[ 126 ] [Book IX. 



CHAP. IX. 



THE BONES OF THE SUPERIOR EXTREMITY ? WITH 

 A BRIEF COMPARISON OF THE HUMAN SKELE- 

 TON WITH THAT OF BRUTES. 



Bones of the Humerus. Os Braccbii. A tilrac'.liunt. Bones cf the 

 Hand. Refemblince between the fuperior and inferior Extremi- 

 ties. Campari/on between the Human Skeleton and that of Qua- 

 drupeds. 



TH E fuperior extremity is divided into the hu- 

 merus or fhoulderj the brachium or arm; 

 the antibrachium or fore-arm j and the manus or 

 hand. 



The humerus is compofed of two bones, the fca- 

 pula or fhoulder-blade, and the clavicula or collar- 

 bone. The point where thefe tv/o bones unite is the 

 tpp of the fhoulder. The fcapula is a flat thin bone 

 of a triangular fhape. It is fituated at the upper part 

 of the back, and extends from the firil to about the 

 feventh rib. One of the furfaces of the fcapula, which 

 is concave, is applied to the trunk of the body ; the 

 other, which is convex, and more uneven, is turned 

 outwards ; fo that the form of the bone may be plainly 

 difcerned in the living perfon. The external furface 

 is divided by a projecting ridge of bone, called the 

 fpine of the fcapula, into two parts, the upper of which 

 is much narrower and fmaller than the lower. The fca- 

 pula has three angles, and three fides or margins. Witli 

 refpect to the margins, that which is placed next the 

 fpine is by far the longed, and is therefore fometimes 

 called the bafe of the fcapula ; that which forms the 

 upper part of the bone is nearly horizontal, and is pa- 

 rallel to the fecofid rib, -and is the fhotteft and thinnefl ; 

 i the 



