Anatomy. — "The Development of the Shoulder-blade in Man". 

 Bj 0. H. Dijkstra. (Coininiinicaled by Prof. L. Bolk). 



(Communicated at the meeting of March 24, 1923). 



Unlike tiie development of the clavicnla that of tlie scapnla lias 

 received coinpanativeiy little attention. The textbooks of ana(oniy 

 (Cunningham, Gegenbauer, Rauber — Kopsch, Merkei,, Poirier — Charpy, 

 Testut) contain only general notions snch a8 the information tiiat the 

 ossification of the slionlder-blade bogins in the vicinity of thecollnm 

 scapnlae at the end of the second or in the beginning of the third 

 month. Poirier and Charpy speak of an incipient ossification between 

 the 40"' and 50"' day. Bahdeleben reports a periostal ossification (snch 

 as occnrs with the bones of the cranial vault) beside and nnder 

 the spina scapulae at the end of the 10"' week. 



Bryce alone enters into more details in Quains's Elements of Anatomy. 

 According to his description the rudiment of the shoulder-blade is 

 in the 6"' week entirely cartilaginous, proc. acromialis and proc. 

 coracoideus are present, but the spina sca|)ulae is wanting. (Nevertheless 

 Bryce reproduces the diagram of Lewis'), in which a spina is really 

 indicated). In the 8"' week ossification begins with a centre near 

 the collum scapulae, developing into a triangular plate, at whose upper 

 margin the spina appears in the 3"^ month as a low ridge. At birth 

 coracoid and acromion, margo verfebralis and the margin of the spina 

 are still made up of cartilage. This description by Bryce agrees fairly 

 well with the one we find in Broman's textbook of Embryology and 

 in that of Keibel and Mali,, in which Bardeen deals with this subject. 

 Broman, like Bryce, states that no spina is to be found at the cartila- 

 ginous scapula. Nonetheless he reproduces the figure of Lewis, in which 

 there is indeed a spina. Kollmann, Schenck, Minot, Parker do not 

 speak of the first development of the shoulder-blade and only dwell 

 on stadia of advanced ossification. In Hehtwig's Entwickelungsgeschichte 

 Braus and also Hertwig himself report a separate centre of ossification 

 in the spina scapulae; according to the latter the spina in the neonatus 

 still consists of cartilage sometimes; according to Kölliker (cpioted 

 by Bade, Arch. f. raikr. Anat. LV) this is even always the case. 



') Am. Journ. Anat. Vol. 1. 1901— '02. 



