Limbs : Upper Li ml) 



75 



the middle of which the embryonic " spine " ends (Fig. 58). Sometimes the epiplr 

 does not join the spine by bone, and in such a case the cleaned bone shows a separated 

 acromion : the 1'ne of separation runs as a rule from in front of the angle to the back 

 of the clavicular facet, but may be much further forward, suggesting that the epiphysis 

 has two centres at least for its formation, so that one or both of the pieces so developed 

 may fail to join. 



humrrus 



FIG. 59. The larger drawing is a scheme to show how the dis- 

 position of the fibres of Trapezius accounts for the shape of 

 its marking on the spine. The figure also shows the com- 

 parative attachments of this muscle and Deltoid on the 

 scapula. The small figure is a scheme of the tendinous 

 intersections or slips in the Deltoid at its origin and insertion, 

 with the disposition of the fibres of the muscle ; this only 

 affects the acromial part, on which most strain is thrown. 

 The slips of origin make secondary markings on the acromion. 



Glenoid Cavity (Fig. 57, 4). 



The rim affords attachment all round to the glenoid ligament (B), which is partly 

 continuous above with the origin of the long head of Biceps from the bicipital tubercle : 

 this is really on the base of the coracoid. The rim presents a notch in its upper and 

 front part : this is better marked in the early state of the bone, indicating the junction 

 of the " coracoid " and " scapular " parts of the articular surface, and the part above 

 the notch has a separate centre of ossification. The oval cavity is very shallow, but 



