the clavicula downwards. 



b. Downwards. The sternal end of the clavicula glides up- 

 wards ; the articular surfaces of the clavicle and first rib are 

 strongly pressed upon one another, whereby the art. subclavia is 

 compressed. 



