THE MUSCLES OF THE UPPER EXTREMITY. 133 



odds, the smallest and most delicate muscle of the fore- 

 arm in our present subject. It arises immediately in 

 front of the "greater sigmoid cavity" of the ulna, in 

 intimate relation with the fibres of the anconeus, and 

 from the interosseous membrane close to the head of the 

 radius, and I believe it may even extend to that bone 

 for attachment. Its fibres form a very delicate, straight 

 little muscle, completely hidden from sight by the 

 others that surround it, and which does not exceed 

 three centimetres in length, when it becomes converted 

 into a tendon of absolutely hair-like dimensions. This 

 passes directly to the wrist, parallel and in close connec- 

 tion with the extensor metacarpi radialis longior, to 

 be inserted with it at the base of the first metacarpal, 

 to its palmar side. In its action this little muscle plays 

 the part of a feeble extender of the hand upon the 

 forearm. 



Mivart says that this " muscle may be double and 

 very voluminous, as e.g. in the Chameleon. Even in 

 very near allies of man (the Anthropoid Apes) it ends 

 in two tendons, one going to the trapezium, the other to 

 the metacarpal of the thumb" (Elem. Anat., p. 336). 



Kurzer Mittelhandstrecker. Prechtl, 53. 



Abductor du 'pouce. Gervais et Alix, p. 409 ; Alix, p. 409. 



" Dieser Muskel entspringt, bedeckt vom Ext. imlicis, von den 

 einander zugekehrten Flachen des Radius und der Ulna, und zwar 

 vom proximalen Theile derselben. Hierdurch erhalt der Muskel 

 eigentlich zwei mehr oder weniger getrennte Ursprangskopfe. 

 E'ieselben vereinigen sich zu einer Sehne, die erst die Aussen oder 

 Vordernache des Radius begleitet und dann auf der dorsalen oder 

 Extensorseite von einetn eigenen Bande gehalten, iiber das Os carpi 

 radiale lauft, nm sich schliesslich an dem Vorsprunge des Meta- 

 carpale I. zu inseriren 



" Bei Paradisea, Oriolvs, Corvus nach De Man ebenfalls zweikopfig 

 und zwar ist der radiale kopf der starkere." 



