72 OSTEOLOGY OF THE HORSE. 



verse processes of the sacrum. — The sacro-sciatic iigaments are 

 broad expansions stretched across the sacro-sciatic notch. They 

 are fixed to the transverse processes of the sacrum and those of 

 the two or three anteriormost bones of the coccyx, and to the pos- 

 terior parts of the ileum and ischium, and also to the tuberosity of 

 the latter bone. Towards the anterior part of the notch, the liga- 

 ment exhibits an oval opening, through which pass the sciatic 

 blood-vessels and nerves. — The obturator ligament is the fibro- 

 membranous expansion stretched like a drum-head across the ob- 

 turator foramen: through its anterior part is a hole for the trans- 

 mission of the obturator artery and vein. — The symphysis pubis 

 is formed by the junction of the two ossa innominata, by means 

 of a fibro-cartilaginous substance adherent to the opposing sur- 

 faces. — The sacro-coccygeal articulation, formed between the 

 sacrum and coccyx, is the same as a common vertebral joint. 



FORE EXTREMITY. 



The shoulder-joint* is formed betweien the head of the 

 humerus and the glenoid cavity of the scapula: their adaptation 

 (as dried bones) appears incomplete, in consequence of the com- 

 paratively disproportionate magnitude of the ball to the socket: 

 this is in some degree compensated for, however, by the project- 

 ing border of the cartilage with which the glenoid cavity is lined. 

 The bones are maintained in apposition by — The capsular mem- 

 brane, which is found very loose when denuded of the surround- 

 ing adherent muscles, bagging about the bones, in order that it 

 may not, in the least, restrain their freedom of motion : it is in- 

 serted around the rough margin of the glenoid cavity, and around 

 the neck of the humerus. Its internal surface is synovial ; its 

 exterior is clothed by firmly adherent muscles, to which the chief 

 strength of the articulation is owing; viz. its outer and anterior 

 parts by the antea and postea spinati ; its inner and posterior 

 parts by the subscapularis and teres minor. 



The elbow-joint* is constituted of the condyles of the hu- 

 merus moving in the concavities upon the superior extremity of 

 the arm-bone, the surfaces of which are covered by cartilage. 

 The joint is maintained by — 1st, The capsular membrane, which 

 is thin, infixed around the condyles, including their cartilaginous 

 surfaces and the hollow behind them, and around the edges of 

 the articulatory parts of the arm-bone ; also to the olecranon pro- 

 cess, to the lateral ligaments, and to the tendinous roots of the 

 flexor muscles of the leg. 2d, The lateral ligaments. 



* These well-understood and familiar appellations are preserved in pre- 

 ference to the adoption of those of a new nomenclature, viz., scapulo-hume- 

 rat, humerO'brachial, &c. articulations. 



