BY W. J. S. McKAY. 317 



Ornitiiokhynchus. 



Origin. The teres minor arises by a well developed tendon 

 from a ridge, on the external face of the scapula, which runs from 

 the dorso-anterior border of the glenoid cavity posteriorly and 

 dorsally to meet the glenoid crest at the junction of its unper two- 

 thirds with its ventral one-third. 



Insertion. Running over the excavated area on the 

 external surface of the scapula immediately anterior to the lower 

 part of the glenoid crest, the muscle comes into relation with the 

 capsular ligament, and running posteriorly it is inserted on the 

 posterior border of the ventral aspect of the lesser tuberosity, 

 lying immediately between the sesamoid bone, on which the sub- 

 scapularis is inserted, and the origin of the internal head of the 

 triceps from the proximal end of the posterior face of the humerus. 



Relations. At its origin the muscle is hidden by the infra- 

 spinatus, while the origin of the long head of the triceps is 

 immediately posterior to it. 



Innervation. Echidna et Ornitliorltynchus : from the 

 cord formed from the iv., v., vi. cervical nerves; and in Echidna 

 also from the N. axillaris. 



Westling : idem for Ecliidna. 



Echidna. 



Westling says — "The teres minor is absent as a separate 

 muscle ; and in Echidna and Ornithorhynchus, according to 

 Sabatier, it is quite fused with the infraspinatus." Under the 

 title of subscapularis accessoi'ius (Testut; a description is given of 

 the muscle above described by us as teres minor, and in a note 

 Westling says, "von Fewkes M. teres minor benannt." The 

 innervation is given as from " N. axillaris und ein Nerv, der aus 

 demselben Stamm wie besagter Nerv aber mehr proximal als 

 dieser, entsteht." 



Leche follows Westling, and accordingly states that the teres 

 major is absent in the Monotremes. 

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